evaluation of potential boron dilution following … · 2012. 11. 17. · loop flows for clb that...
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THE I~T~A11~1I!Ia SANALSS COMMITTOEE
ANALYSIS COMMITTEE
EVALUATION OF POTENTIAL BORON DILUTION FOLLOWING
SMALL BREAK LOSS-OF-COOLANT ACCIDENTS
FINAL REPORT
FRAMATOME T E C H N 0L0 G I ES
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EVALUATION OF POTENTIAL BORON DILUTION
FOLLOWING
SMALL BREAK LOSS-OF-COOLANT ACCIDENTS
FINAL REPORT
Prepared for:
Entergy Operations, Inc. Duke Energy Corp. Florida Power Corp.
GPU Nuclear Toledo Edison Co.
Prepared by:
Bert M. Dunn Niranjan H. Shah
FRAMATOME TECHNOLOGIES, Inc. 3315 OLD FOREST ROAD
LYNCHBURG, VIRGINIA 24506-0935
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Abstract
Boric acid is a critical component in the reactivity control of pressurized water reactors
generally being necessary to maintain a plant subcritical. In 1995, the B&W Owner's
Group recognized a possible mechanism for the accumulation of low boron concentration
coolant (deborate), potentially complicating recovery from certain small break LOCAs.
The BWOG established a program to quantify concerns and determine prudent procedure
or equipment adjustments.
This report is the final report in a series dealing with the issue of boron dilution. Results
of earlier studies and BWOG actions taken are reviewed. Analytical results, developed
during the past year, on vent valve performance and long-term SBLOCA recovery are
presented.
The potential for rapid core reactivity insertion, by restart or bump of the main coolant
pumps forcing deborate into the core, is shown to be procedurally restricted to safe
conditions. Natural circulation restart is shown to provide insufficient core reactivity
insertion rates, removing concerns over core or plant damage. It is demonstrated that
vent valves remain open and flowing during both system refill and the restart of natural
circulation. Vent valve operation mixes highly borated water with deborate at the
downcomer entrance, again mitigating core reactivity insertion concerns. It is concluded
that: issues regarding deborate accumulation within the reactor coolant system during
small break LOCA are resolved; B&W-designed plants may operate without expectation
of difficulties during SBLOCA recovery.
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Record of Revision
Revision Description Date
00 Original Release 1/2000
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Table of Contents
Page
Abstract iii
Record of Revision iv
Table of Contents v
List of Figures vi
1. Introduction 1
2. Long-Term Cooling Mechanisms and Vent Valve Effects 7
2.1 Description of Long-Term Operational Modes 8
2.2 Analytical Model 10
2.3 Results of Long-Term Cooling RELAP5/MOD2 Simulation 11
2.4 Summary of Results 15
3. Applicability of Analyses 17
4. Conclusions 21
5. References 23
Appendix A-Analysis of RELAP5/MOD2 Simulation of Long-Term Cooling
33
A. 1 Hot Leg Break, No Operator Action 34
A.2 Cold Leg Break at RV Inlet, No Operator Action, Downcomer
Level Simulation Low 38
A.3 Cold Leg Break at RV Inlet, Mid-Level DC Stratification 41
A.4 Cold Leg Break at RV Inlet, Refill with HPV operation 43
A.5 Cold Leg Break at RV Inlet, SG Blowdown after Refill,
High DC Stratification Level 46
A.6 Cold Leg Break at RV Inlet, Operator Intervention (HPV
Opening, SG Blowdown) 50
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List of Figures
Page
1. SBLOCA Loop Noding Arrangement (177 LL Plant) 25
2. SBLOCA Reactor Vessel Noding Arrangement (177 LL Plant) 26
3. Break, Upper Plenum and Steam Generator Temperatures for Hot Leg Break 27
4. System Temperatures for CLB that Did Not Initiate Natural Circulation 28
5. Loop Flows for CLB that Did Not Initiate Natural Circulation 29
6. System Temperatures for CLB that Did Initiate Natural Circulation 30
7. Loop Flows for CLB that Did Initiate Natural Circulation 31
A. 1.1 0.007 ft2 Hot Leg Break-Systems Pressures 55
A. 1.2 0.007 ft2 Hot Leg Break-Intact Loop Collapsed Liquid Levels 56
A. 1.3 0.007 ft2 Hot Leg Break-Broken Loop Collapsed Liquid Levels 57
A. 1.4 0.007 ft2 Hot Leg Break-Steam Generator Heat Transfer 58
A. 1.5 0.007 ft2 Hot Leg Break-Intact Loop SG-side Liquid Temperatures 59
A. 1.6 0.007 ft2 Hot Leg Break-Intact Loop SG OP and Pump Suction Liquid Temperatures 60
A. 1.7 0.007 ft2 Hot Leg Break-Intact Loop Hot Leg Temperatures 61
A. 1.8 0.007 ft2 Hot Leg Break-Broken Loop SG-Side Liquid Temperatures 62
A. 1.9 0.007 ft2 Hot Leg Break-Broken Loop SG OP and Pump Suction Liquid Temperatures 63
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List of Figures-(continued)
Page
A.1.10 0.007 ft2 Hot Leg Break-Broken Loop Hot Leg Temperatures 64
A. 1.11 0.007 ft2 Hot Leg Break-Downcomer Liquid Temperatures Around Nozzle Belt 65
A. 1.12 0.007 ft2 Hot Leg Break-Upper Plenum Subcooling 66
A.l.13 0.007 ft2 Hot Leg Break-Total ECCS and Break Flow 67
A. 1.14 0.007 ft2 Hot Leg Break-Break Flow Temperature 68
A. 1.15 0.007 ft2 Hot Leg Break-Total Vent Valves Flow Rate 69
A. 1.16 0.007 ft2 Hot Leg Break-Vent Valves Flow Quality 70
A. 1.17 0.007 ft2 Hot Leg Break-Vent Valves Flow Temperature 71
A. 1.18 0.007 ft2 Hot Leg Break-Intact Loop SG Outlet and Cold Leg Flow Rates 72
A. 1.19 0.007 ft2 Hot Leg Break-Broken Loop SG Outlet and Cold Leg Flow Rates 73
A. 1.20 0.007 ft2 Hot Leg Break-Intact Loop Hot Leg Flow at U-Bend 74
A.1.21 0.007 ft2 Hot Leg Break-Broken Loop Hot Leg Flow at U-Bend 75
A. 1.22 0.007 ft2 Hot Leg Break-Deborate Accumulation Due to Steam Condensation in SG 76
A. 1.23 0.007 ft2 Hot Leg Break-Lower Plenum and Hot Legs at RV Flow Rates 77
A. 1.24 0.007 ft2 Hot Leg Break-Normalized Core Power Generation 78
A.2.1 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-System Pressures 79
A.2.2 0.007 ftý Cold Leg Break at RV, DC stratification at CL bottom-Intact Loop Collapsed Liquid Levels 80
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List of Figures--(continued)
Page
A.2.3 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Broken Loop Collapsed Liquid Levels 81
A.2.4 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Total Vent-Valves Flow Rate 82
A.2.5 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Vent Valve, Upper Plenum, Upper Head Voiding 83
A.2.6 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Total ECCS and Break Flow 84
A.2.7 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Break Flow Quality 85
A.2.8 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Break Flow Temperature 86
A.2.9 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Intact Loop Cold Leg Flow Rates 87
A.2.10 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Broken Loop Cold Leg Flow Rates 88
A.2.11 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Loop Circulation Flow Rates At Hot Leg U-Bends 89
A.2.12 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Core Inlet Flow 90
A.2.13 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Reactor Vessel Temperature Distribution 91
A.2.14 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Normalized Core Power Generation 92
A.2.15 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom-Deborate Accumulation Due to Steam Condensation in SG 93
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List of Figures-(continued)
Page
A.3.1 0.007 ft 2 Cold Leg Break at RV, DC stratification at CL Centerline-System Pressures 94
A.3.2 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Intact Loop Collapsed Liquid Levels 95
A.3.3 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Broken Loop Collapsed Liquid Levels 96
A.3.4 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Total Vent-Valves Flow Rate 97
A.3.5 0.007 ft 2 Cold Leg Break at RV, DC stratification at CL Centerline-Vent Valve, Upper Plenum, Upper Head Voiding 98
A.3.6 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Total ECCS and Break Flow 99
A.3.7 0.007 ft 2 Cold Leg Break at RV, DC stratification at CL Centerline-Break Flow Quality 100
A.3.8 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Break Flow Temperature 101
A.3.9 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Intact Loop Cold Leg Flow Rates 102
A.3. 10 0.007 ft 2 Cold Leg Break at RV, DC stratification at CL Centerline-Broken Loop Cold Leg Flow Rates 103
A.3.11 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Loop Circulation Flow Rates 104
A.3.12 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Core Inlet Flow 105
A.3.13 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Reactor Vessel Temperature Distribution 106
A.3.14 0.007 ft 2 Cold Leg Break at RV, DC stratification at CL Centerline-Normalized Core Power Generation 107
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List of Figures--(continued)
Page
A.3.15 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline-Deborate Accumulation Due to Steam Condensation in SG 108
A.4.1 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open At 1 Ohr)-System Pressures 109
A.4.2 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 10hr)-Intact Loop Collapsed Liquid Levels 110
A.4.3 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Broken Loop Collapsed Liquid Levels 111
A.4.4 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)--Total Vent-Valves Flow Rate 112
A.4.5 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Vent Valve, Upper Plenum, Upper Head Voiding 113
A.4.6 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 10hr)-Total ECCS and Break Flow 114
A.4.7 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Break Flow Quality 115
A.4.8 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Break Flow Temperature 116
A.4.9 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Intact Loop Cold Leg Flow Rates 117
A.4.10 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Broken Loop Cold Leg Flow Rates 118
A.4.11 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Loop Circulation Flow Rates 119
A.4.12 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Core Inlet Flow 120
A.4.13 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Reactor Vessel Temperature Distribution 121
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List of Fizures-(continued)
Page
A.4.14 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 10hr)-Normalized Core Power Generation 122
A.4.15 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs open at 1 Ohr)-Deborate Accumulation Due to Steam Condensation in SG 123
A.5.1 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -System Pressures 124
A.5.2 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Intact Loop Collapsed Liquid Levels 125
A.5.3 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Broken Loop Collapsed Liquid Levels 126
A.5.4 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Total Vent-Valves Flow Rate 127
A.5.5 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Vent Valve, Upper Plenum, Upper Head Voiding 128
A.5.6 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Total ECCS and Break Flow 129
A.5.7 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Break Flow Quality 130
A.5.8 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Break Flow Temperature 131
A.5.9 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Intact Loop Cold Leg Flow Rates 132
A.5.10 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Broken Loop Cold Leg Flow Rates 133
A.5.11 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Loop Circulation and Vent-Valve Flow Rates 134
A.5.12 0.007 ft2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Core Inlet Flow 135
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List of Figures-(continued)
Page
A.5.13 0.007 ft 2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Reactor Vessel Temperature Distribution 136
A.5.14 0.007 ft 2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Normalized Core Power Generation 137
A.5.15 0.007 ft 2 Cold Leg Break, Late Operator Action (at 25hr 20m) -Deborate Accumulation Due to Steam Condensation in SG 138
A.5.16 0.007 ft 2 Cold Leg Break, Late Operator Action (at 25hr 20m) -RV Upper Plenum to SG-Secondary Delta-T 139
A.6.1 0.007 ft 2 Cold Leg Break, Early Operator Actions -System Pressures 140
A.6.2 0.007 ft2 Cold Leg Break, Early Operator Actions -Intact Loop Collapsed Liquid Levels 141
A.6.3 0.007 ft 2 Cold Leg Break, Early Operator Actions -Broken Loop Collapsed Liquid Levels 142
A.6.4 0.007 ft2 Cold Leg Break, Early Operator Actions -Total Vent-Valves Flow Rate 143
A.6.5 0.007 ft2 Cold Leg Break, Early Operator Actions -Vent Valve, Upper Plenum, Upper Head Voiding 144
A.6.6 0.007 ft 2 Cold Leg Break, Early Operator Actions -Total ECCS and Break Flow 145
A.6.7 0.007 ft2 Cold Leg Break, Early Operator Actions -Break Flow Quality 146
A.6.8 0.007 ft2 Cold Leg Break, Early Operator Actions -Break Flow Temperature 147
A.6.9 0.007 ft2 Cold Leg Break, Early Operator Actions -Intact Loop Cold Leg Flow Rates 148
A.6.10 0.007 ft2 Cold Leg Break, Early Operator Actions -Broken Loop Cold Leg Flow Rates 149
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List of Figures--(continued)
Page
A.6.11 0.007 ft2 Cold Leg Break, Early Operator Actions -Loop Circulation and Vent-Valve Flow Rates 150
A.6.12 0.007 ft2 Cold Leg Break, Early Operator Actions -Core Inlet Flow 151
A.6.13 0.007 ft2 Cold Leg Break, Early Operator Actions -Reactor Vessel Temperature Distribution 152
A.6.14 0.007 ft2 Cold Leg Break, Early Operator Actions -Normalized Core Power Generation 153
A.6.15 0.007 ft 2 Cold Leg Break, Early Operator Actions -Deborate Accumulation Due to Steam Condensation in SG 154
A.6.16 0.007 ft2 Cold Leg Break, Early Operator Actions -RV Upper Plenum to SG-Secondary Delta-T 155
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1. Introduction
Boric acid is a critical component in the reactivity control of a modem pressurized water reactor (PWR). Except near the end of a fuel cycle, the control rods are not sufficient to maintain the plant in a subcritical condition without the presence of boron. Therefore, events, accidents, or scenarios that postulate the possible removal or depletion of the boron within the reactor coolant system (RCS) have been extensively studied. In 1995, the B&W Owner's Group (BWOG) recognized a possible mechanism for the accumulation of low boron concentration coolant (deborate) within the RCS that was associated with recovery from certain small break loss-of-coolant accidents (SBLOCA). Since that time, the BWOG has conducted a comprehensive program to evaluate the inherent SBLOCA boron dilution event. Because the goals were to quantify related concerns and determine what adjustments to plant procedures or equipment might be prudent, the evaluations were carried similar to risk determinations using realistic or best estimate assumptions. Most important of these are the use of a realistic decay heat correlation similar to the ANS 1979 standard and the use of full ECCS injection capabilities. This report is the final report in a series dealing with the issue. The report reviews the results of earlier studies and actions taken by the BWOG, presents analytical results on vent valve performance and long-term recovery obtained over the last year, and
summarizes the results and conclusions of the entire program.
The possibility of adverse consequences from an inherent boron dilution event was documented by Framatome Technologies Incorporated (FTI) in 1995 as PSC 1-95. The concern relates to the potential effect of the accumulation of stagnant pockets of deborated coolant within the RCS following the occurrence of an SBLOCA. There is a potential for a reactivity transient if that coolant is carried to the reactor core following resumption of either forced flow or natural circulation. During an SBLOCA, a plant may
spend time in the boiler-condenser mode of operation, with water being boiled in the core and steam being condensed in the steam generator. Because boron is not readily volatile, this process concentrates boron in the core region and accumulates essentially boron-free water, deborate, in the steam generator and pump suction piping. As long as there is no
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bulk flow in the reactor coolant system, there is no concern for core criticality because
the core fluid, concentrated in boron, does not leave the core. However, if a bulk flow
initiates, by restart of a reactor coolant pump or by restart of natural circulation, the core
and steam generator fluid would exchange places. If, when the flow is induced, there is
little or no mixing between the fluid regions (an extremely conservative assumption), the
displacement of borated core water by deborated water has the potential to lead to a
substantial positive reactivity insertion.
In January 1996 the BWOG released Reference 1, a preliminary report of findings on
PSC 1-95. The report focused on the identification of possible scenarios and the
establishment and reporting of basic phenomena. The volatility of boric acid was found
sufficiently low that condensate formed from boiled RCS coolant would contain low
boron concentrations. In conjunction with the report a survey of the world industry
experience and opinion on the inherent dilution event was obtained. Concerns were
organized around two differing methods of restarting bulk circulation of water within the
RCS, RC pump restart or initiation of natural circulation. Of these two, the restart of
natural circulation, because it would occur slowly and involve substantial system mixing
opportunities, was considered significantly less problematic than the restart of the reactor
coolant pumps. In fact, the predominant industry opinion was that the restart of natural
circulation was not of concern.
In September of 1996, the BWOG issued guidance on the acceptable conditions for the
restart of reactor coolant pumps. In essence, the guidance delays the starting or bumping
of a RC pump until the boron distribution within the RCS is known sufficiently to assure
that no criticality issue would ensue from a pump start. As an example, if the plant is in
natural circulation with sufficient core exit subcooling and no core criticality transient has
occurred, the boron distribution in the plant is sufficient to prevent criticality transients.
The guidance, underlying studies, and utility implementation programs were documented
in 1998 in References 2 and 3.
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Following this, the BWOG turned its attention to the determination of the result of a
system refill followed by an initiation of natural circulation. Integral system experiments,
which had achieved a refill and resumption of natural circulation, were investigated but
found to be somewhat limited in the range of conditions simulated. The results available
did support a conclusion that a restart of natural circulation would involve sufficient
system mixing of borated and deborated coolant to prevent a core criticality. However,
because the system behaviors during these experiments could not be proven to bound
possible plant behaviors, further analytical investigations were necessary. In Reference
2, the BWOG released the results of the first of these studies as a status report. The
report concluded that analysis of the restart of natural circulation based on reasonable
mixing assumptions showed a substantial increase in the boron concentration of the
coolant entering the core. Although, a worst case deficit of about 300 ppm in boric acid
concentration remained, several analytical conservatisms embodied in the analytical
approach used were identified that would offset the deficit. The report concluded that it
was unlikely that a restart of natural circulation would result in a reactivity insertion
sufficient to raise the plant to a critical condition and even more unlikely that a prompt
criticality would result. The report, however, did not contain a determination of risk for
the event.
In September of 1998, the BWOG produced a report, Reference 3, based on the
evaluation approach documented in the June 1998 report, which contained the event
frequency for restart of natural circulation and consequence information necessary to
evaluate risk. No actual risk evaluation was included. Rather, the probability and
frequency of the events and conditions necessary to restart natural circulation following a
SBLOCA were determined. In addition a consequence evaluation, a calculation of the
outcome of a restart of natural circulation with a boron deficiency of up to 300 ppm, was
performed. This calculation showed that the plant would experience a rapid power
increase but one that was slower and more controlled then the classic rod ejection
accident. After an initial prompt critical condition suppressed primarily by Doppler
feedback, core reactivity was held to a supercritical condition, about 0.3 $, through the
combination of slow reactivity insertion being compensated by both Doppler and
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Moderator feedback. The peak enthalpy for the fuel was limited to less than 90 cal/gram
with the increase spanning at least 15 seconds. Such a result indicates no instance of
cladding failure and thus no adverse consequence for the event. Finally, Reference 3
identified several additional conservatisms that could be incorporated into the analysis
procedure. These conservatisms were evaluated as sufficient to prevent any criticality
excursion whatsoever by a factor of more than two. The September, 1998 report
concluded, therefore, that the possibility of a criticality incident during recovery from
SBLOCA was extremely small and that even if one were to occur it would be limited and
pose no threat to the continued recovery of the plant.
To further establish the conclusions reached in the Reference 3, the BWOG initiated
analyses to quantify the effect of vent valve operation on the downcomer boric acid
concentration during natural circulation restart. The largest, unevaluated conservatism
embodied in the September, 1998 consequence analysis, was the assumption that the vent
valves closed upon the initiation of circulation flow toward the reactor vessel. It has been
demonstrated in several analyses, Reference 3 included, that the vent valves will allow
single- or two-phase fluid to circulate between the core and downcomer under any
condition for which an RCS refill is imminent. Such a circulation mixes borated core
coolant with the downcomer coolant and assures that both the core and downcomer are
sufficiently borated. During fully developed natural circulation as might follow a
SBLOCA recovery, the vent valves will be closed because insufficient pressure drop
between the upper plenum and the downcomer exists. However, the vent valves will
close as a function of the development of natural circulation. If the valves are open while
the deborate is passing the vessel inlet, they will borate the incoming coolant sufficiently
to prevent a criticality concern.
The main purpose of this report, in addition to the summary of previous studies, is to
document the results of the BWOG evaluation of system and vent valve performance
during long-term SBLOCA recovery. The results of these studies show:
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1. That the vent valves are open, passing liquid, and promoting vessel mixing
throughout system refill,
2. That, when the system does not evolve to natural circulation post refill, the vent
valves remain open to promote vessel mixing and the loop flows are small such
that high pressure injection (HPI) boration is very effective, and
3. That, when the system does evolve to natural circulation, the initial loop
circulation flows remain small enough that the HPI provides a substantial increase
in boron concentration and the vent valves remain open more than twice as long
as required to borate the coolant entering the downcomer.
Therefore, the core boron deficit modeled in the September, 1998 report, Reference 3,
does not exist and natural circulation may be restarted following SBLOCA without
concern.
In conclusion, the concerns over the buildup of low boron concentration coolant within
the RCS during a SBLOCA have been resolved through a combination of improved
plant-operating instructions and analysis to demonstrate plant safety. Coolant of low
boron concentration can accumulate within the RCS pump suction piping during certain
SBLOCAs. Although the size range of these events is limited, the probability of
accidents in this size range cannot be eliminated. The consequences of a rapid insertion
of significant deborate into the core, three to five times faster than natural circulation,
remains undefined but may comprise a significant hazard to safe plant operation. The
only potential means of achieving such an insertion, restart or bump of RC pumps, has
been procedurally restricted, allowing pump activity only when plant conditions will not
induce core criticality. The restart of natural circulation has been shown to involve
sufficiently slow reactivity insertion rates to remove concern over core damage and plant
safety. Further, as documented herein, vent valve operation mixes high boration coolant
with deborate at the downcomer entrance, eliminating concerns over this method of plant
recovery. If the long-term cooldown of the plant evolves to single-pass cooling, the
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deborate is either flushed directly from the system or passed benignly to the core with the
vent valves in operation. Therefore, the concerns of deborate pockets building within the
RCS have been resolved and plants may operate without expectation of difficulties during
SBLOCA recovery.
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2. Long-Term Cooling Mechanisms and Vent Valve Effects
Reference 3 presented an analysis of the restart of natural circulation based on the
following scenario:
1. An SBLOCA of concern occurs and proceeds through to initial equilibrium.
2. As decay heat drops, break quality drops and the system depressurizes.
3. Eventually leak discharge quality is low enough to commence an RCS refill.
4. Refill of the cold legs raises the downcomer and upper plenum water levels initiating
two-phase vent valve flow.
5. Plant refill continues, flow from the core through the vent valves borates the
downcomer and pump discharge piping.
6. Hot downcomer liquid is pushed over cold ECCS flow to fill cold legs and steam
generators.
7. Hot legs fill from the core.
8. Deborate is pushed back into the steam generators until liquid spills over the hot leg
U-bend.
9. Fully developed natural circulation initiates instantaneously and the reactor vessel
vent valves close and remain closed.
10. Deborate flows to the core, mixing in the steam generator outlet plenum, the cold
legs, the downcomer, and the reactor vessel lower plenum.
The resultant calculations showed a core inlet boron concentration that peaked in severity
some 300 ppm below the concentration required to maintain the core subcritical.
Therefore, the calculations in Reference 3 involved the occurrence of a prompt critical
condition. Included in the report, however, was a listing of the conservatisms embodied
in the analytical approach that if included would preclude a prompt critical occurrence.
Step nine, instantaneous initiation of full natural circulation flow and vent valve closure,
is the most significant of these. Had the vent valves been accurately modeled, they
would have remained open during the restart of natural circulation, mixing core liquids
with the coolant entering the downcomer from the cold legs. Because core liquid is
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highly borated, this provides a significant additional process by which the boron
concentration of the deborate can be increased. This section documents the results of the
BWOG studies on SBLOCA long-term cooling mechanisms and vent valve performance.
The results of these studies show that the vent valves are open and allow flow throughout
system refill, that they stay open when the system does not evolve to natural circulation
(single-pass cooling), and that if natural circulation initiates the valves are open more
than twice as long as required for the deborate to enter the downcomer.
2.1 Description of Long-Term Operational Modes
The SBLOCA transients of concern for inherent boron dilution issues are those with
break areas large enough to evolve past natural circulation to boiler-condenser operation
yet small enough to remain there for some time. These breaks establish an initial quasi
steady condition with two-phase flow at the break. Energy is transported from the core to
the break via liquid and steam. Relatively cold liquid enters the vessel from the cold leg
where it mixes with and condenses any vent valve steam flow. The coolant is then
transported down the downcomer and into the core where it is heated, and some portion is
boiled. The fluid then passes to the upper plenum and via the hot leg nozzles or the vent
valves to the break. In either case, the break passes liquid and steam in quantities that
maintain an approximate system mass and energy balance for this first post condensation
quasi-equilibrium condition.
As the decay heat drops, the evolution will be toward lower system pressures, decreasing
break flow quality, and increases in system average levels. With time, the system can
reject decay heat as liquid-only break flow. At this point, the break fluid will start to
become subcooled, and it will be possible for a system refill to occur. The rate of refill
will be controlled by the imbalance between the injection flow (ECCS) and leak flow
rates and the ability of the RCS to condense or vent the steam trapped above the break.
