ML20054L833

RO 82-034:on 820621,discrepancies Discovered Re Reactor Coolant Pump Speed & Control Element Assembly Position Indication.Probably Caused by Incorrect Signal Wiring Connections to Core Protection Calculators

ML20054L833
Person / Time
Site:	San Onofre
Issue date:	06/22/1982
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
RO-82-034, RO-82-34, NUDOCS 8207080517
Download: ML20054L833 (2)

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" * " * * " " " ^ * " June 22, 1982 mim>m 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

Dear Sir:

Subject : Docket No. 50-361 Written Confirmation of Prompt Reportable Occurrence Licensee Event Report No.82-034 San Onofre Nuclear Generating Station, Unit 2 In accordance with Appendix A Technical Specification 6.9.1.12.1 to Operating License NPF-10, this submittal provides written confirmation of a prompt reportable occurrence involving the Core Protection Calculator at San Onofre Unit 2. Prompt telephone notification of the occurrence was made to G. Zwetzig of your office at 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> on June 21, 1982.

During performance of post-core hot functional testing, discrepancies were discovered involving Reactor Coolant Pump (RCP) pump speed and Control Element Assembly (CEA) position indication. These parameters are utilized by the Core Protection Calculators (CPC's) for use in calculation of Departure from Nucleate Boiling Ratio (DNBR) and Local Power Density (LPD). Recent investigations have concluded that incorrect signal wiring connections to the CPC's are the probable cause of the noted discrepancies. These conditions would have resulted in incorrect CEA position indication and RCS flow, which in turn could have caused the calculation of less conservative trip setpoints than those assumed in the accident analyses as set forth in the Safety Analysis Report and Technical Specification bases under certain plant operating conditions.

Since the plant has never been in a mode of operation requiring the CPC's, nonconservative operation did not actually occur.

Investigations into the cause, effect, and corrective actions required are continuing with the assistance of the equipment vendor.

8207000517 820622 PDR ADOCK 05000361 PDR g

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• • June 22,1982 t Mr. R. H. Engelken ,

i A 14-day written report detailing the circumstances surrounding this event and a completed copy of Licensee Event Report No.82-034 will be submitted on or before July 5,1982.

Any reporting found to be necessary under 10CFR21 and 10CFR50.55.e (for San Onofre Unit 3) will be addressed by separate correspondence.

. Please contact me if you have further questions concerning this matter.

Sincerely, l Lu cc: A.E. Chaffee (USNRC Resident Inspector, San Onofre, Unit 2) l j

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