ML20085F678

AO 50-259/754W:on 750310,while Running Routine Surveillance Test,High Concentrations of Oxygen Discovered in Drywell. Caused by Mixing of Air Retained in Stagnant Areas of Drywell During Initial Purge & Sampling

ML20085F678
Person / Time
Site:	Browns Ferry
Issue date:	03/20/1975
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E Office of Nuclear Reactor Regulation
Shared Package
ML20085F681	List: ML20085F678 ML20085F700
References
AO-50-259-754W, NUDOCS 8308230136
Download: ML20085F678 (2)

Text

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• reh 10, l'.75 1 '.H t . ;iro..nc ferr; :..:elear :lont unit 1 7 ...tri c tien ,f Oc m rr ~ e Increc':e of dijuell ex c:en concentrction to >h percent.

Cc .-litionn Prior to 0-rurrc re i

Tno unit unn operating at cynroxintely 1,055 I~.le.

I;eceription of Occurrence 7.' nile runnin~ n routine curveill- '.ce tect en "r.rch 10, l'US, r.t npnroxinstePt 2115, the drr.: ell :mycen concentrntion una discovered to be approxinntely I 1

6 percent.

Ann': rent Cr_ure of Occurrence i.

The prircrry cont ti: cent uns inerted nt 0755 hours0.00874 days <br />0.21 hours <br />0.00125 weeks <br />2.872775e-4 months <br /> on L*.crch 6,1975, before goir; a to the RU:: 1.of.e uith the renctor. Fe9 dings et that tir:e choved the oxygen .'

concentrntion to be <h percent. The subcecuent incrense in oxygen concertration k uns appnrently e-uncd b: r.inin~, of cir "nich tr '. been reteined in sternant creas of the dr"vell euch ne pipir.~ inculntion voids, during the initiol rur7e I:

nnd nonplinr,. In rddition, a clicht :ur e cirflou to the TIP cycten uns four! to be contributing nrproni:.ctely 5 ECFli to the dr;r. ell, hr I

Annlynic of Cecurrence /

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There vere no rdverse effects to the public henith and nefaty as n result of thin l occurrence.

Corrective Action None van found except The unit una chce':ed for cir inles>nge into the dry. cil.

the clir.ht parce nir to TII3.

The init.icl corrective cetion unn to requent a change to the technien1 creci:i-cationn which rould h^ve nlleve3 cufficient titc.e to conglete the purr,e ':ith the rer.ctor in the RG *.'o.ie. F.en this requent uca denica tne unit unc chut doun at appronir ntely 2010 tuurc on I:crch 11, 1975, and nitre en introduced to reduce the oxygen concertrrtion to within acceptable limite. Tecdin~s tnhen at 20hD hours on ISrch 11 irliented that the oxygen concentration unc neceptable, and the unit uns returned to service.

1 Uc vil: nonitor dryvell ntnorpherie conditionc nore frenlently follou3ng inerting until certain that an equilibrium nixing co:rlition hr.s been established. ,

Failure Data .

None 8308230136 750320 PDR ADOCK OSOOOP59 S pyp

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E'ne e.nclosed report in to pratitie detnila concerr.ing increcco of Ir

>ll c: 'cen concentration to >b nercent and in cubr.itted in ne 'r inr.ce uith /.pnen il:: '. tr :'e~uletor-- Guide 1.16, Tc ticion 1, Octaber 1973. Thic event occurred on 3rowns icrry Huclear Plent unit 1 on :'nrch 10, 1975.

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