ML20052G633

LER 82-010/03L-0:on 820414,ICP 2.9 Found Not to Provide for Proper Unblocking of Source Range High Flux Reactor Trip Over Small Range of Instrument Readings.Caused by Failure to Identify Subtle Procedural Flow.Procedure to Be Revised

ML20052G633
Person / Time
Site:	Point Beach
Issue date:	05/07/1982
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20052G629	List: ML20052G628 ML20052G633
References
LER-82-010-03L, LER-82-10-3L, NUDOCS 8205180526
Download: ML20052G633 (2)

Text

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[ o l.1 [ flux reactor trip per TS 15.2.3.2.D. This event would allow automatic j lo is! [ unblocking of the source range high flux reactor trip at a power level  ;

IO16IIbelow that in Tech. Specs. This event was reviewed and did not consti g I O l / l I tute an unreviewed safety question under 10 CFR 50. 59. This event is g 0 s l reportable per TS 15.6.9.2.B.l. This event is common to Unit 2. ]

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ji1 jjThe Unit 2 setpoint had been corrected. Unit 1 has instructions pro- i

, ,, ;vided to plant operators to unblock this trip at the proper power level.,

, 3 lThe procedure will be revised and the unblocking setpoint will be cor- ;

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e ATTACHMENT TO LICENSEE EVENT REPORT NO. 82-010/03L-0 Wisconsin Electric Power Company Point Beach Nuclear Plant, Unit 1 Docket No. 50-266 During a review of ICP 2.9, " Periodic Test, Intermediate -

Range Channels N-35 and N-36", it was discovered that this.proce- ~

dure resulted in a setpoint value that, over a small range of instrument readings, would not provide for the proper unblocking of the source range high flux reactor trips. The setpoint resulting from this procedure would allow the automatic unblocking of the source range high flux reactor trips at a power level below that specified in Technical Specification 15.2.3.2.D. This Technical Specification states, " the source range high. flux reactor trip shall be unblocked when the intermediate range flux is <10-10 i amperes". The conduct of ICP 2.9 sets the permissive bistable T trip point at an ideal power level of 10-10 amperes which properly allowed manual bypass of the source rance high flux trip during a power increase. However, the bistable reset point due to normal bistable lockup caused the automatic unblocking to occur at a power level slightly below the required 10-10 amperes.when power was i decreasing. Thus, during a decreasing neutron flux, the operator would receive visual indication that the permissive conditions for the reestablishment of the source range high 'f lux reactor trip were met when in fact the Technical Specification required power level for the reestablishment of these trips had pass id. -

A review of the implications of this event was conducted using the criteria of 10 CFR 50.59 to determine if an unreviewed safety question existed. It was determined that although this trip was mentioned in the safety analysis report as being available, it did not provide a basis for protection for any of the events analyzed in the safety analysis. Therefore, an unreviewed se' ~ y question did not exist. Further, no reduction in public heab.u or safety was experienced as a result of this' event. This event was common to both Units 1 and 2.

The cause of this event was determined to be_that past reviews failed to identify this subtle procedural' inadequacy.

This procedure is being revised to ensure that during both power increases and decreases the source range'high flux reactor trip l

will be properly reflected in the energizing of the permissive t panel lights. In addition, special instructions are being provided

( to operators to7 alert them to this potential problem. Unit.2 has been corrected during a recent refueling shutdown. Unit 1 will be corrected at the next shutdown during which conditions allow.

The NRC Resident Inspector has been informed of this event. This event is reportable in accordance with Technical Specification 15.6.9.2.B.l.

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