ML20062C316

Rept Occurrence 2-78-41/1P:on 781010 During Routine Surveillance Test of Unit 2 4KV Undervoltage Relays,Setpoint of Bus Sequence Loading Relays E-32 & E-42 Were Out of Calibr,Due to Engr Error

ML20062C316
Person / Time
Site:	Peach Bottom
Issue date:	10/11/1978
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
References
NUDOCS 7811080094
Download: ML20062C316 (2)

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PHILADELPHIA ELECTRIC COMPANY Peach..So$ ton Atomic Power Station G f 8 d

Delta,- Pennsylvania ,

17314 .,

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October 11 1973 l l ,

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Mr. Boyce H. Grier l Office of Inspe~c tion. 4 Enfozcement l j Region 1 '

United States Nuclear Regulatory Commission '

631 Park Avenue King of Prussia, PA 19406

SUBJECT:

REPORTAB'LE OCCURRENCE - PROMPT NOTIFICATION -

Confirming J. E. Win z enri esi" s conversation with Mr. G reenm an..

Region.1.-United Scates,Muelear Regulatory Commission on 10/1I/78.

Reference- Decket No q050-177/278

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Peach BottomsUnit-2' '

' Technical Specification : Tabla 3.2.5 - -

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Report.No. 2-75-41/IP Occurence Data: October ~ 10,' 1973. -

Id en ti fi c ation of Occurrsnes; During a Routine Surveillance Test of the Unit 2 4KY undervaltage ~

relays, it was observed that the setpoints of two of the bus sequence loading relays were outsi-de the limits specified.in 'the Technical Specifications. ~

Conditions Prior ti:r Occurrence:

Unit 2 was shutdown' prior to the occurrence for mit annual. refuwl and,maintenanca outage . Unit 3'was operating at 100% power.

Descript; ion of Occurrencer ,

During the surveillance tests of'the 4EY relays the emergency bus sequential loading relays on the E-32 and E-42 ' emergency buses-were found out of the cal _ibratian range . stated in the TechnFcal Speci fi esti ons. The as found setpoints were 41% higher then. the -

4 anximum limit in ,the Tech Spees.

• Further; Envest-igation showed that' the' setpoints. specified in the surveillance testes. were inaccurate thus allowing the ST 'to- be - '-

completed satisfactori ty with values out s-ide the Technical ' ~

Sp ec-i fica tion Limits. Relay ca11' oration was also set at t ha.

upper limit of the specif.~ied rans ; thus a small. setpoint drift placed the' relay setpoiar above the Tech Spec. limit

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h" Apparent Cause of the Occurrenca:

M bh'tb ge@2 cf A The cause of the occurrence is attributed to an. engineering error in determining, the s etpoint s and.the culibration span stated.in the Surve11.lancs Test. -

Analysis of Occur =ence- .

~ Tlie "emerg.ency bus sequential loading relays, Westinghouse instantaneous. SV voltage relays, were found.to be out of specification in the unconservative direction Since these relays-allow the losding of the emergency buses during the loss of power condition.With. the as found setpoints r the diesel generator would-  !

have- Ioaded at a higher voltage (96% instead of. 95% rated l iltaga.)

In reviewing the previous alibration of these relays it was found that the relay on the E-32 bus had been ser ott of specifications i during the previous calibration due to su ryw illa nc e- test inadequacies. The reIay on che E-42 bus had been set at the upper limit and had drifted upwxrd strough to exceed the Technical Specif.1 cation 1.131t .

The safet.y implications. of this occurrence are minimal since diesel 2enerator auta actuation and load acceptance tests had.been performed <r.> both Units d'uring the previous. Tefueling ou.tages-after relay calibration: and the actual setpoint.s. were less than 1%

abnvn t.he upper I.iwit-l

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' Corrective Ac tion : -

the Surveillance T'ests for the 4 KY' en *T2 ency bu s r elay,s calibration i hayw heon reviesad, nr..L deficiencies. revised., The sequential  ;

loading relays on a l.1. emer2ency buses iPor both.U' nit I ands ifnit 3 have been recalibrat edt to aidrange. of. the TechnicaI-Specification

. cyan 15mit Failure D a t a.: ' * '

Similar failures were reparted on the Unit 3 SV Sequential Ioading relays in LER. 3-77-24/3L Decket No. 050-278.

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Very'truly yours, ,,

fW W/L -

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W. T UI1 rich, Superintendent Peach Bottaw Atomic Power Station.. -

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