05000289/LER-1978-001-01, /01T-0:on 780106,B&W Informed Util That During Certain Plant Transients,Difference Between Reactor Power as Indicated by out-of-core Instrumentation & as Calculated by Heat Balance May Exceed 4% of Full Power

/01T-0:on 780106,B&W Informed Util That During Certain Plant Transients,Difference Between Reactor Power as Indicated by out-of-core Instrumentation & as Calculated by Heat Balance May Exceed 4% of Full Power

ML19261F287
Person / Time
Site:	Crane
Issue date:	01/24/1978
From:	Stevens R METROPOLITAN EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19261F286	List: 05000289/LER-1978-001, Forwards LER 78-001/01T-0 05000289/LER-1978-001-01, /01T-0:on 780106,B&W Informed Util That During Certain Plant Transients,Difference Between Reactor Power as Indicated by out-of-core Instrumentation & as Calculated by Heat Balance May Exceed 4% of Full Power
References
LER-78-001-01T, LER-78-1-1T, NUDOCS 7910250731
Download: ML19261F287 (2)

LER-1978-001, /01T-0:on 780106,B&W Informed Util That During Certain Plant Transients,Difference Between Reactor Power as Indicated by out-of-core Instrumentation & as Calculated by Heat Balance May Exceed 4% of Full Power

Event date:
Report date:
2891978001R01 - NRC Website

text

NARRATI7E OF LICEISEE ITEN." REFORT 78-01/1T Metropolitan Edison Ccmpany has been infer =ed by the TMI-1 NSS 7 ender, Sabc0ck and

• 411ccx that during certain power transients, the difference between reacter pcver indicated by the cut-of-core instrunentation and rescter pcVer calculated by a heat balance =ay exceed h5 of fu2.1 pcver. The =axi=u= difference assu=ed in the Safety Analysis Repcrt is h5.

This iten is reportable in acecrdance with Tech-nical Specification 6.9 2.A(9).

The difference between heat balance and indicated power may be noncenservative for a period of ti=e felleving large pcVer transients. Ecvever, during transients frc= lcw pcVer levels, the high temperature trip and high reacter pressure trip serve as backup to the everpever trip.

Because of the short period of time the unit is Operated in a condition -there nu-clear instrumentation could exceed the h5 value and, because of the backup trips discussed above, it is felt that there was no significant reduction in the =argin of safety during past operation.

To reduce the possibility of this cecurrence Met-Ed has:

1.

Revised its operating precedure to increase the frequency of heat balance calibration to ence per shift per 3&W recc==endation.

2.

Initiated a Technical Specificatien Change Request to increase the fre-quency of the heat balance checks to assure that the difference between the cut-of-ccre instru=entation and heat balance is =aintained less than h5.

h.

pending further evaluation, the everpcVer trip bistable setting vill be reduced to a nc=inal setting of 2 955 vithin 2 heurc of a power reducticn belov 905. The bistable setting vill be restored to its normal setpcint when pcVer is increased te equal to or greater than 39.5.

The discussiens with B&W are continuing and you will be infer ed of any new develep-ments.

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