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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
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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
7
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
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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
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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
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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
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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
11
a
C> CD
80,000
70,000
60,000
50,000
40,000
3,000
20,000
10,000
0
15
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
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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
12
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)
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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
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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 --- -
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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
•Z 18
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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- , -
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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)
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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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