ML20086E009

Updated AO 73-22:on 730730,source Calibr of Radiation Monitors Associated W/Reactor Bldg Vent Exhaust Duct & Refueling Floor Zone Discovered Not Performed Since 720408. Monitors Calibr Upon Discovery of Omission

ML20086E009
Person / Time
Site:	Vermont Yankee
Issue date:	08/07/1973
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086E013	List: ML20086E009 ML20086E015
References
AO-73-22, VYV-2914, NUDOCS 8312060013
Download: ML20086E009 (2)

Text

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-q VERMONT Y ANKEE NUCLEAR POWER COR PORATION

!+ SEVENTY SEVEN OROVE STRCCT

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VYV - 2914 e. o. nox is7 VERNON. VERMONT G5*354 August 7, 1973 v)\

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ty, Director [ h g Directorate of Licensing jih U.S. Atomic Energy Commission b s 'y M h Washington, D.C. 20545 - } {g h # '

RiiFlil?ENCE: Operating License DPR-28

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d Docket No. 50-271 Y Abnormal Occurrence No. A0-73-22 c'id

Dear Sir:

As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6./.B.1, we are reporting the following Abnormal Occurrence as A0-73-22.

During a management review of the Surveillance Testing Schedule on July 30, 1973, it was noted that source calibration of the radiation nonitors associated with the Reactor Building Vent Exhaust Duct and the-Refueling Floor Zone had not been performed since April 8, 1972. This constitutes a violation of Tabic 4.2.3 of Technical Specifications which requires a calibration frequency of every three months. Functionally, the circuitry associated with these monitors provides initiating signals to the Standby Gas Treatment System and the Reactor Building Ventilation Isolation System. During this period of time, the . circuitry was functionally tested on a monthly basis and the detcetor indicating units were cicetronically calibrated every three months. All referenced tests and calibrations verified that the devices actuated at the Technical Specification trip settings required in Table 3.2.3 and that either one upscale trip or two downscale trips would have performed the intended system operation.

The menitors were source calibrated immediately upon discovery of the omission. Both Refueling Floor Zone monitors were found to be- .

within the +10% acceptance criteria required by the test procedure. One of the Reactor Building Vent Exhaust Duct monitors was found to be indicating approximately 31*. lower than the standard sct.rce and was readjusted to the proper tolerance. The'second Exhaust Duct monitor was indicating approximately 6% higher than the standard source and it too was readjusted. This monitor would have. caused a proper system operation sooner then the requirel trip setting' imposed by Technical Specifications, Table 3.2.3. pg 0312060013 730007 g. g (o I. .

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I . VERMONT V~4KEE NUCLEAR POWER CORPORATION v

Subsequent to the incident, the required surveillance test was added to j , the plant surveillance test schedule and an audit was conducted to assure i that all other plant radiation nonitor source calibrations required by l, Technical Specifications were being performed, no discrepancies were found.

'l The Plant Operations Review Co::=ittee reviewed the incident and concluded i~ that the corrective action taken was sufficient to prevent reccurrence of a similar incident.

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Sincerely, l VERMONT YANKEE NUCLEAR POWER CORPORATION

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Bradford W. Riley M Plant Superintendent PliT/ca s I

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