ML20029C114

LER 91-010-01:on 900816,axial Flux Differential Outside Tech Specs Limits Due to Malfunction of Turbine Electrohydraulic Governor Control.Operator Training Revised. W/910319 Ltr

ML20029C114
Person / Time
Site:	Point Beach
Issue date:	03/12/1991
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-91-027, CON-NRC-91-27 LER-90-010, LER-90-10, VPNPD-91-099, VPNPD-91-99, NUDOCS 9103250399
Download: ML20029C114 (4)

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Electnc POWER COMPANY

' 231 w Moct9m Po Box 2046. Mwee wi 53201 1414)221-2345 VPNPD-91-099' 10 CPR 50.73 NRC-91-027 March 19, 1991-U. S. NUCLEAR REGULATORY COMMISSION Document Control Desk Mail Station F1-137 Washington, D. C. 20555 Gentlemen:

DQCKET 50_.266 LICENSEE EVENT REPORT 90-010-01 AXIAL FLUX OUTSIDE TECHNICAL SPECIFICATION LIMITS POINT BEACH NUCLEAR PLANT, UNIT 1 Enclosed is Licensee Event Report 90-010-01 for Point Beach Nuclear Plant, Unit 1.

This report is provided in accordance with 10 CFR 50.73 (a) (2) (1) , "Any -event or condition prohibited by the plant's Technical Specifications."

This supplemental report describes operation outside the delta flux envelope for_ greater than fifteen minutes allowed by Technical Specifications and the long-term corrective actions.

If further information'is required, please contact us.

Very truly yours, h.

C. W. Fay Vice President Nuclear Power Enclosure Copies to NRC Regional Administrator, Region III NRC Resident Inspector i

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At 7:07 p.m.-on August 16, 1990, Unit i experienced a load rejection of approximately 100 MWe due to-a malfunction of the turbine electrohydraulic (Ell) governor control.. As a result of the load rejection, the Plant Process Computing System (PPCS) indicated by alarm that the axial flux differential was outside prescribed limits for 17 minutes. Control board indication showed the axial flux differential to be outside the prescribed limits for loss than 15 minutes. In accordance with our Reactor Engineering Instructions (REIs) ,_ the PPCS is to be used for primary _ indication and control board indications will be used if-the PPCS fails.- Contrary to Technical Specification, power was' not reduced after the lapse of 15 minutes with the " Delta Flux -

Outside_ Envelope" alarm on the PPCS.

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EVENT DESCRIPTION AND IMMEDIATE CORRECTIVE ACTION:

At'7:07 p.m. on August 16, 1990, Unit 1 experienced a load rejection _of approximately 100 MWe due to a malfunction of the turbine electrohydraulic (EH) covernor control. As a result of the load rejection, the Plant Process Computing System (PPCS) indicated by alarm that the axial flu ~.. differential was outside prescribed limits for 17 minutes. Control b ard indication showed the axial flux differential to be outside the prescribed limits for less than-15 minutes. In accordance with the Reactor Engineering Instructions (REIs) the PPCS is to be used for

. primary indication and control board indications will be used it the PPCS fails. Contrary to Technical Specifications, power was not reduced _after the lapse of 15 minutes with the " Delta Flux -

Outside Envelope" alarm on the PPCS.

When the " Delta Flux (AO) - Outside Envelope" alarm was received, the control operator stepped rods out.to get the axial flux differential within the allowed band as indicated on the control board. Following the determination of the cause of the load rejectien, the reactor coolant system was borated.to bring the l

-control board indication to the middle of the allowed band. This I

was accomplished within fifteen-minutes-of the axial flux

' differential alarm and power was subsequently _ increased.

However, the readout from the PPCS indicated that the-alarm was in continuously.for seventeen minutes.

At 9:30'p.m., another load rejection occurred due to an EH system malfunction also resulting in a " Delta Flux - Outside Envelope" alarm on the PP( At this occurrence, the. operators verified the cause and ir .diately borated to-set the axial flux

differential in ;ne middle of the prescribed band by control L . board indication. Again, a time lag existed between control board indication and the clearing of the PPCS alarm.

I The defective circuit boards that caused-the EH malfunction were, l

L replaced.

SAFETY ASSESSMENT The health and safety of the general public, as well as plant employees, was not affected during-this event.

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There have been no similar ew nts at Point Beach Nuclear Plant.

-REPORTABILITY This report is submitted in accordance with the requirements of 10 CFR 50.73(a) (2) (1) which requires reporting of any operation or condition prohibited by the plant's Technical Specification.-

LONG-TERM CORRECTIVE ACTION Operator training has been revised and specifically addresses axial flux difference (AFD) with reference to Technical Specification requirements. The training also addresses the use of the PPCS as the primary indication to be used by the control operators. This training is provided to control operators, senior reactor operators and duty technical advisors.

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I N3C Fenn 366A (6 891