ML18107A335

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Rev 0 to 108-193-TW4, Evaluation of MOVs PR6 & PR7 for Pressure Locking During Gradual Depressurization Event.
ML18107A335
Person / Time
Site: Salem  PSEG icon.png
Issue date: 01/27/1997
From: Damerell P, Walker T
MPR ASSOCIATES, INC.
To:
Shared Package
ML18107A331 List:
References
108-193-TW4, 108-193-TW4-R, 108-193-TW4-R00, NUDOCS 9906020088
Download: ML18107A335 (11)
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Text

I

  • ATTACHMENT II NLR-N990254 SUPPLEMENTAL INFORMATION GENERIC LETTER 95 "PRESSURE LOCKING AND THERMAL BINDING OF SAFETY RELATED POWER OPERA TED GATE VALVES" SALEM GENERATING STATION UNITS 1AND2 990b020088 990524 PDR ADOCK 05000272 p PDR

MPR Associates, Inc.

mMPR 320 King Street Alexandria, VA 22314 CALCULATION TITLE PAGE Client Public Service Electric & Gas Page 1 of Project Task No.

Evaluation of MOV Pressure Locking and Thermal Binding 1 08-9658-1930 Title Calculation No.

Evaluation of MOVs PR6 and PR7 for Pressure Locking During 1 08-193-TW4 Gradual Depressurization Event Pre parer/Date . Checker/Date Reviewer/Date Rev. No.

~Luol}µ_ ~.j J. Pxwr1.,1.Lt.l .'t(;v.-.f f ~ ..,. ~_d,.~ 0 Thomas Walker Paul S. Damerell Paul S. Damerell i-:J1-ti7 /-2,1-7')

MPR Associates, Inc.

mMPR 320 King Street Alexandria, VA 22314 RECORD OF REVISIONS Calculation No. Prepared By Checked By Page 2 108-193-TW4 ....,_). \/I { *.' ,,

, W*µ-(.__, 'P;:.ck-l ~*'r-r. vJ.(_

Revision Description 0 Original Issue.

MPR Associates, Inc.

mMPR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By

( I J ' / Page 3 108-193-TW4 \..VJJ J.-*....;::...~, I'~*~~_.,u..LL PURPOSE The purpose of this calculation is to determine the thrust required to open Salem MOVs PR6 and PR7 if the pressure in the pressurizer is decreased gradually. The valves are assumed to be closed with a final stem thrust of 10,996 pounds, which is the maximum allowable closing thrust recommended in Reference ( 1) based on potential thennal binding considerations. Although the valve bonnet will tend to cool down during pressurizer depressurization, the pressure and temperature in the bonnet are assumed in this calculation to remain at the normal operating values.

RESULTS The stem thrust required to open the PR6 and PR7 PORV block valves with gradual pressurizer depressurization is 12,330 pounds, assuming that no bonnet cooling takes place and the pressure in the bonnet remains at the reactor operating pressure of 2235 psig. Per Reference ( 1), the actuator capability for these valves is 13,966 pounds. Therefore, the thermal binding scenario evaluated in Reference (1) bounds this potential pressure-locking scenario.

REFERENCES

l. Evaluation of Salem Valves for Pressure Locking and Thermal Binding, MPR-1693, Revision l, January 1996
2. MPR Calculation l 08-173-EJM-O I, Opening Force Required to Overcome Pressure Locking for Pressurizer Block Valves I PR6, 1PR7, 2PR6 and 2PR7, Revision 0, forwarded by MPR Letter to Robert Lewis (PSE&G) Dated August 29, 1996.

CALCULATION Reference (1) documents MPR's evaluation of Salem MOVs for potential pressure-locking and thermal binding. For the Salem PORV block valves, 1PR6, 2PR6, 1PR7 and 2PR7, Reference (1) concludes that pressure-locking is not a concern for these valves since the bonnets are normally filled with steam. This conclusion assumes that the valve body and bonnet cool similarly to the steam in the pressurizer.

Subsequent to the issuance of Reference (1) a pressure-locking scenario was identified. This scenario is associated with a steam generator tube rupture with loss of off-site power, a transient which can result in trapped pressure in the PORV block valve bonnets at a time when the block valves may be demanded to open. Reference (2) evaluated this scenario using the model described in Appendix H of Reference ( 1),

which predicts the thrust required to open a gate valve with elevated bonnet pressure. The conclusion was that the thermal binding scenario evaluated in Reference (1) bounds the pressure-locking scenario due to steam generator tube rupture. The conclusion in Reference (1) that these valves should not be closed with a maximum thrust of more than 10,996 pounds remained unchanged.

