nrc generic letter 95-07 pvngs pressure locking …

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

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

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

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

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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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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