ML19340E255

LER 80-090/03L-0:on 801205,during Surveillance Testing, Setpoint for Borated Water Storage Tank Low Level Bistables BA312 & BA309 Found Out of Tolerance.Caused by Component Failure.Bistables Recalibr

ML19340E255
Person / Time
Site:	Davis Besse
Issue date:	01/02/1981
From:	Isley T TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340E253	List: ML19340E252 ML19340E255
References
LER-80-090-03L, LER-80-90-3L, TAC-43253, NUDOCS 8101060757
Download: ML19340E255 (2)

Text

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? 8 6J 61 OOCK ET NUYBER EVENT OESCRIPTION AND PROB ABLE CONSEQUENCES h l 3 [ 2 l l (NP-33-80-115) on 12/5/80 at 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br /> during sutveillance testing, the setpoint for I

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the Borated Water Storage Tank low level bistable BA312 was found out of tolerance. l l

[o l4 lOn 12/6/80 at 0750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> during testing, the setpoint for the containment pressure i

tojs; l bistable BA309 was also found out of tolerance. Both occurrences placed the unit in l 1o 96 ; l Action Statement 9 of Technical Specifica* ion 3.3.2.1. There was no danger to the 1 5

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I lote 1l Features Actuation System channels were operable.

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TOLED0 EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE '

SUPPLEMENTAL INFORMATION FOR LER NP-33-30-115 DATE OF EVENT: December 5, 1980 FACILITY: Davis-Besse Unit 1 i t

IDENTIFICATION OF OCCURRENCE: Safety Features A:tuation System (SFAS) Bistables Out of the Technical Specification Tolerance Conditions Prior to Occurrence: The unit was in Mode 3 with Power (MWT) = 0 and Load (Gross MRE) = 0.

Description of occurrence: Ou December 5, 1980 at 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br /> during the performance  ;

of the SEAS Monthly Test, ST 5031.01 on SFAS Channel 3, the setpoint for the Borated Water Storage Tank (BWST) low level bistable was found to be out of tolerance. The L bistable setpoint was 0.552 V and the upper limit is less than or equal to 0.551 V. i On December 6, 1980 at 0750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> during the performance of ST 5031.01 on SFAS Channel 3 to verify operability after maintenance (see Licensee Event Report NP-33-80-113) , i the containt.ent pressure 38.4 psia b: stable was found out of tolerance. The bistable set-point wcs 1.428 V and the upper limit is less than or equal to 1.427 V.

Both occurrences placed the unit in Action Statement 9 of Technical Specification 3.3.2.1.

The action statement requires the inoperable channel to be placed in the tripped condi-tion within one hour. Both bistables were immediately recalibrated per the test proce-dure (ST 5031.01), removing the station from the action staterant.

Designation of Apparent Cause of Occurrence: The cause of these occurrences can be  :

attrr ated to a component failure. The bistables are subject to instrument drift.

The ' .strument drif t was probably aggravated by the 120 VAC problem on the cabinet Common.

Analysis of Occurrence: There was no danger to the health and safety of the public or ,

to station personnel. The remaining three SEAS channels were operable and capable of >

performing their designed function.

! Corrective Action: Upon finding the BUST level bistable BA312 and the containment pres-sure bistable BA309 out of calibration they were immediately recalibrated as per t?e test (ST 5030.01) procedure to within the Technical Specification limits.

Failure Data: There have been five previous similar occurrences of bistable drift, l

see Licensee Event Reports NP-33-78-47 (78-039), NP-33-78-84 (78-070), NP-33-78-140 (78-119), NP-33-79-26 (79-021),and NP-33-79-50 (79-045).

LER #80-090 e

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