ML20062C316
| 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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fo47T fle#weA> m qW PHILADELPHIA ELECTRIC COMPANY f
d Peach..So$ ton Atomic Power Station G
8 Delta,- Pennsylvania 17314 Z,3 October 11 1973
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1 Mr. Boyce H.
Grier Office of Inspe~ tion. 4 Enfozcement c
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.
(
N Reference-Decket No q050-177/278
)
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
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sequence loading relays were outsi-de the limits specified.in 'the Technical Specifications.
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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 -
anximum limit in,the Tech Spees.
4 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
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Sp ec-i fica tion Limits.
Relay ca11' oration was also set at t ha.
upper limit of the specif.~ied ran ; thus a small. setpoint drift s
placed the' relay setpoiar above the Tech Spec. limit
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ge Apparent Cause of the Occurrenca:
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 the diesel generator would-r have-Ioaded at a higher voltage (96% instead of. 95% rated l
iltaga.)
In reviewing the previous alibration of these relays it was found i
that the relay on the E-32 bus had been ser ott of specifications 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%
l abnvn t.he upper I.iwit-
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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 1
relays in LER. 3-77-24/3L Decket No. 050-278.
i Very'truly yours, fW W/L
\\
W.
T UI1 rich, Superintendent
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Peach Bottaw Atomic Power Station..
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