ML20054G263

RO 82-21:on 820609,review of Nonconformance Rept S023-P-230 Identified Const Error.Override Relay Contacts Associated W/Auxiliary Feedwater Pump Motor Installed Normally Open. Caused by Incorrect Wiring Diagram

ML20054G263
Person / Time
Site:	San Onofre
Issue date:	06/10/1982
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
RO-82-21, NUDOCS 8206210340
Download: ML20054G263 (2)

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$7 A f TON M AN AGE R (714) 492 7 F00 June 10 1982 U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 - 5368 Attention: Mr. R. H. Engelken, Regional Administrator

Subject:

Docket No. 50-361 Licensee Event Report No. 82-21 San Onofre Nuclear Generating Station, Unit 2 In accordance with Technical Specification 6.9.1.12.1, this letter confirms our prompt notification of your office by telephone on June 9, 1982, of a reportable occurrence involving the Auxiliary Feedwater (APd) System.

E i i i Review of Non-Conformance Report (NCR) S023-P-230; issued by SCE/QA, identified a construction error in that the override relay contacts associated wit.h the APd pump-motor were installed normally open, based on an incorrect -

wiring diagram. The elementary diagram correctly shows these contacts to be ,

normally closed. This error has now been corrected. .

An evaluation is in progress to determine the potential consequences of this error had it not been corrected. Preliminary results indicate that had the APd pumps- been operating (plant cool dowl) and a loss of off-site power occurred followed by an Engineered Safety Features Actuation Signal (ESFAS), i the Diesel Generators would attempt to start with the APd pump-motors connected to the 4160v emergency buses. This would have caused an under voltage situation in both the 4160v buses and the associated 480v buses. The voltage dip on the 4160v buses would have been acceptable, hoaever, the voltage dip on the 480v buses would have been either marginal or below the design basis.

This preliminary evaluation led to the conclusion that the performance of the Emergency Power System required a corrective measure to prevent its operation in a manner less conservative than that assumed in the safety ZOA analysis. Therefore, prompt notification to your office was made.

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Mr. R. H. Engelken June 10, 1982 This was an isolated case of construction error and since the error has been rectified, no additional corrective measures are required.

A completed LER form addressing this event will be provided by June 23, 1982. If there are any questions regarding the above, please contact me.

Sincerely,

[. k cc: A. E. Chaffee (USNRC Resident Inspector, San Onofre, Unit 2)