ML19323H297

LER 80-042/03L:on 800510,during Performance of Local Leak Rate Test,Combined Leakage for All Penetrations Tested to Date Exceeded Combined Allowable Leakage.Caused by Buildup on Valve Preventing Good Seal.Valve Seats Will Be Relapped

ML19323H297
Person / Time
Site:	Davis Besse
Issue date:	06/08/1980
From:	Rohrer E TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19323H296	List: ML19323H295 ML19323H297
References
LER-80-042-03L, LER-80-42-3L, NUDOCS 8006120347
Download: ML19323H297 (2)

Text

U. S. NUCLE AR REfUL AV@ER7 (BR%iRMLeg -

NRC F09M 366 (1-711

- LICENSEE EVENT REPORT CONVROL BLOCK: l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) g l0 lH lD lB lS l1 l@l 0l 0l 0l 0l LICENSE 0l 0lNUMSER0l 0l 0l 0l 0l@l 25 4l 1l 26 1l 1l 1l@l57 CAT LICENSE TYPE JO l

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EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h l~iTTO l OIP-33-80-52) On May 10, 1980 during the performance of the Local Leak Rate Test, thel g o g 3, l combined leakage for all penetrations tested to date exceeded the combined allowable l lTpp l leakage. The penetrations / valves tested this day were 52/MU242, 53/MU243, 54/MU244, l o 3 l and 55/MU245. The station entered the action statement of Technical Specification l 10 is l l 3.6.1.2.c. There was no danger to the public or station personnel. The backup valve l lTJ'T] l at each penetration was tested at the same time with zero leakage and would have l I

loi8j l insured containment integrity. 80 E CODE S BC E COMPONENT CODE SUBCODE SU E O 9 8

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, i l Work Order 80-123 was issued to repair these check valves. Some of the valves have l

, 7 l been taken apart and inspected. The present plan is to lap the valve seat and retest.[

, 3 l Repairs will be completed prior to increasing reactor coolant system temperattire abovej gl 200 F. Any unusual findings will be reported in a revision. l 80 7 8 9

% POWER OTHER STATUS DIS O Y DISCOVERY DESCRIPTION ST S i s ]@ l 0l 0 l 0 l@l NA l l B lgl Surveillance Test ST 5061.02 So l

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-52 DATE OF EVENT: May 10, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: The combined leakage for the containment isolation valves tested exceeded allowable limit Conditions Prior to Occurrence: The unit was in Mode 6 with Power (MWT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence: On May 10, 1980 at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> while performing Local Leak Rate Test, ST 5061.02, the combined leakage for the penetrations tested thus far exceeded our total allowable combined leakage of 0.015 La (which is 15,000 ccpm). The penetrations that put us over the allowable limit were 52, 53, 54, and 55 which were all being tested the same day. The check valves that failed were MU242, MU243, MU244, and MU245. They each had seal leakage of approximately 4,000 cc per minute, giving a total of about 16,000 cc/ minute with the limit being about 15,000 cc/ minute. With about 80% of the penetrations completed, we had about 6,000 cc/ minute total leakage prior to these four valves being tested.

This placed the station in the action statement of Technical Specification 3.6.1.2.c which limits the combined leakage rate to :6 0.015 La for all penetrations identified as secondary containment bypass leakage paths when pressurized to Pa (38 psig). The action statement requires the leakage rate to be restored within limits prior to increasing the reactor coolant system temperature above 200 F.

Designation of Apparent Cause of Occurrence: The apparent cause is a slight buildup on the valve seats. The buildup is preventing a good seal. Work is presently on-going to clean up the seats and identify the buildup. Any unusual findings will be reported in a revision.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The backup valve was tested at the same time with zero leakage.

If needed, the second isolation valve would have been adequate to insure containment integrity.

Corrective Action: Maintenance Work Order 80-123 was issued to repair these check valves. At this time, some have been taken apart and inspected with the only find-ing being a slight buildup on the valve seat. The present plan is to lap the valve seats and retest. Repairs will be completed prior to increasing reactor coolant system temperature above'200 F. Any unusual fir. ding will be reported in a revision.

Failure Data: This is the first reported fa'. lure of this type check valve.

LER #80-042