To respond to a potential comment that the valve body and bonnet may not cool as quickly as the pressurizer steam space during the gradual depressurization scenario, this calculation uses the same method used in Reference (2) to evaluate the PR6 and PR? valves for this scenario assuming that no

. e MPR Associates, Inc.

mMPR 320 King Street Alexandria, VA 223~4 Calculation No. Prepared By Checked By Page 4 108-193-TW4 '--+-OJoJ._~v p;.~".,.'~~~o cooling of the body and bonnet region takes place. The same valve dimensional inputs that were used in Reference (2) are used for this evaluation except for the following.

  • The opening upstream pressure is set to 375 psig, which is the low pressure setting of the PORV based on Appendix A of Reference (I).
  • The opening disk and body temperatures are set to 653°F, which is the saturation temperature at 2235 psig -- the valve body/bonnet temperature.
  • The opening friction coefficient is set to 0.40, the EPRI Gate Valve Model friction coefficient for a temperature of 653°F (i.e., the same friction coefficient used for closing).
  • The material properties for opening are set equal to the material properties at 653°F, which are the material properties used for the closing stroke in Reference (2).

Note that Reference (2) evaluates these valves with and without the effects of thermal binding included.

This calculation includes the applicable effects of thermal binding. The effect is stem expansion after insertion, which increases the seating load on the disk.

A MathCad model is used to implement the method, as in References ( 1) and (2). The results are shown in Appendix A. The predicted opening thrust is 12,330 pounds.

-- MPR Associates, Inc.

mMPR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By v) f:) Page 5 108-193-TW4  : ..,,{ (1 t..1..:__.: ._

. JC°'~ ;~I l. * '-'-' {,(

APPENDIX A MathCad Printout for Pressure Locking Evaluation

MP!'\ Aaaoclates, Inc., 320 King Street, Alexandria, VA 22~~ , .* .  !,.,\_ , .<- Page No. 108193DHH01 Preparer: J.W< Ir"""'- Checker: _,_(__lj~~-- Print Sheet 1 EVALUATION OF GATE VALVE OPENING THRUST Valves 1PS6. 1PS7. 2PS7, 2PS6 as evaluated in calculation 108-173-EJM-01, except that for opening the upstream pressure is 375 psi and the disk and body temperatures are the same as the temperatures at which the valve was closed. Note that thermal binding force on bonnet cooling is zero in this case rather than 363 lbf as in the reference calculation.

OUTLINE OF CONTENTS:

  • This calculation is divided into the following sections:

Parameter and Inputs Determination of forces for closing Determination of reference wedging interference Determination of forces for opening PARAMETERS AND INPUTS: .

Dimensions:

Disk seating radius: a : == 1.281

  • in Disk hub radius: b :=0.63*in Disk thickness: t :=Q.761*in Hub length from center plane: h :=0.219*in Disk total width at center: dw := l.959*in Body wall thickness: tb := 0.761*in Stem (packing) diameter: ds : ~ l.l 25* in Parameters common to opening and closing:

Reference Temperature: Tr*'- 70*deg Half of Disk Wedge Angle a.c 5.00*deg 9 =0.087*rad Force applied to stem for closing Fsc : -, 10966* lbf Increase in stem force from stem heatup AF Cl-. 4298*lbf Increase in stem force because of differential thermal contraction upon cooldown ll.F c2 :-= O.O*lbf Packing load Fp := 3827*lbf Mathcad Plus 6.0 S76TBPL2.MCD 12:51 PM on 1124197

MPR Assai:lates, Inc., 320 King street, Alexandria, VA 2 w * !JJ\ _ ,1 Page No.108193DHH01 Preparer:~~ H1Zk----Checker: ~ Print Sheet 2 Parameter Closing Opening Puc.: = 2235*psi Puo :=375-psi Upstream Pressure Bonnet Pressure Pbc := 2235*psi Pbo :=2235* psi Pde := 2235* psi Pdo :=O*psi Downstream Pressure Disk Temperature =

Tde : 653*deg Tdo *=653*deg Body Temperature Tbe =653-deg =

Tbo : 653-i.Jeg Friction Coefficient µc := 0.40 µo := 0.40 Disk Elastic Modulus. 6 Ede :=25.0*10 *psi Edo := 25.0* l0 6 *psi vdc :=0.3 Disk Poisson's Ratio vdo := 0.3 6 1 Disk Coef. of Expan. adc := 9.61*l0- -deg* ado :=9.6l*l0- 6*deg* 1 Body Elastic Modulus Ebe :-= 25.0* I06*psi Ebo :=25.0* 10 -psi 6

