ML20086H309

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

ML20086H309
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
ML20086H282	List: ML20086H288 ML20086H295 ML20086H300 ML20086H303 ML20086H307 ML20086H309
References
AO-50-271-72-05, AO-50-271-72-5, VYV-2255, NUDOCS 8401160353
Download: ML20086H309 (2)

Text

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a 0 O VERMONT YANKEE NUCLEAR POWER CORPORATION g SEVENTY SEVEN OROVE STRECT RUTLAND, DOION*r O3701 REPLY Tor VYV-2255 p. o. sox 157 VERNON. VERMONT oS354 September 22, 1972 b

Director

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United States Atomic Energy Commission Washington, D.C. 20545 d, C.hr p 3 g,. g g <-

REFERE! ICE: Operating License DPR-28 '

Docket tio. 50-271 Abnormal Occurrence lio. A0-72-05

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Dear Sir:

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As defined by Technical Specifications for the Vermont Yankee liuclear Power Station, Section 6.7.B.d, we are reporting the following Abnormal Occurrence as A0-72-05.

During the af ternoon of September 21 with the reactor at approximately 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 '

measuring off-gas activity at the outlet from the air ejectors and constituted a violation of Technical Specifications, Section 2.8.A.1. j r;

After discovery of the mis-positioned valve, it was opened immediately

/k D 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 TM 9 showed 145 uc/sec at the air ejectota. The off-gas flow at that time was 15 f) ' 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 Corraittee, it was concluded that the reactor has operated at a power level of approximately pb 15% for about one day without the air ejector off-gas monitoring system in ,

operation so it was considered reasonable to state that off-gas levels were 1 lnever higher than that measured at the time of discovery of the incident. Since  !

' the cause was attributed to an inadvertent. shutting of the . valve _during initial (

operation of the air ejector _ system, plant operating procedures were revised to assign the suction and discharge ' valves-for the a_ir sampling system as locked- i

. open valves. -

8401160353 721024 OY PDR ADOCK 05000273 b PDH }'}1d carc smucasssM

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

with Technical Specifications.

Very truly yours.

VERMONT YANKEE NUCLEAR POWER CORPORATION j/

Robert F'

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Plant Superintendent i

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