ML20082E784

RO 83-099:on 831031,unit Manually Tripped from 62% Reactor Power in Response to Loss of Main Feedwater.Steam Driven Auxiliary Feedwater Pump 3P-140 Failed to Start. Investigation Ongoing.Followup Rept Expected by 831123

ML20082E784
Person / Time
Site:	San Onofre
Issue date:	11/09/1983
From:	Haynes J SOUTHERN CALIFORNIA EDISON CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
RO-83-099, RO-83-99, NUDOCS 8311280315
Download: ML20082E784 (2)

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U. S. Nuclear Regulatory Commission

~ Office of Inspection and Enforcement Region V 3

1450 Maria Lane, suite 210 Walnut Cre?<, California 94596-5368 Attention: Mr. J. B. Martin, Regional Administrator

Subject:

Docket No. 50-362 Prompt Report Licensee Event Report No.83-099 San Onofre Nuclear Generating Station, Unit 3 Pursuant to Section 6.9.1.12.i of Appendix A, Technical Specifications to Facility Operating License NPF-15 for San Onofre Unit 3, this submittal provides the written confirmation of our prompt notification to the NRC on November 8, 198.', of a reportable occurrence involving the Auxiliary FeedJater System.

5, On-October 31, 1983, at 1925, Unit 3 was manually tripped from 62%

reactor power in response to a loss of main feedwater. An Emergency Feedwater Actuation Signal.(EFAS) was received when the unit was tripped, however, the Steam Driven Auxiliary Feedwater Pump 3P-140 failed to start. Pursuant to 10 CFR 50.72(a)7, at

about 1955 the NRC Operations Center was notified of the reactor trip, EFAS actuation and the failure of 3P-140 to automatically initiate. Both electric driven Auxiliary Feedwater Pumps started and remained operable during this event.

D Investigation into the failure of pump 3P-140 by the operator revealed that the pump turbine was in a tripped condition. The mechanical linkage to.the pump's turbine steam admission valve was manually reset,.and while the EFAS signal was still present, the pump started.at about 1936.

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• Mr. J. B. Martin The pump had previously been satisfactorily tested on October 30, 1983, at.1820. Although Control Room instrumentation is available to-identify when the pump turbine is tripped, troubleshooting of the instrumentation subsequent to the plant trip.on October =31, 1983, has indicated that there are intermitent failures of the instrumentation to. indicate when the pump turbine is tripped. An engineering evaluation is being performed _and pending completion of this evaluation and-implementation of any corrective action shown to be necessary, visual verification that the 3P-140 overspeed trip mechanism is not in the' tripped position.will be performed once per shift.

The event was-initially. believed to be a 30-day reportable event.

During the ongoing' investigation associated with this event, it was determined that a Prompt Report pursuant to Section 6.9.1.12.1 of Technical Specifications, is appropriate for this event.

Our-investigation into the cause and corrective actions to be taken is continuing. A 14-Day Follow-Up Report.and a Licensee Event Report (LER) form for Unit 3, LER 83-099, will be submitted by November 23, 1983. In addition, the October Monthly Auxiliary Feedwater System. Report, required by Unit.3 License Condition 2.C(26), will include this event.

If'there are any questions regarding the above, please so advise.

Sincerely, b 5

' J '. G.. AY STATI N MANAGER cc: A. E. Chaffee (USNRC Resident Inspector, Units 1, 2 and 3)

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