As a refill of the system is attempted, there will be a manometric balance between the hot
leg levels and the levels in the primary side of the steam generators. This requires liquid
flow from the reactor vessel or pump discharge piping over the pump to the pump suction
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piping. The liquid level in the pump discharge piping is, therefore, above the pump
overflow, and the downcomer level will be at or above the top of the inlet nozzle. A
water level this high in the downcomer ensures that the vent valves are in a liquid flow
condition and that inner vessel circulation is active. (References 2 and 3 discuss this
point in more detail.)
The rate of system refill is controlled by the ability to clear the steam space above the
break. During the first phase of refill this can be accomplished via condensation in the
steam generators, opening of the RCS high point vents, or slowly by condensation and
heat release through the primary piping. For the final stage of refill it is likely that only
the high point vents or condensation on the RCS piping walls are credible. Which of
these finishing mechanisms is effective depends on the specific actions taken by plant
operators. If the high point vents are utilized, the refill can be expected within the first 22
hours following the accident. If only heat transfer through the piping walls is available it
is probable that refill will occur at times beyond one day.
Post refill the plant takes on one of two modes. If a system energy balance can be
achieved with an upper plenum temperature below the saturation temperature of the
steam generators, the simulation evolves to a direct cooling mode with relatively stagnant
loop flows. In this mode coolant enters the RCS relatively cold, is heated directly from
the core or by inner-vessel circulation through the vent valves, and flows out the break.
Nearly all of the system energy loss is via the break. The steam generator is either
removing very little energy or, most likely, acting as an energy supply. Some small loop
flows are possible in either the forward or backward direction but their magnitude is on
the order of the ECCS and break flows. This mode is termed single-pass cooling. If
system energy flow can not be accommodated by the break without the upper plenum
temperature exceeding the steam generator saturation temperature, the plant stabilizes
with flowing loops. This mode is termed natural circulation because some of the system
energy is being relieved through the steam generators. Water is injected by the ECCS
systems, heated in the core, and flows both to the break and around the loops to the steam
generators. Either one or both generators may be involved. Inner vessel circulation
9
47-5006624-00
continues only so long as a temperature difference between the downcomer and the core outlet of more than 40 F can be maintained. Because a substantial amount of loop circulation and energy rejection can be supported by a loop temperature differential of 40 F or less, it is unlikely that inner vessel circulation is maintained after natural circulation fully develops. Loop flows are substantially above the magnitude of the ECCS or break
flows.
2.2 Analytical Model
It has been demonstrated in several analyses, Reference 3 included, that the vent valves will allow single or two-phase fluid to circulate between the core and downcomer under the conditions necessary for an imminent RCS refill. Such a circulation mixes borated core coolant with the downcomer coolant and assures that both the core and downcomer are sufficiently borated. It can also be shown that the vent valves are closed under conditions of low power fully developed natural circulation. Under such conditions there is simply not enough differential pressure across the vent valves to hold them open. In fact the vent valves close during the natural circulation restart transient as a function of the developing circulation. To determine the timing of these events, the RELAP5/MOD2 simulations used to determine buildup of deborate within the RCS in Reference 3 were extended to simulate plant refill and the establishment of a stable long-term cooling. The RELAP5 model was based on the RELAP5 SBLOCA lowered-loop evaluation model inputs, Figures 1 and 2, with some notable exceptions. The evaluations being conducted herein are to determine realistic expectations for plant behavior. Therefore, the decay heat correlation was adjusted to best estimate levels and the ECCS was modeled at its full capability. Further details of the model are provided in Appendix A. A model of the lowered-loop plant was selected over the Davis-Besse design because the raised-loop embodies a smaller volume within which deborate can accumulate and would, therefore, experience less severe deborate induced transients. As will be discussed in Section 3, the results obtained bound the Davis-Besse plant and can be applied directly albeit with some
added conservatism.
10
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2.3 Results of Long-Term Cooling RELAP5/MOD2 Simulation
For the long-term cooling studies, six RELAP5/MOD2 calculations, one hot leg break
and five cold leg breaks, were conducted. Because the primary goal of these studies was
to determine the nature and timing of system evolution once a system refill occurred, the
RELAP5 modeling was adjusted individually within the runs to enhance certain physical
phenomena. An example of this is the placement of the high pressure injection (HPI)
location in the highest control volume of the pump discharge piping. At this location the
injection is modeled about one and a half feet above its actual position. The alteration
was necessary to facilitate the removal of steam trapped in the RC pump and immediate
pump discharge volumes. Steam trapped in the upper portions of the pump discharge
piping will be readily condensed because of the splash of the HPI stream against the wall
of the RCS pipe as it is injected. RELAP5/MOD2, however, does not have the ability to
simulate this occurrence where it would cross a node boundary. Raising the injection
location slightly accomplishes the proper condensation simulation for the region.
Another example is the cold leg nozzle elevation. RELAP5/MOD2 lacks the ability to
simulate separated liquid-vapor regions within control volumes. For several of the cases
run, this resulted in a suppressed downcomer level because the condensation of steam in
the nozzle belt area required an interface region. With the original modeling, that region
occupied one-half of a cold leg nozzle, excessively limiting the downcomer level. For
the analysis of Section A.5 in Appendix A, the interface level was restricted to the upper
three inches of the cold leg nozzle. These and other special process modeling efforts are
described further in Appendix A along with the results of each simulation.
Case results can be divided into two general categories: those for which loop flow was
relatively stagnant and those resulting in a robust natural circulation. The differentiating
factor for the two lay in the ability of the steam generators to remove system energy. If a
system energy balance could be achieved with an upper plenum temperature below the
saturation temperature of the steam generators, the simulation evolves to a single-pass
cooling mode with relatively stagnant loop flows. Else wise, the system would reinitiate
a bulk natural circulation of liquid within one or two loops.
11
47-5006624-00
Stagnant Loops - Single-pass Cooling
Figure 3 shows the temperature of the fluid in the upper plenum in comparison with the steam generator saturated temperature for the hot leg break. With the resultant
temperature distribution, there is no need for energy transport to the steam generators, no such transport ensues, and no significant loop circulation initiates. The long-term coolant flow path for this case comprised a split in the net flow at the injection location. Most of the coolant passes through the reactor core to the break but some travels backward in the loop over the hot leg bend to the break. Figures 4 and 5 show the upper plenum
temperature comparisons and the loop flow rate for the cold leg break documented in Section A.5 of Appendix A. This case simulated a late steam generator depressurization
in an effort to induce natural circulation. The results show that the case is close to initiating natural circulation and could possibly achieve circulation had the simulation
continued. Figure 4 shows that, by the end of the run, the intact loop steam generator
temperature has dropped below the upper plenum temperature but the broken loop steam generator temperature remains above the upper plenum temperature. Figure 5 shows that
loop flow may just be initiating within the intact loop at the end of the case. However, a substantial plug of cold water has accumulated within the suction piping and is seriously
retarding the development of circulation. Figure 5 also shows that vent valve flow has
been continuous throughout the simulation.
In addition to vent valve flow a common factor within the stagnant loop results was the presence of inter-cold leg circulation. This type of circulation occurs when the flow of
one cold leg in a single loop is backward and the other is forward. Although inter-cold leg circulation has been observed experimentally, the system conditions necessary for
initiation have not been extensively formulated. One requirement is that no dominant
bulk circulation is present within the loop. A dominant loop circulation washes out the
small imbalances in individual cold leg densities that are the likely precursors to intercold leg circulation. Therefore, inter-cold leg circulation is only present when the loop
flows are essentially stagnant. When occurring, inter-cold leg circulation is significant in
12
47-5006624-00
mixing of cold leg and downcomer fluids and providing a substantial influence on the
coolant temperatures and boron concentrations within the cold leg suction piping and the
steam generator lower plenum.
Deborate control for these cases was provided by direct flow of the deborate to the break
or by continuous vent valve flow in combination with low loop flow rates and boration
via HPI. For the hot leg break, Section A. 1, reverse heat flow in the steam generators
heated the coolant in the primary side of the steam generators such that the generators
filled before the hot legs. This resulted in a reverse flow condition that flushed the
deborate directly to the break. A similar situation happened for some of the cold leg
breaks. Where small positive loop flows resulted, the continued vent valve flow results
in a mixing volume comprised of the reactor vessel outlet plenum, the two horizontal hot
leg sections, the core, the vessel lower plenum/lower head, the downcomer, and the four
pump discharge pipes. This is a volume of approximately 4000 ft3 which is gradually to
be mixed with up to 2000 ft3 of low boron coolant. The loop flows achieved in the
simulations only approach the HPI and break flows. Therefore, the boron concentration
within the coolant after passing the HPI injection location would be, at a minimum, the
average between the HPI (assuming the system has evolved to sump recirulation and
2000 ft3 of deborate has been stored in the RCS A 2400 ppm) concentration and the
deborate concentration (ý 200 ppm from 10 % carry over) or 1300 ppm. If none of the
other loop mixing effects applied in Reference 3 are credited, the mixed mean boron
concentration after vent valve induced mixing is approximately 1850 ppm, substantially
bounding the minimum for criticality concentration of 1500 ppm from Reference 3. If
credit is given for the loop mixing processes described in Reference 3 the minimum core
inlet boron concentration increases further. Thus, the deborate is flushed through the
system and mixed with borated coolant and HPI to the extent that its boron concentration
is increased well beyond concern.
13
47-5006624-00
Significant Flow in Loops - Natural Circulation
If natural circulation develops, the vent valves will eventually close and success at
borating the incoming core flow depends on when that happens. The final case, Section
A.6 of Appendix A, of the six calculations performed initiated an earlier steam generator
depressurization. This case achieved sufficiently low steam generator temperatures near
the time of system refill to induce natural circulation in the RCS. Figure 6 shows the
upper plenum temperature and the steam generator saturation temperatures versus time.
Figure 7 displays the loop and vent valve flows. Loop flow develops slowly and
competes with vent valve flow, gradually decreasing the temperature difference across
the reactor vessel. When the temperature difference is no longer sufficient to hold the
vent valves open, they close and the loop flow increases. The timing of the vent valve
closure is longer than required to mix the deborate. Loop flow is well established and
stable by 20700 seconds, 345 minutes, (flow actually started some 500 seconds, 8
minutes, earlier). By 22200 seconds, 370 minutes, all of the deborate has passed into the
downcomer and mixed with the vent valve flow. Vent valve flow stops at approximately
24600 seconds, 410 minutes. Thus, the vent valves were open more than twice as long as
required to mitigate the maximum accumulation of deborate.
The timing of this transient affirms the theory of vent valve closure timing presented in
Section 6 of Reference 3. At the initiation of circulation the vent valves are open and
flowing because of elevation head imbalances set up across the reactor vessel prior to and
during refill. Until sufficient fluid has been transported from the steam generators and
mixed within the reactor vessel to adjust the vessel temperature distribution, the vent
valves should continue to be open and flowing. Within Reference 3, the integrated fluid
flow required to alter the distribution was estimated at somewhat over twice the
integrated flow required to displace the deborate to the downcomer. The timing
displayed in the accident simulation of Section A.6 shows vent valve closing at just
longer than twice what is required to pass the deborate. The same timing relationship can
be expected throughout the spectrum of possible steam generator cooldown and RCS
refill rates. Although the transient will develop more quickly if the generator cooldown
14
47-5006624-00
rate and RCS refill are accelerated to the limits of the EOP guidance (approximately 100
F/hr or 4 times the rate simulated in Section A.6), effective vent valve induced vessel
mixing can be expected until the deborate is well into the reactor vessel. Because the
loop flows during the restart of circulation are approximately equal to the HPI and break
flows, the estimation of core inlet boron concentration is the same as that for the non
circulating system, 1850 ppm (For the circulating case, however, the estimation is
substantially more accurate.) Therefore, no criticality transient will result from a restart
of natural circulation.
2.4 Summary of Results
The studies documented within this section and in Appendix A demonstrate many
possible long-term cooling end states for plant recovery from SBLOCA. Each state
involves some degree of unique interaction with the deborate and its elimination from the
RCS. Long-term cooling modes can be divided into circulating or non-circulating
systems. Analysis of each case shows that the maximum amount of deborate that can be
accumulated within the system was either removed from the system without consequence
or mixed with highly borated coolant and HPI flow prior to entry into the core.
Therefore, all long-term cooling paths have been demonstrated as safe relative to core
criticality concerns.
15
47-5006624-00
3. Applicability of Analyses
The reference plant for the calculations in this report as well as those in References 2 and
3 is Crystal River, Cycle 11. This is a 24 month cycle and has the highest inherent
reactive of any cycle being run by any of the BWOG lower loop plants. The borated
water storage tank (BWST) concentration, 2500 ppm, is a compromise amongst the
plants and was selected in conjunction with the Crystal River core to achieve an analysis
that would be considered reasonable for any of the plants. These selections coincide with
the desire to determine the risk to the plant of a prompt critical excursion during recovery
from SBLOCA. Other plants within the lower loop category could be expected to have
slightly different results if specifically analyzed. However, none would differ sufficiently
to eliminate the margins identified by the evaluation conducted herein or in References 2
and 3. The Davis-Besse (DB-1) raised loop design, however, differs sufficiently from the
lowered loop design to warrant a deeper consideration of applicability.
A review of the geometric and operational differences between DB- 1 and the reference
model concludes that the lessons learned and phenomena observed for the safe disposal
of the deborate in the analyses of the lowered loop plant can be extended to DB-1. The
important plant differences are (1) initial power level, (2) number of vent valves, (3)
ECCS flow capacities, (4) pump suction side volume differences, (5) relative elevation
differences, and (6) the upper head vent path.
The initial power level for the raised loop plant is about 8% higher than that of the
reference lowered loop plant (2772 MWt versus 2568 MWt). This is expected to result in
a time shift in the blowdown of the system. The time shift would be on the order of that
required to adjust the decay heat downward by about 8 percent. The events that occurred
in the lowered loop plant analyses would occur for DB-l at later times. The following
table shows the equivalent times of the two initial power levels.
17
47-5006624-00
Decay Heat Time, Hours Time, Hours Time Shift, Hours MW Lower Loop Plants Davis Besse (Davis Besse - LLPs)
24.8 5.0 6.5 1.5
20.0 10.0 12.7 2.7
17.6 15.0 19.8 4.8
16.2 20.0 27.2 7.2
15.5 24.0 32.8 8.8
There are only four vent valves in DB- 1 compared to eight valves in the reference plant. This is expected to result in a somewhat reduced total vent valve flow. For the same amount of decay heat, the total vent valve flow (W) is related to the total vent valve area (A) as follows. (WDB/WLL) = (ADB/ALL) 21 11, or WDB = 0. 6 3 *WLL. The predicted vent valve flow is more than 300 lbm/s for the lowered loop plant during natural circulation and before the closure of the vent valves. The corresponding natural circulation flow is about 25 to 50 lbm/s per loop. For the raised loop plant, the expected vent valve flow would be more than 0.63*300, 190 lbm/s. This is still larger than the expected loop natural circulation flow during vent valve operation. Therefore, the mixed boron concentration will remain characteristic of the core concentration and the reduced number of vent valves in the raised loop plant are more than sufficient for safe dispersion and
mixing of the deborate.
The ECCS flow capacities differ among the lowered loop plants and between the lowered loop plants and Davis-Besse. The lowered loop plant analyses were done for a representative Crystal River-3, 2-HPI system. For the representative lowered loop plant, the analyzed break size was 0.007 ft2 and the corresponding quasi-equilibrium condition (break flow and core energy matched by HPIs alone) occurred at a system pressure of about 700 psia. For pressures below 1350 psia, however, the DB-1 raised loop plant has a higher HPI injection rate. For example, the DB-1 HPI would be about 33 to 55 percent more for system pressures between 1000 and 500 psia, respectively. This is expected to result in higher quasi-steady pressures and slightly increased HPI and break flows for the raised loop plant compared to the representative lowered loop plant given the same break
18
47-5006624-00
size. It does not alter the energy and coolant movement pattern within the system, only
the pressure under which that pattern operates. Similar, but much reduced, trends would
also be expected for specific lowered loop plants depending on their ECCS flow versus
pressure characteristics. Therefore, no ECCS related special consideration is deemed
necessary. For events expected to remain in solid natural circulation credit has been
given for operator management of the makeup and purification system for DB-1. The
basis for this assumption is the reality of expected operator performance and is the same
as the lowered loop plant assumption that the operators will activate the HPI system
within two minutes of the initiation of the event even without an ESFAS signal.
The pump suction piping volume for the raised loop plant is about 200 ft3 less per loop
than that of the lowered loop plants. This will lower the amount of deborate that can
accumulate within the system and lessen its effectiveness in inducing core criticality
issues. Thus, deborate consequence calculations for DB-1 would be expected to have
less severe results than those for the lowered loop design.
One of the measures of the propensity for natural circulation is the relative elevation of
SG secondary set level with respect to core center. For DB- 1, the relative elevation is
about six feet higher than the lowered loop plants. (The relative elevation ratio for the
raised loop design is about 27 percent larger than that of the lowered loop design.) This
will promote additional natural circulation in the Davis-Besse plant. The higher natural
circulation rate would cause an earlier closure of the RV vent valves. However, the time
it takes to buildup natural circulation will remain sufficient to disperse the deborate
before the valves close. From a simple elevation head balance, flow proportional to
square root of height, the 27 percent relative head ratio amounts to (1.27)0.5 = 1.13, or 13
percent more flow for the raised loop plant. The added 13 percent loop flow should not
have a substantial impact on the ability of the vent valve to provide downcomer mixing
for conditions of natural circulation restart.
For the lowered loop plant restart of natural circulation calculations, Section A.6 of
Appendix A, the system flow increased from about 25 lbm/s to about 50 lbm/s in a span
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47-5006624-00
of about 50 minutes after which the vent valves begin to close. It took an additional 15 minutes before the valves were shut closed. Considering 13 percent more flow potential for the raised loop plant, and the loop flow of 50 lbm/s as the threshold for vent valve closure, the time span before the vent valves begin to close would be about 38 minutes [(50/1.13-25)/(50-25)*50]. Add to this the additional time before the valves would actually close, and the time available for deborate mixing remains substantially greater (more than 50 percent) than the 25 minutes required for mixing in the lowered loop plant. Further, as noted earlier, due to geometric differences, less deborate will be collected in the raised loop plant, and the flow of the deborate to the DB-1 core will be 13 percent faster. Both factors, not accounted for here, would shorten the required mixing time. Therefore, adequate time will be available in a raised loop plant before the vent valves
close.
The Davis-Besse plant has a small vent line connecting the reactor vessel upper head and the inlet plenum of one of the steam generators. The vent line will facilitate filling the
reactor vessel, making it somewhat easier for DB-1 to establish liquid vent valve flow during refill. Further, as refill nears completion, loop circulation through the vent line will precede circulation through the hot legs. The result will be a predisposition for DB-1 to initiate full circulation in the vent line loop and an expansion or lengthening of the low flow initial circulation phase. The early circulation, induced by the vent line, provides DB- I with an expanded opportunity for HPI boration and the vent valves to mix and
borate the incoming coolant. Therefore the vent line comprises a small but positive difference in the treatment of the SBLOCA inherent dilution event.
In summary, there are attributes about Davis Besse that increase the consequences of the
deborate event and there are attributes that lessen the consequences. The possible increase in loop flow is balanced by increased HPI flow such that in combination with the 20 percent decrease in stored deborate volume, the likely core inlet concentration is less reactive (higher relative boron concentration) then has been calculated herein for the lowered loop plants. Therefore, the calculational results presented herein and those
developed earlier in the program can be conservatively applied to Davis Besse.
20
47-5006624-00
4. Conclusions
The BWOG has completed a major multi-year effort to evaluate and understand the
potential safety issues associated with inherent boron dilution events. The deboration of
RCS coolant and subsequent movement of that coolant to the core can result in core
recriticality. Best estimate evaluations have been conducted for both RC pump restart
and the restart of natural circulation subsequent to system refill. Of these only the RC
pump restart was found to pose a significant risk to plant safety. Therefore, restart of
forced circulation, by either bumping or starting the reactor coolant pumps, has been
limited to acceptable conditions by changes to the emergency operating procedures.
The range of applicable break sizes and locations has been identified, and the process for
post-LOCA deboration and the resultant conditions prior to a restart of natural circulation
have been described within the program. Calculations have been performed that
conservatively predict the volume of deborated coolant accumulated and track the
progress of the deborate through the system to the reactor core during refill and natural
circulation.
An evaluation of the frequency of a small break LOCA that would lead to a possible
return to critical has been done and the frequency shown to be small. Only a small
fraction of these events have the potential to proceed to core damage. In particular the
frequency of the most probable (2 HPI) case is 8.1 E-6, Reference 3. As noted above,
this has no potential for core damage. The '1 HPI case' has a frequency of 1.1 E-7. This
case has only limited, if any, potential for core damage. The resulting possible overall
change in core damage frequency is therefore below the 1.0 E-6 definition of a "very
small change."
A conservative consequence evaluation of the impact of natural circulation restart has
been conducted and no core damage was predicted. The excursion was self-limiting and
the maximum enthalpy of the fuel limited to less than 90 cal/gram. The resulting fuel
temperature is less than that experienced during normal operating conditions. More
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47-5006624-00
complete calculations, performed to further investigate the role of vent valve flow in long-term cooling, have demonstrated deborate disposition without core criticality. Plant refill without a natural circulation restart leads to removal of the deborate through the
break or slow migration to the core with substantial HPI boration and continuous vent valve flow to facilitate mixing. Refill and subsequent restart of natural circulation,
although leading to faster core penetration, retains substantial time for HPI boration and the vent valves remain open long enough to assure inner vessel mixing with the deborate.
In conclusion, the potential significant scenarios for inherent boron dilution SBLOCA
events have been evaluated. Where potential concerns existed, procedural changes in the emergency operation of the plants have been incorporated to remove the concerns. For
other scenarios, analyses have been conducted to show that core recriticality would not result from plant recovery operations. Therefore, the SBLOCA inherent boron dilution event is acceptably mitigated by all BWOG plants and is not a concern for safe operation
of the facilities.
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5. References
1. 47-1244436-00, Dunn, BM, Preliminary Report to the B&W Owner's Group on
PSC 1-95 Investigations, Framatome Technologies, Lynchburg, Virginia, January
1996.
2. 47-5001748-00, Dunn, BM, Status Report on Return to Criticality Following
Small Break Loss-of-Coolant Accident, Prepared for the B&W Owners Group
Analysis Committee by Framatome Technologies, Framatome Technologies,
Lynchburg, Virginia, June 1998.
3. 77-5002260-00, Dunn, BM, Evaluation of Potential Boron Dilution Following
Small Break Loss-of-Coolant Accidents, Framatome Technologies, Lynchburg,
Virginia, September 1998.
4. NUREG/CR-5395, EPRI/NP-6480, BAW-2061, Volume 3, Multiloop Integral
System Test (MIST): Final Report, Babcock & Wilcox, Nuclear Power Division,
Lynchburg, Virginia, July 1989.
23
FIGURE 1. SBLOCA LOOP NODING ARRANGEMENT (177 LL PLANT).
FIGURE 2.
t,,
SBLOCA REACTOR VESSEL NODING ARRANGEMENT (177 LL PLANT).
B397 399 (RVWS)
3605
D%_ 310 LU Z 367w 50%
S318 =) c 352 _6_ 50% 2PAE 45601 447.00 ~347-00 320 u~
4" 40 ~ 1 OT
FIG 3: I 1 U P a
FIGURE 3 •Break, Upper Plenum and Steam Generator Temperatures for Hot Leg Break
800
700
600
500
400
300
200
1000
Time (hrs)
ooTEM PF-20501 0000 (Break Node Liquid Temperature) SSATTEMP-680010000 (intact Loop SG Secondary Tsat)
S.............. r............ I............. .............. I... 0 - SATTEMP-78001 0000 (Broken Loop SG Secondary Tsat) ----....................................STEM PF-35201 0000 (RV Upper Plenum Liquid Temperature)
---.. -.... ---- --- ----, . . . . . . .... . . . . . .. . . . . . -. . . . . . . . . . . . . .............. -- -- - -- - -----------.- .............. ............. , ............. r ............ -- - - - - - ---- --- --- ---- --- --- - - - -- ,------- --------
.... ............................................. ,----------.---------..-------------------.---.--- - -------------------
- - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -. .... . . . . . . . --- -- -- -
S............ ,. ............. , ................ ... ..... t. ............ ,.............., ............. ............. -- - -- - - --- --- --- -- - --- --- -- -- - -- - - -.. . . . . -- - -- - - ------------- .. .. . .. .. . .. .. .
---- ---- -- ... .... ... .... .... ... .... .... ... .... .... ....... .... ....... .... ....... .... ....... .... ..----- ---- - - ---- ---- -.----- ---- --- ---- ---- --- ---- ---
2 4 6 8 10 12 14
FIGURE 4: System Temperatures for CLB that Did Not Initiate Natural Circulation Break, RV Upper Plenum and Steam Generator Temperatures
800
700
600
•. 500
000
400
300
200
100
- TEMPF-275010000 (Break Node Liquid Temperature) SSATTEMP-68001 0000 (Intact Loop SG Secondary Tsat) 0 " - 0 SATTEM P-78001 0000 (Broken Loop SG Secondary Tsat) ....................................... A- TEMPF-352010000 (RV Upper Plenum Liquid Temperature)
------ L------ ---- -------------------- L--------------.......------------ ------------ ......------------ --------------------
- --..... ---------------------------- ------------ ............. ......... ------------------- T ----------------------
----- ~ ------. . . .. . . . .. . . .. . .. .. . . .... ..........................---- --- --- -- -- --- --- -- --- --- -- -.---- --- -- --- --- ---.---- --- -- ........... ------------.............
