05000334/LER-1980-085-01, /01T-0:on 801124,two Nuclear Power Range Instruments Indicated Zero Power.Caused by Actuation of High Voltage Protection circuit,de-energizing Detectors.Shift Turnover Checklist Changed to Increase Checking Frequency

/01T-0:on 801124,two Nuclear Power Range Instruments Indicated Zero Power.Caused by Actuation of High Voltage Protection circuit,de-energizing Detectors.Shift Turnover Checklist Changed to Increase Checking Frequency

ML19345D341
Person / Time
Site:	Beaver Valley
Issue date:	12/05/1980
From:	Lacey W DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19345D337	List: 05000334/LER-1980-085-01, /01T-0:on 801124,two Nuclear Power Range Instruments Indicated Zero Power.Caused by Actuation of High Voltage Protection circuit,de-energizing Detectors.Shift Turnover Checklist Changed to Increase Checking Frequency 05000334/LER-1980-086-01, /01T-0:on 801121,pipe Support on Seal Injection Header from Discharge of High Head Safety Injection Pumps Determined to Be in Overstressed Condition.Cause Unknown. Support Mods Made ML19345D336
References
LER-80-085-01T, LER-80-85-1T, NUDOCS 8012120530
Download: ML19345D341 (2)

LER-1980-085, /01T-0:on 801124,two Nuclear Power Range Instruments Indicated Zero Power.Caused by Actuation of High Voltage Protection circuit,de-energizing Detectors.Shift Turnover Checklist Changed to Increase Checking Frequency

Event date:
Report date:
3341980085R01 - NRC Website

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REPO6T D AT E 80 EVENT CESCRIPTICN Ak'Q PRCO A8LE CONSECUENCES h I o ! 2j lAt about 0600 hNrs ory November 20 1980. two oint of four nuclear Icaer rance i

la121 l instruments were indicatinc =cro percent power.

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NAME OF PREPARER

li Attachment To LER 80-85/01T I

Beaver Valley Power Station i

Duquesne Light Company' Docket No. 50-334 4

j At approximately 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> on November 20, 1980, an operator observed that two out of four (2/4) power range nucicar instruments were reading zero (0) percent power. At this time, the plant was actually at 2 percent reactor

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power. Technicians verified that there was no high voltage power supplied to the power range instruments. The lack of high voltage was due to a high voltage " crow bar" circuit that automatically deenergizes the power supply on i

a voltage spike. The reason that this was not annunciated was that the " loss of high voltage" alarm was removed as part of a Design Change Package. A change was made to the Shift Turnover Checklist to address checking the instruments every shift.

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