05000361/LER-1982-073, Forwards LER 82-073/01T-0.Detailed Event Analysis Submitted

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Forwards LER 82-073/01T-0.Detailed Event Analysis Submitted
ML20064M990
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 08/27/1982
From: Ray H
SOUTHERN CALIFORNIA EDISON CO.
To: Engelken R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20064M992 List:
References
NUDOCS 8209080186
Download: ML20064M990 (2)


LER-2082-073, Forwards LER 82-073/01T-0.Detailed Event Analysis Submitted
Event date:
Report date:
3612082073R00 - NRC Website

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Southern California Edison Company n,, , SCE SAN ONOFRE NUC LEA R GENEH A TING ST A TION f' e.

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P.O. D O M 120 S A N C LEMLN T E. C A LIFOR NI A 92672 H. B. R AY TELEPHONE

.T A1,0N . AN Ao E a August 27, 1982 <>m*>=

l U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement '

Region V 1450 Maria Lane, Suite 210 i Walnut Creek, California 94596-5368 r

Attention: Mr. R. H. Engelken, Regional Administrator i

Dear Sir:

Subject:

Docket No. 50-361 Prompt Report and 14-Day Follow-up Report Licensee Event Report No.82-073 -

San Onofre Nuclear Generating Station, Unit 2 Pursuant to Appendix A Technical Specification 6.9.1.12b to operating .

license NPF-10 for San Onofre Unit 2, this submittal provides the written confirmation of our prompt notification to the NRC on August 27, 1982, of a reportable occurrence involving the Refueling Water Storage Tank (RWST), and the requir ed follow-up report with a completed Licensee Event Report (LER) for this occurrence. ,

Limiting Condition for Operation (LCO) 3.5.4 requires that the RWST  ;

shall be operable with a minimum borated water volume of 362,800 gallons above the ECCS suction connection while operating in Modes 1-4. The top ,

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of the ECCS suction pipe enters the RWST approximately 49 inches above tank bottom. Inside the tank, the pipe bends down and is provided with antivortexing devices to permit pumping the tank down to about 12 inches from the tank bottom. Accordingly, this level was used in generating

, the procedural requirement for minimum tank level of 75%, consistent with the Technical Specification requirement for the minimum borated water volume.

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8209080186 820827 gDRADOCK05000 [y 62-305 __ .-

s Mr. R.H. Engel ken August 27, 1982 Recently, a review was initiated involving Station and General Office Engineering personnel to verify capacity versus indicated level over the full range for all tankage referenced in the Technical Specifications.

This review identified that the minimum RWST level should be specified at 87.5% (indicated) based on the Recirculation Actuation Signal (RAS) setpoint which had assumed the tank could only be pumped down to the level at which the ECCS suction pipe penetrates the tank shell. RWST level was maintained above 87.5% while this conclusion was verified, which occurred on August 26, 1982.

Prior to this determination, tank level had generally been conservatively maintained at about 90%. However, review of records indicates that it had been reduced for several periods below the 87.5% level to as low as 80%. Although this was not a procedural violation, it was not consistent with the minimum water volume above RAS setpoint assumed in the safety analysis.

The discrepancy, therefore, between the minimum RWST level required by procedure (75%) and that required based on RAS setpoint (87.5%) resulted from: (1) a misinterpretation of the words "ECCS suction connection" in the Technical Specifications, and (2) a failure to cross-check the result against the safety analysis based on actual RAS setpoint. Other situations where this could have occurred are being checked to verify correct procedural values.

Since receipt of the Operating License, no events have occurred which called for substantial water use from the RWST. Hence, plant operations were not affected and there was no effect on the public health and safety.

If there are any questions regarding the above, please contact me.

4 Sincerely,

/ .

t Enclosure (LER 82-073) cc: A.E. Chaffee (USNRC Resident Inspector, San Onofre, Unit 2)

U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Office of Management Information and Program Control Instititue of Nuclear Power Operations

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