Body Poisson's Ratio vbc :=Q.3 vbo *= 0.3 6 1 Body Coef. of Expan. abc := 9.61*l0- *deg* abo *= 9.6l

  • l0- 6*dcg- 1 Maximum force on disk for closing:

Fe *= Fsc - Fp - ~-ds 2 *Pbe + 6.F CI+ 6.F C2 Fe =9.215' 10 3

  • Jbf 4

DETERMINATION OF CLOSING FORCES:

The vector Pc is: The matrix Mc is:

2 -I 0 2 Pbr.:*n:*b 0 0 0 0

-n:-a *(Puc - Pbc)- - - -

cos( 8) - µc*sin(8) c.:os( 8) 0 0 0 0 -I r µc *cos( 0) sin( 8) 0 0 0 0 Po J Pbo-n*bitoo(0)

Mc - 0 0

0 0

0 0

µe*sin(0)

  • cos(B)

µc*cos( 8) sin(B) 0 0

2 Pbc*n:*b *tan( 8) 0 0 0 I 0 0 Pbc*1t*b 2 0 0 0 0 0

  • Pbc) -- ----**

cos(0)

Fe The unknown force vector Sc is:

Mathcad Plus 6.0 S76TBPL2.MCD 12:51 PM on 1124197

'\

M'PR Assoctetas, Inc., 320 King Street, Alexandrta, VA 22314;k 6~ lL- Page No. 108193DHH01 Preparer:,{!'/;: ~-'wmo.- Checker: < l'..t..

  • Print Sh1111t 3 The forces are:

3 3 9.488* 10 Sue: =Sc 0 Sue = 9.488* 10 *Jbf 4

1.229* 10 Hue =Se 1 Hue = 1.229* 10-1 *Jbf 3 3 4.608' 10 Fuc := Sc 2

Fuc = 4.608* 10 *[bf 3 3 Sc= 9.488' 10 '!bf Sdc ::: Sc Sdc: = 9.488* 10 '!bf 3

4 4 1.229* !0 Hdc .= Sc:4 Hde = 1.229* 10 *!bf 3

4.608' 10 3 Ftlc := Sc 5 Fdc =4.608' 10 *Jbf 4

4 He: :=Sc:6 He= 1.191* 10 *!bf 1.191' 10 DETERMINATION OF WEDGING INTERFERENCE:

Flexibilities for Closing:

Hub: in Ghc *= h Ghc =7.025* 10""9 2 !bf 7t*b *Edc Disk, Pressure: m---*- 1 vdc 6 6 4 2 2 4 a *(7*m+ 3) + b -(rn- I)- a *b -(m+ 7)- a *b *(7*m- 5) ...

+-4*a2 *b*'(a

, 2 *(5*m- l)+b 2 -(m+ l))*ln (a)b a *b"*(m+ IHn\b(a) 4 '

2

_3-(m2 -1)

16*m 2

a2 -(m+ l)+b 2*(m- I)

Ope 3

Gpe =2.446' 10-K m psi Edc*t Disk, Seat Force:

, 4 4 22 22 a 1 22 a- '

'I' -

2

_3*(m -1) a *(3*m+ 1)- b '(m- l)-2*a *b '(m+ 1)- 8*m*a *b *In - - 4*a *b '(m*t- 1)-ln -

(b/

(b )

2 , ,

4*m *7t a**(m + I) 1 b--(m ** I) in Gsc 3

Gsc =1.373' lO "B !bf Edc*t Body, Seat Forces: dw 9 in Ksc:~--*** Ksc =4.013"10 4*7t*(u + tb)*Lb*Ebc !bf Body, Bonnet Pressure: 2 dw Kpc:-=---- 8 m 4*tb*Ebc Kpc = 5.043* JO psi Wedging Interference at Reference Conditions:

wr :. 2*Ghc*Hc -t* (Gsc *t- Ksc)*( Sue t* Sdc) + Gpc*(Puc t- Pde*** 2*Pbc) *I 2*Kpc*Pbc ...

