05000298/LER-1982-002, Forwards LER 82-002/03L-0.Detailed Event Analysis Submitted

Forwards LER 82-002/03L-0.Detailed Event Analysis Submitted

ML20041C368
Person / Time
Site:	Cooper
Issue date:	02/17/1982
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20041C369	List: 05000298/LER-1982-002, Forwards LER 82-002/03L-0.Detailed Event Analysis Submitted 05000298/LER-1982-002-03, /03L-0:on 820121,during Routine Surveillance Testing NBI-LIS-101A Found to Trip at Lower than Tech Spec Limits.Caused by Barton Model 288 Switch Actuating at Random Positions.Switch Replaced
References
CNSS820076, NUDOCS 8203010226
Download: ML20041C368 (2)

LER-1982-002, Forwards LER 82-002/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
2981982002R00 - NRC Website

text

,

COOPER NUCLEAR STAT 1oN Nebraska Public Power District

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G CNSS820076 February 17, 1982 7q

!' 3 M 2 21982 i

Mr. John T. Collins, Regional Administrator N

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U S. Nuclear Regulatory Commission 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 g

reportable occurrence that was discovered on January 21, 1982. A Q

licensee event report form is also enclosed.

g EECEBfED Report No.:

50-298-82-02 Report Date:

February 17, 1982 9-Occurrence Date: January 21, 1989

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FE8 '9 G 1982*w

- 12 IkhQgsg Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 reg 7

4 Identification of Occurrence:

to A safety system setting was discovered to be less conservative than the limiting setting established in Table 3.1.1 of the Technical Specifications.

Conditions Prior to Occurrence:

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

Description of Occurrence:

While performing routine Surveillance Test Procedure 6.1.9, Level Indicating Switch NBI-LIS-101A was observed to trip at approx-imately 10" indicated water level instead of >l2.5" indicated water level as per Technical Specifications.

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B203010226 820217 PDR ADOCK 05000298 S

PDR

o Mr. John T. Collins February 17, 1982 Page 2.

Designation of Apparent Cause of Occurrence:

The cause of the change in trip point on this instrument (NBI-LIS-101A) is attributed to component failure. The switch is a Barton Model 288A.

Analysis of Occurrence:

NBI-LIS-101A is one of four level indicating switches in the reactor protectica system. The switches are arranged in a oue-out-of-two-twice logic. The remaining switches were operable and would have responded to a decrease in level.

Documentation of previous problems with NBI-LIS-101A (LER's 80-38 and 81-26) has cited excessive setpoint drift as the apparent cause of past switch malfunctions. However it is now believed that these instances of excessive setpoint drift were the result of component end-of-life failure.

This occurrence presented no adverse effect to the public health and safety.

Corrective Action

The NBI-LIS-101A low switch assembly was replaced. The new switch was calibrated and verified to be operable.

No further action is planned.

Sincerely, f

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