05000346/LER-1979-118-03, Revised 79-118/03L-1:on 791126,when Reactor Coolant Pump Tripped,Reactor Protection on Sys High Flux Setpoint Reduced to 78.5% Full Power,Exceeding Limit.Caused by Procedural Deficiency Due to Incorrect Info

Revised 79-118/03L-1:on 791126,when Reactor Coolant Pump Tripped,Reactor Protection on Sys High Flux Setpoint Reduced to 78.5% Full Power,Exceeding Limit.Caused by Procedural Deficiency Due to Incorrect Info

ML19323H308
Person / Time
Site:	Davis Besse
Issue date:	12/21/1979
From:	Kocis R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19323H305	List:
References
LER-79-118-03L, LER-79-118-3L, NUDOCS 8006120357
Download: ML19323H308 (2)

LER-1979-118, Revised 79-118/03L-1:on 791126,when Reactor Coolant Pump Tripped,Reactor Protection on Sys High Flux Setpoint Reduced to 78.5% Full Power,Exceeding Limit.Caused by Procedural Deficiency Due to Incorrect Info

Event date:
Report date:
3461979118R03 - NRC Website

text

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63 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 10 l 2 l l On November 26, 1979, a low oil level alarm for Reactor Coolant Pump (RCP) 1-2 was l

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Reactor power was reduced and the RCP was tripped. The Shift Foreman in-l O l4 l l structed personnel to reduce the Reactor Protection System (RPS) high flux setpoint l

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o l s t l to 78. 5% of full power. During a log review at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on 11/27/79, it was found l

l o l6 l l that the value of 78.5% was in excess of the 78.3% value allowed by Technical Specifi ;

o l1] l cation 2.2.1 for three RCP operation. There was no danger; the ectual setpoints ex-l o is l l ceeded the tech spec value by 0.08% of the allowed value.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR PO'<!ER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-135 DATE OF EVENT:

November 26, 1979 FACILITY:

Davis-Besse Unit 1 8

IDENTIFICATION OF OCCURRENCE: After tripping Reactor Coolant Pump (RCP) 1-2, the flux trip setpoint was readjusted to a value slightly in excess of technical opecifications Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 1885 cnd Load (Gross MWE) = 638.

Description of Occurrence:

At 2145 hours0.0248 days <br />0.596 hours <br />0.00355 weeks <br />8.161725e-4 months <br /> on November 26, 1979, a motor lower bearing oil level alarm low (L808) for RCP 1-2 was received in the control room. As dictated by the immediate action of EP 1202.16 RCP and Motor Emergency Procedure, reactor power was reduced and RCP 1-2 was tripped.

Instrument and Control personnel were then called to lower the flux trip setpoint corresponding to three RCP operation.

By 0000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> on November 27, 1979, the new flux trip setpoint value was obtained from the Shif t Foreman and the trip bistables were reset.

During log review at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on November 27, 1979, the 78.5% setpoint value ob-teined from the Shif t Foreman was discovered to be in excess of 78.3% which is the maximum allowed per the Technical Specification 2.2.1 for three RCP operation.

An cdditional setpoint adjustment was completed by 0858 hours0.00993 days <br />0.238 hours <br />0.00142 weeks <br />3.26469e-4 months <br /> on November 27, 1979, to lower the trip bistable setpoint within technical specification requirements.

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Designation of Apparent Cause of Occurrence: The cause for incorrectly setting the flux trip setpoint has been attributed to procedure deficiencies in that correct and concise 3

information was not provided.

The EP 1202.16, RCP and Motor Emergency Procedure used during the trip of RCP 1-2 does not relate a need for resetting the trip setpoints to

'cny value or specify the value.

Analysis of Occurrence: There was no danger to the health and safety of the public cr to station personnel.

By the procedure, trip voltages set into the bistable may h;ve a tolerance of (+) 0.000 VDC to (-) 0.060 VDC with respect to the percent rated thermal pow'er desired. This maintains tapt the actual setpoint applied may be more c:nservative than that specified.

In this case, the actual voltage to which the bistables were set corresponds to 78.46% of rated thermal power.

This value exceeds tschnical specifications (by.08% of the allowable value) which is. expected to be within safety margins.

Carrective Action: Modifications will be prepared to the RCP and Motor Emergency

. Procedure EP 1202.16 and Power Operation PP 1102.04 to reflect technical specifica-tisn requirements for three RCP operation flux trip setpoints.

Failure Data: There have been no previously reported procedural difficulties con-c;rning reactor protection system high flux trip setpoint.

i LER #79-118

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