ML19274E787

LER 79-033/03L-0 on 790321: C Steam Generator Narrow Range Level Indicator LI-1496 Gave Readings w/20% Disagreement W/Two Other Channels.Caused by Steam Leak in One Sensing Line Isolation Valve

ML19274E787
Person / Time
Site:	North Anna
Issue date:	04/18/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19274E780	List: ML19274E779 ML19274E785 ML19274E787 ML19274E790 ML19274E794
References
LER-79-033-03L, LER-79-33-3L, NUDOCS 7904240412
Download: ML19274E787 (2)

Text

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33 34 35 3/ 40 n 42 44 CAUSE DESCRIPTION AND CORRECTIVE ACT!ONS lilO1IThe cause for the erratic indication on LI-1496 is a steam leak on one of two sensina I i i lline isolation valves, (1-FW-134). Due to plant conditions this could not bn I

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Virginia Electric and Power Company North Anna Power Station, Unit No.1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. 79-033/03L-0 Description of the Event .

On 3-21-79, during mode 1 operation, C steam generator narrow range level indicator (LI-1496) was noted to be reading erratically. There was greater than 20% disagreement between LI-1496 and the other two channels of level indication.

The cause of this erratic indication was found to be a body to bonnet leak on one of the two sensing line itolation valves. (1-FW-134). Plart conditions did not allow for immediate repair but a work request was issued and repair was scheduled for the next appropriate outage.

The affected channel of level indication was placed in a tripped condition in accordance with action statement number 14 of table 3.3-3 of Technical Specification 3.3.2.1 and statement number 7 of table 3.3-1 of Technical Specification 3.3.1.1. ,

Probable Consequence of Occurrence The Engineered Safety Feature Actuation System and Reactor Protection System is provided to initiate automatic protective actions in the event of an accident. In this case the steam generator level channels are used to initiate the protective action described by T.S. table 3.3-1 and table 3.3-3.

Placing the affected channel to a tripped condition changes the protective action coincidence from the normal 2 out of 3 to 1 out of 2. This is more conservative and thus the health and safety of the general public is not endangered.

Cause The cause for the erratic indication of LI-1496 was a body to bonnet steam leak on one of the two sensing line isolation valves. (1 -FW-134 )

Immediate Corrective Action Placed the associated level channel in a tripped condition as per action statement #14 of T.S. 3.3.2.1 and statement #7 of T.S. 3.3.1.1.

Scheduled Corrective Action Repair leak on 1-FW-134 as soon as conditions permit. This will be done during the next appropriate outage.

Action Taken to Prevent Recurrence No action required.