------ -- .. . .. .-- --- - - . . . . . . . . . . . --.. . . . .- -.. . . . . -". . . . . . .,. . . . . . .--. . . . ..- -. . . . ..-- -. . . . . . . . . . . . ., . . . . . . .• . . . . . . .
--- .- ----... .- .......-- .......------ ........................... .....-------. ...I ------------L --------. .--------- ...........-- ------------------------------------- ............-----
---. ......... .--------------- ------------. ------ ............-- ------------ ------- ----------........ ............ ------- ------------ ------- ...........
. ,.. .... ---------------- -----... --------.-------...........-----------------.------------- ----.------.......... -- --- ---- --- ---- --- ---- --- ---- ---------- -"- ----............ i i i i i i ii i i ~~~~~~~- .... .... -- -..... --- ...... ..........--.........---...... "--
- -------.---------... ------------- -- ------- -------- ------------- -- -------- --------- - - - - - - - - - - -4 -- - - - - - - - - - - - - -- - - - - - - - - - ---- - - - - - - - - - - - -- - - - - - - - - - - - - -- - - - - - - - - - - - -- - - - - - - . . . . . .
U 2 4 6 8 10 12 14 16
Time (hrs)18 20 22 24 26 28 30
^
i 1 11
I
FIGURE 5: Loop Flows for CLB that Did Not Initiate Natural Circulation Intact Loop U-Bend, Broken Loop U-Bend, and Vent-Valves Flow Rates
450
400
350
300
. 250
S200
0 L4 150
0 2 4 6 8 10 12 14 16 Time (hrs)
18 20 22 24 26 28 30
SIntact Loop Flow at Hot Leg UBend from cvar-459. (filtered and smoothed) - Broken Loop Flow at Hot Leg UBend from cvar-460. (filtered and smoothed)
SVent-Valves Flow from cvar-337. (filtered and smoothed)
-........... -- --.... ........ .. . . .--- ............--.-..---.---- -- U----------- ------------ L... ..... ., ............ I .. .......... - ............ ... ............- . .......................
------ ------------- ------- ------ -, ----- I -------- ------- ------- ------- ------- ------------- ---------
.........................--- - -----,- ------ ---- --- -- ----- --------- --------- --- ... ......... .......
----------------------------- ------------------------------------ --------------- --- ---- --- ---- --- ------------------
100 I1
50 1.
0
-50
FIGURE 6: System Temperatures for CLB that Did Initiate Natural Break, RV Upper Plenum and Steam Generator Temperatures
Circulation
800
700
600
500
o E
400
300
200
1000
G-- TEMPF-275010000 (Break Node Liquid Temperature)
&-- SATTEMP-68001 0000 (Intact Loop SG Secondary Tsat) S---------------------------------------- --- ----- SATTEM P-78001 0000 (Broken Loop SG Secondary Tsat) ----....................................
-- A TEMPF-35201 0000 (RV Upper Plenum Liquid Temperature)
............... ...........-- ........... ...........-- ---- ----- ------- ........... - ----- --- ........... " ...........
f........... ------ ------------------ ........... ------ ---------- -----------...... : .... ...... ,...... ------ ----------- ------ ----------- ---- ----------- ---- ----------
S. .. ..... . ......... . .. -- --- .. .. ..-- ------ --- --- -- -- ---------- --- -- ---- --- -- -- --- --- ---..... ...... -- ---- ----------- ............ :... ........•. . . . . .
.. . . ............. ........ .............
S........... r.......... . . . . . .-- - - - - - - - - - - - -- - - - - - - - - - - - -..... .... -- - -- -..... .... .... .... .... .... .... r-.. .... ...--... .... ..--.... .... . t-..... .... .... .... .-r-.... ....-..... .... .... .... . ---.... ....
I 2 3 4 Time (hrs)
5 6 7 8
I
i
FIGURE 7: Loop Flows for CLB that Did Initiate Natural Circulation Intact Loop U-Bend, Broken Loop U-Bend, and Vent-Valves Flow Rates
600 0Intact Loop Flow at Hot Leg UBend from cvar-459. filtered and smoothed)
+ Broken Loop Flow at Hot Leg UBend from cvar-460. filtered and smoothed) - Vent-Valves Flow from cvar-337. filtered and smoothed) ...........
500 ....... ......... ........... ........... --- ---------------....
S........... r ........... -- -- - - -- - - -- -- - - -........... r........... --- - - - - - -- - -- - --r- - -- - -........... -- -- -- ........... --........--
--- --- -- . .. . .:........ .. .. ............. .. . ........................-- --- - -- -- -- -............ ........ .. ...... - --- --- ----....................
-------------------------------- ------ --------- ----------- r---------- T------
400 -- ----------- -------- --r-------------------------------------------- --------------------------------
300 -------- ..... . ... --------------- ----------- ----------- ----------- ----------- ----------- ----------- -- f-------- .......L......
S. ......... ... ..... ....--------- ------------------ ......................-----------------100
----------.. . ........ -------- -- ...-- --- • - . . .------ ----- ----
0 ---------------.. . .. .... .. . ...-- - - --.-- - -- - -- - -- - - -- - -- - -- - -- - -- - - -- - -- - -- - -- - -- - - -- - -- - -- - -- --.- - -- - -- - -- - -- - -- - - -- - - - - -- - - -
-100 0 1 2 3 4 5 6 7 8
Time (hrs)
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Appendix A
Analysis of RELAP5/MOD2 Simulation of Long-Term Cooling
To determine the transient response and timing of system refill and possible restart of
natural circulation, a series of RELAP5/MOD2 calculations were performed. Of
particular interest was the vent valve performance as it evolved during the establishment
of bulk loop circulation. The RELAP5 runs used to determine buildup of deborate within
the RCS in Reference 3 were extended to simulate plant refill and the establishment of
stable long-term cooling. The model is based on the RELAP5 SBLOCA lowered-loop
evaluation model inputs, Figures 1 and 2, with some notable exceptions. The evaluations
being conducted herein are to determine realistic expectations for plant behavior.
Therefore, the decay heat correlation was adjusted to be best estimate and the ECCS was
modeled at its full capability.
As the cases evolved, it was discovered that further modifications of the model were
necessary. The first of these was the alteration of the HPI injection location to the first
control volume downstream of the RC pump. At this location the injection is modeled
about one and a half feet above its actual position. The alteration was necessary to
facilitate the removal of steam trapped in the RC pump and immediate pump discharge
volumes. Steam trapped in the upper portions of the pump discharge piping will be
readily condensed because of the splash of the HPI stream against the wall of the RCS
pipe as it is injected. RELAP5/MOD2, however, does not have the ability to simulate
this occurrence where it would cross a node boundary. Raising the injection location
slightly accomplishes the proper condensation simulation for the region. Additional
model changes are described on a case-by-case basis. As described in the main, report
the model, although specifically for a lowered loop plant, produced results that bound the
Davis-Besse plant and can be applied directly with some degree of conservatism.
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The cases analyzed comprise a hot leg break and five cold leg breaks. All breaks were
0.007 ft2 in area. Progressive model improvements and more aggressive operator
accident management were inserted into the simulations on a case by case basis. The first
four cases did not induce bulk circulation within the RCS. In some of these, a complete
refill was not achieved. Only the last combination of these, subsection A.6, was
sufficiently aggressive to induce natural circulation.
A.1 Hot Leg Break, No Operator Action
Case Description and Phenomena:
A 0.007 ft2 hot leg break at the 35-foot elevation was simulated with no operator action.
The choice of break elevation, about eight feet above the pressurizer surge line but on the
opposing loop, was arbitrary with a view to achieving a simple transient advancement.
The simulation successfully executed through system refill and subsequent loop
circulation. Refill took almost ten hours on the steam generator sides and about eleven
hours on the hot leg sides. Refill was achieved without high point vents. Break flow was
subcooled during refill and the vent valves were open with a slowly decaying flow of
over 100 lbm/s. Sustained inter-cold leg circulation was evident during refill, as was a
substantial subcooling of the pump suction piping. As a result of strong cold leg
subcooling and reverse steam generator heat transfer, the steam generators filled faster
than the hot legs and established a final RCS flow pattern with net flow through both the
steam generators and the core to the break. For the conditions achieved, the deborate
would not challenge core criticality because the backward flow in the generator swept
most of it directly to the break. The reverse loop flow averaged about 17.5 Ibm/s/loop
over the first 40 minutes after refill, sufficient for all accumulated deborate to be
displaced to the break. It is apparent that the homogeneous modeling of RELAP5/MOD2
accelerated condensation in the upper plant regions beyond what could be reasonably
expected and shortened refill. However, the refill time remained within that achievable
through high point vent operation and the conditions for high point vent opening were
demonstrated. Therefore, the refill process and timing are reasonably modeled.
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Parametric Histories and Discussion of Results:
Figure A. 1.1 is a plot of system pressures. The primary pressure stabilized around 700
psia during refill while the secondary pressures steadily decreased due to sustained net
reverse heat transfer in the steam generators. The secondary side pressures were stable at
about 110 psia in the intact loop steam generator and about 50 psia in the broken loop
steam generator.
Figures A. 1.2 and A. 1.3 show the intact loop and broken loop refills. The steam
generator side refill time was about 10 hours and the hot leg side refill time was about 11
hours. The steam generator sides refilled faster than the hot leg sides because the steam
generator side liquid temperatures were hotter (due to reverse steam generator heat
transfer) than at comparable elevations on the hot leg sides. The steam generator heat
transfer plot is shown in Figure A. 1.4. Primary side liquid temperature distributions for
the steam generator side, pump suction piping, and hot leg side of the intact loop are
given in Figures A.1.5, A.1.6, and A.1.7, respectively. Similar plots for the broken loop
are given in Figures A.1.8, A.1.9, and A.1.10, respectively. Liquid temperatures in the
cold legs at the reactor vessel and downcomer, and lower and upper plenums are shown
in Figures A. 1.11 and A. 1.12, respectively. These temperature distributions show that
steam generator side liquid temperatures are hotter than corresponding elevation
temperatures in the cold legs and hot legs. Figure A. 1.12 also demonstrates the condition
for high point vent opening, should it be needed, as the upper plenum subcooling was in
excess of 100 F after about two hours into the transient.
Figures A. 1.13 and A. 1.14 show total ECCS and break flows, and break flow
temperature, respectively. The break flow became subcooled shortly before 2 hours. At
11 hours, the break and the ECCS injection flows equilibrated, setting up a quasi
equilibrium condition.
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Figures A. 1.15, A. 1.16, and A. 1.17, respectively, show total vent valve flow, quality, and liquid temperature. The vent valve flow during refill is subcooled, gradually decreasing
from 350 to about 150 lbm/s.
Figures A. 1.18 and A. 1.19 show steam generator plenum and cold leg flows for the intact
loop and the broken loop, respectively. Inter-cold leg flow circulation, meaning flow in
one leg being in the opposite direction of the flow in the other leg of the same loop, is evident. The steam generator refill flow is small in comparison to the cold leg circulation flows. Due to the slow refill rates and reverse steam generator heat transfer, the steam generator side liquid temperature column remains relatively hotter than the cold leg and hot leg side temperatures. Upon refill of the steam generator sides of the loops, there was a switch in the direction of the inter-cold leg circulation in the broken loop; the direction
of inter-cold leg circulation in the intact loop did not change. However, both loops changed flow direction frequently once the hot leg side refilled. Although inter-cold leg circulation behavior is not well understood at this time, it is important to note that any
such circulation would gradually remove the suction side deborate to the reactor vessel
which is highly borated.
Figures A. 1.20 and A. 1.21 show the intact loop and the broken loop flows over the hot
leg U-bends. A noticeable reverse flow of about 10 Ibm/s began after the steam generator
sides were filled. This occurred shortly after 10.5 hours. Significant reverse flow started after the hot legs were filled at around 11 hours. The flow increased from about 10 lbm/s to an average high of about 70 ibm/s and then dropped to an average of 10 Ibm/s within 10 to 15 minutes. Roughly estimated, the total back flow was about 10*30*60 = 18000 Ibm/loop before 11 hours and 0.5*(l0+70)*10*60 = 24,000 Ibm/loop in the next 10
minutes, giving a total of 42,000 Ibm/loop. This displaces the accumulated deborate,
about 40,000 Ibm/loop as shown in Figure A. 1.22, to the hot leg and the break. The
reverse flow, thereafter, should bring in highly borated water to the hot legs.
Figure A. 1.23 shows the flow in the lower plenum and in each of the hot leg pipes near
the reactor vessel. The intact loop, shortly after refill at 10.5 hours, was negative
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indicating flushing of the deborate to the upper plenum. The lower plenum flow during
the same period was positive indicating no net flow of the upper plenum deborate to the
core except through the downcomer via the vent valves. The broken loop hot leg flow
from the vessel was in the positive direction indicating flushing of the upper plenum
deborate to the break. The deborate coming from the broken side U-bend goes out the
break. In short, the backward flow in the generators would sweep most of the deborate
directly or indirectly to the break. The deborate that found its way to the upper plenum
would mix there and some could flow down the baffle region and then cross-flow to the
core. However, due to subcooled core conditions, baffle flow would be small. The
combination of the mixing of the deborate in the upper plenum before entering the baffle
region and the small cross-flow that carries it to the core is not expected to challenge core
criticality.
Figure A. 1.24 is a plot of normalized core decay heat. It shows that the core power was
about 0.75 percent of the initial power at the time of refill.
Key Results and Observations:
"* Loop flows after refill were small with no bulk circulation.
"* Break flow was subcooled and the vent-valves were open throughout the
simulation, both during and after refill.
"* Sustained inter-cold leg circulation was evident throughout the simulation.
" Core criticality was not challenged because the deborate was vented directly
to the break.
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A.2 Cold Leg Break at RV Inlet, No Operator Action, Downcomer Level Simulation
Low
Case Description and Phenomena:
The case input was modified to shift the break location to the pump discharge piping at
the reactor vessel inlet. As in the hot leg break, no operator action was simulated. The
downcomer cold leg piping elevations from the SBLOCA evaluation model were
preserved for this case. Those elevations cause RELAP5/MOD2 to simulate the
downcomer liquid level at approximately the elevation of the bottom of the cold leg piping. This is acceptable, even desirable for EM calculations, but it does limit the ability
of the model to achieve a proper simulation of a system refill calculation. Later cases
made adjustments to the model to raise the downcomer level. The simulation executed
beyond system refill. It took almost 20 hours to fill the hot legs. The steam generator
primary side filled only to within four feet of the hot leg U-bend. The loop flow after
refill was small, about 2 to 7 lbm/s in the normal direction. Break flow was subcooled
through out the simulation. The vent valves were open and the flow was highly voided
with a slow flow rate of about 15 Ibm/s. The core continued steaming during and after
refill resulting in two-phase vent valve flow and saturated hot leg temperatures.
Therefore, the hot legs were refilled and the steam generator sides were not. Sustained
inter-cold leg circulation was evident during refill, as was a substantial subcooling of the
pump suction piping. For the conditions achieved, the deborate would not challenge core
criticality due to the low loop flow rates and inter-cold leg circulation.
Noteworthy for this case is that substantial flow chattering was observed in the system.
The chattering at the core inlet resulted in the heating of the lower plenum water and
energy transfer propagated up the downcomer. This resulted from the lower downcomer
level modeling and is considered an atypical plant response. The next case partially
revised the elevation modeling and achieved results that are more realistic.
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Parametric Histories and Discussion of Results:
System pressures are shown in Figure A.2.1. The primary pressure stabilized around 680
psia during and after refill, while secondary pressure steadily decreased due to a sustained
net reverse heat transfer in steam generators. The secondary side pressures stabilized
around 200 psia.
Figures A.2.2 and A.2.3 show the intact loop and broken loop refills. The hot legs
refilled in about 20 hours and the steam generator sides did not refill. The hot leg refilled
rather than the steam generator sides because of a core steaming that kept the hot leg
temperatures warmer than those at the corresponding steam generator level. Figures
A.2.4 and A.2.5, respectively, show total vent valve flow, vent valve quality, and vent
valve and upper plenum void fractions. The plots show that the upper plenum and vent
valve flows remain two-phase during refill. The vent valve flow gradually decreased
during refill and was about 15 lbm/s post-refill.
Figures A.2.6, A.2.7, and A.2.8 show total ECCS and break flows, break flow quality,
and break flow temperatures, respectively. The break flow became subcooled shortly
after 2 hours and became more subcooled out to around 20 hour. Soon thereafter, the
break and the ECCS injection flows remained roughly matched, establishing a quasi
equilibrium condition.
Figures A.2.9 and A.2.10 show cold leg flows for the intact and broken loops,
respectively. Inter-cold leg flow circulation is evident. The circulation directions
switched during refill but not after. In general, the broken leg flow remained in reverse
direction. Although there are concerns on the reliability of this type of circulation, it
would gradually remove the suction side deborate to the break or to the highly borated
reactor vessel; thus reducing the amount of problematic accumulations.
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Figure A.2.11 shows the intact and broken loop flows over the hot leg U-bends. The
flow rates were less than 10 Ibm/s, mostly 2 to 5 lbmis. The deborate flow to the vessel
is low and should not challenge core criticality.
Figure A.2.12 shows the core inlet flow and Figure A.2.13 shows the reactor vessel liquid
temperature distribution in the downcomer and lower plenum. The core inlet flow chatter
is representative of chatter seen at other locations in the system. Due to core inlet chatter,
there is a net energy transfer to the lower plenum, heating it up unrealistically. The
chattering suggests that the RELAP5 model may need to be adjusted for low power, slow
flow simulations. The flow pattern shown near the end of refill and thereafter is not
representative of the calculations due to plot point editing that was inappropriately phased
with the intermediate flow oscillations calculated by RELAP5.
Figure A.2.14 is a plot of normalized core decay heat. It shows that the core power was
about 0.63 percent of the initial power at the time of refill and out to about 20 hour into
the transient.
Figure A.2.15 is a plot of deborate accumulation due to steam condensation in the steam
generators.
Key Results and Observations:
"* The case exhibited atypical flow and energy exchange between the core
region and the downcomer.
" Prolonged inter-cold leg circulation was observed.
"* The deborate did not challenge core criticality due to low loop flow rates and
prolonged inter-cold leg circulation.
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A.3 Cold Leg Break at RV Inlet, Mid-Level DC Stratification
Case Description and Phenomena:
The downcomer cold leg noding was modified to produce a transient downcomer liquid
level near the middle of the cold leg nozzle. As discussed in the Section A.2, EM
modeling produces nonphysical behavior during and after system refill. The adjustment
was made by raising the cold leg node elevations such that the modeled elevations
correspond to the plant physical elevations (the modeled elevation is slightly depressed in
the EM model). The case was simulated with no operator action. The case was executed
for 24 hours of transient simulation but only partial refill was achieved. The refill process
started at about 4 hours but the levels stagnated just above the steam generator upper tube
sheet elevation at 20 hours. The stagnation is attributed to the model not containing a
provision for atmospheric pipe heat losses. Steam in the upper regions of the loop has no
condensing mechanism other than mixing with the nodal liquid. If the system inventory
stagnates, when a level is at or near a node crossing or the nodal liquid becomes
saturated, the RELAP5/MOD2 simulation lacks surface condensation potential to remove
trapped steam. The potential for such a result was present in the previous cases but not
realized. The break flow was subcooled during refill and stagnation, and after stagnation
it remained matched to the ECCS injection. The core was steaming during refill and
stagnation resulting in a two-phase flow through the vent valves. Vent valve flow was
voided with a moderate flow rate of about 35 lbm/s. Reflecting the alteration of the
downcomer level, this flow is about twice that achieved in case A.2. Sustained inter-cold
leg circulation was evident during refilling, as was a substantial subcooling of the pump
suction piping. For the conditions achieved, the deborate did not challenge core
criticality because the deborate in the steam generators could not move due to stagnation.
Substantial deborate was dissipated by inter-cold leg circulation. Had a refill occurred,
deborate behavior similar to that of case A.2 would have removed any potential for a core
criticality excursion.
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Parametric Histories and Discussion of Results:
Figure A.3.1 shows a plot of system pressures. The primary pressure stabilized around
680 psia during refilling and stagnation. The secondary side pressures were about 250 to
310 psia at the end of the run.
Figures A.3.2 and A.3.3 show the intact loop and broken loop liquid levels. The hot leg
and steam generator side levels stagnated at about 8 to 11 feet below the hot leg U-bend
spillover elevation. Figures A.3.4 and A.3.5, respectively, show total vent valve flow,
and vent valve quality and vent valve and upper plenum void fractions. The plots show that the upper plenum and vent valve flows remain two-phase during refill and
stagnation. The vent valve flow gradually decreased and stabilized at 35 lbm/s.
Figures A.3.6, A.3.7, and A.3.8 show total ECCS and break flows, break flow quality,
and break flow temperatures, respectively. The break flow became subcooled shortly
after one hour and remained so for the rest of the transient, increasingly becoming more
subcooled. The break and ECCS injection flows remained roughly matched after about 10 hours, setting a quasi-equilibrium or stagnation condition.
Figures A.3.9 and A.3. 10 show cold leg flows for the intact and broken loops,
respectively. The inter-cold leg flow circulation is evident. The circulation directions
remained stable after about one hour.
Figure A.3.11 shows the intact and broken loop flows over the hot leg U-bends. The
flow rates were almost nil during refilling. Hence, the deborate should not challenge core
criticality as long as stagnation persists.
Figure A.3.12 shows the core inlet flow and Figure A.3.13 shows the reactor vessel liquid
temperature distribution in the downcomer and lower plenum. The upper downcomer
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temperature is slightly higher due to mixing and condensation of vent valve two-phase
flow.
Figure A.3.14 is a plot of normalized core decay heat. It shows that the core power was
about 0.61 percent of the initial power at the end of the case, 24 hours into the transient.
Figure A.3.15 is a plot of deborate accumulation due to steam condensation in the steam
generators.
Key Results and Observations:
"* The case did not achieve a refill after 24 hours.
"* Break flow remained subcooled during refill.
"* Core steaming persisted during and after the partial refill.
"* The vent-valves were open continuously throughout the run.
"* Inter-cold leg circulation persisted throughout the run.
"* The deborate did not challenge core criticality.
A.4 Cold Leg break at RV Inlet, Refill with HPV Operation
Case Description and Phenomena:
To induce loop refill, the previous cold leg break case was modified to include an
operator action to open high point vents (HPV) at ten hours into the transient. The HPVs
were kept opened for about 45 minutes, with a steam escape rate of about 1.3 Ibm/s, and
then closed. The case was run to 20 hours.
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The broken loop refilled first after about 11 hours and a slow circulation was established in the normal flow direction until about 12 hours. After flow reversals, the flow dropped
to near zero at 13.5 hours. The circulation between 11 and 12 hours was sufficient to displace the entire broken loop deborate. Vent valve flow was continuous at about 40 Ibm/s. The displaced deborate would be borated in the upper downcomer by the vent
valves. Parts of the mixed deborate would discharge out the break.
The intact loop refilled by 13.5 hours. Flow, however, remained small or near zero except for several flow spikes at 14 and 15.5 hours. Only about 40 percent of the
deborate in the intact loop would be displaced by the conditions achieved. Inter-cold leg circulation, frequently oscillating after about 12 hours, would mix any remaining
deborate.
The break flow remained subcooled during and after refill. It roughly matched the ECCS injection flow rate after 13 hours. The core was steaming during and subsequent to refill.
The upper plenum was 5 percent voided after 12 hours.
Parametric Histories and Discussion of Results:
Figure A.4.1 shows a plot of system pressures. The primary pressure stabilized around
680 psia during loop circulation. The secondary side pressure was about 300 psia and
gradually decreased at the end of the run, 20 hours.
Figures A.4.2 and A.4.3 show the intact and broken loop liquid levels. The broken loop hot leg was liquid full by about 11 hours and the intact loop in about 13.5 hours. The steam generator side levels mostly remained about one foot below the U-bends.
However, for up to an hour after the hot leg refilled, the broken loop steam generator side was also liquid full. Figures A.4.4 and A.4.5, respectively, show total vent valve flow,
and vent valve quality and vent valve and upper plenum void fraction. The plots show that the upper plenum and vent valve flows remain two-phase during refill and loop
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circulation. The vent valve flow gradually decreases during refill and stabilized to about
35 to 40 lbm/s during loop flow.
Figures A.4.6, A.4.7, and A.4.8 show total ECCS and break flows, break flow quality,
and break flow temperatures, respectively. The break flow became subcooled shortly
after one hour and remained so for the rest of the transient, increasingly becoming more
subcooled. The break and ECCS injection flows remained roughly matched after about
12 hours. The break flow, however, was highly oscillatory due to oscillatory inter-cold
leg circulation.
Figures A.4.9 and A.4. 10, respectively, show the cold leg flows for both loops. The
inter-cold leg flow circulation is evident. In the intact loop circulation direction switches
at 10 and 11 hours and becomes quite oscillatory after 12 hours. The broken loop
simulates this behavior but does not achieve the switch at 11 hours and while the
magnitude of flow oscillates after 12 hours the directing is stable.
