ML19242D176

LER 79-014/03L-0 on 790712:during Surveillance Testing of Drywell to Torus Vacuum Breakers,Loss of Containment Air Monitor Occurred.Caused by Corrosion Seizure of Vanes.Spare Pump Was Installed & Failed Pump Repaired

ML19242D176
Person / Time
Site:	Vermont Yankee
Issue date:	08/09/1979
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19242D173	List: ML19242D172 ML19242D176
References
LER-79-014-03L, LER-79-14-3L, NUDOCS 7908140658
Download: ML19242D176 (2)

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VTVYS1 05000271 LER 79-14/3L EVENT DESC'lIPTION AND PROBABLE CONSEOUENCES During surveillance testing of the drywell to torus vacuum breakers, drywell to torus SP was reduced in accordance with plant operating proce-dures. As required by these procedures, the Containment Air !!onitor (CAM) pump was st'trted to maintain the required flow to the containment air monitor. The CN1 pump successtully started but failed after five minutes of operation. By this time, the drywell to torus aP had been reduced to the point that it could not maintain the proper flow to the containment air monitor. Loss of the containment air monitor is con-trary to Tech. Spec. Section 3.6.C.2. Since the drywell sumps were operable and did not indicate any unusual leakages during or af ter this occurrence, there were no undetected s team leaka>;es and therefore no consequences to the health and safety of the public. Similar occurrences were reported as RO 77-33, 76-04 and 75-23.

CAUSE DESgtIPTION A"D CORRECTIVE ACTION The CAM punp is a Conde Milking Machine Company Dri-Ai r !!adel No. 6, dry vane positive displacement pump.

Inoperability of the pump was due to corrosion seizure of the vanes.

A spare pump was installed and the failed pump overhauled. An engineering review is in progress which is expected to lead to improvement of the reliability of the system.

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