ML20004E998

Forwards Response to IE Bulletin 81-02, Failure of Gate Type Valves to Close Against Differential Pressure. Valve MOV-2869B Will Be Qualified for Intended Svc

ML20004E998
Person / Time
Site:	Surry, North Anna
Issue date:	05/22/1981
From:	Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
313, IEB-81-02, IEB-81-2, NUDOCS 8106160333
Download: ML20004E998 (5)

Text

.

\\

• m, r' E, -

a

$\\

\\l,

.\\

[

F. C i ~> '-

.Vraatsrat2 0 0 ~ELzCTR{

• AND Powan COMPANY h

9 10 Hrcuasown.VrmoxwzA ass 6n p$

o

'll F.SY N b

- 'I ay 2, 1981 4 h,y N Mr. James P. O'ite111y, Director Serial No. 313 Office of Inspection and Enforcement N0/DWSjr:jmj U.S. Nuclear Regulatory Comission Docket Nos. 50-280, 50-281 50-338, 50-339 Region II 101 Marietta Street, Suite 3100 License Nos. DPR-32, DPR-37 Atlanta, Georgia 30303 NPF-4, NPF-7

SUBJECT:

I.E. BULLETIN 81-02 This is in response to I.E.Bulletin 81-02, " Failure of Gate Type Valves to Close Against Dif ferential Pressure". Our responses for Surry Power Station Unit Nos.1 and 2 and North Anna Power Statica Unit Nos.1 and 2 are attached.

The information contained in the attached pages is true and accurate to the best of my knowledge and belief.

Very truly yours, e

G r.

y

• j u.

B. R. Sylvia a Manager - Nuclear Operations and Maintenance Attachment City of Richmond Commonwealth of Virginia

-.(

i l

Acknowledged before me,this22 day of /H,19p l

l 1

ci. % (

h#h Notary Public

_,19jf 2 - 24 My Comission expires:

SEAL cc:

Mr. Steve A. Varga, Chief Operation Reactors Branch No.1 (ff Division oE Licensing Mr. Robert A. Clark, Chief s

t l

Operating Reactors Branch No. 3 l

Division of Licensing

/[

I l

8186160 333

Attachm:nt 1 RESPONSE TO IE BULLETIN 81-02 FAILURE TO GATE TYPE VALVES TO CLOSE AGAINST DIFFERENTIAL PRESSURE SURRY POWER STATICT NRC REQUEST 1.

Within 30 days of the issuance date of this bulletin, ascertain whether any of the affected valves have been installed, or are maintained as spares for installation, where they are required to close with a differ-ential pressure across them in safety-related systems or as PORV block valves. The dif ferencial pressures of concarn include the following:

For the W-END manufacutured valves, values in excess of the thres-a.

hold values in Table 1.

Re sponse A review has been completed of the valves in safety related systems that meet the above prerequisites. One valve has been identified as'being applicable to this bulletin: W-EMD Model 0300lGM99FN BOD 000W750004, Vepco Mark No.: MOV-2869B.

NRC REQUEST 2.

If any affected valves are identified.as being installed, take corrective action and evaluate the effect that failure to close under any condition requiring closure would have on system (s) operability pprsuant to the facility technical specifications for continued operation.

Response

The affected valve, MOV-2869B, is a normally closed valve and does not receive a " safety signal" to perform its' function. Long term recovery procedures, following a LOCA, require the alternating of ECC flow between the cold and hot legs. MOV-2869B, Hot Leg Recircu-lation Isolation, is opened 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> af ter the initiation of the LOCA. Subsequently, the MOV will be closed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> later, when shifting to " cold leg recirculation". However, the failure of this valve to fully close will not prevent the ECCS from performing its' intended function. Therefore, there is no affect on the ECCS oper-ability purstant to technical specifications.

NRC REQUEST 3.

If any affected valves are identified as spares, either modify the valves so that they are qualified for the intended service or obtain qualified replacements prior to installation.

Response

None of the affected valves are spares. Furthermore, any valve

3.

Response (continued) that is maintained as a spare or used as a replacement will be qualified for the intended service.

NRC REQUEST

4.

• Within 45 days of the issuance date of this bulletin, submit a report to NRC listing the affected valves identified, their service or planned service, the maximum dif ferential pressure at which they would be required to close, the safety consequences of the valve's failure to close, the corrective action taken or planned, and the schedule for completing the corrective acc h,

Response

(a) The affected valve is a W-EMD Model No. 0300lGM99FNB0D000 W750004, Vepco Mark No. MOV-2869B. This valve functions as a Hot Leg Recirculation Isolation valve.

(b) The maximum dif ferential pressure, as obtained from original startup testing data, is 870 psi.

