ML19352A086

RO 50-219/77-7-3L:on 740407,test Results Indicated Failure of Secondary Containment to Demonstrate Capability to Maintain 2.250 Inches of Water Vacuum Under Calm Wind Conditions.Caused by Deteriorated Manway Door

ML19352A086
Person / Time
Site:	Oyster Creek
Issue date:	05/02/1977
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
RO-50-219-77-7, NUDOCS 8103040210
Download: ML19352A086 (2)

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OYSTER CREEK NUCLEAR GENERATING STATION t Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/77-7-3L 1 Report Date May 2, 1977 Occurrence Date April 7, 1977 Identification of Occurrence Failure of the secondary containment to demonstrate the capability to maintain a .250 inches of water vacuum under calm wind conditions with a standby gas treatment system filter train flow of not more than 4,000 CFM. This event is considered to be a reportable occurrence as defined in the Technical Specifi-cations, paragraph 6.9.2.b.(4).

Conditions Prior to Occurrence The major plant parameters at the time of the occurrence were:

Power: Reactor, 1392 MWt Generator, 471 MWe (

Flow: Feedwater, 5.07 x 10g)lb/hr Recirculation, 54.5 x 106 lb/hr Stack Gas: 11,200 pci/sec Description of Occurrence On April 7, 1977, at 1140 hours0.0132 days <br />0.317 hours <br />0.00188 weeks <br />4.3377e-4 months <br />, a secondary containment capability test was perforned following the installation of a penetration through the reactor build-ing wall. The test results indicated a vacuum of .233 inches of water with a standby gas treatment system filter train flow of 2,700 CFM.

The cause of the low vacuum condition was traced to air in leakage through the reactor building roof manway which is an airlock with an inner and outer door.

The inner door was found to be not fully closed and the outer door had excessive leakage through its seal. Following repairs, the reactor building was retested and a vacuum of .281 was achieved.

Apparent Cause of Occurrence The reactor building roof manway doors are designed such that either door can be opened and .250 inches water vacuum maintained. The cause of the occurrence is attributed to the deteriorated outer manway door gasket. Gasket deterioration was attributed to age.

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Reportable Occurrence No. 50-219/77-7-3L Page 2 May 2, 1977 Analysis of Occurrence The secondary containment is designed to minimize any ground level release of radioactive material which might result during accident conditions. The requirement to maintain a .250 inch water vacuum with the standby gas treat-I ment system in service assures that the leak tightness of the secondary contain-ment is being maintained. The safety significance of the failure to demonstrate sufficient leak tightness is considered to be minimal since the margin of failure was small (.017 inches of water) and there were no accidents for which secondary containment was required to function.

Corrective Action I The outer door was temporarily repaired by packing the hatch seal with rope and caulking it in place. The inner door was closed and latched.

An investigation is being conducted to determine if the seal gaskets and latching mechanism can be improved. In any event, the latching mechanism will be locked and the keys will be placed under the control of the group shift supervisor.

Failure Data N/A 1

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