nrc generic letter 95-07 pvngs pressure locking …
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY SBackground
"* PVNGS model development began (1994)
"* G.L. 89-10 supplement 6 (March 1994)
"• PVNGS modification development began (July 1994)
"• G.L, 95-07 (August 1995)
"* PVNGS modification implementation start (Oct. 1995)
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY * Background
•Industry pressure locking testing (Dec. 1995)
"• Other industry pressure locking models (1994-1998)
". NUREG/CR-6611 INEEL pressure locking testing (May 1998)
". Limitorque technical update 98-01 (July 1998)
"* PVNGS modification implementation completion (May 2000)
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY * Pressure Locking Modifications
e Scope o 60 of 69 valves hardware modification and peak cracking limit
o 9 valves controlled peak cracking limit
• Types °Peak cracking limit
oBonnet relief
oGear change
oActuator upgrade a_4L
oValve internal upgrade
NRC GENERIC LETTER 95-07
EQIDS Recommended Corrective Actions
AF-34/35 -Install bonnet relief valve (1880 psig Bonnet Press. Limit) Motor AFP Iso Valves to SGs -Upgrade weak link by 35%
AF-36/37 -Install bonnet relief valve (1880 psig Bonnet Press. Limit) Turbine AFP Iso Valves to SGs -Upgrade weak link by 35%
SG-134/138 -Replace the actuator with an SB-1-60 (OAR=42.50) SG Steam Supply Iso Valves to AFP Turbine -Upgrade weak link by 35%
SI-604/609 -Admin Control of maximum cracking thrust LTC HPSI Valves
SI-651/652 -Install Bonnet Relief Valve (2936 psig Bonnet Pressure Limit) SDC Iso Valves -Admin control of maximum cracking
SI-653/654 -Install Bonnet Relief Check Valve (465 psig Limit) SDC Iso Valves -Admin control of maximum cracking
-Increase Actuator OAR (OAR=124. 1)
SI-655/656 -Install Bonnet Relief Check Valve (465 psig Limit) SDC Ctmt Iso Valves -Install a bonnet bypass spring check valve
-Increase Actuator OAR (OAR=124. 1)
SI-671/672 -Replace the actuator with an SB-1-40 (OAR=27.20) CS Control Ctmt Iso Valves
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NRC GENERIC LETTER 95-07
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EQID Recommended Corrective Actions
SI-685/694 -Increase Actuator OAR (OAR-61.64) SDC Hx Inlet Iso Valves (LPSI Pump)
SI-686/696 -Replace the actuator with an SMB-2-60 (OAR=80.00) SDC HX Disch Iso Valves
SI-688/693 -Increase Actuator OAR (OAR=61.64) SDC Hx Bypass Iso Valves
NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
* Model Comparison
"• Comparison w/results of model w/o line pressure o 10" 300# Borg-Warner Flexible Wedge
Gate "• Comparison w/results of model w/line
pressure o 10" 900# Crane Flexible Wedge Gat
Open Thrust vs. Bonnet Pressure (Low Closing Thrust)(10" 300# Borg-Warner Gate Valve)
60,000 A INDUSTRY
MODEL
Adjusted Predicted Open Thrust . MeasuredPL Load
50,000 Load
* 1.4* INDUSTRY MODEL
* 1.2* 40,000 ____ INDUSTRY
MODEL a PV MODEL
2 Linear S30, - (INDUSTRY T. •MODEL)
- -- Linear 0 (Measured PL
20,000- - _ _ _Load) 2 0_ _-- - -Linear(1.4*
INDUSTRY
Measured Open Thrust MODEL) . - . - Linear (1.2*
INDUSTRY 10,000 MODEL)
-Linear (PV MODEL)
0
0 100 200 300 400 500 600 700 800 900 1,000
Bonnet Pressure (PSIG)
C9
Open Thrust vs. Bonnet Pressure (High Closing Thrust) (10" 300# Borg-Warner Gate Valve)
60,000
50,000
40,000
Adjusted Predicted Open Thrust
Measured Open Thrust
Bonnet Pressure (pslg)
* Measured PL Load
* PV MODEL
A INDUSTRY MODEL
x Adjusted 1.4 INDUSTRY MODEL
x Adjusted 1.2 INDUSTRY MODEL
o Outlier Test Point
- - Linear (Measured PL Load)
-Linear (PV MODEL)
Linear (INDUSTRY MODEL)
-- - -Linear (Adjusted 1.4 INDUSTRY MODEL)
- - - - Linear (Adjusted 1,2 INDUSTRY MODEL)
.0 30,000
20,000
10,000
00 50 100 150 200 250 300 350 400 450 500
SlAr 10
Open Thrust vs. DP (Low Closing Thrust) (10" 900# Crane Flexible Wedge Gate Valve)
200 400 600 800 1000
Bonnet Pressure - Line Pressure (PSID)
1200 1400 1600
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a
C> CD
80,000
70,000
60,000
50,000
40,000
3,000
20,000
10,000
0
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I.C Ol
o Test Data
o Model Data
* Industry Model
* Industry Model * 1.2
ULinear (Model Data)
- - Linear (Test Data)
- .-. . Linear (Industry Model)
- - - Linear (Industry Model * 1.2)
0
