ML20085M217

AO BFAO-743W:on 740109,during Startup Test Program,Lpci Break Detection Pressure Switches PS-3-186A & PS-3-186B Found Valved Out.Caused by Personnel Error.Instructions Revised to Ensure Instrument Alignment Following Maint Work

ML20085M217
Person / Time
Site:	Browns Ferry
Issue date:	01/17/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085M218	List: ML20085M217 ML20085M224
References
AO-BFAO-743W, NUDOCS 8311080124
Download: ML20085M217 (2)

Text

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i O O TENNESSEE VALLEY AUTHOAITY MM CHATTANOOGA, TENNESSEE i  ?

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January 17, 1974 $$$$3

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Mr. John F. O' Lean , Director Directorate of Licensing Office of Regulation U.S. Atomic Energy Cor: mission Washington, DC 20545

Dear Mr. O' Leary:

TENIiESSEE VALLEY AUTHORITY - BROWS FERRY UUCLEAR PLAllT UNIT 1 -

DOCKET UO. 50-259 - FACILITY OPERATIHG LICENSE DPR ABNOPl'AL OCCURRENCE REPORT BFAO-743W

! The enclosed report is to provide details concerning LPCI break detection pressure switches not in service which occurred on Browns Fern nuclear Plant unit 1 on January 9,1974, and is sub::iitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, i

October 1973.

i Very truly yours, TEIiUESSEE VALLEY AUTHORITY

sc'74W E. F. Tho

: as Director of Power Production m .

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Enclosure

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I Mr. Hornan C. Moseley, Director .

2 ;fh t3 '-y Region II Regulatory Operations Office, USAEC ygh j 230 Peachtree Street, NW.

Atlanta, Georgia 30303 d k(5[v4 1 #

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. ABNORMAL OCCURRENCE REPORT Report No.--BFAO-743W Beport Date--January 17, 1974

• Occurrence Date--January 9,1974

. Flacility--Brevns Ferry Nuclear Plant unit 1 3

Identification of occurrence LPCI bMak detection pressure switches not in service. '

Conditions Prior to Occurrence Reactor at 50-percent power during startup test program.

Description of Occurrence During routine surveillance testing of the LPCI logic on January 9,1974, reactor pressure switches PS-3-186A and -186B vere found valved out of service.

I The pressure switches had been isolated to pemit work to be perfomed during

' a recent outage. They were not valved back into service when the work was completed. -

Analysis of occurrence '

The pressure switches operate relays that are arranged in a one out of two taken twice logic in the LPCI break detection system. This logic is used to delay loop selection upon receipt of an accident signal until reactor pressure drops below 900 psig. It is effective if one recirculation pump is mnning and is used to optimize loop selection sensitivity.

Although the reduced reactor pressure requimment was bypassed due to the isolated pressure switches, a 2-second time delay was still available to l remove initial perturbations and allow momentum effects to settle before

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loop selection is initiated by the d/p switches on the recirculation loop '

risers. -

Corrective f.etion All other instruments (134) that ve e isolated during the outage were checked and found in service. Instructions am being revised to include additional controls requiring certification of proper instrument alignment i following maintenance vek.

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