ML20005G580

Forwards Technical Review Rept AEOD/T921, Inadequate Capacity of 4,160-Volt Switchgear at Fitzpatrick. Licensee Agreed Not to Operate Plant in Any Configuration Where Max Fault Current Can Exceed Breaker Rating

ML20005G580
Person / Time
Site:	FitzPatrick
Issue date:	12/27/1989
From:	Mazumdar S NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Rosenthal J NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
Shared Package
ML20005G581	List: ML20005G580 ML20005G587 ML20005H198
References
AEOD-T921, NUDOCS 9001190356
Download: ML20005G580 (2)

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AEOD/T921 1

-MChiramal KBla'ck L

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MEMORANDUM..FOR:. Jack E. Rosenthal, Chief Huilliams

Reactor Operations Analysis Branch VDenaroya P

Division.of. Safety Programs, AE0D

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. Matthew Chiramal, Chie'f CHe)temes-

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Subinoy1Mazumdar, Electrical Engineer FROM:-

Engineering Section.

A Reactor _ Operations Analysis Branch R

Divisioniof Safety Programs, AE0D L

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SUBJECT:

i LINADE00 ATE CAPACITY 0F 4160V'SWITCHGEAR M. ' ",

AT F.ITZPAT. RICK

AE0D/T921 c

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, Enclosed is a Tech' icaliReview report on the. use of 4160V switchgear beyond its n

lM rating:at FitzPatrick Huclear Plant. During-the. monthly 1-hour load testing of.

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the;Diergency Diesel Generators (EDGs) the licensee operates the EDGs in

parallel,with the' Normal

Station Service. Transformer' (NSST). The parallel l({

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lconnedionf is madelatDthe'4160V switchgear. - A licensee evaluation has s

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,-established that-during such testingJthe maximum fault current nay exceed the f 3-14160V switchgear monentary rating by 27 percent and the interrupting rating by'

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m 3.7 percent sThe: licensee-has issued a Justification for Continued Operation s

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f(JCO)xon-the basis that during this testing'the probability of occurrence of a Q4 g

fault exceeding the _switchgear breaker rating-is less than E-6.

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-c m i 1 0n October!2, 1989 in_a telephone conference call between the NRC and the N; E, ' '

Tlicensee, we expressed our. concern about the use of the 4160V class 1E switch-

gt.ar-beyond its. rating.

A failure of ~ a switchgear in its momentary duty or l interrupting dutyJean cause catastrophic explosion and/or fire which can-danage

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part orEallLof-the adjoining equipment. Thus, such a failure in this particular 2;

' " ' application can1cause loss of the EDG'underEtest, a loss'of the NSST, and even

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.aHfailure of=the bus transfer from the'HSST to the Reserve Station Service iTfansformer (RSST) thus causing a totcl loss of all AC pcwer to one train.

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JFurthermore, theilicensee has based his JC0 on an LER data base search that

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indentified only'five 3-phase and phase-to-phase faults in the medium voltage

'M (between 2.4KV and.13.8KV) system in all nuclet plants in the USA between 1972 1

En yand-1989 while'our LER data base search indicates occurrence of 57 electrical mb faults between 1980 and 1989, indicating that the probability approach used in the JCOLis' questionable, R

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iAs4asconsequence-ofourfconc' erns,it'he'licenseehasagreed:nottooperate:the s

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71antiin any' configuration;in'which the maximum fault' current can exceed the.

lE M areakee, rating.y /The' licensee isii_nvestigating: possible alternatives to resolve '

the problem.E No; additional AE0D.actionLis recommended at thisitime.

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- Subinoy Mazumdar, Electrical Engineer ;

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Engineering'Section

1. 1 sc, Reactor. Operations; Analysis Branch v #w

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