ML20086H345

AO 50-271/72-05:on 720921,supply Valve to Offgas Sample Chamber Found Closed.Caused by Inadvertent Shutting of Valve During Initial Operation of Air Ejector Sys.Procedures Revised to Assign locked-open Valves

ML20086H345
Person / Time
Site:	Vermont Yankee
Issue date:	09/22/1972
From:	Rosalyn Jones VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086H319	List: ML20086H317 ML20086H321 ML20086H324 ML20086H336 ML20086H343 ML20086H345 ML20086H355
References
AO-50-271-72-05, AO-50-271-72-5, VYV-2255, NUDOCS 8401170050
Download: ML20086H345 (2)

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' VERMONT YANKEE NUCLEAR POWER CORPORATION SEVENTY SEVCN OROVC STREET RUTLAND, VERMONT 03701 REPLY TO:

VYV-2255 p. o. sox is7 VERNON, VERMONT 05354 September 22,.1972 1  ?

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Director Directorate of Licensing @['i(3J g

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United States Atomic Energy Commission w

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REFERENCE:

Operating License DPR-28 fgf) fh Docket No. 50-271 .g j Abnormal Occurrence No. AO-72-05 s

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Dear Sir:

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I As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7.B.d, we are reporting the following Abnormal l j

Occurrence as A0-72-05.

lI During the afternoon of September 21 with the reactor at approximately k 15% pouer, the supply valve to the Off-Gas Sample Chamber was found to be closed. This closed valve prevented the installed monitoring system from l; measuring off-gas activity at the outlet from the air ejectors and constituted a violation of Technical Specifications, Section 2.8.A.l.

Af ter discovery of the mis-positioned valve, it was opened imediately and a neasurement was made using the installed system which indicated an off-gas activity level of 5 mr/hr. Additionally, a grab sample was taken which showed 145 uc/sec at the air ejectors. The off-gas flow at that time was 15 ,

cfm corresponding to a hold-up time of approximately 300 minutes. The stack monitor prior to and during this period indicated essentially background.

Af ter review of this incident by the Plant Operations Review Comittee, it was concluded that the reactor has operated at a power level of approximately 15% for about one day without the air ejector off-gas monitoring system in operation so it was considered reasonable to state that of f-gas levels were never higher than that measured at the time of discovery of the incident. Since the cause was attributed to an inadvertent shutting of the valvt during initial operation of the air ejector system, plant operating procedures were revised to assign the suction and discharge valves for the air sampling system as locked-open valves, 8401170050 721101 " dpf'f PDR ADOCK 05000271  ?/17p' S PDR C

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VERMONT YANKEE NUCLEAR POWER CORPORATION i United States Atomic Energy Commission September 22, 1972 Page 2 i The off-gas monitoring system is currently operabic in accordance -

with Technical Specifications.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION

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RobertF( ones Plant Superintendent DUE/rph L

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