05000369/LER-1981-055, Forwards LER 81-055/03L-0.Detailed Event Analysis Encl

Forwards LER 81-055/03L-0.Detailed Event Analysis Encl

ML20009G158
Person / Time
Site:	McGuire
Issue date:	05/15/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009G159	List: 05000369/LER-1981-055, Forwards LER 81-055/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-055-03, /03L-0:on 810416,cold Leg Injection Accumulator Declared Inoperable Due to High Level Alarm.Caused by Cold Leg Accumulator Discharge Check Valves Leaking.Valves to Be Repaired & Retested
References
NUDOCS 8108030383
Download: ML20009G158 (2)

LER-1981-055, Forwards LER 81-055/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981055R00 - NRC Website

text

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DUKE POWER COSIPANY

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May 15, 1981

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Srcane P.coucTios 373-4083 Mr. J. P. O'Reilly, Director U. S. Nuclear Regulatory Commission Region II g

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Re: McGuire Nuclear Station Unit 1 J L,_, l 'lg y Docket No. 50-369 a

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Dear Mr. O'Reilly:

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o Please find attached Reportable Occurrence Report R0-369/81-55. This report concerns the cold leg injection accumulator A being declared inoperable.

l This incident was considered to be of no significance with respect to the health and safety cf the public.

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• William O. Parker, Jr RWO/djs Attachment Mr. Bill Lavalee cc: Director Office of Management and Program Analysis Nuclear Safety Analysis Center U. S. Nuclear Regulatory Commission Post Office Box 10412 Washington, D. C.

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McGUIRE NUCLEAR STATION INCIDENT REPORT REPORT NUMBER: 81-55 REPORT DATE: May 5, 1981 OCCURRENCE DATE: April 16, 1981 FACILITY: McGuire Unit #1, Cornelius, N.C.

IDENTIFICATION OF OCCURRENCE: Cold leg injection accumulator A declared inoperable due to high level.

CONDITIONS PRIOR TO OCCURRENCE: Mode 3, Hot Standby DESCRIPTION OF OCCURRENCE: At 0934 hours0.0108 days <br />0.259 hours <br />0.00154 weeks <br />3.55387e-4 months <br /> en April 16, 1981, cold Icg injection accumulator A was declared inoperable. The accumulator A high level alarm (64.5%) was received in tLe Control Room. This indicated that the contained volume was above 8496 gallons of water and thus, reportable pursuant to Technical Specification 3.5.1.1.

APPARENT CAUSE OF OCCURRENCE: The cold leg accumulator A discharge check valves 1N159 and 1N160 were apparently leaking which allowed reactor coolant system (NC) water to fill the accumulator above its alarm setpoint.

ANALYSIS OF OCCURRENCE: A Periodic test, (Reactor Coolant Pressure Isolation Valve Leak Rate Test) performed April 25-28 found that cold leg accumulator

'A discharge check valves 1N159 and 1N160 were leaking past their seats.

On April 16, the NC System pressure was approximately 1800 psig and the cold leg accumulator A pressure was approximately 425 psig. Thus, it is probable that the discharge check valves ( IN159 and 1N160) were leaking and the accumulator filled above its high level alarm setpoint.

SAFETY ANALYSIS

The cold leg accumulators are passive and would only be used during an accident involving a large NC System break.

Since there was only new fuel in the core, safe plant operation and the health and safety of the public were not affected.

If the reactor had been at power and a large NC System break had occurred, cold leg accumulator A would have functioned as designed because the water level was close to its alarm setpoint. Furthermore, the accident analysis indicates that the contents of only three accumulators need to be injected in order to ILnit the peak fuel clad temperature at or below the maximum allowable during an accident.

CORRECTIVE ACTION

Cold leg accumulator A was drained below the high level alarm setpoir and was operable at 1007 hours0.0117 days <br />0.28 hours <br />0.00167 weeks <br />3.831635e-4 months <br /> on April 16.

Work requests were written to repair the leaking valves.

After the valves are repaired, they will be retested.