ML20038C586
| ML20038C586 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 12/04/1981 |
| From: | Oprea G HOUSTON LIGHTING & POWER CO. |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, IEB-81-02, IEB-81-2, ST-HL-AE-763, NUDOCS 8112110251 | |
| Download: ML20038C586 (8) | |
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' The Light Company n-..,, ugniw - m n.m iroo noi,,ci<.m,,ooi aimmen December 4,1981 ST-HL-AE-763 SFN: V-0530
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'v'"i Regional Administrator, Region IV I
Nuclear Regulatory Commission
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Dear Mr. Collins:
f, South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Final Report Concerning Westinghouse EMD Gate Valves On July 2, 1981, pursuant to 10CFR50.55(e), Hocston Lighting & Power Company notified your office of an item concerning closure problems with Westinghouse (W) Electro-Mechanical Division (EMD) manufactured gate valves.
Our final report regarding this item is attached.
If you should have any questions concerning this item, please contact Mr.
Michael E. Powell at (713) 676-2592.
Very truly yours,
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Exac tive Vice President MEP/blt Attachment f
8112110251 011204 PDR ADOCK 05000498 S
$I I l L
llouston Ligh:ing & Power Compam ec:
G. W. Oprea, Jr.
December 4, 1981 J. H. Goldberg ST-HL-AE-763 J. G. Dewease SFN: V-0530 D. G. Barker Page 2 C. G. Robertson H. Pyle, III R. A. Frazar D. R. Beeth J. W. Williams J. W. Briskin J. E. Geiger D. E.
Sells (NRC)
H. S. Phillips (NRC)
J. O. Read (Read-Poland, Inc.)
M. D.
Schwarz (Baker & Botts)
R. Gordon Gooch (Baker & Botts)
J. R. Newman (Lowenctein, Newman, Reis, & Axelrad)
STP R'4S Director, Office of Inspection & Enforcement Nuclear Regulatory Commission Washington, D. C. 20355 R. L.
Range /G. W. Muench Charles Bechhoefer, Esquire Central Power & Light Company Chairman, Atomic Safety & Licensing Board P. O. Box 2121 U. S. Nuclear Regulatory Commission Corpus Christi, Texas 78403 Washington, D. C.
23555 R. L. Hancock/C. Pokorny Dr. James C. Lamb, III City of Austin 313 Woodhaven Road P. O. Box 1088 Chapel Hill, North Carolina 27514 Austin, Texas 78767 J. B. Poston/A. vonRosenberg Mr. Ernest E. Hill City Public Service Board Lawrence Livermore Laboratory P. O. Box 1771 University of California San Antonio, Texas 78296 P. O. Box 808, L-46 Livermore, California 94550 Brian E. Berwick, Esquire William S. Jordan, III Assistant Attorney General Harmon & Weiss for the State of Texas 1725 I Street, N. W.
P. O.
Box 12548 Suite 506 Capitol Station Washinton, D. C.
20006 Austin, Texas 78711 Lanny Sinkin Citizens for Equitable Utilities, Inc.
Citizens Concerned About Nuclear Power c/o Ms. Peggy Buchorn 5106 Casa Oro Route 1, Box 1684 San Antonio, Texas 78233 Brazoria, Texas 77422 Jay Gutierrez, Esquire Hearing Attorney Office of the Executive Legal Director U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Revision Date 10-29-81
O Final Report Concerning Westinghouse EMD Gate Valves December 4,1981 I.
Description of the Incident On July 2, 1981, pursuant to 10CFR50.55(e), Houston Lighting & Power Company (HL&P), notified your office of an item concerning closure problems with Westinghouse (W) Electro-Mechanical Division (EMD) manuf actured gate valves. }[ had identified to HL&P that several three (3) and four (4) inch gate type valves had been shown by tests and/or analyses by }[ to have a potential for not closing against dif ferential pressure.
Subsequent to HL&P's July 2,1981 notification, HL&P received NRC Inspection & Enforcement (I&E)Bulletin 81-02, Supplement #1, " Failure of Gate Type Valves to Close Against Differential Pressure", which identified that }[
had performed analyses which predicted that closure problems could be anticipated with 6, 8, 10, 12, 14, 16 and 18-inch gate valves in addition to the 3 and 4-inch gate valves.
An evaluation program is being conducted by 1[ and includes flow tests and analyses. Based upon the results to date, f has determined that modifications will be necessary to valves supplied to the South Texas Project (STP) in order to assure that the functional requirements are ree.
However, failure of the valves to meet these requirements does not create a substantial safety hazard.
II.
Corrective Action Depending on the syst.em closing differential pressure requirements and the valve model in questien, the modification to guarantee full clocure can vary. The modification could involve any combination of the following items:
(1) Torque switch adjustment; (2)
Increasing the operator gear ratio to guarantee adequate thrust capacity at eighty percent (80%) voltage; (3) Rewiring the operator for limit closing control; (4) Changing the operator torque switch spring pack; (5)
Changing to a larger foot-pound rated motor; or (6) Changing to a larger size Limitorque operator.