+ - dw*adc-( Tdc - Tr) *I* dw*<Xbc* ( Tbc ** Tr)

'"4 wr=:7.29447*JO *in Mathcad Plus 6.0 S76TBPL2.MCD 12;51 ?M on 1124197

j,

~PR Associates, Inc., 32D King Street, Alexandria, VA 223~/ Page No. 1081930HH01 Preparer:.(/r- J. l.(..rh-Checl<er: Print Sheet 4 DETERMINATION OF OPENING FORCES:

Flexibilities for Opening Conditions:

Hub: h -*9 in Gho - - - - Gho =7.025* IO lbf Disk, Pressure: m *-. vdo 6 6 4 ., J 4 a *(7*m+3)+-b *(m- 1)- a *b-*(m+7}- a-*b *(7*m- 5) ...

2 2 +-4*a 2 *b 2 *(a2 *(5*m- l)+-b 1*(m+ l))*ln (a)'

b - 16*a *b *(m+ l)*ln (a)'

4 2 b

_3*(m - I)

<ti 2 2 2 I6*m a *(m+ l)+b *(m- I)

-g m Gpo.--- Gpo =2.446" 10 Edo*t3 psi Disk, Seat Force:

., ra l.Jl=3*(m--l)_

4

  • ( 3 *m + 1} - b 4
  • ( m-2 I ) - 2 a *b 2
  • { m + 1) - 8*m*a 2 *b 2
  • In(-~)

1bJ

- 4*a -b 2 2

-( m + I )*In ( ~ j2

\b1 2 2 2 4*m *rr a *(m+- l)+b *(m- I)

Gso * = - -

't' -s in Gso = 1.373* IO Edo*t3 lbf Body, Seat Forces:

dw -9 in Kso:=------- Kso =4.013* tO 4-rr*(a+ tb}*tb*Ebo !bf Body, Bonnet Pressure:

2 dw Kpo : .. ---*--

Kpo = 5.043" 10

-s in 4* tb* Ebo psi Wedging Interference at Opening Conditions:

4 wo "wr *1* dw*cxclo*(Tclo .. Tr) ** dw*cxho*(Tbo *Tr) WO== 7.294" 10 *in The vector Po is:

4 Define: W -wo *- Gpo*(Puo

  • Pdo 2*Pbo) 2*Kpo*Pbo W::, 6.042* IO *in Mathced Plus 6.0 S76TBPL2.MCD 12:51 PM on 1124197

.MPR Associates, Inc., 320 King Street, Alexandria, VA 223)(;{ ' /"?~~\.

  • ,/ Pagv No. 1081930HH01 Preparvr: .le/'. )1 e--n--, Checker:' /~C<l'V)"\..,V'-""'-- Print Sheet 5 r " Pbo*7t*b 2 1

-lt*a-*(Puo- Pbo)- cos(B}

I () '

1 r 6. 79 I

  • I 03 I Pbo*1t*b 2*tan( 9) lo

' 243.8!5 Po:=

0 I ()

  • Jbf Pbo*lt*b 2-Lan( 8) Po='

1243.815 2 3 2 Pbo*1t*b ' 8.724* 10 l~405*

-1t*a -(Pdo- Pbo) - - - -

cos( 9) 0 4 10 w

Gso-t- Kso The Matrix Mo is:

-I 0 0 0 0

µo*sin{B) cos(B) 0 0 0 0

- µo*cos( 9) sin( 8) 0 0 0 0 0 0 - µo-sin( 9) - cos(9) 0 Mo:= 0 0 0 -µo*cos(9) sin( 8) 0 0 0 I -1 () () ()

0 0 0 0 0 -1 2*Gho*cos(B) 0 0 0 0 0 Gso + Kso The unknown force vector So is: So:= Mo- 1-Po The forces are:

r 1.334* 10 4 Suo: ** So Suo = 1.334* 104 *tbf 3 0

6.545* 10 3 Huo
So 1 Hua =6.545* I 0 *Jbf 3

14.987' 10 3 I Fuo.

  • So Fuo = 4.987* I 0 *Jbf 2

4

' 1.52* 10 Sdo: *So Scio= 1-52* I0 4

'!bf So=* *!bf J 3 3 i 6.479' 10 Hdo:

  • So 4 Helo =6.479* 10 *tbf I 3
5.737* 10 3

Fdo. - So~ F<lo =5.737* 10 *tbf 3

6.985* 10 3 Ho :--So 6 Ho =6.985* 10 *lbf 1.072* !0 4 Fo :- So 7 Fo = !0724.9 *lbf Fo is the force on the disk required to open the value. The packing load must be added to this and the stem rejection load subtracted to get the force on the stem by the actuator.

Fso *c Fo 1 Fp 1:.ds 2-Pbo Fso = 12330.3 *!bf 4

Mathcad Plus 6.0 S76TBPL2.MCO 12:51 PM on 1124197

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