Figure A.4.11 shows the intact and broken loop flows over the hot leg U-bends. The
broken loop refilled first after about 11 hours and flow was established in the normal
(forward) direction in the U-bend. The flow quickly rose to about 80 lbm/s, gradually
decreasing to about 17 Ibm/s after 11.5 hours. The flow reversed shortly after 12 hours,
returned to the forward direction after 12.5 hours, and finally dropped to near zero after
13.5 hours. The circulation was sufficient to displace all 46,000 Ibm of the broken loop
deborate in less than 40 minutes. The displaced deborate would mix with the highly
borated HPI injection in the pump discharge piping and the reactor vessel water in the
nozzle belt region. Parts of the mixed deborate discharge out the break. The intact loop
hot leg refilled by 13.5 hours. The system flow, however, was small or near zero except
for spikes of about 60 lbmis and 30 lbm/s at 14 and 15.5 hours, respectively. This would
displace about 40 percent of the 48,600 Ibm of deborate in the intact loop. The inter-cold
leg circulation should displace most, if not all, of the remaining deborate.
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Figure A.4.12 shows the core inlet flow and Figure A.4.13 shows the reactor vessel liquid
temperature distribution in the downcomer and lower plenum. The upper nozzle belt
temperature is slightly higher due to mixing and condensation of vent valve two-phase
flow.
Figure A.4.14 is a plot of normalized core decay heat. It shows that the core power was
about 0.63 percent of the initial power at the end of the case, 20 hours.
Figure A.4.15 is a plot of deborate accumulation due to steam condensation in the steam
generators.
Key Results and Observations:
"* The break flow remained subcooled during and after refill.
" The core was steaming throughout the run. The upper plenum was 5 percent
voided after 12 hours.
" The vent valves were open throughout the run.
" Inter-cold leg circulation persisted throughout the run.
" The deborate does not challenge core criticality.
A.5 Cold Leg Break at RV Inlet, SG Blowdown after Refill, High DC Stratification
Level
Case Description and Phenomena:
Although the transient downcomer level in the previous analyses had been increased to
the middle of the cold leg nozzles, at that height it remained unrealistically low compared
to the liquid levels in the cold legs. To better represent the downcomer liquid level, the
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node elevations for the downcomer nozzle belt nodes and the cold leg pump discharge
nodes were increased to provide a downcomer level within a few inches of the top of the
cold leg piping. To limit the possibility that the inter-cold leg circulation was being
driven by injection of the HPI high in the pump discharge volume, the HPI injection level
was shifted to the design location after cold leg refill. In an attempt to induce natural
circulation, an operator action was invoked to slowly blowdown the steam generators
after loop refill. The operator action was credited at about 25.3 hours into the transient.
Both the steam generators were blown down at a rate of about 20 F/hr. The case was run
to 29 hours.
The case successfully ran through system refill and subsequent loop circulation. It took
almost 16 hours to fill the intact loop and about 22.5 to 25 hours to fill the broken loop.
In both cases steam generator sides refilled before the hot leg sides. Loop circulation
flows, after refill, were small (about 3 to 6 Ibm/s) and in the reverse direction. With the
operator action at 25.3 hours to blowdown the steam generators, loop flow adjusted to the
normal direction. By 29 hours, the intact loop flow was about 3 lbm/s and slowly
increasing. The broken loop flow was about 0.5 lbm/s and steady. After the operator
action, secondary side cooling led the primary in the steam generator regions. However,
the secondary did not cool sufficiently to become a major energy sink and natural
circulation had not started by the end of the run.
Due to the higher downcomer stratification level, the intra-vessel flow circulation
improved resulting in a subcooled core. The upper plenum, vent valve region was
subcooled after about 11.5 hours. The upper head filled just before 13 hours with a
subcooling of over 100 to 150 F thereafter. The vent valves were open during loop refill
and steam generator blowdown. Once the vent valve region was subcooled, the vent
valve flow increased to about 350 Ibm/s and then slowly decreased to about 225 lbm/s by
29 hours.
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Inter-cold leg circulation was evident in both the loops during the time when the upper plenum was two-phase. Circulation in the intact loop was suppressed after approximately
6 hours. Broken loop inter-cold leg circulation, however, remained active.
Parametric Histories and Discussion of Results:
Figure A.5.1 shows a plot of system pressures. The primary pressure stabilizes around 670 psia while secondary pressures decrease steadily to about 90 psia for the intact loop and 290 psia for the broken loop before operator action is taken at 25.3 hours. After that, the secondary side pressure decreased rapidly to 30 psia in the intact loop and 115 psia in
the broken loop.
Figures A.5.2 and A.5.3 show the intact and broken loop refills. In both loops, the steam generators fill before the hot legs. It takes about 14.5 to 16.7 hours to fill the intact loop
and about 22.5 to 25 hours to fill the broken loop.
Figures A.5.4 and A.5.5 show the total vent valve flow, the vent valve quality, and the vent valve and upper plenum void fractions. The plots show that the upper plenum and vent valve flows were liquid-only (subcooled) halfway through refill. Once the vent valve region becomes subcooled, at about 11.7 hours, the vent valve flow increases to
about 350 Ibm/s and then slowly decreases to about 225 Ibm/s by 29 hours.
Figures A.5.6, A.5.7, and A.5.8 show total ECCS and break flows, break flow quality, and break flow temperature. The break flow becomes subcooled shortly before an hour and highly subcooled for the remainder of the transient. The break flow and the ECCS
injection flow remain closely matched after about 19.5 hours.
Figures A.5.9 and A.5.10 show cold leg flows for the intact and broken loops. Inter-cold leg circulation is evident. Inter-cold leg circulation gradually removes the suction side deborate to the break or to the highly borated reactor vessel, thus, reducing the amount of
deborate.
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Figure A.5.11 shows the intact and broken loop flows over the hot leg U-bend. The loop
flows, after refill, are small (about 3 to 6 Ibm/s) and in the reverse direction. However,
with operator action at 25.3 hours to slowly blowdown the steam generators, the loop
flows readjust and start flowing in the normal direction. By 29 hours, the intact loop flow
is about 3 ibm/s and slowly increasing; the broken loop flow is about 0.5 lbm/s and
steady. Before operator action, the steam generators are cooled by the primary.
However, after operator action, secondary side cooling leads the primary, resulting in a
primary column cold enough to change loop flow to the normal direction.
The Figure A.5.12 shows the core inlet flow, and Figure A.5.13 shows the reactor vessel
liquid temperature distribution in the downcomer and lower plenum. The whole inner
vessel becomes subcooled after about 10 hours.
Figure A.5.14 is a plot of normalized core decay heat. It shows that the core power is
about 0.8 percent when the inner vessel becomes subcooled and about 0.6 percent at the
end of the transient.
Figure A.5.15 is a plot of deborate generation due to condensation in the steam
generators.
Key Results and Observations:
" The high stratification in the downcomer resulted in a subcooled upper vessel
and a substantial increase in vent valve flow after RV refill. The vent valves
remained open after RCS refill with a flow rate of approximately 225 to 250
lbm/s.
"* The case executed through system refill and subsequent low-level loop
circulation but did not restart natural circulation.
49
47-5006624-00
"* Break flow was subcooled during and after refill.
"* The deborate did not pose a challenge to core criticality.
A.6 Cold Leg Break at RV Inlet, Operator Intervention (HPV Opening, SG
Blowdown)
Case Description and Phenomena:
The previous case of late operator action was replaced by an earlier intervention to
simultaneously open the high point vents and initiate steam generator blowdown at 4.3
hours. This case is of particular importance because it resulted in a restart of natural
circulation and the closure of vent valves. As in the previous case, downcomer and cold
leg noding elevations were set to provide a reasonable representation of the downcomer
liquid level. HPI injection level was similarly shifted to the design location after cold leg
refill. The case was run to over 7 hours. Steam generator blowdown was fixed at a steam
flow of 5 Ibm/s/generator. This resulted in a cooldown rate of about 120 F/hr that slowed
gradually to around 50 F/hr. Two hours after initiation of operator action the core exit to
steam generator temperature difference was about 25 F, less than the operation guidelines
of 50 to 100 F. The existing operator action guidelines suggest opening of the PORV
followed by steam generator blowdown before HPVs are opened. However, for analysis
convenience, the PORV was not opened. Timing of the operator action was chosen based
on existing plant operation guidelines.
The upper plenum and vent valve region became subcooled by about 5 hours, shortly
after the beginning of operator actions. The upper head refilled about an hour later.
When the upper plenum became subcooled, the vent valves flow increased from about
150 lbm/s to about 500 lbm/s. The flow then gradually decreased to 300 Ibm/s by about
6.5 hours when the vent valves closed rapidly.
50
47-5006624-00
Both the loops refilled by around 5.75 hours, about 1.5 hours after the initiation of
operator intervention. The hot legs filled slightly ahead of the steam generators. Loop
circulation was established in the normal flow direction at about 25 to 50 lbm/s before the
beginning of vent valve closure. As the vent valves started closing, the intact loop flow
increased to more than 450 lbm/s. Circulation was sufficient to displace all the system
deborate to the downcomer within 25 minutes after loop refill. The displaced deborate
would mix with the highly borated flow from the vent valves in the downcomer nozzle
belt region. Some portion of the deborate would also be discharged out the break.
The operator actions resulted in a moderate degree of primary and secondary cooldown
and initiation of natural circulation. Displacement of the deborate occurred safely before
the vent valves closed. The deborate does not challenge core criticality. The time margin
available after the refill to displace the deborate and before the vent valve closure was a
factor of two. If operator action was more aggressive, in keeping with existing
guidelines, there would still be sufficient time to dispose of the deborate before the vent
valves closed.
Parametric Histories and Discussion of Results:
Figure A.6.1 provides a plot of system pressures. The primary pressure dips below the
core flood tank actuation pressure briefly during refill before stabilizing around 600 psia.
The secondary side pressure steadily decreases to about 90 psia in the intact loop and to
about 75 psia in the broken loop at the end of the transient, about 7.25 hours.
Figures A.6.2 and A.6.3 show intact and broken loop refills. Both loops fill by about
5.75 hours, the steam generators filled at approximately the same time as the hot legs.
Figures A.6.4 and A.6.5 show total vent valve flow, vent valve quality, and vent valve
and upper plenum void fractions. The plots show that the upper plenum and vent valve
flows are liquid-only (subcooled) by 5 hours. The upper head becomes solid shortly
before 6 hours. After becoming subcooled, the vent valve flow increases to over 500
51
47-5006624-00
Ibm/s and then slowly decreases to about 300 ibm/s at 6.5 hours, just before the valves
close.
Figures A.6.6, A.6.7, and A.6.8 show the total ECCS and break flows, break flow quality,
and break flow temperature. The break flow becomes subcooled shortly before an hour
and continues to be subcooled for the remainder of the transient. The break and the ECCS
injection flows remain stable after about 6.6 hours, differing only by an amount equal to
the high point vent discharge.
Figures A.6.9 and A.6. 10 show cold leg flows for the intact and broken loops. Inter-cold
leg circulation is evident after about 3.1 hours.
Figure A.6. 11 shows the intact and broken loop flows over the hot leg U-bends along
with the total vent valve flow. Natural circulation begins at about 5.75 hours with a
moderate flow of about 25 Ibm/s/loop, gradually increasing to about 50 lbm/s at 6.5
hours. As the vent valves close, the intact loop flow rapidly increases to around 450
lbm/s. The broken loop flow decreases at first but is starts to increase at transient
termination. Once the loop is refilled, natural circulation is strong enough to displace the
deborate in 25 minutes, well before vent valve closure. The deborate will mix with HPI
injection at the pump discharge and with the vent valve flow in the downcomer nozzle
belt region. Some of the deborate will discharge out the break.
The Figure A.6.12 shows the core inlet flow, and Figure A.6.13 shows the reactor vessel
liquid temperature distribution in the downcomer and lower plenum. The inner vessel
becomes subcooled after about an hour, even before operator intervention.
Figure A.6.14 is a plot of normalized core decay heat. It shows that the core power was
about 1.0 percent when operator action was initiated, 4.3 hours, and about 0.9 percent by
the end of the transient, 7 hours.
Figure A.6.15 is a plot of deborate generation from condensation in the steam generators.
52
47-5006624-00
Figure A.6.16 is a plot of reactor vessel upper plenum liquid temperature at the core exit
and steam generator temperature. Between the initiation of circulation and the start of
vent valve closure, 5.5 to 6.5 hours, the core exit-to-steam generator temperature
differential varies from 19 to 28 F.
Key Results and Observations:
"* Steam generator cooldown stabilized at about 50 F/hr. The core exit to steam
generator temperature difference was maintained at about 25 F.
" The upper plenum and vent valve region became subcooled by about 5 hours.
Vent valve flow was about 500 ibm/s decreasing to 300 lbm/s just prior to
valve closure.
" Both loops refilled. Before the vent valves begin to close, loop circulation
was established in the normal direction at about 25 to 50 lbm/s. Circulation
was sufficient to displace all the system deborate in about 25 minutes. The
amount of time available for mixing prior to vent valve closure was about 50
minutes. Therefore, the deborate will not challenge core criticality.
"* Inter-cold leg circulation continued through system refill but stopped when
full natural circulation commenced at about 7 hours.
53
FIGURE A.1.1 : 0.007 ft" Hot Leg Break. System Pressures
2400 2--e P-352 (RV-UP-1)
**--E P-670 (SG-1-Sec) SP-770 (SG-2-Sec)
--- --- ----- -- ----- --- -- --- -- --- -- --- -- I -- --- -- -I-- --- --A --t P-897 C FT ) 2 0 ............. ............. I ............. .............. I............. I ............. I .............. r .............. I ............ I .......... .I ------- --9-89 I T -- ------------ -----
2000 -------. . .. . ..--.----------------- T
1600 ,-Bre* at S5. 1 FT elevation, 2-fiPIs availablen peato ctlon ---------~~+ -- -- ---- ------- -------- -------------- --------------...... ............. ............ ------t 1200---------------------------------------- --------.
0 0 2 4 6 8 10 12 14
Time (hrs)
80
60
20
6 12Time (hrs)
14
I I I
FIGURE A.1.2: 0.007 ft2 Hot Leg Break. Intact Loop Collapsed Liquid Elevations
, 0-0 CNTRLVAR-1.0o (HL-1 CollapsedLevel) 8-a CNTRLVAR-140 (SG-1 Tubes) 0- CNTRLVAR-1 51 (SIG-1 Above Tubes)
* A-A CNTRLVAR-614 (SG-1 Secondary) ------------- ------------- ----------- -------------------- _ ----------------- ------------- ------------- ............. ------ -.C N T R L V A R - 4 0 8 (P re ss u re iz e r)
,, e
t . . . . . . . . ...................................... ....... --- - ------.... .............. :... . . . .. ............ ",...................................... .......... .......... ...........
........ ----------- ------ ------------------ --------------------- ---- ------
00 2 4 8 10
FIGURE A.1.3 : 0.007 ft2 Hot Leg Break. Broken Loop Collapsed Liquid Elevations
80 * eG-e CNTRLVAR-200 (HL-2 Collapsed Level) * --a CNTRLVAR-240 (SG--2 Tubes) 0-c CNTRLVAR-251 (SG-2 Above Tubes) 6-- CNTRLVAR-714 (SG-2 Secondary)
60 .. . ... . . .. . . .. . . .. . .-- --- ----------4- ------- ----.............. :"........ . . . . . . . . -.. .. .. .. . .. .. .. .. . .. .. .. ............ ............................
"-40
..............................-- ------... ....... ...............- -.-- -.-- -----. .-- ---.-- --
4 6 8 10 12 14
Time (hrs)
FIGURE A.1.4 : 0.007 ft2 Hot Leg Break. Steam Generator Heat Transfer
Time (hrs)8 10 12
1000
f.-,
r, H
00
ci)
0
-1000
-2000 ' 0 2 4 6 14
I I
---------- ---- ------ ------------ ---------- -----------------
---------- ---------- ----------- ------
8II
--- -------- - ----------
. . ........... .........
L
0-0 Filtered SG-2 HT from cvarooi SFiltered SG-1 HT from cvar002
.. ... ....------
FIGURE A.1.5 : 0.007 ft2 Hot Leg Break. Intact Loop SG-side Liquid Temperatures
I I
800
700
600
S500
"t" 400
300
200
2 4 6Time (hrs)
8 10 12 14
G-e TEMPF-120010000 (SG-1 U-Bend) 8 - TEMPF-125010000 (SG-1 HL Stub) 0- TEMPF-130010000 (SG-1 Inlet Plenum) -A TEMPF-135010000 (SG-1 Upper Tube Sheet)
' 4ITEMPF-150010000 (SG-1 Upper Tubes) --- ------- ------------ ------------- ------------- .-------- ................................. x--- TEM PF-1 50050000 (SG-1 M id Elevation Tubes)
*-*TEMPF-150110000 (SG-1 Lower Tubes) -+--+ TEMPF-155010000 (SG-1 Lower Tube Sheet) V--V TEMPF-158010000 (SG-1 Outlet Plenum
------j .................... .... .. ........ ... ... ...... ...... ....... ...... ....... ....... ....... ....... ....... ....... .....
............. ... ..... ........ ........ ........ .... .... ....... ......... .. ...... ..-.... -- ----- ------, ------- ------ ------- ------- ------ ------- --- ... ...... ....... ....... ...... ....... ..... .... ... ... ... .... ... .---- --- --- --- --- --- -- ---- --- -- ------- --- - ---- --- ---- --- --- -- ---
1000
FIGURE A.1.6 : 0.007 ft2 Hot Leg Break. Intact Loop SG OP and Pump Suction Liquid Temperatures
600
500
o400
-.)
"300
200
1000
0--e TEMPF-1 55010000 (SG-1 Below Tubes) a-a TEMPF-158010000 (SG-1 Outlet Plenum) 0-* TEMPF-1 60010000 (CL-1 A Suction Pipe)
I ----. . . . . . . . . . . . . . ............ ....... A-ATEMPF-180010000 (Cl-lB Suction Pi e)
------ -..........
-- -- -- -- --- -- -.- -......-- --- -- -- --- -- ---.- -- ----..---.-- ............. ..... ... ........ .. . ...-- ------------------ .. ... .. -- ----------------- ------------.. -- -----...... ........... i .............. .. .. -----------S............ ... ..... ! . ...... ........ ------------ -------------- ---------... ......... ..... - .. ... ...-.. ... ...---. .. ....-.. ... ..--.. ... ..--.. ... ..
-- -----. . . . . . .. . . . . . .. . . . ............................ -- ----- -- ------ ------- ------- ----- -.. ----. ................. .. .. .. . .. .. .. ... .. .. .. .. . .. .. .. .
---------------------------- -------------------- ------ ----------------- ----------------- --
2 4 6Time (hrs)
8 10 12 14
SI II i
FIGURE A.1.7 : 0.007 ft2 Hot Leg Break. Intact Loop Hot Leg Temperatures
800
700
6001J
500
400
300
200
1000
Time (hrs)
o-OTEMPF-100010000 (HL-1 at RV) D TEMPF-1 05010000 (HL-1 at PRZ) 0-* TEMPF-110010000 (HL-1) < TEMPF-110020000 (HL-1)
TEMPF-110030000 (HL-1) ----------- .......... --------------------- I - ------ • TEM PF-1 10040000 (HL-1)
*TEMPF-115010000 (HL-1 U-Bend) +-- SATTEM P- 115010000 (Tsat)
........ ~~ .. ....... .....---- -------------------- ------------------------ ..................... ----------- ----------
S............ ............. ............................ -------- ------- ------..- -----.. ....... ....... .......- ------.- ------ -----
-- - - - - -............. -- - - - - -.. . . .. . . -- - - - - -.. .. .. .. .--.. .. .. ..--... .. .. .- , .. . . . . .1. . . . .. . -. . . . ............... ............. -- -- - -- - ............. i -- -- -- -- -.........--- -- -- - --- - - - - -------------
2 4 6 8 10 12 14
i i I i
FIGURE A.1.8: 0.007 ft2 Hot Leg Break. Broken Loop SG-Side Liquid Temperatures
10Time (hrs)
800
700
6001
500
E
400
300
200
100
12
-TEMPF-220010000
STEMPF-22501 000 O-OTEMPF-2300100OO 6- TEMPF-235010000
TEMPF-25001 0000 ................................................................................................................................----- TEMP----------0 --------............... S- TEMPF-250110000
+-* TEM PF-25501 0000 V--+ TEMPF-255010000 v-VTEMPF-258010000
--------------- ~ ~ ~ ~ • -- ---- ----- - ------ .. . .. . .-- ------- --- --- ---- ---. .. .... .-- --- ---.- -- ----...- -- -
.... ....... .. .................... ---... .. .. .. .. .. .. .. .. ... .. .. .. .. .. .. .. .. .. i . . . . . . . . . ... ..... .. -- -- --- ----: ---- -------------
0 2 4 6 148
600
500
r' 400
* 300
200
1000 2
FIGURE A.1.9 : 0.007 ft2 Hot Leg Break. Broken Loop SG OP and Pump Suction Liquid Temperatures
--o TEMPF-255010000 TEMPF-258010000
: - TEMPF-26001 0000 ---- ------.. .. . . . . .. . ............ --A T EM P F-280010000
----------- ------------- ------------- ............. - -........................... ............. -------.-- ---------
- - - - - - -- ---.-.I -- - --.......... I . . . ............ I ... . ......... ...... .............--- ------------- I ............. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
-- - - - - - ---- --- --- ---- --- --- ,.. . . . . . . . ......... . . .... ,.......... ............. ............. -- --------- --............. ........................... .............
-----........ ............... J............. ............. • . . . ....o ............ -- - - -............. --- -- ---........... .. .. ... .. .. .. .
4 6
Time (hrs)8 10 12 14
FIGURE A.1.10: 0.007 ft Hot Leg Break. Broken Loop Hot Leg Temperatures
800
700
600
S500
.-.
400
300
200
1002 4 6
Time (hrs)8 10 12 14
&-- TEMPF-20001 0000 (HL-2 at RV) G--8 TEMPF-205010000 (HL-2 at PRZ, Break Node) 0-0 TEMPF-210010000 (HL-2) A-6 TEMPF-210020000 (HL-2)
-- TEMPF-210030000 (HL-2)
-TEMPF-215010000 (HL-2)U-Bend)
.. .- ------------- ------ ------............., ............. ...... .....
------------- ~~~ ~ ------- ------- --------------. ------
0
i i
800
700
600
0 8 IU
Time (hrs)11f
Downcomer Liquid Temperatures Around Nozzle Belt
G-0 TEMPF-175010000 (CL-1A at RV) ,3--, TEMPF-195010000 (CL-1B at RV) 0-0 TEMPF-27501 0000 (CL-2A at RV) ,-A TEMPF-29501 0000 (CL-2B at RV) STEMPF-30301 0000 (Above Nozzle Belt)
------------- .................................................... .................................... TEMPF-310010000 (Upper Nozzle Belt) -TEMPF-31801 0000 (Lower Nozzle Belt)
+-+ SATTEMP-30301 0000 (Tsat)
---- ---- --- ......... ............. .............. .....................................................................-- ------ ------------
--- - - - - - - - - - --- --- ----.. ...... ... ... ...... ... . .............
-- - - - - -.. . . . . . . . . . . ............. -- - - - - - T . . . . . .-- - - - - - -- -- - -- --I-- - -- -- --......- -- -- - -- --,- - -.. .. .. . .... .
500a.)
a.) 0�
400
300
200
100U 2 4
FIGR I I 0 f H L Break.
FIGURE A.1.11: 0.007 ft2 Hot Leg Break.
1,4
FIGURE A.1.12: 0.007 ft Hot Leg Break. Upper Plenum Subcooling
800
700
600
S500
0~ H
S400
300
200
1000
Time (hrs)
e-o TEMPF-.314010000 (Lower Plenum at Core Inlet) s-e TEMPF-352010000 (Upper Plenum at Core Exit) 0-eOSATTEMP-352010000 (Upper Plenum Tsat)
-- - - - - -. . . . . . .,. . . . . . . . . . . . . . . ......... ¢ . . ...... -- - - - - - .. ... ..... . • ............ -- - - - - - -- - - - - - - .- - -- - --............ 11 ------------- I -- - - - --.-- - - - --............ .............
------------ ~ ~~~~ - ------------- ------ - ------------------------ ............. ------------- ............
2 4 6 8 10 12 14
I I [ !
FIGURE A.1.13: 0.007 ft2 Hot Leg Break. Total ECCS and Break Flow
9--e CNTRLVAR-601 (Total ECCS Flow) a,- MFLOWJ-501000000 (Break Flow)
S. . . . . . .:. . . . . . .•. . . . . . .•. . . . . .............. ------------...I ........................... ........................... 4............. -- - - - - - -- - - - - - ....... .....- ............. -- -- - -- - .............
-. - . . .-.- . . . .. .. ..--. .. ............... ............. ------------ j .... ... ... - ............. ......... .4 ------- - --............ 4 ----
------- ........ -- ------------------------------- -------------- ------ -------------- ....... ------
200
180
160
140
o 120
100
V 80
g U 60
40
20
06
Time (hrs)8 10 124 14
------------ ----- -- --- --- ----- ---.. ......... ...! .... ........... ... ----------- ............ ...... .. ..