The modifications of the subject valves will be made in accordance with the 1[ procedure for administering field changes. A Field Change Notice (FCN) will be issued by 1[ which will provide the scope of the corrective action to be taken. Based on the current }[ schedule, the FCN for both South Texas Project (STP) Units will be issued by the end of March,1982, with modifications / repairs to be completed by December, 1982.
i III. Recurrence Control A recurrence control program is not considered necessary because the situation appears to be unique to E EMD gate valves.
IV.
Safety Analysis An evaluation of the safety consequences of the valves failing to close was performed in response to NRC I&E Bulletin 81-02, Supplement #1.
Based on the evaluation, failure of these ialves to close would have no significant safety consequences. The attached table - from our response to the subject Bulletin lists the subject 3 gate valves intended for use in safety-related systems, their planned service, the differential pressure against which they will be required to close, and the safety consequences of the valves failing te close.
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P. I cf 7 ATTACHMENT W-DE)
PLANNED SERV!CE MAxjMuM VALVE ID APPlTCATTON HTIP7AllE # (W)
AP (psi)
FAlluRE ANALYSIS 3GMB8FNB Pressurizer PORV Block Valve IRC 001 A B 2500 The present design does not require the block valves to close
, (1-8000 A,B) under full flow conditions. These valves are used to isolate PORV's if they are leaking. The failure of one of these valves to close under full flow conditions would be the same as a Failed Open PORY (assuming PORV is already opened and falls to close). The consequences of this failure are covered by present accident analysis in the FSAR.
6GM72FBA Volume Control Tank Discharge XCV 112 B 100 These valves in series are located on the VCT Discharge Ifne Isolation (LCV-!!2 B) that provides suction to the CVCS charging pumps. These XCV 113 A valves are closed upon opening of the valves that permit CVCS (LCV-Il3A) charging pump suction from the RWST and when either SI signal or VCT lo-lo level signal is present. Failure of one valve to close completely may reduce the differential pressure across the second valve sufficient to permit its closure. Fall-ure of these valves to close would have no significant safety consequences.
6GM72FBA CVCS Charging Puns Suction to XCV 112 C 200 These valves are in parallel flow paths from the RWST to the RWST (LCV-Il2C)
CVCS charging pump suction header. These valves are normally XCV 113 8 closed and are used only in abnormaisituations when the (LCV-1138) charging pumps are used to provide water from the RWST to the Reactor Coolant System. These valves are interlocked to prevent closure when an $1 sional or VCT 10-10 level signal is preserit, Failure of these valves to close would have no significant safety consewences.
These two valves in series provide isolation of tMs CVCS let-4GMB8FND CVCS Letdown Upstream of LCV 465 2500 Regenerative Heat Exchanger LCV 468 down from the RCS. These valves would be automatecally closed on Pressurizer low level that might be caused by a break la the safety class 2 pipe of the regenerative heat enchanger downstream of the valves. The two valves in series provide redundancy. Failure of one valve to close completely may re-duce the differential pressure across the second valve suf-ficiently to permit closure. If the blowdown is not
- p. 2 cf 4 -
W.EMO PtANNCD SFRVICF VAL 4E ID APPLICAllON HL&P VALVE # (W) yfpsh FAILURE ANALYSIS g
terminated, the consequences are covered by present accident analyses in the TSAR. Failure of the valves to close com-pletely has no unreviewed safety consequences.
4GM74FEB CVCS Letdown Containment Iso-XCV023 700 These valves provide a Containment Isolation function. High lation Valves (8133) differential pressure would occur on a Containment Isolation ICV 024 Signal. For a pipe break inside Containment, the dif feren-(8134) tial pressure across the valves would be reduced issnedtately.
permitting the valves to close.
For failure of the two upstream isolation valves (Westing-house EMD valves) in conjunction with a letdown pipe break outside Containment, there are motor-operated packless metal diaphre @ valves used as Letdown Orlfice isolation valves that could be manually operated to terminate flow, bl.E re the flow is reduced, the valves LCV 465, LCV 468 XCV 023 (8133) and XCV 024 (8134) would then be able to close. Also, partial closure of one valve may reduce the differential across the seccM valve suf ficiently to permit the second valve to close. Failure of XCV 023 (8133) and XCV 024 (8134) to close would have no significant safety consequences.
4GM78FPA CVCS Charging Line Isolation XCV 025 3100 The failure of this valve for a pipe break inside or outside (8135)
Containment reduces **e redundancy for Containment ! solation.
For outside Cor.tainment, there are 3 check valves downstream that would prevent blowdown of the RCS. For inside Contain-ment, the Charging Pumps can be stopped and the differential pressure across the valve would be reduced issnediately, per-mitting the valve to close.
