ML20081H435

RO 83-087:on 831026,in-core Detection Monitoring Sys Computer Failed,Rendering Limiting Condition for Operation (LCO) B.10.2 Unsatisfied.Lco 3.0.3 Invoked.Cause & Corrective Actions Will Be Submitted by 831110

ML20081H435
Person / Time
Site:	San Onofre
Issue date:	10/27/1983
From:	Haynes J SOUTHERN CALIFORNIA EDISON CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
RO-83-087, RO-83-87, NUDOCS 8311070436
Download: ML20081H435 (2)

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S 7/G Southern California Edison Company 3 $3

$4N ONOFR E NUC LE AR GENER A TING S T A TION !e P.O. Bo x 12 8 S AN C LEMENTE, C A LIFORNI A 92672 fi

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October 27, 1983 e

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

Subject:

Docket No. 50-362 Prompt Report Licensee Event Report No.83-087 San Onofre Nuclear Generating Station, Unit 3 s

Pursuant to Section 6.9.1.12.b of Appendix A, Technical Specifications to Facility Operating License NPF-15 for San Onofre Unit 3, this letter provides the written confirmation of our prompt notification to the NRC on October 27, 1983, of a reportable occurrence involving the Incore Detector Monitoring System.

" On October 26, 1983, with Unit 3 in Mode 1 at 50% power, the plant vias performing the "CPC Power Distribution Constant verification" physics test. This testing required the Regulating CEA Group No. 6 to be fully inserted and the remaining CEA's fully withdrawn. This testing is controlled by Special Test Exception Limiting Condition for Operation (LCO) 3.10.2, in which the provisions of LCO 3.1.3.6 for Regulating CEA Insertion Limits and sequencing are suspended. Special Test Exception Surveillance Requirement 4.10.2.2 requires the linear heat rate be continuously monitored by the Incore Detector s Monitoring System.

At 1019, the plant computer which operates the Incore Detection Monitoring System failed. When the plant computer failed, LCO 3.10.2 could not be satisfied, and since the withdrawal sequence of LCO 3.1.3.6 was not satisfied, LCO 3.0.3 was invoked.

8311070436 831027 PDR ADOCK 05000362 S PDR l l

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Mr. J. B. Martin October 27, 1983 At 1049, the plant computer was returned to service and the Incore Detector Monitoring System returned to operable status.

Unit 3 shutdown was not required since corrective actions were taken within one hour to permit operation under LCO 3.10.2. The health and safety of the public was not affected by this event.

r We are continuing our review into this event and will submit a 14-day follow-up report by November 10, 1983, delinaating the cause of the event and corrective actions.

If you require any additional information, please so advise.

Sincerely, W

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

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