ML20081H472

RO 83-130:on 831021,train B Emergency Chiller E-335 Tripped Following Planned Plant Evolution in Which Power Supply to Control Room Isolation Sys Realigned from Unit 2 to Unit 3. Flow Adjusted & Chiller Returned to Svc

ML20081H472
Person / Time
Site:	San Onofre
Issue date:	10/24/1983
From:	Haynes J SOUTHERN CALIFORNIA EDISON CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
RO-83-130, NUDOCS 8311070460
Download: ML20081H472 (2)

Text

e Southern California Edison Company 5fE 5 AN ONOF RE NUC LE A R GENE R A TING S T A TION P.O. Bo x 12 8

.., SAN C LEME N T E. C A LIFORNI A 92672 T October 24, 1983 a '

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U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, suite 210 Walnut Creek, California 94596-5368 5 Attention: Mr. J. B. Martin, Regional Administrator

Subject:

Docket Nos. 50-361 and 50-362 Prompt Report Licensee Event Report No.83-130 (Docket No. 50-361)

San Onofre Nuclear Generating Station, Units 2 and 3 Pursuant to Sections 6.9.1.12.b of Appendix A, Technical Specifications to Facility operating Licenses NPF-10 and NPF-15 for San Onofre Units 2 and 3, respectively, this submittal provides the written confirmation of our October 21, 1983, notification to the NRC of a reportable occurrence involving the on-site power distribution system.

On October 21, 1983, at 0130, with Units 2 and 3 in Mode 1, Train B Emergency Chiller E-335 tripped following a planned plant evolution in which the power supply to the Control Room Isolation 3.

System (CRIS) was being realigned from Unit 2 to Unit This operation results in the starting of Emergency Chiller E-335; however, the chiller tripped on low Component Cooling Water (CCW) flow. The CCW flow to Emergency Chiller E-335 was adjusted and the chiller was successfully returned to service within 40 minutes at 0210.

8311070460 831024 g DR ADOCK 05000361 PDR I

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- Mr. J. B. Martin October 24, 1983 Loss of an Emergency Chiller renders all equipment inoperable in rooms in both units where chilled water is provided to cool ambient air. Several Limiting Condition for Operations (LCO's) govern plant operation in this situation. The most restrictive LCO for a loss of the chiller is LCO 3.8.3.1. The loss of the Train B Emergency Chiller renders two inverters inoperable in each unit. Since LCO 3.8.3.1 requires all four inverters and their associated busses to be operable in Modes 1 through 4 in each unit and since the associated Action Statement only addresses the loss of one such inverter and its associated bus, LCO 3.0.3 was invoked at 0130. The chiller was returned to service at approximately 0210, restoring operability to the two inverters in each unit and associated A. C. Vital busses, and LCO 3.0.3 was exited.

Since the occurrence involves a shared systcm between Units 2 and 3, in accordance with NUREG-0161, a 14-Day Follow-Up Report and a single Licensee Event Report (LER) form for Unit 2, LER 83-130 (Docket No. 50-361), will be submitted by November 4, 1983.

If there are any ques.tions regarding the above, please so advise.

Sincerely, 4

J. G. HAYNES STATION MANAGER cc: A. E. Chaffee (USNRC Resident Inspector, Units 1, 2, and 3)

J. P. Stewart (USNRC Resident Inspector, Units 2 and 3) p i

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