05000271/LER-1979-030-03, /03L-0:on 791110,during Steady State Operation, Increasing Trend in Torus Water Level Observed.Caused by Leaking Bypass Valve for Torus Level Transmitters.Water Indication Restored Per Tech Specs

/03L-0:on 791110,during Steady State Operation, Increasing Trend in Torus Water Level Observed.Caused by Leaking Bypass Valve for Torus Level Transmitters.Water Indication Restored Per Tech Specs

ML19210F010
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	12/10/1979
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19210F007	List: 05000271/LER-1979-030, Forwards LER 79-030/03L-0 05000271/LER-1979-030-03, /03L-0:on 791110,during Steady State Operation, Increasing Trend in Torus Water Level Observed.Caused by Leaking Bypass Valve for Torus Level Transmitters.Water Indication Restored Per Tech Specs
References
LER-79-030-03L, LER-79-30-3L, NUDOCS 7912130385
Download: ML19210F010 (2)

LER-1979-030, /03L-0:on 791110,during Steady State Operation, Increasing Trend in Torus Water Level Observed.Caused by Leaking Bypass Valve for Torus Level Transmitters.Water Indication Restored Per Tech Specs

Event date:
Report date:
2711979030R03 - NRC Website

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NAME OF PREPARER

VTVYS1 05000271 LER 79-30/3L EVENT DESCRIPTION AND PROBABLE CONSEQUENCES During steady state operation, Control Room personnel observed an increasing trend in indicated torus water level on Control Room Indicators LI 16-19-46A/B.

Wheg an indicated level of 1.26' was reached (corres-ponding to 70,000 ft ) an orderly shutdown was initiated as necessitated by Technical Specification 3.7.A.8.

Upon investigation, it was determined that a bypass valve for the torus level transmitters had developed a packing leak thereby slowly draining the transmitters common reference leg and causing the erroneous readings.

Technical Specification 3.2.G requires this post-accident in-strumentation be operable during reactor operation. At no time was the torus water inventory out of specification.

Since this indication was restored within the limiting 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of Tech. Spec. Table 3.2.6, the plant shutdown was terminated and power operation was continued.

Based on the above, the potential consequences to the health and safety of the public were minimal.

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