ML19263C048

LER 79-002/03L-0 on 790117:reactor Protective Sys for Axial Power Distribution Channel a Trip Setpoint Fluctuated Nonconservatively.Caused by Bell & Howell Potentiometer Module Part 384612/001 Failure

ML19263C048
Person / Time
Site:	Fort Calhoun
Issue date:	01/24/1979
From:	Connolley J, Gordon Peterson OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19263C046	List: ML19263C045 ML19263C048
References
LER-79-002-03L, LER-79-2-3L, NUDOCS 7902020195
Download: ML19263C048 (3)

Text

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ao 61 COCKET NUMBER 68 69 EVENT DATE 74 75 REPCRT CATE 80 EVENT DESCRIPTION AND PROBABLE CONSECUENCES h io 2 lDuring steady state power operation it was noted that the A channel of the reactor i o 3 l protective system (RPS) for axial power distribution (APD) trip setpoint was fluctu '  :

o ., ling in the nonconservative direction. The RPS A channel for APD was bypassed with thel o s Ithree remaining channels still operable. l o s  !

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u 47 CAUSE OESCRIPTION AND CORRECTIVE ACTICNS i;a lThe Bell and Howell Potentio=2ter Module Part No. 38h612/001 failed allowing the RPS I

, i lA channel APD setpoints to fluctuate in the nonconservative direction. The module was1

, , , , l replaced, recalibrated and tested and the channel was rett:rned to normal. The RPS wilh 3 l continue to te monitored by both visual inspection and surveillance testing to detect i i 4 lany future failures. t 7 8 9 80

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LER 79-002 Omaha Public Power District Fort Calhoun Station Unit No. 1 Docket No. 05C00285 Attachment No. 1 Safety Anal sis The Reactor Protective System (RPS) is so designed that no single failure can prevent the safe and systematic shutdown of the unit if required.

During the time the RPS A channel for Axial Power Distribution ( APD) was inoperable, the three remaining RPS channels were operable to perform their design function, providing adequate reactor protection.

The RPS A channel for APD was repaired, calibrated and tested and returned to service; this and all RPS channels vill continue to be monitored by both visual inspection and the surveillance testing program to detect any future failures.

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'LER 79-002 Omaha Public Pover District Fort Calhoun Station Unit No. 1 Docket No. 05000285 Attachment No. 2 Failure Data This is the first event of a potentiometer medule failure in the reactor protective system.

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