05000338/LER-1980-025-03, /03L-0:on 800215,channel III Steamline Pressure Protection Bistable for P2 Greater than P1 Safety Injection Initiation Tripped at Unacceptable Setpoint.Caused by Setpoint Drift in Signal Comparator Card Circuitry

/03L-0:on 800215,channel III Steamline Pressure Protection Bistable for P2 Greater than P1 Safety Injection Initiation Tripped at Unacceptable Setpoint.Caused by Setpoint Drift in Signal Comparator Card Circuitry

ML19290E953
Person / Time
Site:	North Anna
Issue date:	03/14/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19290E951	List: 05000338/LER-1980-025, Forwards LER 80-025/03L-0 05000338/LER-1980-025-03, /03L-0:on 800215,channel III Steamline Pressure Protection Bistable for P2 Greater than P1 Safety Injection Initiation Tripped at Unacceptable Setpoint.Caused by Setpoint Drift in Signal Comparator Card Circuitry
References
LER-80-025-03L, LER-80-25-3L, NUDOCS 8003170375
Download: ML19290E953 (2)

LER-1980-025, /03L-0:on 800215,channel III Steamline Pressure Protection Bistable for P2 Greater than P1 Safety Injection Initiation Tripped at Unacceptable Setpoint.Caused by Setpoint Drift in Signal Comparator Card Circuitry

Event date:
Report date:
3381980025R03 - NRC Website

text

NRC FORM 366 U. S. NUCLE AR flEGULATORY COMMISSION (7-71) 1 LICENSEE EVENT REPORT CONTROL BLOCK: l l

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8 60 61 DOCKET NUYB E H 68 69 EVENT DATE 74 75 HEPOHT D AT E 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h l O 12 ]

On February 15, 1980, the Channel lII Steamline Pressure Protection histable for P2 l

o 3 ; greater than Pl SI initiation tripped at an unacceptable setpoint during the per-l lo [4 ] l formance of the monthly surveillance test.

The bistable tripped at a dif ferential l

lo [s j l pressure of 141 psi versus the maximum allowable value of 112 psi.

The channel was i

O 6 l 1 eft in the tripped condition and declared inoperable.

Since redundant protection f

[ O l 7 l l channels remained operable to initiate a safety injection if required, the public heallth g o jn l l and safe ty were not. affected.

'Ihe occurrence is reportable pursitant to T.S.

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40 41 42 43 44 47 33 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l The bistabic tripped at too high a setpoint because of setpoint drif t in the signal i

O li j i l l comparator (NAL) card circuitry.

The NAL card was replaced and the new card was calf-l brated in accordance with applicable calibration procedures.

The surveillance test j,,7; was than reperformed satisfactorily and the channel was returned to service.

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'W Virginia Electric and Power Company North Anna Power Station, Unit #1 Attachment :

Page 1 of 1 Docket No. 50-338 Report No. LER 80-25/03L-0

Description of Event

On February 15, 1980, the P2 greater than F1 SI initiation bistable for Steam 1Lne Pressure Protection Channel III tripped at a pressure differential setpoint which was higher than acceptable during the perf ormance of the nonthly channel functional The comparator tripped at a dif ferential pressure of 141 psi as compared to test.

the maximum allowable trip setpoint of 112 psi.

The af fected channel was lef t in the tripped condition and declared inoperable.

This event is contrary to T.S.

3.3.2.1 and reportable pursuant to T.S. 6. 9.1. 9. b.

Probable Consequences of Occurrence The consequences of this event were limited because redundant Steamline Pressure Protection Channels II and IV remained operabic to initiate a safety injection on a high differential pressure between steamlines 1 and 2 (P2 greater than P1) if required.

As a result, the health and safety of the general public were not af fected by this occurrence.

This event has no generic implications af fecting Unit 1 and Unit 2 process instrumentation.

Cause of Event

The steamline differential pressure histable tripped at too high a setpoint because of setpoint drift in the loop's NAL card circuitry.

Immediate Corrective Action

The signal comparator (NAL) card was replaced and the new card was cali-brated in accordance with applicable calibration procedures.

The periodic functional test was then satisfactorily ceperformed and the protection channel was returned to its normal operating condition.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence No further actions are required.