ML19209C442

LER 79-102/03L-0:on 790911,bistable for Containment high- Risk Pressure Channel I Actuated High Pressure Signal & Failed in Low Pressure State During Test.Caused by Bad Signal Comparator Card.Defective Card Replaced & Calibr

ML19209C442
Person / Time
Site:	North Anna
Issue date:	10/11/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209C435	List: ML19209C434 ML19209C442
References
LER-79-102-03L, LER-79-102-3L, NUDOCS 7910150568
Download: ML19209C442 (2)

Text

U. S. NUCLE AR REGULATORY COMMISSION

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/ 8 w 61 DOCKET NUYdEH f,d O'J LVENT DATE EVEN T DESCP!PTION AND PROB ABLE CONSEQUENCES O'o O 2 l On September 11, 1979, the bistable for Containment High-High Pressure Channel I 1 o 3 i actuated on a high pressure signal and failed in tSc low pressure state during the l 0 ., [ perforcance of the monthly surveillance test. Since Containment High-High Pressure l 0 s Channels II, III, and IV remained operable to initiat.e a CDA if required, the health l

O g i l and safety of the general public were not af fected . by this event. Reportable l FOT77 l pursuant tO T.S. 6.9.1.9.b. l

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47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h iiiO; l The bistable for Containment High-High Pressure Channel I failed because of a bad gisii signal comparator card. The channel was left in the blocked condition and the i

, , l defective comparator card was replaced. The new card was then calibrated, the loop i, 3i l functionally tested and the channel returned to the normal condition. l 11 1411

• 8 9 80 ST S  % POWER OTHER STATUS iSCOV RY DISCOVERY DESCRIPTION li l5 l l El@ j 0 8l6l@ NA l Bl@l Surveillance Test ACTIVITY CG TENT RELEASED OF RELE ASE AVOU.<T OF ACTIVITY LOCATION OF RELE ASE i 6 NA NA l 7 8 9 L.ZJ @ LZJ@i 10 It 44 45 80 PERSONNEL EXPOSURES NUVRE R TYPE D ESCR:PTION '

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER 79-102/03L-0 Descriction of Event On September 11, 1979, curing Mode 1 operation at 86L power, the bistable for Containment High-High Pressure Channel I actuated on a high pressure signal and failed in the low pressure stde during the performance of the monthly surveillance te:t. The channel was left in the blocked condition and declared inoperable.

Probable Consequences of Occurrence The consequences of this event were limited because Contair. ment High-High Pressure Channels II, III and IV remained operable to initiate a Containment Depressurization Actuation if required. As a result, the public health and safety were not jeopardized by this event. This occurrence has no generic implications affecting Unit 1 and Unit 2 instrumentation.

_Cause of Occurrence The bistable for Containment High-High Pressure Channel I failed because the signal comparator card was defective. The failure was not the result of a W-104 component problem.

Immediate Corrective Action Containment High-High Pressure Channel I was left in the blocked condition and signal comparator card PS-LM100A-3 was replaced. The new card was then calibrated, the loop functionally tested, and the channel returned to the normal condition.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence No further actions are required.

1145 355