ML20086J187

Telecopy AO 74-30:on 741125,relay 14A-K9B in Lpci/Core Spray Low Reactor Pressure Permissive Logic Failed to Makeup Consistently.Caused by Dirty & Slightly Misaligned Relay Contacts.Contacts Burnished & Realigned

ML20086J187
Person / Time
Site:	Peach Bottom
Issue date:	11/26/1974
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086J183	List: ML20086J180 ML20086J187 ML20086J188
References
AO-74-30, NUDOCS 8401230284
Download: ML20086J187 (1)

Text

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PHILADELPHIA ELECTRIC COMPANY DELW G D [0 I L. . Pg Battom Atonic Power StatfC MR LA.)BL t B Al2 N AW Delto. Psnnsylvania j j 17314 I**D'Y 20e 1974

Mr. James P, O'Reilly, Director iUnited States Atomic Energy Commission

• iDirsetorate of Regulatory Operations

,631 Park Avenue iKing of Prussia Pennsylvania 19406

Subject:

g normal occurrence 24-ilour Notific_atio_n

Ccnfirming W. T. U11 rich's phone conversation with Mr. Walt Baunack, A.E.C. Region 1 1R2gulatory Operations Office on November 26, 1914 iR3ference

License Number DPR-56 Technical Specification Ref erence Table: i 3.2.B -

!Rsport No.: 50-278-74-30 4R3 port Date: November 26, 1974

! Occurrence Date: November 25, 1974

Pccility

Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314

! Identification of Occurrence:

Failure of relay 14A-K9B in the LPC1/ Core Spray low reactor pressure permissive logic t3 make-up consistently.

Conditions Prior to Occurrence

Unit 3 operating at.63% power, iDoccription of Occurrence:

During a routine instrument surveillance test on PS-3-3-52B, its relay (14A-K9B) to th2 LPC1/ Core Spray low reactor pressure permissive logic failed to makeup consistentlyj

Decianscion of Apparent Cause of Occurrence:

Dirty and slightly misaligned relay contacts.

.Analyais of Occurrence:

Beccuse this switch / relay combination operates in a one-out-of-two-twice logic, the icilure of any one of the four devices will not render the logic inoperable. There-fare, the safety implications of this single failure are minful.

Carrective Action:

Inysstigation revealed that a slight contact misalignment coupled with dirty contacts led to the inconsistent relay contact make-up. The contacts were burnished and realigned and the relay operation again checked repeatedly with no further failures.

JPailure Data: '

Previous relay contaee problegs reported as. 50-277-74-5, 50-277-74-9, 50-277-74-50.

WO3 WRG 3,i]Gw m l,a p, p s.,...fy,f .

-Vary truly yours, j'. y *fffd' O I I Yid E Ogg yzgg W. T. Ullrich, Superintendent Deach Botton Atomic Power Statio63413339 ,

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