ML20086K462

AO 74-35:on 740702,condenser Low Vacuum Scram Pressure Switch Setpoint Found Less Conservative than Limiting Safety Sys Setting.Caused by Instrument Drift.Switch Recalibr, Checked for Setpoint Repeatability & Returned to Svc

ML20086K462
Person / Time
Site:	Peach Bottom
Issue date:	07/12/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086K464	List: ML20086K462 ML20086K471
References
AO-74-35, NUDOCS 8401270126
Download: ML20086K462 (2)

Text

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Deputy Directcr of Recctor Projects Uni ted S t a tes At oni c Energ) C cnm i s s i on DircatorcLe of Licensing Wshi n g t on, DC 20545 Oc,ar Mr. Gicmbusto:

Subject:

Abnormal Occurrence TI c follo. zing c;currence was repor ted to Mr. Tom Shedlewsky, A.E.C. Region 1 Regulatcry Operations Office en July 3, 1)/h. tir i t ten noti f icat ica was rode to Mr. Jirno s P. O 'Re i l l y, Region 1 Regulatory Operat ions Of f ice on July 3,197h.

In accordcocc with Section 6.7.2.A of the Technical Specificetions, Appendix A of DPR-44 for Unit 2 Peach Gottor Atcmic Fc,er Static,, the f ol lowing repor t is bein.) suiaitted to the Dirccterate of Licensing as an Abnorraa! Occurrence.

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50-277-74-35 Report Date:

July 12, 1974 Occurrence Date: July 2, 1974 Facility:

Peach Bottom Atomic Power Statico R.D.

1, Delta, Pennsylvania l'/314

. Identification of O_cc_urrence:

Condensor i cr. i vacuum scrcm pressure switch setpoint found to j

bc less censer vative than the limiting safety system setting.

t Condit ions Pr ion t o Occurrence:

The reactor was at 39,/, pcwer.

l Pa sc r ip t i on r Occurr'nte:

e D ur i ng a. c.o t i ne i n s t r o:ra t surveillence test of P5-2-5-ilA, main condenser le.s vacuu irip input into the reactor protectic-n system, the sub jec t switch was found to trip at 19.2 in. Hg.

Tiiis is j.8 in. tl3 less c onrcrvative than the Technical '.pec i f i ca t i on s rp 'nt of greater than or equal t o '!? i n, lig.

G401270126 740712 PDR ADOCK 05000277 e

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Mr. A. Giar. basso p

July 12, 1974 v'

Page 2 pesignation of Apnacent cause of crcurrence:

Se rpoi n t failure is attributed to instrument drift.

Analysis of Occurrence:

PS-2-5.llA is one channel in a one-out-of-two-twice logic arrangement. The setpoint foilure would net have preven ted t he eevice tran initiating a trip signal.

The protection p ovided by tha other three channels 0+ condenser vacuum voald have becn sat isf actory fr ea a standpoint of clant s a f e t :,. Therefore, thi., ccourrcnce Ses raininal safety implications.

Corrective Action:

Tha. subject switch was immediately recc.!ibrated, checked fur setpoint repeat ibili ty and returned t o service. The ot her thrce d tchra monitoring condenser vacuum end providing the RPS inpats were irned i a t e l y tested cr.d founa t o be s a t i s f a c t r;r y.

Foilure Data:

.This is the fourth setpoint f ailure of this type of de ice in this service.

Other occurrences are as follo',s:

PS-2-5-!!A cn w ear- ';. 1974 IS-2-5-;iD en scanuary [ ly/4 PS-2-5-i l A on Apr i l 8, 1974 After the two setpoint f ailures of PS11A. the device was rc-placed in kind. Tnis f ailure is the fir st se t p a i n t failure of the re-placement device.

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4 M. i. C oeney A s s' ' t Gen ' l S uper. iintendent Gt'ocr a t i on fii v i s i on ec:

Mr. J. P. O'Reilly Director, Region i Uni ted St ate s At e:nic Energy Cov.ission

(;31 Park Avenuc King of Prussia, PA 19406

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