05000395/LER-1983-100, Revised LER 83-100-01X-1:on 830831,PORV PCV-445A Declared Inoperable Due to Concern Re Possible Inadvertent Opening of Valve Upon Power Loss to Protective Cabinet 4.Caused by Design Error

Revised LER 83-100-01X-1:on 830831,PORV PCV-445A Declared Inoperable Due to Concern Re Possible Inadvertent Opening of Valve Upon Power Loss to Protective Cabinet 4.Caused by Design Error

ML20080A225
Person / Time
Site:	Summer
Issue date:	01/27/1984
From:	Dixon O, Mckinney C SOUTH CAROLINA ELECTRIC & GAS CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
LER-83-100-01X, LER-83-100-1X, NUDOCS 8402030418
Download: ML20080A225 (4)

LER-2083-100, Revised LER 83-100-01X-1:on 830831,PORV PCV-445A Declared Inoperable Due to Concern Re Possible Inadvertent Opening of Valve Upon Power Loss to Protective Cabinet 4.Caused by Design Error

Event date:
Report date:
3952083100R00 - NRC Website

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. EvewT OssemirTsoN AND PROSASt.E CONSEQUENCES On August 31, 1983, with the Plant i e 1, Pressurizer Power Operated Relief I;,p g l '

Valve (PORV) PCV-445A was declared inoperable when a concern was identified over MI l

[ the possible inadvertent opening of the valve upon loss of power to Protection Cabinet IV. he present plant design, with a loss of power to the protection cabinet, would arm and actuate the MRV by means of the Cold Overpressure Protection System.

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SOU,TH CAROLINA ELECTRIC & GAS COMPANY POST OFFICE 764 COLuusiA. south CAROUNA 29218 O. W. OrxoN JR.

vice PaessoENT - * ! I j-; 31 AGEnMy 27, 1984 NucteAn OPERATIONS Mr. James P. O'Reilly Regional' Administrator U.S. Nuclear Regulatory Commission Region II, Suite 2900 101 Marietta Street, N.W.

Atlanta, Georgia 30303-

SUBJECT:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Fourteen Day Written Report LER 83-100, Revision 1

Dear Mr. O'Reilly:

Please find attached Revision 1 to Licensee Event Report #83-100, for the Virgil C. Summer Nuclear Station. This revision is being submitted to provide updated information. This Fourteen Day Report was previously submitted on September 13, 1983 in accordance with Technical Specification 6.9.1.12.(i) as a result of entry into Action Statement (a) of Technical Specification 3.4.4, " Relief Valves," on August 31, 1983.

Should there be any questions, please call us at your convenience.

Very trul yours,

/

O. W. D xon .

CJM:OWD/mac/fjc Attachment cc:- V. C. Summer C. L. Ligon (NSRC)

T. C. Nichols, Jr./O. W. Dixon, Jr. G. J. Braddick E. H.' Crews, Jr. D. J. Richards E. C. Roberts NRC Res. Inspector n' . A. Williams, Jr. J. B. Knotts, Jr.

D. A. Nauman I&E (Washington)

Grouc Managers Document Management O. S. Bradham Branch C. A. Price INPO Records Center D. A. Lavigne NPCF J. F. Heilman File OFFICIAL COPY ,

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Mr. James P. O'Reilly LER No.83-100, Rev. 1 Page Two January 27, 1984 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES South Carolina Electric and Gas Company (SCE&G) has identified a concern with the channel assignment of an input to the Cold Overpressure Protection System (COPS). The concern involves the possible inadvertent opening of a Pressurizer Power Operated Relief Valve (PORV) due to a single failure.

During installation of the Reactor Vessel Level Instrumentation System (RVLIS) at Virgil C. Summer Nuclear Station, Westinghouse found it necessary to move a wide range hot leg temperature loop (T-433) from Channel I Protection Cabinet to Channel IV Protection Cabinet. This temperature loop is used by RVLIS for density com-pensation and was moved to a channel of the same separation group as the RVLIS channel to resolve a channel separation / independence concern. The present design creates a situation where a loss of power to Channel IV Protection Cabinet will inadvertently open PORV PCV-445A via the COPS.

CPUSE AND CORRECTIVE ACTIONS The cause is attributed to design error as described above.

The immediate corrective action taken by SCE&G was to close and de-energize the block valve for PORV-445A in accordance with Action Statement (a) of Technical Specification 3.4.4. SCE&G then contacted Westinghouse and requested that a safety evaluation be performed to determine the safety significance of an inadvertent opening of a PORV. Westinghouse's final safety evaluation indicated that even though a loss of coolant accident (LOCA) due to an inadvertent opening of a PORV has a higher probability of occurring, the Virgil C. Summer Nuclear Station safeguards equipment is adequate to mitigate the consequences. Furthermore, the inadvertent opening of a single PORV coincident with an initiating failure of another PORV is bounded by the spectrum of FSAR small break LOCA analyses.

> #9 Mr. James P. O'Reilly LER No.83-100, Rev. 1 Page Three-

- January 27, 1984 CAUSE AND CORRECTIVE ACTIONS - Continued The final corrective action taken by SCE&G.was to request a Technical Specification change in a letter dated October 21, 1983, (Mr. O. W. Dixon, Jr. to Mr. H. R. Denton) , for the use of the Residual Heat Removal System (RHRS) relief valves as the primary

- method of mitigating cold overpressurization transients. SCE&G f eels that this solution not only resolves the undesirability of operating with the PORV blocked, but also eliminates the necessity of performing hardware modifications to the PORV circuitry. The  ;

PORV_will'no longer be required to perform in a cold overpressurization mitigation capacity once the RHRS relief valves are approved as the method of mitigating cold overpressurization transients.

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