05000298/LER-1982-022, Forwards LER 82-022/03L-0.Detailed Event Analysis Submitted

Forwards LER 82-022/03L-0.Detailed Event Analysis Submitted

ML20028B461
Person / Time
Site:	Cooper
Issue date:	11/22/1982
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20028B462	List: 05000298/LER-1982-022, Forwards LER 82-022/03L-0.Detailed Event Analysis Submitted 05000298/LER-1982-022-03, /03L-0:on 821025,RHR Time Delay Relay 10A-K45A Failed to Operate within Required Time Limits.Caused by Setpoint Being Set Too Conservatively.Relay Readjusted & Correct Operation Verified
References
CNSS820669, NUDOCS 8211300402
Download: ML20028B461 (2)

LER-1982-022, Forwards LER 82-022/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
2981982022R00 - NRC Website

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• n ' d COOPER NUCLEAR STATroN h~ M Nebraska Public Power District

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o CNSS820669 Novenber 22, 1982 Mr. John T. Collins, Regional Administrator U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.1 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occur-rence that was discovered on October 25, 1982. A licensee event report is also enclosed.

(Cb Report No.:

50-298-82-22 Report Date:

November 22, 1982

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Occurrence Date:

October 25, 1982 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which may have resulted in operation in a limiting condition for operation established in Table 3.2.B of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was operating at a steady state power level of 100% of rated power.

Description of Occurrence:

During routine testing of the RHR System, time delay relay, RHR-TDR-K45A was found with a setpoint out of the Technical Specification limit. The relay was found to actuate with a time delay of 5.84 minutes. The Technical Specification requirement for this relay is between 4.25 and 5.75 minutes.

Designation of Apparent Cause of Occurrence:

No apparent reason for the increased time delay was established. The equipment history revealed that this time delay relay has shown no abnormal drift in the past two years.

Analysis of Occurrence:

RHR-TDR-K45A is a time delay relay (General Electric Model CR120K) that is energized whenever LOCA conditions exist. This relay prevents an C2113OO 8

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Mr. John T. Collins November 22, 1982 Page 2 operator from throttling the RHR (LPCI) System reactor vessel injection valve, 27A, for five minutes after a loss of coolant accident initiation.

The redundant RHR System "B" was operable with its time delay setpoint within limits. The five minute time delay prevents operator action after receipt of a LOCA signal. The setpoint was actually set more conserva-tively than the Technical Specification liniw, thus this occurrence pre-sented no adverse potential consequences from the atandpoint of public health and safety.

Corrective Action

The time delay relay RHR-TDR-K45A was readjusted at the time of the occurrence. The setpoint history was reviewed for the past two years on both RHR-TDR-K45A and K45B, no significant drift was noted. This was the only case of drift outside the Technical Specification limit. The possibility of an error on the part of the instrument technician was investigated, but the time delay was measured with an electronic timer hooked to test connections in the circuit, thus eliminating the possibility of a technician timing error. No further action is planned.

Sincerely,

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L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.

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