ML20009B064

LER 81-034/03L-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

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: ML20009B059 ML20009B064
References
LER-81-034-03L, LER-81-34-3L, NUDOCS 8107140729
Download: ML20009B064 (2)

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- LICENSEE EVENT REPORT (PLE ASE PRINT OR TYPE ALL REQUIREo)NFORMATION)

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LICENSEE CODE 14 lb LICENSE NUMi$ER 2b 26 LICENSE TYPE JO $7 CAT 56 CCYT l0l11 SURC60l Ll@l_ Ol SI 01 l dl 11 4I 6@l 68 69 01 EVENT 61 01 DATE 1I RI74 1 @l0 7b l7 l0DATE REPORT l2 l8 80l1 l@-

7 8 61 DOCKET NUMBER 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 30j5j l that one of the valves lifted early ..

g l0 l6 l l was declared inoperable.

The station entered the action statement of T.S. 3.7.1.1.

l The valve would still have served]

Icl7j l There was no danger to public or station personnel.

g its intended function of relieving pri.sure had'a trip occurred. 80 l0 ta 1 i COVP. VALVE SYSTEM CAUSE CAUSE SUBCODE SUBCODE CODE SUSCODE COMPONENT CODE CODE E I ci cl@ LxJ@ LZ_J@ I v l A l L l V l E l X lh Jh J h 9 to 11 12 13 18 19 REPOf$T 20 REVISION 7 8 SEQUENTIAL OCCURRENCE

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! 33 34 35 f CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h Testing and ex- l

! i O l The cause for the apparent early lifting is unknown at this time.

l safety valves will be done durine the upcominc 1 l lijijl amination of some Main Steam Lee

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Any problems found at that time will be evaluated and l

, g g seal repair outage.

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, 3 l corrective action taken.

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80 iSCO RY DISCOVERY DESCRIPT.vN

% POWER oTHER STATUS STA 5 l l l B j@l PT 5193.01 lT]T] ]@ l 0l' 7l 3l@l NA v2 o 44 *s 4s 80 7

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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 Conditions Prior to Occurrence: The unit was in Mode 1 with Power (MWT) = 2018 and 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 No. 1 side. After reviewing all of the available data from the swing, it was deter-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 safety valve on Main Steam Line 1 was declared inoperable. The station entered the 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 operating condition, the high flux trip setpoint had previously been reduced to 80%

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

Designation of Apparent Cause of Occurrence:

The cause for the apparent early lifting

~

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.

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

Corrective Act' or : The setpoints for some safety valves will be checked during the next outage 8 ,y p-oblems found at that time will be evaluated and corrective action taken.

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

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