05000346/LER-1981-034-03, /03L-0:on 810601,found That When Unit Experienced Power Swing During Turbine Generator Control Valve Test, Main Steam Line Code Safety Valves Lifted Early.Cause Unknown.Investigation Will Be Done in Upcoming Outage

/03L-0:on 810601,found That When Unit Experienced Power Swing During Turbine Generator Control Valve Test, Main Steam Line Code Safety Valves Lifted Early.Cause Unknown.Investigation Will Be Done in Upcoming Outage

ML20009B064
Person / Time
Site:	Davis Besse
Issue date:	07/02/1981
From:	Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20009B060	List: 05000346/LER-1981-034, Forwards LER 81-034/03L-0 05000346/LER-1981-034-03, /03L-0:on 810601,found That When Unit Experienced Power Swing During Turbine Generator Control Valve Test, Main Steam Line Code Safety Valves Lifted Early.Cause Unknown.Investigation Will Be Done in Upcoming Outage
References
LER-81-034-03L, LER-81-34-3L, NUDOCS 8107140729
Download: ML20009B064 (2)

LER-1981-034, /03L-0:on 810601,found That When Unit Experienced Power Swing During Turbine Generator Control Valve Test, Main Steam Line Code Safety Valves Lifted Early.Cause Unknown.Investigation Will Be Done in Upcoming Outage

Event date:
Report date:
3461981034R03 - NRC Website

text

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CCYT 68 69 EVENT DATE 74 7b REPORT DATE 80 60 61 DOCKET NUMBER 7

8 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h Turbine Generator control l

10121 l (NP 33-81-39) on 5/31/81 at 0300 knn,.= W 1. p o,. r,,,. q., g Valve Test, the station experienced a power swing. During the swing, one of the Main, pl Steam Line code safety valves lifted. After reviewing data, it was determined On 6/1/81 at 1555 hours0.018 days <br />0.432 hours <br />0.00257 weeks <br />5.916775e-4 months <br />, one safety valve l

that one of the valves lifted early..

30j5j l The station entered the action statement of T.S. 3.7.1.1.

g l0 l6 l l was declared inoperable.

l The valve would still have served]

l There was no danger to public or station personnel.

Icl7j intended function of relieving pri.sure had'a trip occurred.

g its 80 l0 ta 1 i COVP.

VALVE SYSTEM

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Testing and ex-l l The cause for the apparent early lifting is unknown at this time.

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safety valves will be done durine the upcominc 1

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Any problems found at that time will be evaluated and l

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-81-39 DATE OF EVENT: June 1, 1981 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: One code safety valve on Main Steam Line 1 declared inoperable The unit was in Mode 1 with Power (MWT) = 2018 and Conditions Prior to Occurrence:

Load (Gross MWE) = 672 Description of Occurrence: On May 31,1981 at 0300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> while performing Turbine Generator Control Valve Test, PT 5193.01, the station experienced a power swing down to 550 MWe.

During the swing, one of the main steam safety valves lifted on the After reviewing all of the available data from the swing, it was deter-No. 1 side.

mined that one of the safety valves lif ted early. On June 1,1981 at 1555 hours0.018 days <br />0.432 hours <br />0.00257 weeks <br />5.916775e-4 months <br />, one The station entered the safety valve on Main Steam Line 1 was declared inoperable.

action statement of Technical Specification 3.7.1.1 which allows power operation to proceed provided that within four hours the high flux trip settnint be reduced to 4m92.91% full power. As the station.was already in a three reactor coolant pump the high flux trip setpoint had previously been reduced to 80%

operating condition,

' full power. The conditions of the action statement were being met.

The cause for the apparent early lifting Designation of Apparent Cause of Occurrence:

is unknown at this time. Testing and examination of some main steam line safety

~

valves will be donc during the current Reactor Coolant Pump seal repair outage.

There was no danger to the health and safety of the public Analysis of Occurrence:

or to station personnel. The power swing was not severe and was controlled without difficulty after suspending turbine control valve testing. The safety valve apperently lifted only 4% 1cuer than its setpoint. The valve would still have served its intended function of relieving pressure had a trip occur. red.

The setpoints for some safety valves will be checked during the Corrective Act' or :

8,y p-oblems found at that time will be evaluated and corrective action next outage taken.

Previous safety setpoint problems were reported in Licensee Event Failure Data:

Reports NP-33-79-51 (79-049), NP-33-79-34 (79-032), NP-33-79-25 (79-020),

NP-33-79-23 (79-018) and NP-33-78-145 '~8-124).

LER #81-034