ML20064H344

/01T-0 on 781129:during Test,Noted That Containment Leakage Rate Greater than Allowable.Discovered That Vent Valves Were Leaking.Caused by Leakage Past the Seating Surfaces

ML20064H344
Person / Time
Site:	Oyster Creek
Issue date:	12/14/1978
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:
Shared Package
ML20064H341	List: ML20064H338 ML20064H344
References
LER-78-029-01T, LER-78-29-1T, NUDOCS 7812190107
Download: ML20064H344 (3)

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gation, the following leaks were identified: 150 condenser vent valves __ __ _ , j ig C V-14-1, 5, 19 and 20 were isolated; reactor building to torus vacuum l'

@l breaker pressure switches DPS-66A and 66B ucre isolated;._and dryyiell vent I to l i l l_ valves V-27-1 and 2. V-27-2 was repaired. The leak rate test was re- l

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(201)4 % 8200 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/78-29/IT-0 Report Date December 14, 1978 Occurrence Date November 29, 1978 Identification of Occurrence Violation of the Technical Specifications, paragraph 4.5.B.I.2, when results of the primary containment integrated leak rate test failed to meet the allowable leakage requirement of one weight percent per day as stated in the referenced Technical Specification. This event is considered to be a reportable occurrence as defined in the lechnical Specifications, paragraph 6.9.2.a.3 Conditions Prior to Occurrence The plant was in a cold shutdown condition.

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Reactor mode switch: Shutdown Moderator temperature: Approximately 160*F.

Reactor vessel head in place.

Containment pressure: Approximately 36.6 psia Description of Occurrence On November 20, 1978, at approximately 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br />, the primary containment vessel was pressurized to 36.9 psia (22.2 psig) for the purpose of conducting a Type A containment leak rate test. During the course of conduct ing the Type A test, it was discovered that the containment leakage rate was greater than allowable. investigation as to the cause of the excessive leakage continued until approximately 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> on November 23, 1978. During this time period, the follcwing leaks were identified and isolated or repaired:

(I) Isolation condenser vent valves V-14-1 and 19 and V-14-5 and 20 were isolated by closing V-l-71 (boundary extension).

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Iteport able Occu r: cote No. 50- 219/ /8-2'J/ I 1 -0 Page 2 December 14. 1978 (2) Reactor building to torus vacuum breaker dif ferential pressure sensing switches, DPS-66A and DPS-66B were Isolated.

(3) _ Drywell vent valves V-27-1 and V-27-2. V-27-2 was repaired.

The test was then restarted at 1905 hours0.022 days <br />0.529 hours <br />0.00315 weeks <br />7.248525e-4 months <br /> on November 23, 1978 and was successfully completed at 0248 on November 24, 1978.

Apparent Cause of Occurrence The failure of the reactor building to torus vacuum breaker D/P sensing switches are the subject of LER 50-219/78-26/1T.

f- The cause of failure of the Isolation condenser vent valves is attributed to excessive leakage through the seat sealing surfaces. (Type C test was not performed prior to Type A test.) The cause of failure of the drywell vent valves is attributed to excessive leakage past the butterfly disc / boot seating the surfaces for V-27-1 and through the disc to stem taper pin which was found to be loose. (Type C test was performed prior to Type A test and passed.)

Analysis of Occurrence Under design basis loss of coolant accident conditions (LOCA)., the containment isolation valves function to limit the leakage out of the containment structure-to 'less than one (1) weight percent of the containment atmosphere per day.

Conformance to this criteria assures that the release limits set forth in 10CFRl00 will not be exceeded. The test results indicated that the limit of one (1) weight percent per day would have been exceeded.

k Corrective Action The necessary corrective actions required to satisfy the operational leak rate criteria were:

(1) Switches DPS66A and B were replaced with switches of a higher pressure rating and successfully Type C tested at 35 psig. No leakage was detected. Reference LER 50-219/78-26/IT for further information.

(2) The isolation condenser vent valves were repaired and successfully Type C tested at 35 psig. The results of the test were added to the Type A test results.

(3) Both drywell vent valves were replaced af ter successful completion of the Type A test and were successfully Type C tested. Additionally, we will evaluate the feasibility of establishing criteria to include the primary containnent isolation valves into the preventative maintenance program to insure leakages are kept to a practical minimum.

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i Reportable Occur rente flo. 50 - 21 ')/ 78- 2 'J / l 'l - 0 Page 3 December 14, 1978 Fa i l u re Da ta I (1) Isolation condenser vent valves Manufacturer: Skinner Type: 3/4" globe valve Operator: Air to open, spring to close (2) Drywell vent valves Manu fact ure r: Rockwe11 Type: 18", 150 psig butterfly Ope ra to r : air to open, air to close l

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