ML20086K946

AO 74-5:on 740220,RHR Relay 10A-K33A Failed to Perform Design Functions in RHR Loop a Select Logic.Caused by Dirty Contact or Foreign Dirt Particle Preventing Proper Closure & Wipe.Contacts Cleaned & Relay Action Checked

ML20086K946
Person / Time
Site:	Peach Bottom
Issue date:	02/28/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086K950	List: ML20086K946 ML20086K959
References
AO-74-5, NUDOCS 8402070086
Download: ML20086K946 (3)

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.- PHILADELPHIA ELECTRIC COMPANY  : -

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February 28, 1974 Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, D. C. 20545

Subject:

Abnormal Occurrence The following occurrence was reported by telephone to Mr.

Thomas Shedlowsky, A.E.C., Region I Regulatory Operations Office on February 21, 1974. Written notification was made to Mr. James P.

O'Reilly, A.E.C., Region I Regulatory Operations Office on February 21, 1974. In accordance with Table 4.2.B of the Technical Specifica-tions, Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-44, Amendment Number 1, Appendix A revised October 1973 Technical Specification Table 4.2.B Report No.: 50-277-74-5 Report Date: 2/21/74 Occurrence Date: 2/20/74 Facility: Peach Bottom Atomic Power Station'- Unit 2 R. D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

RHR Relay 10A-K33A failed to perform its design function in the RHR "A" Loop Select Logic. s

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Unit 2 generator gross load was' 230 MW and the Unit 2 reactor power was 800 MW thermal. Plant conditions were stable.

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7 Mr. A. Giambusso s February 28, 1974 J O e se 2  !

h Description of Occurrence:

During normal surveillance testing of the "A" RHR Logic System, [

i Relay 10A-K33A failed to conduct through its contacts and therefore the l loop selection logic sequence could not be completed.

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Designation of Aoparent Cause of Occurrence:

The relay coil did energi ze, but the relay contacts did not conduct. A dirty contact or a foriegn dirt particle apparently prevented

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proper closure and/or wipe. 7 Analysis of Occurrence:

i During the RHR logic system functional test the relay logic is set up specifically to test the operation of relay 10A-K33A by hold-ing in the break detection reset pushbutton. When this relay failed the loop selection logic could not be completed in the surveillance test I mode. Under normal plant operating conditions, the loop selection logic would be completed even if this relay f ailed. The only adverse effect of this relay f ailure would be if less than two recirculation pumps are running the loop selection logic wnuld not be scaled in. However, the l '

"B" RHR logic would perform this function and therefore the RHR logic system in its entirety was not operabic.

Corrective Action:  !

The relay contacts were cleaned and the relay action was checked by relay technicians. Af ter this work was completed, the relay performed satisf actorily in the RHR loop select logic.

As a result of this occurrence, the PORC directed that both RHR logic system functional surveillance tests be performed. The "A" RHR Logic performed satisf actorily. The "B" RHR Logic performed satis-factorily with one minor exception. Relay 10A-Kil3B failed to open its contacts when the relay coil was energized. Upon investigation of this failure, it was determined that the relay cover was on upside down (G.E. relay type HGA) and this mechanically prevented the relay contacts frcm opening. The relay is used only for surveillance test purposes and has no safety implications in the RHR logic. All other similar relay covers were checked for proper orientation and several were also f ound to be installed upside down. These covers were re-moved from the relays. The relays found with their covers upside down serve either as alarm relays or surveillance testing relays. They do ,

not prevent the RHR logic system from performing its design function under accident conditions. F ur thermore , it was observed that an upsido down cover does not in itself render the relays inoperabic. The cover c

l must be both upside dowr. and vertically misoriented so as to interfere j with the relay spring lever and thus prevent relay contact motion. No

! safety related f ailures could have resulted from this relay cover problem.

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rm (O Hr. A.*Giambusst V February 28,197] 4 Page 3 Failure Data:

Nonc previous.

Very truly yours,

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H. J. Cooney /

Ass't Gen't Superintendent Generation Division cc: Mr. J. P. O'Reilly Director, Region i United States Atomic Energy Conmission 631 Park Avenue King of Prussia, PA 19?06 t

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