ML20085G161

AO BFAO-50-260/7436W:on 741218,drywell Sampling Monitor Found 2-RM-90-256 Inoperable.Caused by Failure of Four 150- Watt Bulbs Used for Heating Monitor Internals.Permanent Heating Sys in Drywell Requested

ML20085G161
Person / Time
Site:	Browns Ferry
Issue date:	12/27/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G165	List: ML20085G161 ML20085G180
References
NUDOCS 8308240330
Download: ML20085G161 (2)

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eAEHOR "AL OCCURRE:!CE RETORT 9 -

Report No.: EFAo-50-260/743GW Report Date: December 27, 1974 Decurrence Date: Decembcr 18,197h Facility. Erowns Ferry Huelear Plant unit 2 I'lentification of Occurrence Unit 2 drywell air campling monitor (2-RM-90-256) wac inoperable for approxi-mately 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />.

Conditienc Prior to Occu"rence The reactor was operatinr at approximately 96-percent power during ctartup tccting.

Descriptien of Occurrence At 16h5 on Dece:ber 18, _197h, the dcwnscale alarm accociated with 2-R"-90-256 was received in the control room. Invectigation revealed that two of the four 150-wat t ligP ' '-"' k - uced for centing the monitor internals were burned out and that toictu"r wac prccent in the detection cherJoerc. The monitor internalc .rere nil owed to dry cvernight, and the inctrument was returned to service at 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br /> on December 19 Decicnntion of Arrnrent Ctuce of Occurrence The iryr:11 nir carplinc monite" is 20erted bc.lt its nciplin~ linca. Thc camplin; linec are heat traccd and the moniter internalc cre heatcd by four 150-;mtt tulic to prevcnt cankncation. Failure of the two bulbs allcwed toiccure in the drywell canple strcan to condence and collect, chorting out the particulate photo cultiplier tube initiating the alarm.

Analycic of Cecurrence The drywell air carpling renitor ic cne of two independent cycteac recuired by the technical crecificatienc for curveillance of drywell lea.kn;e. The redundant cump leak detectica cyctem was operable during the occurrence.

Analycic of the cump intccrator readings for Decc=ber 17-20 indicatec no significant chan;e in either the unidentificd or identified drywell lesk ratec. Alco, crab c1 ples of the drywell atmosphere, taken while the dry-well air canplinc scnitor was out of service, did not indicate eny cicnifi-cant increace in airborne activity. There .fere no adverce effects on the health or cafety of the public as a result of this failure.

Corrective Action A design change has been cutmitted recuesting that a permanent heating cycten be inctalled in the drywell air campling monitor to replace the light bulbc.

In addition, another decicn change rea.uect will be submitted to relocate the drywell air campling conitor atore its compling linec. Until thece chances are inplemented, the hett tracing and heat lamps accociated with the conitor vill be checked at least once a shift to encure operability.

Failure Data E PC 0 S

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, T EN N i~5S EE V A L LEY A L; i i 10 7.1 TY cs.u rt,Narr., tc ecssEt a;. c:

Deccrber 27, 1971+

r. Edcon G. Case Acting Director of Licencir.;

Office of Ise;ulation

'd.S. /-tenic Ener J Conniccion

..ashington, DC 205! 3 4

Dear I:

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00CWJ.E,ca PlF02T E.'AO-50-260/7Q SI The enclosed r2 port is to provide details concerning unit 2 dry rell air cmplin r.cnitor (2-:L:-53-256) Unich wac inoperable for r:pprcri-m natel'; 16 hcure and is cubnitted in accord"nce with Appendix I. to Legnlatcr/ Guide 1.16, Revision 1, Cctober 1973 Taic ccent occurred on 3ro',:nc ierr/ i.uclear Plant unit 2 cn December 18,19'/h.

Vert trul. yours, TE!I;EESEE V/Ei I.UTI:Oi1ITf

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( Director cf Fo,rer Production Enclocure i

CC (Enclocure):

I.", i cr: n C. I:occicy, Director I F.egion II Leculer org C;eratiorn Office, USAUC 230 Teachtree Street, L~ ,, Cuite bl3 Atl m t.?, Georgin 30303

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