05000336/LER-1978-033, Update LER 78-033/03L-1:on 781205,while Operating Diesel 12U for Surveillance,Low Cooling Water Alarm Received & Confirmed.Caused by Flow Restriction Due to Mussel Debris in Heat Exchanger.Svc Water to Diesel Modified

Update LER 78-033/03L-1:on 781205,while Operating Diesel 12U for Surveillance,Low Cooling Water Alarm Received & Confirmed.Caused by Flow Restriction Due to Mussel Debris in Heat Exchanger.Svc Water to Diesel Modified

ML19338G171
Person / Time
Site:	Millstone
Issue date:	10/22/1980
From:	Clement C NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19338G168	List:
References
LER-78-033-03L, LER-78-33-3L, NUDOCS 8010280541
Download: ML19338G171 (2)

LER-1978-033, Update LER 78-033/03L-1:on 781205,while Operating Diesel 12U for Surveillance,Low Cooling Water Alarm Received & Confirmed.Caused by Flow Restriction Due to Mussel Debris in Heat Exchanger.Svc Water to Diesel Modified

Event date:
Report date:
3361978033R00 - NRC Website

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@ l While operating the 120 diesel for surveillance, the low cooling water flow alarm was l,

g I received. The cooling water low flow was confirmed by high differential pressure across l In accordance with Tech. Spec. Section 3.8.1-1, action statement l

oI41 I the heat exchangers.

o TTl I a, the diesel was declared inoperable and the operability of the remaining AC sources wasl i + 161 I verified.

The diesel is a Fairbanks Morse, 38 TD 8-1/8, rated at 2,750 KW.

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43 44 47 CAUSE DEsCR;PTION AND CORRECTIVE ACTIONS h t lal l Investigation revealed mussel sheels in the heat exchanger.

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LER 78-33/3L-1 Millstone Unit 2 Docket No. 50-336 Cause Description and Corrective Action Mussel debris has caused a flow restriction in the diesel heat exchangers on five previous occasions.

Only this incident has occurred after the chlorine system diffuser modific.ation was completed.

No mussel incidents have occurred after the 12/5/78 incident.

The service water to the diesel has been modified to include a duplex basket strainer at the heat exchanger inlet of each diesel engine. The weekly cleaning and inspection of the diesel heat exchangers has been discontinued.

The duplex basket strainer will be inspected weekly.

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