05000259/LER-1978-035-03, /03L-0 on 781201:during Test,One Wheeler Reservoir Level Monitoring Switch Failed to Operate Due to Moisture Short Circuiting the Amplifier Printed Circuit Board.Switch Calibr & Returned to Svc

/03L-0 on 781201:during Test,One Wheeler Reservoir Level Monitoring Switch Failed to Operate Due to Moisture Short Circuiting the Amplifier Printed Circuit Board.Switch Calibr & Returned to Svc

ML19305A102
Person / Time
Site:	Browns Ferry
Issue date:	12/28/1978
From:	TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19305A099	List: 05000259/LER-1978-035, Forwards LER 78-035/03L-0 05000259/LER-1978-035-03, /03L-0 on 781201:during Test,One Wheeler Reservoir Level Monitoring Switch Failed to Operate Due to Moisture Short Circuiting the Amplifier Printed Circuit Board.Switch Calibr & Returned to Svc
References
LER-78-035-03L, LER-78-35-3L, NUDOCS 7901040129
Download: ML19305A102 (2)

LER-1978-035, /03L-0 on 781201:during Test,One Wheeler Reservoir Level Monitoring Switch Failed to Operate Due to Moisture Short Circuiting the Amplifier Printed Circuit Board.Switch Calibr & Returned to Svc

Event date:
Report date:
2591978035R03 - NRC Website

text

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U.S. NUCLEAR HEGULATORY COMMISSION

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LICENSEE EVENT REPORT cO'NTROL DLOCK: l l

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8 60 68 DOC A ET NUVBER tid 69 EVENT DATE 14 75 REPORT D A1 E 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h [oTTI I While perfoming surveillance testing on the Wheeler reservoir level nonitoriny switches, l one of two switches failed to operate.

The redundant switch operated satisfac-l O 3 l torily.

Failure of the one switch placed the system in a degraded mode in accordance l o 4 0 s l with T. S. tabic 3.2.11.

There was no hazard to the public health or safety.

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40 di 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l 5 l o l l Moisture caused a short circuit in the amplifier printed circuit board. The amplifier l lin the Model 351-A switch was replaced.

The switch was calibrated and returned to I

i l service within a few hours. This problem was considered random in nature and no l

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LER SUPPLEMENTAL INFORMATION BFRO-50 259

/ 7835 Technical Specification Involved 3 2.H

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6.7.2.b.2 Reported Under Technical Specification Date of Occurrence 12/1/78 Time of Occurrence 1500 Unit common Identification and Description of Occurrence:

L.S.23-75B level switch failed to operate during surveillance 'esting.

t Conditions Prior to Occurrence:

Unit 1 - shutdown for refueling-

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Unit 2 - operating at 97% power.

t Unit 3

, operating at 24% power.

Action specified in the Technical Specification Surveillance Requirements met due to inoperable equipment.

Describe.

Returned to service within thirty days.

i Apparent Cause of Occurrence:

Moisture caused a short circuit in the amplifier printed circuit board.

Analysis of Occurrence:

Redundant switch, LS-23-75B, was operable; consequeritly, an annunciation would have occurred if the reservoir level had risen.

Corrective Action

Amplifier printed circuit board was replaced, calibrated, and returned to service.

Failure Data:

l l

None Tennessee Valley Authority - Brown Ferry Nuclear Plant 1