.. . .. . . -- - - - - -,... .. . . -- - - - - ............ •. .............. ............- • ............ .- .... ... ... ... ... ...
- 4 - - -
* ' tt Il ' : L I IIi , I I I' *
*.. . . . . . . . . . . . . . . . . . . . . . .I. . . . . . ., . . . . . .. I.. . . .. . . . . . . . . . . . . . . -; . . . . . .• . . . . . . I I I,
I,
* -. - - - - - - L - I- - . - - - - - - -I I I I
I
0 2
I I I i
.. .......------
FIGURE A.1.14: 0.007 ft2 Hot Leg Break. Break Flow Temperature
800 G-0 TEMPF-205010000 (Liquid Temperature) a--5 SATTEMP-205010000 (Saturation Temperature)
7000 ----------r. ---------.............----------...-------. I-----------.I-------------------.--.--------------.--.-------------.-------.--.----------.--------
070
300 ~ ~~~~ ~~ -- ------- --- - --- - - - - - - - - - - - - -- - - - - - -I. . . . . . .. . . .............. ... ....... .. ............. -- - - -- -.. .. .. .. .--.. .. . .. .--... . .. ..--... .. .. .
1500 .......................... .............. --------------------------------- ------- ------- ----------------------- I ------0
[
00- 4 6 8 10 12 14
Time (hrs)
(ssq) OLtI!0I 8 9 z
---..--------.-,.............. .......... ....I,.............. ................... ......... 4 ----------------------------- ------------- ------------.. ---------------------------... ---...........- , .-.........-
†-- t ----------- - -........ .........----------------------------0- - ---- ---- I-------A---I----
................ ............... ........................................ .................... •............ -- - -- - - ............ --.. ... ...
-- - -- - - - - - - - -.. . .. . . ------------------------------------------.. '.. ........... ,. ............. . ............. t............. t,. . . . . .............. --- .... ... ... --.. .. .. .. . ---.. .. .. .
------ (----- ----------------------- --- - ------ - - -.. L.-.- - -.
(MOld: SAIRA IUOA i8101) 000,000666-IMOIdLJ N0-S
ILeIN MOldI SQAILA IUQA P•10L 'lug-afl 201 JOH zjJ L00"0 :s'1rv 3WHflDI
Si 1I I
0oor
'0
.el
PCD
CD
rac
C')
ON %0
008
0001
I i I
171 UZI
00t7
009
I I
FIGURE A.1.16: 0.007 ft2 Hot Leg Break. Vent Valves Flow Quality
1.0
0.6
0.4 I--------
0.2 I-- -
0.0
-0.20 2 4 6
Time (hrs)8 10 12 14
r-h
•0'
o eto
0>
0)
0.),
- -. . . . . .. . .- °
n
0-- QUALS-36901 0000 (Vent Valve
---- -- - I -- - -- -- -- - - - - ----- - - - -
------------------------------ ------------- ----- ......
e ei e -ee :
0.8 I-4---1- ..
IJv v
FIGURE A.1.17: 0.007 ft2 Hot Leg Break. Vent Valves Flow Temperature
800
700
600
,400
300
200
1000
&-c TEMPF-36901 0000 (Vent Valves T-Liquid) Sa--a SATTEM P-36901 0000 (T-s~at)
.... .. .. ... ..... .. .. .. --- -- -- -- -- -- -- --- -- -- -- -- -- --- ------------------.. ... .. .... .......... .......i.. .......... .-- ------------.... ... ... -- .. ... ..------------ -------------. .................. -- --------... ...........
..... . . . .4 ------- T ------ ------ -----
-- - -- -- .. . .. . . ---- --- --- --- --- --- --
....... ------- ---------------------------------------..... ... --------------- ------ ... ------
---------- --------- ---------- --------- --------- ---------- ......... ------------------ ---------- 7---------- * ---------- r--------- I .........
2 4 6Time (hrs)
8 10 12 14
FIGURE A.1.18: 0.007 ft2 Hot Leg Break. Intact Loop SG Outlet and Cold Leg Flow Rates
800
700
600
500
400
S 300 E
- 200 t')
o 100 rT
0
-100
-200
-300
-4000 2
00M FLOWJ-1 55030000 (SG-10OP) ..... .... ---------- --- ---------------.... ............... W---- ----- B -010000065 10 00 0 C(C L A Pu p) ....P...... ..
0- MFLOWJ-1 8501000000 (CL-1 B Pump
--- ------ - ---------- ---- --- --- ------- -- - --- -- - -- -- -- --- -- - -- -- -- -- --- --- --
- ---- -------- -.I.-.-.-- --------.-- -.-- - --- ---.-- --.-- -----.-- --.-- ------.I.-- --.-- -------- r . . . . . . . . . . . . .I, . . . . . . . . . . . . . ,. -------------I., ---------- ---r -- -- -- --. . . . . . . . ..I- - -- -- --
--------- ...............r - ---- --------------------------------------------------- -------------
-- ----------4 -------------- ----- --------- -------------------- ---------- --------- ------------------------------ -------------------
.. ............. ...... ----- --------- -------------------- ---------- --------- ---------------------- *------- T -----------------
........ ----- ----- --------- ---------- --------- ---------- ------
--- - - - - -- - - - - - --- - --- - -T - - - - - --, - -
- - ----- --------- -------------------- ---------- ------- -------------------------------- --------------------
4 6Time (hrs)
8 10
I I
12 14
I I I I
800
700
600
500
400
300
200
100
2 4 6Time (hrs)
8 10 12
' I i i lo-e MFL'OWJ-255030000 (S'G_20p) uri S------ - -------------- ------.................... I-- -------------------------... MFLOWJ-26501000000 (CL-2A Pump)
:"0- MFLOWJ-28501000000 (CL-2B Pump)
.. ... .. ..... .... ..... .... --- --- -- --- --- -- --- --- -- --- --- -- --- --- --.. 1 2 ..... • ...............i ... ..................... ................. .... ..................... T~~~ ---------- I -------....................................................----------- ---------------------------------
-- - - - - -- - - - - - - - - - --I- - - - - - - - - - - - -I- - - - - - - ............ I' . ......... I ........... I" .......... .. I ........... T - - - ---i"- -- - - -
.. .. .. . I-- -- --- -- ---- -- ---I -- --- -- I--- -- -- ----- --- -- - I .. . ................I ............ ............... ..........................--- --- --I --- -- --
S........... A............. .. .. . ... ..... ... . . . ........
. ... .. .. .. I -
.0 -.-,I
0D
-100
-200
-300
-400 0 14
FIGURE A.1.19: 0.007 ft2 Hot Leg Break. Broken Loop SG Outlet and Cold Leg Flow Rates
FIGURE A.1.20: 0.007 ft2 Hot Leg Break. Intact Loop Hot Leg Flow at U-Bend
100
. . . . . . .. . . . . . . . . . . . .------- ------- ------- -- . . . . . . . ...- - - -- - - - - ------------- -- - - -- - ------------- -- - --- - ---.. . . . • . . . . . . . . . . . . • . . .. . . .. . . . . . . . . . . . . .. .
* 'I
Time (hrs)8 10
MFLOWJ-120010000 (HL-1 U-Bend)II-- Filtered
-- --- ------ ------ ------- 9-- ------------- - --- ---- -.---------
---- ---- --- ----- ---- - -- --- ---- - -- ---- ---- ---- ---- --- ---- ---- ---- ---- ---- ---.. ............. ............. .............
.- --- . - ----- - - - -_-- .... .. 9 ------------------------ ------------------------------------- 9-------------
9 ~ ~ E E 999
12 14
-.. ............... --..........---
801
601
40
Ct
2
20
0
-20
-40
-60
-80
-1000 2 4 6
w rl
Iq
-- -------------------------------------
----------- --------------------------
-----------
-------------- ------------------------ ------------ ------------
-----------
FIGURE A.1.21: 0.007 ft Hot Leg Break. Broken Loop Hot Leg Flow at U-Bend
100 . :-a Filtered MF.OWJ-22001 0000 (HL-2 U-Bend)]
2 0 - ----- E ---------- T-------4------
S,
-0.... ......................................................
-40 ------- -- ---. ... ..--------------------------- --- --- ----- -- - --- ----- -- ----.-- --- -
6 0 ....... . ...... .. .. ............. ,. . . . . ............................. -- --- - - ---- --- ------- --- ---- --- ---- --- --- ---- --- --- -- - - - -- -- - -- - - - --... . . -- - - - -.. . . . . . . . . .. . . . . . . . . -. --------------------------
-100 .
0 2 4 6 8 10 12 14 Time (hrs)
FIGURE A.1.22: 0.007 ft2 Hot Leg Break. Deborate Accumulation Due to Steam Condensation in SG
01
-20000
Time (hrs)10 12
SI I
S- CNTRLVAR-137 (SG-1 Deborate) 3n--o CNTRLVAR-237 (SG-2 Deborate) o-0 CNTRLVAR-238 (Total Deborate)
--------............... ............. ........... -- .............. ............. ------------ ------------- .--......... .
... 1~------- .........-........---.......- .......................................................... .................. ,..................
------------. .. ........ . .--' ---. .... ° ----• o ! . - ,. .. . . . ., .. . . . . . . -- . . .. ; . .. . .6 . . ..' 5 ....... .. • ......... -........... 5 •..... ........---
E
r.0
C;
CA
-40000
-60000 1
-80000
-1000000 2 4 6 8 14
FIGURE A.1.23: 0.007 ft2 Hot Leg Break. Lower Plenum and Hot Legs at RV Flow Rates
800 0-0 MFLOWJ-1 05010000 (Intact Loop Hot Leg Near RV)
a-E MFLOWJ-205010000 (Broken Loop Hot Leg Near RV) : MFLOWJ-313020000 (Lower Plenum)
6000------------..... - ---. --. ---.-.-.-. ---. ----. ---------------- ----... ........ ......I. -------.-. ----.I.-- ------.-.-.I.-------- --.-..I.-----------.--. ------------...---- -------- .-.-.-------
5 0 0 . .. . . . . . . . . . .. . . .. . . . . . . . . . . . .I . . . . . . . . . . . . ..I ..-.- . .. . . . . . . . . . . . .. . . . . . . . . . ... . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . .. . .... . . . .. . .. . . . . . . . . .. . . . . . . . . . . ...-- ----- -------- -------
700
400 ...................... -- ------------- -----------------------------------------------------------------------
E -- -- --------------... ............................... -- ---------.......
0 2000.... ....... .......--- ---- --- - .-- .-- .--- ---. --- --- --.- -.L--.- --- -----.- -.-- --- ---............... ....... ....... . ...... ...
10 --0--- - -- --- --- --.-- --.---.-- ---.-- -- -- --'......... ... .. .......-.-- -- -- --- -- --- --
-200 - - _____ ____
0 2 4 6 8 10 12 14
Time (hrs)
(siq) OW•JL VI U 01 8 9 V Z 0
t7*0
---- ---- --- ---- --- --- --- --- ------- ---- ---- --- ---- --- --- --- --- ----I ----- ---- -- ---- ----- -- r-- - -- --- --- -- --- --- -- --- - I-- --- --- -- --- --- --- --- --- ---- r-- --- -- --- -- T-- -- -- --- --- 9
'0
"0
0I 0
0
........................------------------------- -----------.- -----------------------------. ................. ...........------------.-- ----------.-- --------.-- -0-0
------------- --- ----------------------------------------------------- 9
~~~~~~~~~~~~~~~----------------------------------------------------------------------------------------------------- ...............................
0.0z
U UdI P0
.......... .... ................ ...........-. -----------.-. -----------.-. ----------... ............................ .............. ...........-. -------------------------.-. ----------.-. --------
S............. ---------- --...... -- ... . . . . ,............. •............. -- --- -- ------------- -- -- --- - -------------.. . .. . . . .. .. .. ............ ............. "............. "............ "..... .. .
:: [ i I: (Jo,8MOd WoOO pOz!leWJON) Z'0I.001. ,696-HVA'I"INO 0--olii:
uoIIL'JuQo aaMOd aQm;D pQzTIL'tmoN
")i•g'a '- ý l JOl ZJJ L00"0 :tZ*I'V 3lIflIlA
FIGURE A.2.1 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom System Pressures
2400 0-0 P-352 (RV-UP-1) 0-- P-670 (SG-1-Sec) 0-0 P-770 (SG-2-Sec) -...........----------_-------- --- --------------- . ........................ P-897 .........O -
200----------------------------------------------------------------------A P -89CT) 2 0 0 00 . ......--- . ..... ... .. ..... ... .. ..... ...... ..... ..... ..... ...... --. ..... ....--..... ..... ..... ..... . .... ..... . .... ..... ...... ..... ..... ..... ..... ..... ..... ..... -- ------ -------- ---- -- ----------
No Operator A~ction, HPI injections next. to RC Pumps 1600- - . .
C) 1200--.----------------- -------------------------- 4------------
r.) 120 ...... ...... -- -- --- ---- --- -.... .. .... ... ...I ... .. ...I.. ... .. -- -- --- --- --- -- --- --- ----- --- --- ... .. .... .. . .8 .......... ......................................................................................................
800 ------ ------ .............................. ......................................................................... ............ .......... iiiiiliiiiiil iiiiil
0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
FIGURE A.2.2: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Intact Loop Collapsed Liquid Elevations
80
60
0 00 .- 40 CD
240
0)
20
0 2e0 12 14 16 Time (hrs) 18 20 22 24 26 28 30
0-0 CNTRLVAR-100 (HL-1 Collapsed Level)
&--a CNTRLVAR-140 (SG-1 Tubes) 0- CNTRLVAR-151 (SG-1 Above Tubes)
A-A CNTRLVAR-614 (SG-1 Secondary)
............... ..NTRLVAR-4...........8 .(Pressureiz.............
------- ------I ........ .-- ----.-- ------------ ----.-- ---. .-- -----.-- ---- ------ ------ . . . . . . . . . . . .I -- --------- --------
FIGURE A.2.3 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Broken Loop Collapsed Liquid Elevations
80
60
00 t 40
20
0
e-e CNTRLVAR-200 (HL-2 Collapsed Level) *S-a CNTRLVAR-240 (SG-2 Tubes)
,, o-0 CNTRLVAR-251 (SG-2 Above Tubes) ',S SA--A CNTRLVAR-714 (SG-2 Secondary)
............. ... ....... ......... .. ............... ........... .... ....... ......... ..----.......-.. . ............ ... ........----.... ...... .......... .---............
.........-.-----
..................... ..... .--..........------------------------------------. --------------------....... -------I.. ... --------....... ------I.. ... -------..........................-
0 2 4 6 8 10 12 14 16
Time (hrs)18 20 22 24 26 28 30
FIGURE A.2.4 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Total Vent-Valves Flow Rate
600 60ooTotal Vent-Valves Flow from cvar-337, filtered and smoothed)
5 0-.. . . . . . . . . . .I. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . ..-- - - - - - - -- - - - - - -500-----------------------I-----------
500 ------------------ I ------------ I------ ------ ------------ ------------ ------------ ------------ ------------ ------------ -------------------------
-Q 400 -------------------------------------- ---------------------_--------------- I ------------ T - - - - -.. .. .. .. .. .. .. .. .. .. .. .. -- -- -- -- ............ ............ -- - -- - -.. . . . . . . . . . . .............. I............ ............ -- - -- - - ------------ ............ . . .. . . ............ I -------- ..
000 0
o9
0 0 - - - - - --- - - --- -- - - - - - -I- - - - -- -1 - -20 0-1 - - - -- - - - - - - - - - - -- --I- - -- - - - - -- - - - - - - - - - - -- - - - - - --L- --. -- - -- -
0 ............ ......... .. .......... .... ............. .. ...... .. . --. -------------..I .- -----------.- -----------.I.-- -- .-.-- _ --4 -------.-- --.f.-- ----------.-- ---------------. . ----------. -----. ......
I 9
C) I
o 100 9 II
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
SII F I ii i
FIGURE A.2.5 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Vent Valve, Upper Plenum, Upper Head Voiding
1.2 _ _ _ _ _ __
--e QUALS-36901 0000 (Vent-Valves Static Quality) a-E VOIDG-36901 0000 (Vent-valves Void Fraction) 0-0 VOI DG-35201 0000 (Upper Plenum Void Fraction) A•--A VOIDG-39001 0000 (Upper Head Void Fraction)
1.0 A A - .............---------................
ci,
0
. 0.6 ----------......... •-......... •............
>
I-' 00
0 .2 .. . . . . -...... .. q........ .I. .. ........ . . . . . . . . . . . . . . . . .. ' .... ... . . . .......... . ... ... .. -- - - - - - - - - - - ----------. -... .. ...., ............ • ............ •............
-0.2
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (hrs)
i I I I I
(ssq) 0W!l 27 97 t7Z zz 0z QT OT t 7T 71 AT 0 0 4. I?
AMOI DaEIg pum S333 IJIO1 uoploq f 1e uo!jUNlJ!UJlas iu 'Al l Wualag •?Ol PlO jJ L00o"o: 9ZV 3llfIDA
0
oz
-- - f 07 v
S.... ..... . L-..---------... .------------. ---------...--... ..... .. --..... .... . ........... .. . . . .-- - - - - - - - - - - -.. . . . . .A.. .. . . . . . . ... -- - - - - - - - - - - - L......... . ......... . ----.....
------------ ............. ..----------- ------------..............------------.----------.-- ---.--... .. .. .--... .. .. .--.. . . .. .. " -.. .. .. . --. .. .
S... ... ....• . .... ... .7 ... .... ... .... ... .... ... .... ' . .... .... ............. -- - ---- .. . . . . . . . . . . . . . . . . . . . . . . .-- - - - - ........... . . . . . . . . . . . . .
-- - - - - - - - - -- -. . . . . . ;.. . . . . .,.. . . . . . . . . . . . . . . . .............. " ............ -- -- - -- -I. . . . .-- - - -- - - - -- - - - ---------........................................... -------- ............ ". . . . ....
------ ------------ -- --- --------------------------. ••- ------------ --... ... ..---.. ... .. .- ..... . .. ......... .---- --- --- --- --- --- -- --- --.. . .. . . -- -- ..... ..... .... .. .........
------------. .............. . . . . . . . . . . . . . . . . ............. - ............ ------------.. . .. .-. .. . .. . ". .. . .. .-. ..... ..... -- --- -- ..... ..... -- -------- -- -- --- --- -- --- --- -- ---
S............ -- -----.. . .. . . -- --- -------------- I ------------- -- --- -------------- -- -----.. . .. . . -- --- -- ------------ -- --- -------------- ,-.. . .. . .. . .. .. . .--.. . .. ..--.. .. . ..- ... . . ..:............-............
--------- --- --- --- --- --- ---- --- --- --- --- --- --.. ... .--... ... .--... ... ... .. ... .- ... ....--. .. ...--. .. ... ... ... ... ... ... ............... -- --- --- --- --- --- --- --- --- --- --- --- --........... ------------. (Mo'•eS)0600000LOS'-r'MO-I-N (MO4 OO::1leO.)109-8IVAIEIJNO G-
00
091
081
O0
I I
o0:
I I
09M
08CL
-t CD
00o1
ON0
0171 a'I
FIGURE A.2.7 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Break Flow Quality
1.2 [-0-0 QUALS-27501 0000 (Break Volume Static Qualit
1.0 ....................... --------------------------------------------------------------------------------- -------------------------------
0 .8 - -- -- -- I -- - - - - I .............. ... .. .. . .. . . .. .. .. .------ -----... . . ............ •...........
004--------1--------- -------- T -------------- *-------- ------------------------ --------------
0.2
0.2 - - ------- ------------ ----------0-- I. . , 0 0 -0 0. . .- ............ 01 ..--....- * 0- C .... ....... ' .......... . ............. T ............ I ----------
0. L ----- e e ie @e e e e e e i , e e 9 ------------ -----
-13 L0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
I
FIGURE A.2.8 : 0.007 fte Cold Leg Break at RV, DC stratification at CL bottom Break Flow Temperature
800
700
600
S500
• 400
00
o 300
200
100
0
0-0 TEMPF-27501 0000 (Liquid Temperature) I 3mSATTEMP-27501.0000 (Saturation Temper~a tu r:9
---------- I ....... •........... I ............ -------.......------------- ------ ------ ------ ------ ------------------
................... . ....... . .. ............... r............ ........ ----------------------------------------------------------.. ........................... •............ ---- .............. -------------. .-------............ .------------. ------------. -------------------------------------. ..-------------------------. .-------. .....- -. ..........- ........... • ...........I -------------------
0 2 4 6 8 10 12 14 16 Time (hrs)
18 20 22 24 26 28 30
I I I I I I I I I I I
i
FIGURE A.2.9 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Intact Loop Cold Leg Flow Rates
600
500
400
300
200
100
0
IC
0 2 4 6 8 10 12 14 16 Time (hrs)
Ft edMLO J1600 A- Filtered MFLOWJ-1850100
S ............ :-........... --- - - - - ------------ ----------- . .. .. .. .- ........... .. . ... . ............
S..... . • . ..... . . ---....... ... --.. .... ....- ............ ............ • ...........
-- - -. . ... . . . . . . . . . ... ............ .. .......... I ------------- I ------------ -- -- ... ... ...
... .. -- -- - ....... ...---.......... .. -- - -- - - .. .......... •............ r........ .... ............
18 20 22 24 26 28 30
.0
00 00 r
-100
-200
-300
-400
0000 (CL-1A Pump)I 0000 (CL-1B Pump)
-------- -------- ---------------- --------I -----------------
~~ii
-- -- -- ------------ ... . . .. i............ :-............ :..............:.............• ............
- - - - - - ------------ -----------..---... ........- ... . . . ........... ............ •.............
......................... ............ ............ i ........... .........................
-.. . . . . . . . . . . . . . . .............. ............ ............ ----- ---- - ---- --- -- --- -- --- --- -- --- --
-400
FIGURE A.2.10: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Broken Loop Cold Leg Flow Rates
600 ; _ ; _ _ ;
0-0 Filtered MFLOWJ-26501 000000 (CL-2A Pump) A-A Filtered MFLOWJ-28501000000 (CL-2B Pump)
5 0 0 -- . . .. .-- . . . ...---. . .. . ..--. . .. ..--. . .. . . . . . . .. ..-- .. . .. . .-- ---- ---- --- --- --- --- --- I ------------ I ------------ -- --- -- ......................... -- --- -- ------------ -- -- -- - ... ... ...---... ... ..
300 ..................... --- ---------------
.. ' ' 200100 ----- .. .. ------- ....... ---------------------------------- ------- . ..... .... . .. . -----
_ 1o o .. ..".. ...------------------- ---------- -------------------T -------------- -- --- -...... ..... .....
000
10 12106 18 2 2 4 2 8 3
0 - -I (hrs)
S100 , - ... - - - - - - ------400
0 0 1 4 1 i 0 2 4 2 8 3
Tie0hs
I I
FIGURE A.2.11: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Loop Circulation Flow Rates at Hot Leg U-Bends
20 0-0 Filtered MFLOWJ-1 2001000000 (Intact Loop HL at UBend) A-A Filtered MFLOWJ-22001000000 (Broken Loop HL at UBend)
10--------. ------------------------------------------------------------------- ---------------------------------
10----------------- ------------------------------ T------------ ---------..
00
04
-0 --' - - - --- -------- --- -
-10 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
FIGURE A.2.12: 0.007 ft" Cold Leg Break at RV, DC stratification at CL bottom Core Inlet Flow
600 a- Filtered MFLOWJ-31302000000 (Lower Plenum Flow near Core Inlet
500 .... .... • ..... .... ', .... .... .!.... .... .. ,... .... ...--.. .... ....--........... . . . . . .. I ------------------------------------------------ .. ..... ... -------------------------
3 0 0 ......... -- -- ----------- -- ----.... ... ...- ....--. .... ....- ,... ... ...- ,. ... ... ..--.. ... ....- ,-... ... ...--........... -- --- -- .. .. .. .. -- --------- -- ----- ------------ ------------.
200 ................ ...1 ............... ."......... ... ......... .............. ---............-'-....... .....-"- .............---.. ......................-"-...........---...........
03
C4 100----------....I.......r-......I------- -----
S'0'
,. -100 ....... ................. . .... . . . . . . . . .. . . . . .............................
f¢• ..... ...... ------ ------ -------I.....F ................ ......... .....................
0
k -20. ...
-300 -------------.-------- -------------------------- - ......................... --------- ------------------------
S -500 .............. .. ....I.--- --- -- -.I-.--- -- --- -- --- -- -- .-- -- .-- -...---- -- --.......................- -- ----- ---- - -- ---- - ....I. .. .... .... ...
-600 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
FIGURE A.2.13: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Reactor Vessel Temperature Distribution
800
700
600
~5(0
S400
300
200
100
- -- - ---. ".- -- -- ------.,- - I --- ---- ---
18 20 22 24 26 28 300 2 4 6 8 10 12 14 16 Time (hrs)
0-0 TEMPF-30301 0000 (At a-a TEMPF-310010000 (UF 0-E TEMPF-318010000 (Lo
* A-A TEMPF-324040000 (Lo .TEMPF-314010000 (Lo x-x TEMPF-35201 0000 (Ur * SATTEMP-35201 0000
-------------- ------ - -----
b P )V
•v
)v
P
-- -------- ~ ~ ~ ~ ............ ........ ........ .. ............ .... ..... .. .................... ...... ...................