4GM72FBA Charging Pump Suction Valve XCV 218 0
This valve is nonna11y closed and provides a means to have from Boric Acid Transfer Pump (8358)
CVCS Charging Pumps take suction from 4 weight percent boric acid solution. The valve is in series with a check valve; fallere to close would permit flow from boric acid transfer pumps to the suction of the charging pianps. Flow may be stopped by turning off the BAT pumps. Backflow into BRS is precluded by check valve. The failure of this valve to close has no significant safety consequences.
- p. 3 cf 4 w.EMD PL ANNED SERVICE gjyg7y VALVE ID APPLICA110N HL&P VALVL # (W) 47 { psi)
FAILURE ANALYSIS 16GM72FBA Safety injection Suction Valve XSI 001 A, B, C 200 Valve is closed for recirculation phase following a LOCA.
from RWST (8801 A.B.C)
Failure of the valve to close would result in a loss of redundancy for preventing backflow to the RWST. Failure of the valve to closa has no significant safety consequences.
6GM77 FHA High Head Safety injection Pump XS! 004 A, B, C 100 This valve provides pump isolation and also serves as the Discharge Isolation Valve /
(2804 A.B.C)
Containment Isolation Valve. The valve is norselly open.
Containment Isolation Failure rf the valve to close against backflow from the kCS has nc significant safety consequences because there are 2 che.9 valves which could prevent blowdown of the RCS.
6GM78FNB kHSI to Accumulator Isolation XSI 006 A, B C 0
This valve closes for switchover from Cold Leg injection to Valve (8806 A,B,C)
Hot Leg injection. Failure of valve to close during recir-culation will degrade flow to Hot Legs. Pressure differen-tial across valve can be reduced to permit closure by momen-tarily interrupting SI (by stopping pump or manual action).
Failure of the valve to close reduces the redundancy for Hot Leg recirculation.
6GM78FNB HHSI to Hot Leg Injection Iso-XSI 008 A, B, C 0
This valve is opened to provide SI switchover from Cold Leg lation Valve (8808 A.B.C) injection to Hot Leg injection. If switchover back to Cold Leg is required, failure of the valve to close would degrade Cold Leg injection flow. However, SI could be momentarily interrupted to reduce differential pressure across valve permitting it to close.
16GM72FBD Emergency Sump Recirculation XSI 016 A, B C 100 This valve must open to permit SI recirculation. The valve Isolation Valve (B816 A.B.C) is required for isolating a passive failure between the sump valve and the next motor-operated valve. High differential pressure should not be present when the valve is required to close.
8GM74FEA low Head Safety injection Pump XSI 018, A, B, C 100 This valve serves as a pump isolation valve and as a Contain-Discharge Isolation Valve / Con-(B818 A,B,C) ment Isolation Valve. The valve is normally open. Reverse tainment Isolation Valve flow in the line is stopped by the inside Containment check valve. Failure of the valve to close reduces Containment Isolation redundancy.
- p. 4 ef 4 W-EMD m Amarn (rnutrr MAXIMUM c
VALVE ID APPLICATION HL&P VALVE f (W) gp (psi)
FAILURE ANAL [1[5 BGM78FNB LHSI to Hot Leg Injection Iso-XRH 019 A, B, C 200 Some as for ASI 008 (8808) lation valve (8819 A.B.C) 8GM78FNB LHSI to Accumulator Isolation XRH 031 A, B, C 200 Same as for XS! 006(8806)
Valve (8901 A B.C) 12GM78FND Accumulator Tank Discharge Iso-XSI 039 A, B, C 0
This valve is normally open during power operation and is lation
- (8949 A,B.C) closed only when required to prevent blowdown as RCS is de-pressurized in a normal shutdown. The accumulator may also be depressurized by venting the N2 to the Containment. The failure of the valve to close under high differential pressure has no significant safety consequences.
12GMB8SEB RHR Suction Isolation Valves XRH 060 A, B, C 700 These valves are normally closed valves and can only be opened from RCS (9000 A.B.C) when RCS pressure is less than approximately 425 psig. When XRH 061 A, B, C the valves are open, they automatically close when RCS (9001 A.B.C) pressure is approximately 750 psig. If valves fail to r. lose under high differential pressure, the operator can take steps to reduce RCS pressure untti the valves are able to close.
Also, with two valves in series, partial closure of the first valve may reduce differential pressure across the second valve permitting its closure. Failure of these valves to close would reduce redundancy.
8GM74FCA CSS Pump Discharge Isolation ICS 001 A, B, C 200 These valves are normally closed. They open to provide Con-Valve / Containment loslation valve (9100 A.B.C) tainment spray and are used for Containment Isolation af ter Containment spray has been terminated. A check valva (IRC) would provide isolation capability. Failure of these valves to close reduces Containment isolation redundancy.
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