ML19253B789

LER 79-024/03L-0:on 790920,abrupt Change Noted in Indicated Torus Water Level on Control Room Indicators.Hpci Suction Valves Shifted Lineup from Condensate Tank to Torus.Caused by Dislodged Fitting on Torus Level Transmitters

ML19253B789
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	10/18/1979
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19253B775	List: ML19253B774 ML19253B789
References
LER-79-024-03L, LER-79-24-3L, NUDOCS 7910220243
Download: ML19253B789 (2)

Text

NRC FORM 366 U. S. NUCLt AH H tGUL Ai UH Y COMMlbbiUN (7 77) ..

LICENSEE EVENT REPORT LER 79-24/3L CONTROL BLOCK: l l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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7 8 60 61 69 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l o 3 l See attached sheet I

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@ 36 3/ 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i O l l See attached sheet I

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NAME OF PREPARER

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VTVYS1 05000271 LER 79-24/3L EVENT DESCRIPTION AND PROBABLE CONSEQUENCES During steady state operation, Control Room personnel observed an abrupt change in indicated torus water level on Control Room Indicators LI-16-19-46A/B. Channel A increased from 1.15' to 4.54' while Channel B increased from 1.15' to 6.13'. Additionally, the HPCI suction valves shifted line-up from the condensate storage tank to the torus.

Upon investigation, it was revealed that contractor personnel, while erecting staging, dislodged a fitting on the torus level trans-mitters thereby draining the leg and causing the erroneous readings.

Technical Specification 3.2.G requires this post-accident instrumenta-tion be operable during reactor operation. At no t'me was the torus water inventory out of specification. Since this ituication was re-stored 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 continued power operation. The potential based on the above con-sequences to the health and safety of the public were minimal.

CORRECTIVE ACTION TAKEN The fitting was repaired, the reference leg refilled, and the in-struments returned to operation. It has been further reemphasized to all contract personnel of the necessity to proceed with caution during all phases of their work activities.

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