- - - - - - -- - - - - - - - - -- - -- - - - - - - - - - - - - - - - - -............. . . . . . . . .,. . . . . ---- --- ---- --- --- ---- --- --- ---- --- ---
ove Nozzle Belt) per Nozzle Belt) wer Nozzle Belt) wer Downcomer) wer Plenum at Core Inlet) per Plenum at Core Outlet) ------. . . . Upper Plenum Tsat) I
.............---------------------------------
-- - -- - - -
---------- -------
-- -----------
-- - -- - - - - - -
(ssq) OwIL Oc 8z 9 l OZ 81 91 tl Ui 01 8 9 17 Z 0
------------ ------------ --------~~~~ ~ ~~~~~~~~~~~~~~~-- ---.. .. -.. .. .. . -... .. . . --- - -- -- - ---- -- -- --- -- -- - -- -- - - ----- - -- -- --- -- -- -- - -- -- - -- ---- - -- ---- - -- - Og
.......... -------------------. ........................................ -----.--.-.----------------.----------------------- -----------------..---------
............ ............ -- -- -- - -.-- - -- - -- -- - -- ---.- - ---.- -- - -- - -----------.... .... ..... ..... ..... .... ..... ..... ..... .... ..... ..... ..... ...- ............ -- - - - -... .. .. .. ... .. .. .. ... .. .. .. ..
............ •................................... ---------------------------.....------------------------------------ -- ---------- ------------- ------------- CD
............. "............ i........... "........... ,................ ......................... I- ------ I......... i ... I............. I........ • ............ • ..... I....... -. ............ I, ............. o0 1 CD
............ • ............ -........... :....... :-............---............- -............ -........... I. . ... . ... I............ I............ - -----------...... ... ...- Z*T
------------,. . . . . . . . ..- - . . . . . . . ..--. . . . . . ..---. . . . . . . .... . . . . . . . .... .... . . . . . .... .... . . . . . . .. . . . . . . . ...- -. . . . . . ...-- -. . . . . . ..... .. . . . . . . . .. ... . . . . . . . ., -... .. . . . ..-... . . ...
------------. .............. ,........... -. ........... ............. I ............ -- --- --............ ........... • . ... . . ............ I ------------ --- -- --............ L . ........... -. .. ......- ...... " -------------------- ------------------------------------- ------------ --- --------------------------- ------- ---- T 9.
I III I -..-...-.... ------- ------------ --......... -...... ... ........... ....................... ............ ------ ............ . ...... ............ i............ ------- ------------ --...... - -- - --- -- -- - I- -- - - - - - - - - - -
(OMOd WO0 poziWiON) ZO" 1./00 . 69S-U VA-II.NO G
07
uOltJu9o flaXOd o0D Poz!WI.UJON
tuoljoq -ji pu uoijuji!uals Miu 'A l Il w 0I 2ag p1oj Z$j LO0"O :I'UzV 31Hfl9DII
FIGURE A.2.15: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL bottom Deborate Accumulation Due to Steam Condensation in SG
00 0 I & ---o CNTRLVAR-137 (SG-1 Deborate) B-- CNTRLVAR-237 (SG-2 Deborate) 0-c CNTRLVAR-238 (Total Deborate)
-1020 00 --- ---------.I ------------------------------------------------------------------------------.-----------.4.--------------------------------------------------.j.-----------.4.-----------------------
_20000 .. .. ............... .. ..I- -----I- ------I ............ I ------------- I ------------- I ........... ... ... .... .......... I ------------- -- --- --............,i ...... I ----- ---- ------............ ............. ..
-10000 .. ...--- '----------- - ------ ---------------- -------- --- '- " - - --- ---------- --------- --- --------
-0000 .. . . . . . .. . .I
S. . ..I.. . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .I ....... .. . . . . . . . . . . . .. . . . . . . . . . . . . I.. . ." . . . . . . . . . . . . .
-6 00 ------- -------------- ------- ------------- ------------------- I ------- I -------------------- -----------
.0
U¢
-7 0 0 0 0 .. .. ... -- --... ... ... ... ... ... ------------.. .. .. .r .. . .. .. ............ -- --- -------------- -- --- -- ............ I ------............ ............. I --- --- --- ----- --- -- I ............ I.............. .. . . .
- 800000 ....... ......-. --------.I.-.-.---------.I ............ -------------.I.------------.I...............I........... .Y ..---------------------- .--- -------- .----------- .-.------ ---- .------------ .----------
052'
- 0 0-- - ---------- --------- -------------------------- -----------------
10 00 ------- ------ ...... I ----------- ------ ------- I ---- ------ --------- I ------
-60000 0 2 4 6 8 10 12 14 16 18 22 24 6 28 30
Time (hrs)
FIGURE A.3.1 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline System Pressures
2400 2..e-e P-352 (RV-UP-1)
a-a P-670 (SG-1-Sec) 0-0 P-770 (SG-2-Sec) S)............................................ ---------------............... ------- -------------........ ----- ------------..............
.. A-a P-897 (CFT)
2000±
.. .. .r . . . . ............. -------------------------------------- ...----------- .----------- .--.--------- .-.--------- .--- .------------ .------- .----- .----- .------ ...........-- ............- -...........
No Operator Action, HPI injections next- to RC Pumps
---1- --6 0- ------------------------ ---
1600 ...... ... ......... .......... ------------------------------------------------------------------------------------.........................-"..........--.......... -------------------------
O 8100 --------------- - --- --- --------------- -----............ ..................................... .................. ...... --............ - ------------ ..................... ...... . ............
0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
'I• • I I:
80
60
18 20 22 24 26 28e10 12 14 16 Time (hrs)
FIGURE A.3.2 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Intact Loop Collapsed Liquid Elevations
0-0 CNTRLVAR-100 (HL-1 Collapsed Level) I--• CNTRLVAR-140 (SG-1 Tubes) 03-0 CNTRLVAR-151 (SG-1 Above Tubes)
i-CNTRLVAR-614 (SG-1 Secondary) I -- -- .......... ---.......... ............ I -------------............. I ............. I ............ - -. . - I - I 4 CNTRLVAR-408 (Pressureizer)
................ .............. ....... ....... ..................................... ............................................................... ---- -........................ .. .. ...
L .. . .. . -- - - - - - L .. . .. . . .. . .. . . .. . . . . . - - - -- - - . . . . . .
400
%Z
20
030
i ! I I
0
FIGURE A.3.3: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Broken Loop Collapsed Liquid Elevations
80 ..... CNTRLVAR-200 (HL-2 Collapsed Level) o-e CNTRLVAR-240 (SG-2 Tubes)
CNTRLVAR-251 (SG-2 Above Tubes) CNTRLVAR-714 (SG-2 Secondary)
.............------- I-------I------------
60 : 6 .......... I ........... . . . . . .I ............------------------------------------------- ------------ .--------------------- ..I.------------ .I.------------ .------------ ............. ............. 1-...........
..................... iii.. ........... ............. ............. ...............I ................ ........I ............I .........................-------I -------I ............ 20~ ~~~~~~~~~~~~ ~ ~ ~ ~ .. .. ....... ......... -- --- ---- ---- ---- --- ---- ---- ---- ------ ------------- ------------I- -----............ ............ ............
2 0 . . . . .r . . . . . .• . . . . . . . . .. .------ -- ---- ------ :.. . . .. . . . .. . .. .. . . . . .. .. .. . .. . . .. ...- -------------------.... . . . .. . .. . .. .... .. ..... . . . . . . . . . . . . . . . . . . . ... .. .. .. .. .. " .. . . .. .. . . . ." . . .. . . . .. . . .-----
0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
i ii I1 f I I [ I
FIGURE A.3.4 : 0.007 ft' Cold Leg Break at RV, DC stratification at CL Centerline Total Vent-Valves Flow Rate
600
[-• Total Vent-Valves Flow from cvar-337, filtered and smoothed)
.................................................--- --------I------- 1 --------....... .... ...------------I------------------------------
............ . . . . . . . . . . . .....- ........................................................................................... . . . . . . . . . - - - - - - -..............................
400 -- - - - --- - - - - - -- - - -- ..... -----. . . . .--------- - ------------ ------.------ - ... ............ - -----------------------E
--00 ... .. . ..-- . .. . ..--. .. . ...- ,.. . .. . ..--. .. . .. .. . .. . ...--.. . .. ..- . . ..--. .. ,............ ,............ I ------------ L ---- ------I- ------ ------- ............ L .. . . . . ............. -- --- -- -----------
3 0 0 -- - - - - -- - -- .. . . . . . - - - -- - - -- - - -- - - - - - - - - -- -- - - . . . . .. . . . .4 - - - -- - - -- - - - -- - - - - -- - - -
00 O
" " >5
•1 2 0 ........................................................... :....................................................... ............ . ......
---- .. . . .-- . .. . . ."-. . .. . . .-. . .. ..---. . .. ..---. . .. ..---. .. . ..- :. . .. . . .4 . . .. . ............. -- - -- - - ------------ --............----- "-- - ----- ----- -- - -- - - ............ ------------.
; S S ',S,, . .
'• 100 ----- .. . . . . ......... ------- --------
---- ---- ---- --- ---- ---- ---- --- T .. . . . . .•. . . . . . . .. . . . . .. ..........- ... .... .... .... .... .. .. .... -- --- --- --- --- ... .~~~~~~~~~~~~~~~~~~~~~ .... ...... L -------- ----.............. -- ---.... ... .......... ------- -------...........----------- --------------------
............ ........... ------------. ............ -- - ---- -- ----- ----- --... . .. . -.. . .. ..--- . . . ...--. .. . ..--. . . . .. . . . .. . . . .. . . . .-- - -- - - ------------ -- - - - - -- - - -- - - -- - - - - - ------------ 4 ---- --- --- --- --- --
-100, 0 2 4 6 8 10 12 14 •16 18 20 22 24 26 28 30
Time:(hrs)
FIGURE A.3.5 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Vent Valve, Upper Plenum, Upper Head Voiding
1I1)G-0 QUALS-36901 0000 (Vent-Valves Static Quality) &--e VOIDG-369010000 (Vent-Valves Void Fraction) o-e VOIDG-35201 0000 (Upper Plenum Void Fraction) A-A VOIDG-39001 0000 (Upper Head Void Fraction)
1.0 . . . ... .
S0 .8 ..... .. . . . . .. . . . . .-- •---- ---... .... . ... -- ----- ------ -- --- ---..-- ---- -..--- ---.-- -----.-- -- ---I-- --_
~L0.
00
S0 .4 .. .... ... . . .-.. . . . . . . . . . . . ,. . . . . . .-- ---. .. . . . .. . . .-- ... ... ... -- -- ------... -- .. . .. . .-- - .. ............ ................ .... --.-- - ------- ---- ............ -- ---I............-- --- -
0
r• 0 .0 1 ...... -- ----- -- ----- ---- ---. .......................
-0.2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
200
180
160
140
0 120
V.*
100
"Cl 80
. U 60
2 4 6 8 10 12 14 16 Time (hrs)
18 20 22 24 26 25 iU
FIGURE A.3.6 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Total ECCS and Break Flow
-CNTRLVAR-601 (Total ECCS Flow) B-B MFLOWJ-501000000 (Break Flow)
- - - - - -.. . . . . . . . . .. ............. --- - - - -- - - - - - -- - - --- - - - - - - ------------------------------- ------------------------------, ............ . . .. . .-- ,----------- ------- -----------............ ---.......................... ............ . - -...............--.
------- ---- ------ ............ ---- --------- I... ------- --- ----I- -- --- ............ ........... ------- ............
-----------.-.- -------- --------------------------------------I.. . . . . . . . . . . . . . . ..= . . . . . . . . . . .:.. ............ .. ... ... ... ... ...--. ..........- ............L .... ..........-- ----------- -----
-.. . . ... . . . . .................................... " ............ " ------------ - ------------ --------- - - - - - --............ . . . . . ..........................-- -.-
------------ .......................................------------.---..-------.--.---------.I--------------.--.------.-..............----........--.........--------------------------------------
40
20
00
FIGURE A.3.7: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Break Flow Quality
1.2
FO QUALS-27501 0000 (Break Volume Static Quality
1 .0 ...... ..... ..... ..... ..... ..... -- --- -- ------------ -- --- --.. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .I .... .... ... . .... ... -- -- ..... ..... I --- --- -- --- -- --- -.. -- --- --I............
0.80 . ....... I --------------------------------- ----- - -.- I ........... I ....-------- 1 ------------ I ------------ - I - ........... -------------.------------- - -.- -- - - - - -
CY 0 0.8.. .. . ... •
0.4 ...... . ..----------- .-- - - - - - - - - - -- - - --............ - ------------ , ----------- --.........-- - - - -.-- - L- - - ......... ------ - - - - -- a I ............ ------------.. ...........
0 .0 . , , ...... ... ... ............ - ............
-0.2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (hrs)
S/ I I I t
FIGURE A.3.8 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Break Flow Temperature
800
700
600
• 500
400
0 300
200
100
0
eo-TEMPF-275010000 (Liquid Temperature) SATTEMP-275010000 (Saturation Temperature)
~~~~~~-- - - - - - -.. . . .. . . . . . . . . . . . . . . . . . . . . . . . .. ............ . . ......r--------.. . .. . . . . .. . .. . .. . .. . .. . .. . .. .. . .. ..--------.. . .. . . . . .. . .. . .. . ...-
----------- . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .- -- - - --- --- -- --- --. ....... .. . . • . . . . ... ............ . .. . ............... 1 - -- - - -- - - I -----..... ..... ..... ..... .....---
-- - - - - - - - - -- - - - - - - - - - -- - - - - - - - -.-- - - - -.-- - - -.-- - - - -.-- - - --.-- - - - - - - -- - - - - - - - - - - -- - - - - - - - - - -
----- ------ --------------------------.-..........- ............ ........... I ............ ............ ........................-- ........... I ............ I ............
0 2 4 6 8 10 12 14 16 Time (hrs)
18 20 22 24 26 28 30
S.....ý0 ....-4 "........... ..... -' -. - " -.. .. I ..- -- - - --: - .. . .. . .- --------.. 4 --- --- --- ......-- --
i i
FIGURE A.3.9 : 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Intact Loop Cold Leg Flow Rates
600 0-0 Filtered MFLOWJ-16501000000 (CL-1A Pump) A-- Filtered MFLOWJ1 8501000000 (CL-1B Pump)
400
500 .... .... .... .... ... - -------- ------ ------ ............ .. . . . . . . . . . . . . . . . . ..,. . . . . .. . . . . . ............. ............ L ............ -, -- -- -- ----- --- -- --- -- --- -- --- -- -L ------... -- - -- -- -- ---- -- -- -- -....---
4000 ------------.-.--- -------------------.---- .------ ....... .... . ........ ......:..... .. .............................. .---------- - ..----------- .-.---------.--- .-------- .-- - .------- .----- .----
3' 00 -----..-- -.--.---- --.-- ---- .-.-- ---- -- .- .---- ----................ ....................... . . . . . . . -- -- -.. .. .. .. .. .. .. .. .... .. . ........................ . .
.• 100 ------......................................... . ............ ..................................... .. ......................................
0
20 -- -- .... . ... ... ... . .... ... . ... .... ... .... ... ..............t ............ ,............ ......................... ............ ............zLt ............ -- - -- - - ------------.
o-10...............•
-100 ------ ------------ ------------------200 -
-400 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
FIGURE A.3.10:0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Broken Loop Cold Leg Flow Rates
600 ___
0-- Filtered MFLOWJ-26501000000 (CL-2A Pump) A--A Filtered MFLOWJ-28501000000 (CL-2B Pump)
500 ... .. ... .. ... .. ... .. .. ... .. ... .. ... .. ... .. ........................................ -- --- -- ------------.. ..... .... ..... ........................................... L........... -----
500------------------------------ ------------------------------------ - ---------- ----------- --------------------------------------
4 0 0 ... .... .. . ............ --- ------ -----.. .. .. .. .. .. .. .. .--... .. .. . --. .. .. .. . . .. .. .. ..--.. . . .. ..--.. .. .. ..--.. .. .. .. ........... ............ -- ----------- .. . .. . .------- ............ ---- ---- ---- -- -- ---
400- i 4 ii
0
10 0
• 0
_200o ------.-------.------.........................................-----.-.I.---.-.------.-------.-----.I.-----.-.----...----. -.... ---.. .------- .-.
_300o ---- -- .--- ..---- .--- -........ ........ ......................... ................ ........ ........----------.-.---- -----.--- -.------............. , --------- -.------ ----- ..--------
-400 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
FIGURE A.3.11:0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Loop Circulation Flow Rates
20 -0-4 Intact Loop Flow at Hot Leg UBend from cvar-459. filtered and smoothed) x--x Broken Loop Flow at Hot Leg UBend from cvar-460. filtered and smoothed)
... ....... ........... I.............I--------. ---. ----.----------------...-------..--------..----------------..------ ------ -----------
1 0 --------- - - - - - - - - - - ---- - - - - - - - - -.......... .. --- --- --- - - - - - - - - - ------------- ------------ ........... ........... ......... , .- -- 4 ------ - -- -----------
0 ......... ........ .• ! ,• = i = i • •• ........... •............. I -----------
00
-10 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
! ! ! I I [ !/I
FIGURE A.3.12: 0.007 ft Cold Leg Break at RV, DC stratification at CL Centerline Core Inlet Flow
600 ;
- RV Lower Plenum Flow from cvar-458 (J-313-02), filtered and smoothed
........... . . . . . . . . . . . . . . . . ............. -- - -- - - ------------... ... -- - - - - - - - - -- - - - - - - - - ........................ •............ ...................... . ........................................
500-------..
4 0 ........... F . . . .... -- - - - - -- - - - - -.. . . .. . I ............ {.. . . . . . . . . . . .. . . . . ............... I - - - - - -- - -- - - - .. . .. . .-- -- - - -- - - - - - . .. . . . . . . . . .............. I ------------ -- - - - - --- --- --- -- --- --- -- I -----------
S400- ....................... . .. .... . . .......................... . . . . . . . . . . . . . . . . . . . . . . . . .........................
------- .............. I ....... I ---------------
3 0 0 . . . . . . ...- - . . . . . . .. . . . "•. . . . . . . . . . . . ------- -------- -- --.. . . . . . .. . .• . . . . . . .: . . . . . . .. . . . . . . . . . . .----- --I. . . . . . . . . ...- ------------- . . . . . . . . . . . . . . . . . . . . . . . .------- . . . . . . . . . . . .------- -------. . . ..
-' -----------------------------------------------.----------- .... . . . ............ ............. . . . . .-- ---- I............-- ------------ ... . . . ............ I ........... . ............ I ------ ............ ýA 00 - -- - - --- -----.... ..
S10 0 - - - - - I- - - - - - - . . . . . . . . . . . . . . . . . . . . . . . . . .- - -------- ------. - ---. ---- -------.- ------- --.-.- -- -------. .- -.- -- -----.. .. .... ... ....I.- - --.- ----.. . .- --- ---.-. .- -------- --.I. .-.- -----
-..---------- -----------. .............. ................ . .. . .. ....... ...--- ---.... . .......... ....... ..... -------------------------. ,, ............ , ........... -- - -- - -... ... ...---... ... ..
a.), .' , . O
.. . .. . .-------- ---- --- ------- -- .......... -- -- - - - - ------------... .. r.. .. .. .. ............ ............ . . . . . . . . . . . . .-- - - - - ------------..... ...... ...... ..... ...... ...-- ............ - - - - -
-100
0 2 4 6 8 10 12 14 1'6 1'8 2'0 22 24 2'6 28 30 Time (hrs)
FIGURE A.3.13: 0.007 ft' Cold Leg Break at RV, DC stratification at CL Centerline Reactor Vessel Temperature Distribution
800
700
600
CO.D
500
400
0 2 4 6 8 10 12 14 16
Time (hrs)18 20 22 24 26 28 30
I I I I I I
0-0 TEMPF-30301 0000 (Above Nozzle Belt) o-Ea TEMPF-310010000 (Upper Nozzle Belt) 0-0 TEMPF-31801 0000 (Lower Nozzle Belt) A-A TEMPF-324040000 (Lower Downcomer) STEMPF-314010000 (Lower Plenum at Core Inlet) x--x TEMPF-352010000 (Upper Plenum at Core Outlet) *-* SATTEMP-35201 0000 (Upper Plenum Tsat)
"---------L ---.----.---------------------------------------------------- ........ ---------..----------------
- - - -- - -------------,. . . . .. . -. . .. . . ..- ... . . . . ; . . . . . . . . . . .. -- -- -- -.. . . . . . -- ------- . . . . . . .; . . . . . . . . .. . . . . . .. . . .., , . . .... .--- --- -- --.. . . . . . . . .
S......... - ........- , ......... I ........ ÷......... •......... - ........ .......... . ......... T ........ r ........ , ......... , ..................-- ........
I-' 0 0*�
300
200
1inn100
(ssq) omq!± OE s 9z vt z o 81 91 171 ti 01 8 9 V7 Z 0
7'0
------------.. ............. ........... ......................................- ---........... ----.......... . ...................................... ............. ............. .......................
........ . . . .. .. .......... .... ....... ... ... ... ............... ............. .......... .-----------.- ----------. .- ---------.- -.- --------.- --.- ------.- ---.- -----.- -----.- --.- ----------- 9
S............ ------------ . . .. . • . . .. . . . .. . . .. .. . . .. ............. .. . . . . ---- --- --- --- --- --- ------------.. ... .. -- - - - - .. . .. . .-- - - - - -- - - - - - .. . .. . .- --- -- -- --- -- -- - -- -- -- -- -- - - - - -- - - - - -....
---- --- --- ---- --- --- ---- --- --- ---- -- ------ -----
S............................................. ............ I ............ ......................... ......................................... I . .... ............ •'[ 0
~~~~~~~~~~~~~~~~~~----- ............................ .............................................. ............................................................ -- '-
... .. ................................... ............ ........... ............. I......................... ............ ............ ............ . ..........................---- - I
-- -----------.......................... . . . . ... . . . . . . . . . . . . ........................... ............ ........................ ............ ......................... ............" "
..................................... L ............ J.............• ............ •.............L ............ ........... J............... ............ A............ L............. L .................... ..
JOMod e20o peZIleWJON) 1.00 I. L 696- VA1IJNO 0--0 0"7
U1O•o IuQ9 IAXOd Q0OD pPz!IUWION au!jlJaluaD3 1j J UO!JBIJB!lJJs iu 'Al lf a l ploD ZjJ LtOOo :FIEV 3HI9DIl
'm II ] i I! I ] ]} I Iz
I I
FIGURE A.3.15: 0.007 ft2 Cold Leg Break at RV, DC stratification at CL Centerline Deborate Accumulation Due to Steam Condensation in SG
0G- (CNTRLVAR-137 (SG-1 Deborate) 3-s CNTRLVAR-237 (SG-2 Deborate)
C CNTRLVAR-238 (Total Deborate)
-10000 ..-......... I ------------------------ 4 ---------------------------------------------------------
-00-------------------------------------------------------- ---------------------------
-40000------------------L------ --------------- -- - --200000 .---- .------- ................. .---------.-.-------.-..----------------------------------------------------------------.------.. --.-. -----.-.. -. ---------. ---... -.....................
-400000 -----.-.----.-.---------.-.-----------------------.........................-. ----------... ......... .... ......... ---. ----------------------.L..... .........L.-.-.--------------------------------
Si
0 0- 6 0 0 0 0 .. .. . .. .. . .. . .. .. . .. . ------------.. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...............-- -----------............
-50000--------------- ....------------------------------------- --------
-1 -60000 ------------ - - ' - I...........-- L............ ............ I ------------- I ............ 0 .....................................-- ............ .
-100000------
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (hrs)
I
FIGURE A.4.1 : 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). System Pressures
2400
2000
1600
- • 1200
800
400
00
4
2 4 6 8 10 Time (hrs)
12 14 16 18 20
1 1
0-0 P-352 (RV-UP-71) a--a P-670 (SG-1-Sec) 03- P-770 (SG-2-Sec)
. . .. - P-897 (CFT)
Oprator Action at lOir of openinmg high oint Vents f@r about 45mi 4 . . . . . . . . .-- - - - - - -- - -- -- -.. .. . -- - - -.. . . .-.. . . . . .. . . . . . . . . . . .4 ---- -------- ---- ......... ......... .I ....... .. .... ... .... .... I ......... . . . . . . . . . . . . . . . . . . . .
----- ..-- .--------------------------- ---------------------------........... . ........ ......... ,......... T. .... . .• ......... I ........ I ......... -- - - - --------.............. ........ I ........ .
.. ................ . . .... ..... .......... i........ ........ ......... -- ---------. ".......... .... .... ..... .... .. ... .... ... .. .. .. ...
.........
...... ..... ..... ................ ...!....... -- ----- ----- --- ................... ....L --- ---- .... .. ....... ...... ........................... .................... ........... ---------.
