ML19209C621

LER 79-119/03L-0:on 790914,high Steam Line Differential Pressure Loop 2 Channel II Bistable Failed to Trip During Surveillance Test.Caused by Loose Lead on Signal Comparator Card.Card Replaced & New One Calibr

ML19209C621
Person / Time
Site:	North Anna
Issue date:	10/12/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209C617	List: ML19209C616 ML19209C618 ML19209C619 ML19209C620 ML19209C621
References
LER-79-119-03L, LER-79-119-3L, NUDOCS 7910160497
Download: ML19209C621 (2)

Text

U. S. NUCLE AR R' GUL ATORY COMMISSION NRC FORM 366 (7 77)

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t vent orsCn!PTION AND PHOP Allt E CONSEQUENCES h o 7 On September 14, 1979, during flode 1 operation, the high steam line differential j

, ,  ; pressure loop 2 channel II bistable (P-1484-2) failed to trip during the performance j Since the channel was placed in the tripped condi- j g ,) { the monthly surveillance test.

j g , ,, j j tion and loop 2 high steam line differential pressure channels III and IV remained j g gperable, the health and safety of the general public were not jeopardized. Reporta g t, ,

ble pursuant to T.S. 6.9.1.9.b.  ;

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CAUSE DESCHIPTION AND CORRECTIVE ACTIONS h i o 1The bistable failed because of a loose lead on the signal coyarator card. After the li li j l channel was placed in the tripped condition, the comarator car _d_was replaced and -the__]

j,j,j inew card was calibrated. The periodic test was then reperformed with satisfactory 1 j

i 3 tresults.

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

Attachment:

Pagt 1 of 1 Docket No. 50-338 Report No. LER 79-119 /03L-0 Description of Event on September 14, 1979, during steady state operation at 34" power, the high steam line differential pressure loop 2 channel II histable (P-1484-2) f ailed to trip while performing the nonthly surveillance test. The channel was placed in the tripped condition and declared inoperable.

Probable Consequences of Occurrence Stean line pressure indication is used to initiate a safety injection when two out of three channels (II, III, and IV) indicate a low line pressure as compared to both other lines. Since the af fected channel war, placed in the tripped condition and loop 2 high stean line differential pressure channels III and IV remained operable, the health and safety of the general public were not affected.

Cause of Occurrence The reason the histable did not trip was because the comparator card had a loose lead which connected to a normally energized terminal.

Inmediate Corrective Action The affected channel was placed in the tripped condition and the defective c omparator card was replaced. The new card was then calibratec and the periodic test reperformed satisfactorily.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence No further actions are required.

1168 153