(c) As stated in item 2 above, the valve's intended function is to provide the capability of alternating ECC flow between the cold and hot legs. Westinghouse has shown that this type of valve will operate through 75% of its full stroke under design differ-ential pressures. This equates to about 5% of the total flow area unsealed. Hence, less than 1% of the total ECC flow, that should be injected into the cold legs, would be diverted to the hot legs. This amount of flow would not negate the conclusions presented in the FSAR and would not have any significant affect on LOCA.

(d) Vepco will be working with Westinghouse to qualify this valve for its intended service.

(e) This valve vill be modified, during the next outage of sufficient duration following the receipt of the required materials.

Estimated man-power expended in review and preparation of this report is forty-two (42) man-hours. No estimate of man-days is presently available for implementing corrective action.

9 I

t 1

~

Attrchm:nt 2 RESPONSE TO IE BULLETIN 81-02 FAILURE OF GATE TYPE VALVES TO CLOSE AGAINST DIFFERENTIAL PRESSURE NORTH ANNA UNITS 1 & 2 1.

Three valves, all installed in Unit 2, were identified:

'. a) MOV-2536 (3GM88 E-EMD manufactured valve)

This valve is installed as PORV Block Valve, b) MOV-2373 (3GMB8 E-EMD manufactured valve)

This valve is installed in the common charging pump recirculation flow path, c) MOV-22898 (3GM99 W-EMD manufactured valve)

This valve is installed in the normal charging line and serves to isolate normal charging flow path in the event of a safety injection.

2.

See responses to items 3-5.

3.

An evaluation was performed of the effect of these valves not being able to fully close on system (s) operability pursuant to Technical Specifications:

a) MOV-2536 - The operability of this valve is not addressed in Tech Specs.

Westinghouse has stated that " typically, these valves operated through 75% of their full disc travel leaving about 5% of the flow passage unsealed". Therefore, the valve would serve to effectively isolate a stuck open PORV such that charging pump flow could maint,ain RCS

(

inventory and hence pressure.

l b) MOV-2373 - This valve was recently modified (Design Change 80-563) to remove the automatic Safety Injection closure signal. Presently, emergency procedures call for this valve to be manually closed only if RCS pressure decreases to below 1485 psig.

In addition, once the

- individual charging pump recirculation isolation valves (2775 A,B,C) are closed, there will be negligible AP across MOV 2373 and it would fully close.

c) MOV-2289B - This valve provides Train B isolation of normal charging flow path in the event of a safety injection. Since this valve is I

l installed in series with the Train A isolation valve (MOV-2289A), it will see negible AP once the Train A valve closes. As a result, MOV-2289B would fully close af ter MOV-2289A closes.

4.

None of the affected valves were identified as spares.

5.

a) Mov-2536 - The maximum dif ferential pr' essure this valve would be exposed to is approximately 2400 PSI..The fact that the valve will close to significantly restrict flow means that the charging pumps l

should be able to maintain RCS inventory.

During the May, 1981 Unit 2 outage, the following modifications were compleced on this valve to ensure full closure for rated conditions:

~

1.

The motor pinion / worm shaf t gearset was changed to be made compatible with the required thrust range.

2.

The control circuit wiring for the limitor'que operator was changed to limit closing to ensure a positive and predictable seating load.

b) MOV-2373 - The maximum differential pressure this valve would be exposed to is approximately 2600 PSI (i:he shutoff head of the charging pump). Since this valve is in series with the 2775 A,B, C valves, it would fully close once these valves closed.

During the May,1981 Unit 2 outage, the same modifications done on MOV-2536 were also completed for MOV-2373. This work completes all modifications required to upgrade these valves to their original rating.

c) MOV-2289B - The maximum differencial pressure this valve would be exposed co is approximately 850 PSI (assuming S.I. initiated by RCS low pressure at 1765 PSIG). Since this valve is in series with the 2289A valve, MOV-2289B would be assured of fully closing once the MOV-2289A closed.

The modifications to this valve will be accomplished in two stages.

During the May,1981 Unit 2 outage, the following work was completed:

i 1.

The originally installed SMB-000 operator was replaced with a SB-00 operator. The SB-00 operator was modified with a new motor pinion / worm gearset to be compatible with the required thrust range.

In addition, the motor operator,was fitted with a new stem nut to make the operator compatible with the original valve stem. Finally, as was done for the other two valves, the control circuit for the limitorque operator was changed to limit closing.

During the next Unit 2 outage presently scheduled for October,1981, the modifications will be completed by replacing the original 1.125 inch i

valve stem with a 1.250 inch valve stem, reboring the valve bonnet to accommodate the larger stem, and replacing the stem nut in the operator l

to make it compatible with the larger valve stem.

Once these changes have been completed, this valve will be upgraded to mset its original rating.

i Estimated manpower expended in review and preparation of this report is twenty-four (24) manhours. Estimated manpower expended to implement corrective action is five (5) man days.

l

-