FIGURE A.4.2 : 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Intact Loop Collapsed Liquid Elevations
80
60
0 1= 40
20
0
G-e CNTRLVAR-100 (HL-1 Collapsed Level) 8-E CNTRLVAR-140 (SG-1 Tubes) 0-0 CNTRLVAR-1 51 (SG-1 Above Tubes) A--A CNTRLVAR-614 (SG-1 Secondary)
* ......... . . .... ......... - -------------------------------- - -------- - --------................ ... .... I CNTRLVAR-408 (Pressureizer)
U 2 4 6 8 10 Time (hrs)
12 14 16 18 20
I I I I I I I II I
FIGURE A.4.3 : 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Broken Loop Collapsed Liquid Elevations
80
60
0 "-= 40
20
00 2 4 6 8 10
Time (hrs)
0- _CNTRLVAR-200 (HL-2 Collapsed Level) a-a CNTRLVAR-240 (SG-2 Tubes) 0- CNTRLVAR-251 (SG-2 Above Tubes) A-6 CNTRLVAR-714 (SG-2 Secondary)
I. . ... . . . . . . . . . .. ......... I ........ I ... .. .. .. ... . . .. .. I -- - - --.--- - .-- - - -I.- - -- - - -- - - - -- --.. . . ...... . ... I. . .. .I.. . . .
...... . . . . . t , 2......... -- - - - - - - - - - - - - - - - --------- -- -- - --------- -- -- - .................. . . . . . . . . . . . . . . . . . . .......... .........
, ....................... ...... ..... ...... ...... ....--...... ...... .. --....... -..... .--... ....-- ......-- ... ...-- .......-......-.... ....- ......-..... ...-.. ...... ...... .-.... ....-12 14 16 18 20
I 1 1. 1
I
FIGURE A.4.4 : 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Total Vent-Valves Flow Rate
600 00- Total Vent-Valves Flow from cvar-337, filtered and smoothed)
500 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~---- .......................................................................................................................................
5400 -............... 400-------
5 ------ - --------- .......... - I - - - ---------- I ......... - - r- I --- ---------...........................--................. • --------- -------- I ........
--------J---------------t ......... I ......... ......... .....---------------------------
0
I ....................I..........I.----------------------------------------------------------. ---------------------------.--------.---------.--------.--------.-------- ----- ....................
- C.)
0 ....... ....... I ......... L, ........ •......... ;... ...... . ...... ........ . .. A_ --------- .I -----.. •. . . ..,. . . . . . . . . .. ...... . ...... . I --- -- ----- --- -- A ---------- I ......... I. ---------.... ..
--0 .. .. .. ---- . . . . . . . . . .".. . . . . . . . . . . . . .. . . . .. . . . . . . ... . ... ......... .. ... ... ........ • . . . .. -- A.. . . _ ......... I .. .. ..--.. .. ..--.. .. .
-- 200----------------
-100 0 2 4 6 8 10 12 14 16 18 20
Time (hrs)
S i• III I I I I
FIGURE A.4.5 : 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Vent Valve, Upper Plenum, Upper Head Voiding
1',
0-0 QUALS-36901 0000 (Vent-Valves Static Quality) o-a VOIDG-369010000 (Vent-Valves Void Fraction) 0-E VOIDG-352010000 (Upper Plenum Void Fraction) A--A VOIDG-390010000 (Upper Head Void Fraction)
1.0
0
10.4 0.- -. . .. .. . . . . . - --
... ... .. .. .. -- --- - ... . ... . --- ----.. -- ----......
-0.2 -0,
0 2 4 6 8 10 12 14 16 18 20 Time (hrs)
(siq) oingl 0z 81 91 V7 ZI 01 8 9 V z 0
0
----- ----- ----- 09 - S S S S S I ~a
..............--- -S - - -5- - - - -- - -- ----- --------------- - - - - - - - - - -- - - - -
--- - ---- - - ---- .......--------- I ---------------------- I ----- I ---- 08 P. S
, ',
001 S...................................................................................................................................................................................-----...-----:009
.... .....I. -----. --. -- ---- --- ---..... ....--- ----.-- ---- --- -----.- ---- --.-.-- --.- --- ---..- -- ----.-- --- --.- ---- --.--.- --.---- ----I ------'I........... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .I -- --- -I --------'7 0
M0d 0 8J 000600010 rMld'JsI(Mold So003eo 1-0 [9 UVAUIiNO &-0
MOld t3ifl Pmt sMH WMIQL (qj lie peuado SAdH) uoipy aowndo p'w 'jueig 2rI pgoj I £oo:* 9f V 3HfDII
I I
1.2
1.01
0.8 1
) 0.6
o 0.4
0.2 I-
0.0
-0.20
FIGURE A.4.7 : 0.007 ft Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Break Flow Quality
:10-0 QUALS- 275010000 (Break Volume Static Quallty)]
.. . . . . . ............ ........ ......... ........ .................... j --- --- --- --- -- -- -- - -- -- --.......- - -- - - -- - -- - -.. . .. . .. . . .. . .. . .. . . .. . .. . .. . . -- -- - --------- -- -- .. .. .. .. .. .. .. .. .
S.. . . .T. . . . .r. . . . . . . . . . . ." . . . . . . . . . .... " ......... -- -- ......... ;......... -- -- - j. . . .-- - - -"-- - - - - - - - - - -- - - - - ........ " ......... L --- -- ----- -- -- I' -- -- --..... " ......... "........ ".........
- - - -- - -- - - -- - -- - - -- - - -- - -- - - -- - - -- - -- - - -- . . .. . .. . . .. - - -- ---- - -- - - -- - -- - - -- - - -- - -- - - ---- -- ---- - - - - - - - - - - - - - - -
: E E e E e E E E a
2 4 6 8 10 Time (hrs)
12 14 16 18 20
P
FIGURE A.4.8 : 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Break Flow Temperature
800 80--e TEMPF-27501 0000 (Liquid Temperature)
-SATTEMP-27501 0000 (Saturation Temperature)
Ei
3 00 -------- ... .. -- -- - -------. -.. . .. I ........ ,. . . . . . ............. .................. ... ......... ,......... -------------------------------.......... . . ..... .........
1300 ------------------------------------------------------------------------------- I---------- -------- -------- --------
200
100
0 0 2 4 6 8 10 12 14 16 18 20
Time (hrs)
1 I•!I [ I
FIGURE A.4.9 : 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Intact Loop Cold Leg Flow Rates
6006 600 I I 0-- Filtered MFLOWJ-16501000000 (CL-lA Pump)
A-• Filtered MFLOWJ-18501000000 (CL-1B Pump)
500 -------------------------------i---------------- ------I--------------I-----------------------1----------. .........
4 0 0 ... .. .. ... I -- - - - .- - - - -q- - - - - - - - - - - - - - - - - - -I - - - -- I-- - - - - - - - --1- - - - - . . . . .. . . . .. . . . .. . . . . .. . . .. . . . .. . . . . . . . . . 300
100 .... . -. . ... • . . . . -. . . . . . . . . . . .- . . . . . . . . -. . . . . . . . . . . .......... ......... --- -- - -------......... -- ----- --- ........ ...... . :........ -- -- - -------. -- -........-- -- ,-- - ---- --- ---- --,0,
3 0 00 .........I..... ......-- --------.I.-- -----.I.. .... .....I. ........I... .......---------.-- ------.-- ------ -------.-- --- ..........I.-- -----.I.-- --------.-- ---.-.- •-- ------.-- ------.-- ------.-- -----
-2 0 0 ----------... .. ... .. ... .. ... .. ... .. ... .. ........... ........ -- --- -- ----I- ---. -................ ....... ....... ........ ....... ....... .......
-.a •
-40
o 0
0 2 4 6 8 10 12 14 16 18 20
Time (hrs)
FIGURE A.4.10: 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Broken Loop Cold Leg Flow Rates
600 3 3 0-0 Filtered MFLOWJ-26501 000000 (CL-2A Pump)
6 A--A Filtered MFLOWJ-28501000000 (CL-28 Pump)
500 -------- ....................I.... .................. .................... ......... . . . . . . . . .................... - -- -- .. ---------
300 .......- :. . .... t ........ ---------------- ..---------------------------------------------- .----.-.----------- ..---- .- . .-------- .--------- .............................+- .... ...--- .........- -.......- -........
t• 200 ... ... -- .. . . .. . . . . . . . . . . . . . ......... --- ---. .. -- ----- ---------- -------- .. . . .......... -- :-- -- . .... ......... :......... . . . . .• ........ -- --- ---- --- ---- --
, 10 0 -------- ---------- I -------- I ---------- -------- ... .. . . " ...................... .......... 4200 ................ , ...
030
~0
- 3 0 0 ----.... .... ..... ........ ....... . . . . .------ . .. ...--.. .. .. .. ... . . .. ...- --- - -- - -- - -- - .. . ...- .. . . ..-. .. . . .. . . . . . . .. . . .. . . ...- --- -- - -- - - - --- --- -- - - - --------- -- -- - ---------....
-400 0 2 4 6 8 10 12 14 16 18 20
Time (hrs)
FIGURE A.4.11: 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Loop Circulation Flow Rates
100
80
60
10
-- -- -- -- -- -- ..... ..... .... .. . . . .. . . . --- - - -- - - - .................. .................... - - - - - - - -
-- - - - - - -----. . a. . .r. .. . . . . . .. . . . .. . . . ................... • .................. -- - - - - - - - - -- - - - - - - - - ------------------- ------------------.
12Time (hrs)
14 16 18
*----o Intact Loop Flow at Hot Leg UBend from cvar-459. filtered) A--A Broken Loop Flow at Hot Leg UBend from cvar-460. filtered)
-............................................................................ - --------------------------------------------------------------------------.- - -L-----------
....---------- i... ---------------- - - -- S - - - - - - i
I ~I I
--------- --------------- ------------------ ------- ------------------ ------------------ ------------------- ---------~5--------
------------------- ............ ..... ............... ----------------------------- .-. .. - - ------------------- ..................
. ........... ................... .............. -------------------.. ... .. .... ..................... i.......... : ..... ..... .... ..4 ... ..,0
0a
40
20
0
-20
-408
------------------ .................. ------------------ ------------------ ------------------.................. .................. -------------------
"1"
FIGURE A.4.12: 0.007 ft Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Core Inlet Flow
600 [-- RV Lower Plenum Flow from cvar-458 (J-313-02), filtered and smoothed)
500 ........... ............................................................................................... -------
500 ------------------------- ------ -- -- --------- --- a----
5 0 0 ....--------------------------- ....---------------------.-------- ...-------------- .----- ..-------- ...................... ---------, ---------- ------------------------------- ...-- ........ -........--........
2 400
00------------------ --------- -------- --------- --------- I---------- --------- -------- -------- *
---00-------------------------------------------------------------........- ------.. ......- -----.- ------ ------......... .......- -----.- ------ .............------.- -------------------.- ----
0
N))
2 0 0 ---- --- .-- .-- .---- --------- .L ..-.------ ----- ............. .. ..... ..... -- -- - - .. .. .-- -- -I....- .------ ---- ------- -- ----- .--- ...... ..................----- .......----- ........ --...... .... .. ...... ...... ....
-20-----------------..----------------.---.............------------------..----------------.--------.----..--.-----.. -. -------... --------.. -------.... ------........................
0 0 - - - - -I- - - - - --- - - - -- ---- - --- - -- - ----
0
0F, 2 4 6 8 10. 12 1.16 . 8.2 ------------. . . . . . ...-- --. . . ..Ti me... . . . .- --- . . . . . ..(h r s . . . . . . . . . -------. . .. . . . . . . . - L.. . --------. . .. . . . .
-100 0246810 12 14 16 18 20
Time (hrs)
FIGURE A.4.13: 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Reactor Vessel Temperature Distribution
800
7001-
600
c,,
500
, 400
300 1
200
1000
0-0) TEM PF-30301 0000 (Above N &--e TEM PF-31 0010000 (Upper N 0-0 TEMPF-31 8010000 (Lower N A-A TEMPF-324040000 (Lower D
,4-4 TEM PF-31401 0000 (Lower P x-x TEMPF-35201 0000 (Upper P
-*SATTEM P-35201 0000 (Unne
ozzle Belt) Dzzle Belt) ozzle Belt) owncomner) enumn at Core Inlet) enumn at Core Outlet) rPlenum Tsatl
---------. . . . .:. . . . .".. . . . . . . . .• ...... ". .......... ---------- --- --- -- -- --- -- -- -- --... . .--.. .. --.. . ..-- .. . . . . .. .......... -- - - - -- - - - ........ " ........ -- - - -......... --.... .. " -.... ..
-- ------- ------ .... ... ... ... .. . ... ... ... ... ... ... - .. .. ... ... ... .. ... .. .. . ----- --- -
S. .. . . .. . .. . .. . .., . . .. .• . .. .. , ........ I,. . . . . . . . . . . . . .--- --- --------- -- -- - --------- ---------. ......... -- --- -------- - -- -- -... .. .. .. .. .. .. .. .. -- -- - --------- -- -- -... ... ... ... ...
I * S S S S S S S S S S
2 4 6 8 10 Time (hrs)
12 14 16 18 20
i i i i ozzle Belt) ozzle Belt) ozzle Belt) owncomer) lenum at Core Inlet) lenum
at Core Outlet) r Plenum Tsat)
I
FIGURE A.4.14: 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Normalized Core Power Generation
2.0 =9-o CNTRLVAR-369 * 100/1.02 (Normalized Core Power
1.6 .. ..... ... ...................... .. . . . . . . . .. . . . . . . .....................• r -- ------ --- --- --- -- ..................... . . . . . . . . . . .• -- --- ,,. . . . . . ..................... , -- -------------- --- - ------ -------
16 ..
•,-4 124 00 ~~~~~~~~~- ---------....... ........... ... -------22 2 2 22 2 2 2 : 2 2 2 2 22 : 2 : i : i 2 2 2 : 2 2 : 2 2g 2 2 2 1 2 2 1 2 1 2: 2 1 2 2 2 2 2 i 2 1 2 2 1 2 1 2 2 2
a,)
0.8
0 . .. . . . . . . . . . . . . .. . . . . . ....................................................... .... .. . . .-. . . . . . .......................-- --------- ---------- ------ ----- ----................ . -- -- ... .. ... .. ... .. ... ..
ui
0.4 0 2 4 6 8 10 12 14 16 18 20
Time (hrs)
0
-10000
-20000
-30000
-40000
2 4 6 8 10 Time (hrs)
12 14 16 18 20
FIGURE A.4.15: 0.007 ft2 Cold Leg Break, Mid Operator Action (HPVs opened at 10hr). Deborate Accumulation Due to Steam Condensation in SG
* .__ 0 CN'TRLVAR-137'(SG-1 'Deborate)
's- CNTRLVAR-237 (SG-2 Deborate) ,, CNTRLVAR-238 (Total Deborate)
----------------- ......... ------ - --.......... . ....................... .............................................. ............. 4 .
--- --.. . . . . . ..- -.. . ..- ---i - . . . . .. . .- - ... . . . . . . . . . . . . . . .
.. ... .. . . . . . . . . . . . .. . . . . . . . . . .......... ... ........... ... . . .------ - ---- ------ ----.------ -.---- ----.------ ------ ------ ------ ----- ------ ------ ------ ---......... ......... ........ .......... .I.. .....
------ i - ----- ---- ---------------------------- ,--- ----..........--
- - - - - - - - -
.0
aS
0) -60000
-70000
-80000
-90000
-100000
-1100000
-500001
FIGURE A.5.1 : 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). System Pressures
2400 ..-. P-352 (RV-UP-1)
a-s P-670 (SG-1-Sec) P P-770 (SG-2-Sec)
"..........."........... ............ ------------ ------------ ------- .-P-897 0 FT2000-----------------------87-C T
2 0 0 0 .. . .. .-- - -- - .. . . . . . .. . . ..I -- - - - - I. . . . . .r. . . . . ............. I .. . . . . .I. . . . . . .I. ............... .... ...--.... .... ..--..... .....---..... .... .... .... . .... .... .. .. ..... ... . .... .... f---- -- -- ---- - - - - - - - -- - - - - - - -
Operator Actiqn at 25hi 20m, SO Blowdown at about 2019/hr
1600 ------ I------ ------ ------- I-------I------------------------------------------------------------------------------------------------
1200 ---- --- ---.I. ---. -- --.. --. -- --- - ------------ -- ------------- -----. . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................... -----
coo • 1200-------------.....
8 0 0 . . . . . . . . . . . . .. . . . . . . . . . . . ... . . . . . . -------.- --------------------------- ------------------------- -------- ------- --------------------
0 2 2 2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
l I i II II I I
FIGURE A.5.2: 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Intact Loop Collapsed Liquid Elevations
80 * e-- CNTRLVAR-100 (HL-1 Collapsed Level)
o--E CNTRLVAR-140 (SG-1 Tubes) $-O CNTRLVAR-151 (SG-1 Above Tubes) A--A CNTRLVAR-614 (SG-1 Secondary)
S.. . . . . . . . . . . . . . . . . . . . . . . ..... . ... . . ...-- ---- -- -----. . . .. . . .. .. . . . . . . . .... .. .r- ------r ------ . .. . . . . . . . .I . .. .. .. . . . . . .. .. .. .. . .. . -4 - C N T R L V A R - 4 0 8 ( P r e s s u re iz e r)
0 2) 49 60 8 10 12 14 16 18 20 2 26 8 3
6 0. . . . . . . .. . . . . . . . . . . .. . . . .. . . .. . . . . . . . . . . .. . . . . . . .. . . . ... . . . . . . . . . . . . . . . . . . . ..T. .m. . . . . . . . . . . .
-- ----------------------------- ...... .... .: j : .... •..... .-------- --------- I .......... I ..... :..... •... ..... I ------------ I ----- ........... I ............ I -----------
44
C11
.......... .......... ......... .....--- ---.-.---------- --------- -------- -------- -------- --------- ----.-.-------- "-- ----- ------.
20
0 210 8 t 12 14 16 18 20 22 24 26 28 30 Time (hrs)
FIGURE A.5.3 : 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Broken Loop Collapsed Liquid Elevations
80
60
40
20
0
0 2 4 6 8 10 12 14 16 Time (hrs)
18 20 22 24 26 28 30
I I I I I I I I
G-__ CNTRLVAR-200 (HL-2 Collapsed Level) a-a CNTRLVAR-240 (SG-2 Tubes) o-0 CNTRLVAR-251 (SG-2 Above Tubes) A-A CNTRLVAR-714 (SG-2 Secondary)
- -• - - - ----- i -r
----------- ----------- ---........ ...I.............I.... .........-- ---------..-----------.I..-.----- --- I ----- ------ r -- --------.-- -------- .I.----------- ----------
------------.-.----- ... . . . "............ I ............ ............ I ............. . . . . .. .. . . . . -- - - - - - - - - -- - - - - - - - --
-- - - - - --------- -- - - - - -- -- -- -- -- -- -- -- -- -- -- -- - -- - -- - -. . . . . . .. . . . . .•. . . . . . . . . . . .. . ......... • .......................... . . ...... ............ I ............ I ............ I ............ •.............
(
FIGURE A.5.4 : 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Total Vent-Valves Flow Rate
600 0-0 Total Vent-Valves Flow from cvar-337, filtered and
5 0 ......................--............................... ................... .................. ................... ................... .................. ................... ..................
------- ............------------................... --- - ------- I . . .- ----------
C 400. , . . I .. I .............
50 0 ........... -----------... .......... I ... .... ..... - ............. . - ------- I ------- ."".;. ..:... ..
300 --------- ------ ----------- ------------ --------- ---------- ------------ ------------ ----------- ------------ -----------
0
>
j > 200 ---- ----.L............------------.I.............--------.--.............----------.-.-------------------------------------------------------------------------------------------------II 20 - - -- --- -
--------------- I-
S00 ------------------------------------- --- --I .... :j i....... I•-- ---------- -- ----I- ----- ............ I ............ I --- --- --- --- --- --- I -- --- -- - -- -- --- --- -..... --- ---
0 ............ -- ------ -----4.. . . . -- ----------- ------------ -- --- --.. . . . . .--.. . .. .--... . . .--.. . . . ..'. . . .. ..- . .. . . ..--. . . . ..- . . .. . . .. . . . .-- --- -- ------------ -- --- -- ------------ -- --- --- --- --- --- --- --
-100 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
FIGURE A.5.5 : 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Vent Valve, Upper Plenum, Upper Head Voiding
1.2 0--o QUALS-36901 0000 (Vent-Valves Static Quality)
s VOIDG-369010000 (Vent-Valves Void Fraction) 0-E' VOIDG-352010000 (Upper Plenum Void Fraction) A-A VOIDG-390010000 (Upper Head Void Fraction) 1.0 ' ,::, . ............. L ................................................ ............ -- --- --..................... ......... ......... ........
01.
0.8
Cý
U9- 0. n- -BO 0--
-0.
00' m(
- 0.2 . . . . . ..
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (hrs)
f Ii
SI I
FIGURE A.5.6 : 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Total ECCS and Break Flow
200 0-0 CNTRLVAR-601 (Total ECCS Flow)
1-80 MFLOWJ-501 000000 (Break Flow)
180 -------------.-.---------.-.----------- I ............ •............ •............ :". . ...... -- ------ -----I............-- .... . . . . ............ •............ L ............ L, ............ ............ •.............
16 4 i I S160 ............ '............I-------q------ ------...... ------------ I------------- ------------ ----- ------......
..--.. ... .. ---" ............ --............ ---................ ......... ............ ........................................... .....................T ...........---............ ---...........
100"2 0 ------. ---------. --- ----------. ------------ ..............r ......... ... .I.----------------- ------------------------ -------------------- .-- ---------.-------------- ----------------------
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (hrs)
FIGURE A.5.7: 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Break Flow Quality
G5-O QUALS-275010000 (Break Volume Static Quality)j
1.0 ------- -----............ ,.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . ........................... ...................... ------............-- -----------.......... ............ ............ -----
1.0-- ----- ---------- ------------------ ---------------------------------------------------------------------- ------------ -----------------------------
0.8------ ............ ........... ............
0.6,
OOA
O 0.0 & .. ........ .......... . .. . .. . .. . .. . .. . .. . .. . .. .. . .. ... . ... ...... .. . .. . .. .. . .. . ... .. . ... .. . .. . .. . .. ... .. . .. .e. .. . ...e". .. . .. .
0.0 .. '
-0.2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
SI ,I I
FIGURE A.5.8 : 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Break Flow Temperature
800 i
0- TEMPF-275010000 (Liquid Temperature) SATTEM P-275010000 (Saturation Temperature)
700 -----------
100 ... .... .. .. .
30 ....... . . . . . . . . . . .. . . . . . . . . . ......................... .... ... i............................................................ -- - - -- -, ............ I ............ I- - - - - - -I............
0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
I I I [ I I I I I I
(ssq) •3Wu 0U 8 9z VZ ZZ 0z 81 91 vi Ui 01 8 9 17
............ ............I............. . ........... - ....----- ---- -. ........... ............ ............ ............
-- --- -------------- -- --- -------------- -- --- --...... ...... ... ...... i ............ i ............ i ........... i ........... !............ !............ !............ ....
............. ... ........ ....... ......... ..... ...... ......... .. ............ . .......... ....--------, ....... --............ . .......... ..... ...... ......... .. ......... -------" -........
............ -. .. . . . .-........................ ---- --- --- --- --- --- -- - -- - -.. . .. . . -- - - - - -.. .. .. . . -"-.. . .. ..--- .. .. .. .- ............ -- - -- -- ------------ ---- --- ---- --- ---- --. -- -- - -- -I.. . . . . . . . . . . ............
VJW4,'¶ ~ 1 1,,~
(dwnd El [-1o) 000000 I098 L-rMolJ q pe ell!' 7-V : (dwnd V L-o) oooooo0o00•-rg'MOjrj poeGl h 0-0-
ooz
001-
0 0
C-4
001 '9
OOZ ý3o0
005
0017
009
009soV•t ,OJJ &q ploD doo-I PoTluJ
"(moz qS li) uoi'y .zojunado awvr 'l1vJil u1 plo) - LO0O : 6"S'V 31F19
000--
FIGURE A.5.10: 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Broken Loop Cold Leg Flow Rates
600 _
0-0 Filtered MFLOWJ-26501000000 (CL-2A Pump) iA--A Filtered MFLOWJ-28501000000 (CL-2B Pump)
500 ............. ------- ............ ..'............ • ............ I ............. • ........... .- .............', ............ ............ ............ ............ -. ........... ............ ............
4 0 0 . .. .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
200 ................... .. ................................................................................... ...................................... - .........................
4..00 . . . . ...- ---.......
~0
-1 0 .. . . . . . . . .... .. .......... ..I- ------I-- ------ ------- ------------ -- --- -- -- --- ---- --- -- --------------------.. . .. .. .. .. . .. .. .. . .. .. .. .
- 100 ------------ .... .. .. .. .. ------.. . .. . .. . .. . .. . .. ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ... . .. . .. . .. . .. .............
- 2 0 0 ------------. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... . . . .. . . . . . .. .. . . .. .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...-- -------------,
-400
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (hrs)
FIGURE A.5.11: 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Loop Circulation and Vent-Valve Flow Rates
10
0
-10
-200
4-4 Intact Loop Flow at Hot Leg UBend from cvar-459. filtered and smoothed) x Broken Loop Flow at Hot Leg UBend from cvar-460. filtered and smoothed)
...............---------------------------------------------------- ------- .......------- -------------- ------
2 4 6 8 10 12 14 16 Time (hrs)
18
V
20 22 24 26 28 30
IIIIII I I I I I I
------------ ------------------------ ------------ ------------ ------------ ------------ ---------
............. ........................................................................... ----------
------------ ----------- -------------------------------------- ------------ ------------ ............
