ML20052A386

LER 82-003/03X-1:on 820212,prior to Fuel Load,Vital Instrument Ac Panel Undervoltage Alarm Received in Control Room.Inverter IY-11 & Panel PY-15 Tripped When Manually Switched Off.Cause Unknown

ML20052A386
Person / Time
Site:	Diablo Canyon
Issue date:	04/22/1982
From:	Scott W PACIFIC GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20052A381	List: ML20052A380 ML20052A386
References
LER-82-003-03X, LER-82-3-3X, NUDOCS 8204280288
Download: ML20052A386 (2)

Text

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,. ,5 A. tv D. . .0 EVENT DESCMIPr3ON AND PROS ASLE CONSEQUENCES h g IPrior to fuel load, the operators received a vital instrument AC nanel I j

i g ni i undervoltage alarm in the control' room. An operator was dispatched to i o . iinvestigate the source of the undervoltage alarm. When the feeder breaker i s i to inverter IY-11 was manually switched off to check for a tripped breaker.1 o . inverter IY-11 tripped. The operator ininediately placed panel PY-11 on i g i ack-up b power and proceeded to check the remainder of the breakers and i o d

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CAUSE DESCRIPr10N ANDCORRECnyt ACTIONS h i o IThe causes of the undervoltaae alarm and the panel PY-15 trip are unknown. I g i nvestigations I into possible causes revealed no problems and equipment has ,

gi since operated as designed. Inverter IY-11 tripped when normal AC power wasi

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ATTACHMENT TO LER 82-003/03X-1 l f

Item 10, Event Description and Probable Consequences - continued tripped condition. PY-15 was placed on back-up power. The breaker was reset and PY-15 was placed back on normal power. From 1137 hours0.0132 days <br />0.316 hours <br />0.00188 weeks <br />4.326285e-4 months <br />, when inverter IY-11 tripped until 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />, both channels of the Plant. Vent Radiation Monitor (RM 14A & B) were inoperable because the sample pumps do not restart when power to the monitor is restored. Furthermore, from 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br />, when it is suspected that PY-15 tripped, until 1210 hours0.014 days <br />0.336 hours <br />0.002 weeks <br />4.60405e-4 months <br />, when power to the panel was restored, the Plant Vent Iodine Monitor (RM-24) and the Plant Vent Flow Recorder (FR-12)wereinoperable. Technical Specification 3.3.3.10 requires at least one channel of each monitor and flow recorder be operable at all times. The appropriate Technical Specification Action Statements were entered and satisfied. Since the plant has not attained criticality, no release of '

radioactive effluents occurred. This event in no way affects public health and safety. Reportable per Technical Specification 6.9.1.13.b.

Item 27, Cause Description and Corrective Actions - continued Vent Radiation Monitors were not immediately restarted because loss of the sample pumps does not cause a channel failure alarm. A design change has been recommended to provide sample pump alarms in the control room.

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