ML20009C131

LER 81-035/03T-0:on 810624,concluded That Containment Purge & Exhaust Valves Could Not Be Closed from Open Limit of 65 Degrees During Dba.Caused by Design Deficiency.Mod Will Limit Full Open to 55 Degrees

ML20009C131
Person / Time
Site:	Davis Besse
Issue date:	07/08/1981
From:	Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20009C124	List: ML20009C123 ML20009C131
References
LER-81-035-03T, LER-81-35-3T, NUDOCS 8107200310
Download: ML20009C131 (2)

Text

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- LICENSEE EVENT REPORT c6MTROL BLOCK: l  ! l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATIOM) io l id lSl 0 l LICENSEE H l D CODE l B l S l 1ISl@l 0 l 0 l -lLICENSE 0 l 0Nuv6EH l 0 l 0 l 0 l - l230 ] 260 ]@l 4 l TYPE LICENSE 1 l 1JJ l 1bil car j@

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T DATE 7 8 60 31 OOCKET NUYSER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h l'oTilI (NP 32-81-02) On June 24, 1981, a review of the analysis of the operation of the l l o la i l containment purge and exhaust valves CV 5005, 5006, 5007 and 5008 concluded that they l 1014l I could not be closed from their present open limit of 65 degrees open during a design [

l o i s i l basis accident. This was determined reportable under Technical Specification 6.9.1.8.,

Ioisl l 1. There was no danger to the health and safety of the public or to station personnel) j o l 7 l l Most purges are Conducted in Modes 5 and 6. Purges in other modes are limited to a l

'i ls time would be repotc 1 o la 1 I total of 90 houts. The change of a design basis accident during 60 r 7 8 9 COMP. VALVE

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7 8 9 10 11 12 13 OCCURRENCE REPORT REVISION SEQUENTIAL REPORT NO. CODE TYPE NO.

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33 34 33 31 40 43 44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h li l o l ! The cause is a design deficiency bv the vendor. Henry Pratt. The present 6,5 degree l A new analysis concludes tFat an i l1 t i l l open limit is the result of a preliminary annivsis.

I It 121l oPen limit above 55 degrees would result in forces being created in the valve that g l would overstress the stub shaft and prevent the valve from closing. Under FCR 79-434Al L' 14 j i a modification will limit the full open to 55 degrees during the next refueling nutacet 7 8 9

% POWER OTHER STATUS ISCO RY DISCOVERY 0ESCRIPTION ST S l

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NA 80 7 8 9 11 12 LOSS OF OR DAVAGE TO FACILITY TYPE D ESC RIP TION 3 9 NA 80 7 8 9 10

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810 200310'~810708 'an Stotz PHONE:

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNI' ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-81-02 1

DATE OF EVENT: June 24, 1981 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Analysis of the containment purge and exhaust valves determined that these valves would not operate per design of the Final Safety Analysis Report (FSAR)

Conditions Prior tc Occurrence: The unit was in Mode 1 with Power (MWI) = 2051 and Load (Gross MWE) = 680.

Description of Occurrence: On June 24, 1981, a review of the analysis of the opera-tion of the containment purge and exhaust valves *CV 5005, 5006, 5007, and 5008 dur-ing a design haa.s accident concluded that these four valves could not be closed from their present allowable open Jimit of 65 degrees (with 90 degrees being fully open). These containment isolation valves are Henry Pratt Company butterfly valves, Model No. T-520-SR-1, Serial Nos. 30566-1, 30566-2, 30566-3, and 30566-4. These valves are normally closed and are only opened to purge. When they are open, they create a direct path from contairment to the environment. This condition was deter-mined to be reportable under Technical Specification 6.9.1.8.1 as the performance of a component that requires corrective action to prevent operation in a manner less conservative than assumed in the FSAR. Part 21 data has been included in order to satisfy the requirements of a 10 CFR 21 report, which is required for this design deficiency.

Designation of Apparent Cause of Occurrence: The cause of the finding is a design deficiency by the valve vendor, Henry Pratt Company. The opening of these valves is presently limited to 65 degrees open by Facility Change Request 79-434. This limit was the result of a preliminary analysis. A new analysis concludes that thest valves i

could not be closed from 65 degrees open under design basis accident conditions, i

From greater than 55 degrees open position, the delta pressure across the valve would create forces in the valve that could prevent it from closing and could overstress the stub shaft should the valve have to close under these conditions. This anafysis was conducted for valves with a pneumatic actuator as installed and would dif fer for the same valve with a motor actuator.

i Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. These valves were normally in a closed position. They were opened to purge containment atmosphere, and this is normally done in Modes 5 and 6. Previously any purging done in Modes 1, 2, 3, or 4 is limited to a total of 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> or one percent of a years time. The chance of a design basis accident occurring during this limited time frame is remote.

LER #81-035 9

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. TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-32-81-02 1 Corrective Action: The initial action of the station was to ensure these valves were de-energized in their safety position, closed. From now on, these valves are tagged to prevent their use while in Modes 1, 2, 3, and 4 until Facility Change Requsst 79-434A has been completed to modify the valve actuator to limit the valve to 55 degrees fully open.

Failure Data: There have been no other reports of a design deficiency concerning these valves.

LER #81-035

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