I
I I I ii /
FIGURE A.5.12: 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Core Inlet Flow
600 I-e RV Lower Plenum Flow from cvar-458 (J-313-02), filtered and smoothed
S400 ---------.-------- .-- .------- .---- .---------------------- ......--- ...------------...... --------- - - --- - - - - - - - -. . . . ...... .................................................................
S300 .. ... -- ----- ... ------ ----------------------------------..........-- .. . .... ..... ... . . ..... ............ ------- ............ ------- ............ ------ ------------ ------------.
0
4
4-A
0 4 ------------:
-- 200 . . ......... .......... ........... .........- ........ ....: ............ . ............-,- ........... :............ . . . . ... I ---- --- --- --- --- --- -- --- -- -----------------------... ... . . ... .. ..
0
0 --------
-- - - - - ------------ -- - - -- - - ----.. .•.. . . .. . ...... . . ., ............ , ............ - ............ : ............ , ............ • ............ • ............ • . .. . . . ........... .,............ . ............
-100
....... ..... .. ............. . .......-------- ............. ............ .... ...----...-----. .. ..................------..*.....-,..--.----------..... ..----. ........----.. .......----... ......
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (hrs)
FIGURE A.5.13: 0.007 ft2 Cold Leg Break, Late Operator Action (at.25h 20m). Reactor Vessel Temperature Distribution
800
700
600
S500
, 400
300
200
100
0-0 TEM PF-303010000 (Above Nozzle Belt) G- TEMPF-310010000 (Upper Nozzle Belt) 0-0 TEM PF-318010000 (Lower Nozzle Belt) A--A TEMPF-324040000 (Lower Downcomer) < --3 TEMPF-314010000 (Lower Plenum at Core Inlet) x-x TEMPF-352010000 (Upper Plenum at Core Outlet)
I*-* SATTEMP-35201 0000 (Upper Plenum Tsat)
--..-.-.----------- ------------. .............. ............. ...............------------. .-----------.------------- ------------- ------------- --........... ---- -- -- -- -- -- -- -- -- -- -- -
.. .. .. .... . ...... ,, . , . ',,,. ......
S... .. .. .. ,' . . ....... -'............ . . . .... . '}. . . . . .. .- . . ....... -. . .... ... -- --... . . "- ... ... ... -- - -- - - ----------... .. .. . - -.. . . . - -- - - - -- - - - -.. . . . . .-.. . .. . . . . . . . .
0 2 4 6 8 10 12 14 16 Time (hrs)
18 20 22 24 26 28 30
I I I I I I I
(ssq) owq.! O0 8; 9z ZZz z OZ 81 91 t1V TI O0 8 9 17 z 0 S~vO
------------..------------. ----------.-. -.------------------------ .. ... .... -------. ---. ............. .. ...... ...... ------. -----. ------------------. -------. ------------- ----------------.........
--------------------------- 4---------------------------------------- ------------ 9*O
--- -- - -- . -------- I
I I
--- --- . . . . ... . . . . . . .. .. ........................... ............................................................................. -- --- -- -.....--- ....... : ...... .......... •............. -- -- -- -- 8
S. . . . . . . . . . . . . . . . . . . .................................................... - - - - - - - - - - - - - - - - - --- - - - --................................. •............ •............ ..... . . . . ...........- ....
..............................................................................................................................................................................................--
i i (.•e: od eWoo pez!l'e"UON)•0 Z /00L 6 9C-dV.A-1UJNO G-0I
uoll-elougo JoAOd QO~tD pozTIltUUON "*(mUo qSZ 19) uo~lj3V.0oU.aodo ajur '3iloalff 2ar lo P10 Z LO0"O :tlT'S"V •H•dffI•
FIGURE A.5.15: 0.007 ft2 Cold Leg Break, Late Operator Action (at 25h 20m). Deborate Accumulation Due to Steam Condensation in SG
0. G-Oe CNTRLVAR-1 37 (SG-1 Deborate) :a- CNTRLVAR-237 (SG-2 Deborate) 03-- CNTRLVAR-238 (Total Deborate)
-10000----------------- -- -------------------- -....... -.. . . .. . . -.. ------------------------
-20000.......------------------------------------------------- ---------- ----- ------- I------------ ---------------- ------------ -----
oo • - 40000 .. .. .. ..- -------- ---------------- --------------------. -- ---........... -----... ........ . ......................... ............ ........... L ------,-- --- ............ ............
C,.)
-70000 ----- ---. I ............ I ........................... -
-8000--------------------------------------- ------------------------------------------------------------ -----
-110000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (hrs)
I I ¶ I .
(ssq) owurjL OE 8f 9z 1Z Zz O 81 91 H i 01 8 9 1 z 0 001
------. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .---- ------ N0 0
------- I ------- ------- ------- L------ I ------- I..S
...... -.... ... .... ... " ........ .................. -- --- --I............- ... .. . ............ I. ............ ------------ i ....... -- --............ ------.. .... ... o
...... ............. ,, ------.---- ----.--.--- .........................----.-........... 001V , ]O N
------ .... ------- - -. ... ........ ................. Eto
-------------.. . . . . . . . . . . . . . . . . . . .... . .. .. . . . .. . . . . .-: . . . .. . . . . . . . ---------.. . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . .---. . . . . . ..-" . . . . . . ..- . . . . . .. . . ..- --
--------- ....... ............... ............ ------- ............- ............ ------- ------------ ------- ------------ -------------------------- ............ ------- ....... ............ ...... ...... oo es. AI.puooS S doo- loulUl) 0000 LOO5 -dShliVJ 0l5 s kpuooS S 5dool 5ejul) oooo5oo89-d530
(wunueld jeddn-iAH) 0000 LOZ96--IdlVYJ.I.
008 ,l-mloI XjupuooQS-OS oi tnuold joddfl ASt
"*(u0Z: qSZ 11) uolj;v.aoluaodo alu-] '3luaafl 2ao" 10po 3 0009';V "llI Szl S S H S S I I S
FIGURE A.6.1 : 0.007 ft2 Cold Leg Break, Early Operator Actions. System Pressures
2400...... 2 40 P-352 (RV-UP-1)
B-0 P-670 (SG-1-Sec) 0-0 P-770 (SG-2-Sec) A--6P-897 GET1
2 0 0 0 .-.-- -- .- -----------. ----. -----.- -----.- --............ ...........I.. .........- ---------------.- --------------------------.- ---------.- ---------.- ----------- ----------- --------
Op. Actn at 4hr 20m., SG Blowdown.- HPV Open
1 0 -----------------------------------------------------...................... ... .........I ...........- ----------120 --- --- -- -- ---------------... .... .. .. -- --------------- -- -------------. ........... ............. ...........- ........... ! ........... i ........... ! ........... i ........... i........... ......
• " ..... ............ p c n a .h!......20 •,!...... G B 0 dw[...... ......HV O ei........... --- ----------- ------ -----------
---0 -----. ---..- -.-.......... . ........... ........... ........... --------................... . . . . . .. . . . . . . .... . . . . . . . . . . . . . . . . . . . . . . ......................................-- ---- -------
4 00• ............ I. ........ I ... ..... .................... ............ ... I ........ Fi.... -- ----. ... i .......... -------------- ....... ... ---..... ..... ---... ....... ---.......... --.......... --- ......... ........... ........... ........... ........... ........................ •i........... ............ i........... ----- ----- ...... i........... i........... ........... ...........
0.)
0 2 3 4 5 6 7 8 Time (hrs)
I I I
I I I
80
60
0
)-*
20
0
FIGURE A.6.2 : 0.007 ft2 Cold Leg Break, Early Operator Actions. Intact Loop Collapsed Liquid Elevations
Go-0 CNTRLVAR-1 00 (HL-1 Collapsed Level) :B-8 CNTRLVAR-140 (SG-1 Tubes) * -CNTRLVAR-151 (SG-1 Above Tubes) i CNTRLVAR-614 (SG-1 Secondary)
.. . ... .. .. .. . --- -- -- -- --- -- -- --- -- R-- -- -- - -- -- -- -4--- --- -P ressu-- -- --- -- --e-- -zerriz r
............ ... ........... ........ ..................... ,..... .... ,........... ------ ----------- ........... ------ ----------- ------,----- ........... i F ]C T L A - 0 P~ s u e z r
B B
-------- .... ........------------------.-------------------.----- ---------. --------- ------- -----------iiii ----------- il ------
-- - -..... -- .......... - - - - - -..... .... -- - - - - - - ----- ------ . . . . . . . . . . . . . . . . . ... • ........ ... ! .......... ........... ........... •.... ....... ......... .. L............ ........... •............
0 2 3 4 Time:(hrs)
5 6 7 8
I I I
I
FIGURE A.6.3 : 0.007 ft2 Cold Leg Break, Early Operator Actions. Broken Loop Collapsed Liquid Elevations
80 --0 CNTRLVAR-200 (HL-2 Collapsed Level) 0--a CNTRLVAR-240 (SG-2 Tubes) 0-0 CNTRLVAR-251 (SG-2 Above Tubes)
CNTRLVAR-714 (SG-2 Secondary)
6.... .. . . . . .. . . . . . . . . . . . . . ......... -- -- .......... -- ---- ----------- -- ---- . ............ . . . . .. . . .........................-- -- -------------------------------
....... ....... ....... ....... ....... ........... ........... ........... ................ ------- ------- ---.... ......
20~ ~~ ~ -- -- ------- ----------- ----. ---- ---- ---- -----. ......... I ........... i........... i.......... i........... !. ....... I ------------ ---- ------- . ..... I ...........
""4 .. . . ............. .................................................. ........-- - .. ... .. .. .. .. ... .. .. .. .. --- -- -- -- -- --- -- -- -- -- -
- C)
0 0 1 2 3 4 5 6 7 8
Time (hrs)
I I i, ! I I I
FIGURE A.6.4 : 0.007 ft2 Cold Leg Break, Early Operator Actions. Total Vent-Valves Flow Rate
600
=,0 Total Vent-Valve Flow from cvar-337, filtered and' smoothed S. ... .i. .....i. .....i. .....i........... ........... ........... -- --------------- -- --------------- ........... ........... ........... ........... ........... ........... -- --------------
.0 ......... " ........... -- ----.............. ............. ............. ............. ............. . . .. .. .. .. .. .. .. .. .. .. .. .. .-- --- - -------.. -- ----------- -- ---- ----------- -- ---- ----------
40 . ........" . . . . ............ .. .. ........... i. ........ -- ---- ----------- I ------------ -- ------ ------ ---- -.......... I ...... . . i ....... I ........... -- ---- ----------- I -----------
-.. 400------
.0
41 ........ ------ ------------------------- -----300 ------ ----
..........------------------- -------- ---------------------- ---- ------ --- ------ ----------- ----------- ----------- ---- ------ ----------- ----------I• 21 0 0 . . .. . .. .. '. ... . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .... . . . ..... . . : . . . ... -- -- -- ----. .. .. . ...- -- -- --
-- - --- - -- -- -- - ------------I ------------I . ... . . . . . . . . . . .. . . . . . r.. ... .... ... .. .. . . . . . . . . ....... . . . . . . . .... .
--- -- ---. --.---..- ----.-- ....... .. .. .. ....... .. ...-- -- ---- --- -- ---.----- ---- -- --.---- ---.--- -- --.. ..... .. .. ......... .. ..... .. .. ..
.1 -t
o-100------
0 ---------- (hrs)------------------ -- - -------------- -S -100SS SSS
0 1 2 3 4 5 6 7 8 SSS
S ~~~ ~ Tm S S S Ss)S S S S S S
FIGURE A.6.5 : 0.007 ft Cold Leg Break, Early Operator Actions. Vent Valve, Upper Plenum, Upper Head Voiding
0-0 QUALS-36901 0000 (Vent-Valves Static Quality) VOIDG-369010000 (Vent-Valves Void Fraction)
0 VOIDG-35201 0000 (Upper Plenum Void Fraction) VOIDG-390010000 (Upper Head Void Fraction)
1.0- -" ----------------
0 .8 -- ---.- ------ ----- ---- _ ------ --.- --.- --- ----.- -----. -- ------.. . .. . . .. . . .. . . .. . .. . . .. . . ---------------.......
0
03
-- - - -0.4------I.)
• p,,,A
-0.24
Time (hrs)
I 1 I I 1 I
I I I I
21
1
o -1
V) u0
u,
W
2 FIGURE A.6.6 : 0.007 ft Cold Leg Break, Early Operator Actions.
Total ECCS and Break Flow
00 ' -o CNTRLVAR-601 (Total ECCS Flow)
B-0 MFLOWJ-501 000000 (Break Flow)
8 0 ----..- ---------------------------. ----. .. ........................ ........ ...... .I.- -----------I ..........._ RO----------------- ---------- ---------------- -------------------- -----------------
6 0 ........... -- ---- ----------- -- --- --I.. . . . . . . . . . -- ---- -- --- ---- -- ----.......-- t- -- --- --- -- -- -.. . . . . . . . . . -- - --- --- -- -- ---- ----- ---- --- --- -- -- ---- -- -- -
40 ------- --- -. ,- --- ~ ~ -----------------' ----- L--------------- ........... I ----------- I ------------ ----.........-----80 0 ---- ..---- .L.- .- .--- . ---. -- --.-.L.. ........... ........... ........... L --- -- -- L.... . ... I ----- ..... .. ... ----- ---- --L- ---------
--- --- --- - . ... .. --- --- --.... ... ...... ... .. --- --- --- --- --- ---- --- --- --- --- --- --- --- --- --.--- ---.-- --- --- ,-- --- --- .-- --- --
60 ----
80 2.......... 3- 4.............................
.... .. 5
6 .0. .... ..... -- ---- ----------- -- ---------------- --------- --.... .. -- ---- ----------- ------- -------------- --... . .. .. ... . ............. . . . . . . . . . .-- ---- -----------. ...........
0 2 3 45678
Time (hrs)
I I i
FIGURE A.6.7 : 0.007 ft2 Cold Leg Break, Early Operator Actions. Break Flow Quality
16--! QUALS-27501 0000 (Break Volume Static Quali
1.0----------------------- ............ .............---- ........... -----------------------" . . . ------------------------------ ........... - - - ----- --------
0.8 ---- -....................... ------ ----------- ------ ----------- ------ ----------- -----------. -----------............ ------ ............ ------ -------.. ------ ----------
..0 0.6 i .. .....r.......... ------ -----------------------...... ------ ........... -- ....... ÷.......... ........... ------ -----------....... ........... ........... -----------.
0 0 .44 ----.-.-.-.- ---------.--- ---------------- --------------.----------------- -----........... -----------.--- ------- .-------- ---.I.---------- .I.------------- ---------------- --------------
08
0 .2 .................. ..... . . - ...........
0 .02 ....... - -----........... r ----------- -----------
-0.2 0 2 3 4 5
Time (hrs) 6 7 8
I ( I I
FIGURE A.6.8 : 0.007 ft2 Cold Leg Break, Early Operator Actions. Break Flow Temperature
800 G- TEMPF-275010000 (Liquid Temperature) o-- SATTEMP-275010000 (Saturation Temperature)
600 ............................-- - - - - - - - - - - - - - -........ .............. ...... ..... ... .. ... .. .. ... ......... ....... ....... ................ .......
60
- 1,
O 300 ..............
0 0 1234 5678
Time. (hrs)
FIGURE A.6.9 : 0.007 ft2 Cold Leg Break, Early Operator Actions. Intact Loop Cold Leg Flow Rates
600
I z 3 T 4 Time (hrs)
I [ I I II t
500
400
300
200
100
0
-- Filtered MFLOWJ-16501000000 (CL-1 A Pump) A Filtered MFLOWJ-1 8501000000 (CL-1A Pump)
------ -------- ------------------------........--..----..--.-- --------------------------.I------- I ------.....................................................---. .
...... .. ......-.. .----.-. .-.-..----------..... .... ..... .... .... .. .. ............ ... -- - .....-- - ... .........--- --- -- --- --- --- ---
S',
-----------~~~~~~~ ~ ~ ~ ~ ~ ............................. ------ ----- ----- -- -- ----- ----- ----- -- ......... .--- ---------------------------------------
........... ........... ........... -- - - - - ----------- -- - - - - -------.. -- - -- - - - - - --...... .. ....... .. . .... -- - - - - -- - - -- - - -- - -
..... ..... ..... .... ..... ..... .... ..... ..... .... ..... ....---- ----- ..... ....-... ......- r-. .... ....--.... .....---. ..... ...- -----------. .. . . .. .. .. -- - - - - -- - - - - -- - - - - ........... ...........--
00
0
-100
-200
-300
-400U 8.3 0 I
FIGURE A.6.10: 0.007 ft2 Cold Leg Break, Early Operator Actions. Broken Loop Cold Leg Flow Rates
600
ff -0 Filtered MFLOWJ-26501000000 (CL-2A Pump) A-A Filtered MFLOWJ-28501000000 (CL-2B Pump)
5000 -- --- --. --- --- -- - --- --- --- --- --- --.*... ... ...I.. ... .....-- --- ---.-- --- ---- --- --- --- --- --- ---- --- --- --- --- --- ---- --- --- --- --- --- ---- --- --- --- --- --
400 ---------- ........... - ----------- ----------- .. ..-...-.. ..-.. ..-. . ..-.. ..-. . .----------------------- -.......... -------- - ----------
400 - ------------------------------------------------------------------------- -------- ------------- --..........
300--------- --------- ------------------------------------------------ -------- ..-........... - - :----------------
° ........... -- --- - .. ----- ...........
-3400------
.. .. . .. .. . . . .---- - -- - - .. . .. . .. - - -- - -.--- - - -- - -- - -- - - -- - -- - - -- - -- -.-.--- - -- - - .-- -- --. - ---..- - -- - - -- - - - - --- --- -
-400 0 1 2 3 4 5 6 7 8
Time (hrs)
FIGURE A.6.11: 0.007 ft Cold Leg Break, Early Operator Actions. Loop Circulation and Vent-Valve Flow Rates
600act Loop Flow at Hot Leg Uend from cvar-459, filtered and smoothed) *-+ Intact Loop Flow at Hot Leg UBend from cvar-459. filtered and smoothed) 4--------- ------Broken Loop Flow at Hot Leg UBend from cvar-460. filtered and smoothed)
5 ........ 0............ -- v Vent-Valves Flow from cvar-337. filtered and smoothed) ----------...................................
500 . . . ...............---..------------ - -------- ---------..................
-----------..... .. ... ----.. ....... ---.. .... .. . ----.... ..... ----......... ----..... .... .............. ......... .... ........ ..... .-.. ...... ...----- . .. ......--- ....... ..... ---......... 300 .......... .... .. ...... .......... ... ....... ...... ......................... ....... --- ---- ---.-.... i i ....... ........... -- -- -- - ---------------- r------ r ---------------- ----------- ----------
A-4 .. ........I............ ............... ........ ------ -----.I. ------ ----. ----------. ------------ ---- _ --- _ ----- -------------- ------------.----------.--.------ .-------- -- ...........
3 0 . . . . . .... ., ........... • ........... • ............ ----------- -- --- - ----------- -----------. .... . . . .......... . ... ....,-- --- ---- ........ . -----------.
0g -- - - - - -- -- -- --I.. . . . .. ... . . . . . . I - - -- --100
-- 300------------- ....
I0 f
0------..... ----- -- r ...... A ... .....
-100 1 2345678
Time (hrs)
Si I I I $
FIGURE A.6.12: 0.007 ft Cold Leg Break, Early Operator Actions. Core Inlet Flow
600 RV Lower Plenum Flow from cvar-458 (J-313-02),filtered and smoothed
..... --- -- .... ....-- ........... .I ...... ....... ...... ....... ..... .. ...... ....... .....I ........... I ..... . . .,......... L .............. . . . . . . . . . . .I -- -- - -- I.................- 1 -- - 'O - - - - -- -- -I -- - --
500------ - ........... ...........-. .......... . -----------
0 0 . . . ., .. . . . . . . . . . . ........... ........... . . . . . . . . . .............. -- - - - - - - - - - - - - - - - - - - - ---- -----..... ..............
~ 0-- --------I
S
i-i
2 0 0 --- --- --- --. . ............1 0 0 . . . . . . . ............. ......................... .... .. .. .. ...... .. .. ...... .. .. .. ..
------------------- --------- ----------- ------- ------- ---------------- ----------- ----------- ......----------- ----------
.-.......... . ........... •........... ------ ........... ........... ------ ----- ........... ...........; ........... ------- -------......--------------
0 --- --- --... .. .. ........ .....r.-- --- ---.r-- -- --- --..- -- -- ---r.--- -- --.r.-- --- --.r.-- -- ---.T--- -- ---.T-- --- ---" ........... I ........... I .............. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
-100 0 1 2 3 4 5 6 7 8
Time (hrs)
FIGURE A.6.13: 0.007 ft2 Cold Leg Break, Early Operator Actions. Reactor Vessel Temperature Distribution
800
700
600
S500
V1 E
400
300
200
1002 3 4
Time (hrs)5 6 7
I I I I
G-0 TEMPF-30301 0000 (Above Nozzle Belt) &--a TEMPF-310010000 (Upper Nozzle Belt) 0--- TEMPF-318010000 (Lower Nozzle Belt) A-A TEMPF-324040000 (Lower Downcomer) 4-< TEMPF-31401 0000 (Lower Plenum at Core Inlet)
.x-x TEMPF-352010000 (Upper Plenum at Core Outlet) -SATTEMP-35201 0000 (Upper Plenum Tsat)
...... Z. ... ... . ......... {.......... --- ----------------- ------- ----------------- ------ -------------- ...........-----
. . . . . . . . . . . . . . . . . . . . . --. . . . . . . . -- - - - - ------------ --.. . . . . . . . -- - - - - -----------r ----------- -- - - - -.. . . . . . . . . . . . . . . . . . .-- - - - - ----------
. ....... ....... ...... .. . ... .. -- ---- -- --...----...- --....---. --- --- --- ... . . . •. . . . .. . -.. . . . --..... ...... --.. . . . --.. . . . --.. . . . --.. . . . --.. . . . . . . . . . --.................. -. .... ......
. ... ...... ... ... ... ... ... ... .. ... .. -- --- - -- --- --- --- --- --- --- - - --- --- --- --- -- - - -- - - --- --- - - -- . ... ... ... ...
--.--.-..-.--.- r r..- ..-.-- .- ..- -- - ..-.-- .-.-- .- --- ....-.-- .- ..- -- - ....-- .- ..-.-- --- .- ..-.-- .- ..- -- - ..- ..-.- ..-.-- - - .-- ...-- .- ..- -- - ..-.- ..- ..-.--.-..-.--.-.....-.-.--.-..-.--.-....--.-..-.--.-..-.-.....-.--.-.--.-..-.--. ...-.--.-..-.--. r .. .............
0 8I
(ssq) OWTuI S 1 9 17 E £Z 1 0
S. . . . . . . . . . . .". . . . . .•........... -- - - - - - - - - - - - - - - - - ----------- - ----------.. ---. --------. -----------.. -----------.. ---------.... ---.......... -........... •-...........•-...........•-........... ...........
S S S O 'S I
go
--------------- -------------------------- - - - - - - - - - - - - - -
- - - - -
8"I
0"
uo1I•Iuoo flMOd 31o3 p3ZIJPtUfoN "suoipv .iownado Xlae3I 'hpVafq [laj plo3 zl £O000 :F1I9"V 3I11fl9I
----------- I.. - . . I . - - -
FIGURE A.6.15: 0.007 ft2 Cold Leg Break, Early Operator Actions. Deborate Accumulation Due to Steam Condensation in SG
0! O, •. i 0-0-- CNTRLVAR-2 37 (TGta Deborate)
i&-o CNTRLVAR-137 (SG-i Deborate)
0-0 CNTRLVAR-238 (otal Deborate)
-40000 ................ . .. .. • . . .... -- -- - ----------- -- ---- ----------- -- ---- ----------- • . . . . . . . . . . . . ......• ..... ...... • ........... • ........... .......... ........... -- ---- -----------.. ... ..
a)
- V
. -60000 ----------------------- ----------------- --- -- - - - - - - - - - - - - - --...........-........................ . . . . . . . . . . . . . . . ..------ ---------- I ----------- I ------------
-80000------
0 1 2 3 4 5 6 7 8 Time (hrs)
RELAP5/MOD2 B&W V20HP
I.. . . . . . . . . .. . . . . . . . . . . .I.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIGURE A.6.16: 0.007 ft Cold Leg Break, Early Operator Actions. RV Upper Plenum to SG-Secondary Delta-T
800
700
600
S500
400
300
200
1000
... TEMPF-352010000 (RV Upper Plenum) :- SATTEMP-68001 0000 (Intact Loop SG Secondary Tsal) 0-0 SATTEMP-78001 0000 (Intact Loop SG Secondary Tsal) A-- SATTEMP-352010000 (Upper Plenum Tsat)
-........... -- U-- ----------- L -----------...-- ........... - ----------- ------------- ------------- - - -..... ...................... -----
.......... --------- ..... ........---------.---------- ---------.--------- --------.---------.--------.... ......-------------------- .--------- ..........
........... r........... r........... r . . ..... r----........ r ............ . . . . . . .r -- - - -- - ......-- r- -- - - --r- -- - - - f ----------- I ----------- T ----------- If .... ... .. .. ... ... I -----------.... .. r -----------
I 2 3 4 Time (hrs)
5 6 7 8
I