Open Thrust vs. DP (High Closing Thrust) (10" 900# Crane Flexible Wedge Gate Valve)
120,000
100,000
80,000
60,000
40,000
20,000
0
0 200 400 600 800 1000 1200 1400
Bonnet Pressure - Line Pressure (PSID)
1600 1800 2000
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4-_
C
U a= I
I 0
Predicted Open thwrust
Measured Open Thrust
o Test Data
o Model Data
* Industry Model
* Industry Model * 1.2
-Linear (Model Data)
-- ULinear (Test Data)
-- - - Linear (Industry Model * 1.2)
..-. . Linear (Industry Model)
NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
* NRC RAI questions
"• Utilization of test specific valve factors
"* Clarification of "additional" margin
"• Basis for 10% margin w/bonnet pressure >200 psig Criterion
"* Application utilizing PVNGS PL Model
"* Exceptions to 10% margin criterion • 13
NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
SUtilization of test specific valve factor "* Review of test traces
"• Application of test values
• Resulting valve factors
o 0.44 valve factor (Borg-Warner)
o 0.31 valve factor (Crane)
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
SClarification of "additional" margin * Minimum of 10 % margin between capacity
and predicted loads o Maintained when applying model unless otherwise
justified
* Basic margin between measured loads and predicted loads o Difference between test and model linear
regression curves more...
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ý t-4ýý --- -
NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
* Clarification of "additional" margin Exception at one high closing thrust data point o Borg-Warner 10" 300# test 80 o Outside conditions for PVNGS Borg-Warner 300
class valves
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
SOther inherent uncredited margins
Conservatism and rigor of model o Validated for 10" 300# Borg-Warner Valve w/high seating loads
o Difference between model and test linear regression curves
more...
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
SOther inherent uncredited margins .Conservatism and rigor of input
variables o Utilization of high valve factors and COFs
o Difference between maximum closing load and field measurement
o Conservatism of input pressures
o Utilization of minimum voltage and Limitorque TU 98-01
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY SBasis for 10% Margin w/bonnet pressure >200 psig criterion * Based on slight convergence of model w/Borg
Warner test results for high seating loads in initial model.
* Ensure enveloping of identified nonlinear BorgWarner data point 80 at 467 psig bonnet pressure and 32,000 lbf closing force.
* Allowance for other uncertainties based on initial small sample of data points above 400 psig bonnet pressure and greater than 17,000 lbf closing force.
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
*Application utilizing PVNGS PL Model + Added some conservatism into model
* Review of input variables
* Review of actuator capacity and limits
+Calculated 10% margin between valve capability and pressure locking loads
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11111 ý75771.17 77- , -
NRC GENERIC LETTER 95-07 MOV Capability Compared to Predicted Required
230.0%
"1220.0% 210.0%
200.0%
190.0% 180.O% -, o
170.0% 0.0
U 150.0% -------- E A A
140.0% _•130.0%
• 120.0% A * A
S110.0% ->. 0 10a0.0%
S90.0% 80.0%
MOV Equipment identification Nunfters
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* Minimum DESIGN MOV Capability
- Required Capability
* Worst CaseACTUAL"AS-LEFT" MOV Capability
* Beat ACTUAL "AS-LEFt" MOV Capability
to
I
(-1)
NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
SExceptions to 10% margin criterion
3" 1500# Borg Warner valve CH-536 w/ bonnet pressure of 97 psig and closing force of 7,800 lbf (calculated design margin 9%, minimum actual calculated margin 18%)
o Low bonnet pressure, low closing force, rigid disk
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NRC GENERIC LETTER 95-07 PVNGS PRESSURE LOCKING
METHODOLOGY
+ Exceptions to 10% margin criterion 6" 900# Anchor Darling valves AF-36/37 w/ bonnet pressure of 1816 psig and closing force of 41,000 lbf (calculated design margin 7%, minimum actual calculated margin 15%)
o Conservatively high bonnet pressure
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