05000261/LER-1981-004-03, Primary Coolant Sys Leak Found.Caused by Sample Cooler Tube Bundle Leakage Due to Normal Wear.Bundle Replaced.Review of Maint Records Revealed No Generic Problems

Primary Coolant Sys Leak Found.Caused by Sample Cooler Tube Bundle Leakage Due to Normal Wear.Bundle Replaced.Review of Maint Records Revealed No Generic Problems

ML20009H358
Person / Time
Site:	Robinson
Issue date:	07/30/1981
From:	Paine E CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009H356	List: 05000261/LER-1981-004, Forwards Updated LER 81-004/03L-1 05000261/LER-1981-004-03, Primary Coolant Sys Leak Found.Caused by Sample Cooler Tube Bundle Leakage Due to Normal Wear.Bundle Replaced.Review of Maint Records Revealed No Generic Problems
References
LER-81-004-03L, LER-81-4-3L, NUDOCS 8108100008
Download: ML20009H358 (2)

LER-1981-004, Primary Coolant Sys Leak Found.Caused by Sample Cooler Tube Bundle Leakage Due to Normal Wear.Bundle Replaced.Review of Maint Records Revealed No Generic Problems

Event date:
Report date:
2611981004R03 - NRC Website

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NRC Ff)RM 36h Update Report - Previous Report Date 2/13/81 ' S. NUCLEAR REGULATORY CoMMISSloN 1

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60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h l o l 2 I lAt 1228 hours0.0142 days <br />0.341 hours <br />0.00203 weeks <br />4.67254e-4 months <br /> during normal operation on 1-16-81, indication of leakage to the CCW l

I o l a i ISystem prompted a RCS leak rate test which verified a 2.37 gpm leak rate.

Inves tiga-l 10 l 4 l l tion revealed that the leak path was from the pressurizer through the pressurizer i

tolsl l liquid space sample cooler to the CCW System via a leaking tube bundle in the sample l

I o 16 l l cooler. The lenkage experienced is contrary to the requirements of T.S. 3.1.5.2 and j

l o l 7 l lis reportable per T.S. 6.9.2.b(2). All leakage was contained within a closed plant l

l o is l l radioactive system and there was no threat to plant or public health or safetv.

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CAUSE

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33 34 35 36 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l i l o l [Ihe sample line isolation valves were closed as immediate corrective action. The root l l3 lij lcause of the event was the failure of the sample cooler tube bundle. The tube bundle l

l3 l7; [was replaced to prevent recurrence. Failure was attributed to normal operational l

lil3l l wear. Review of maintenance records revealed no generic implications with the reportedl L g [ failure. Therefore, a further action is necessary.

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Cause Description and Analysis On 1-16-81 at 1228 hours0.0142 days <br />0.341 hours <br />0.00203 weeks <br />4.67254e-4 months <br />, the combination of a volume control tank

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makeup signal, an increasing component cooling water- (CCW) surge tank level and an increasing radiation reading from the CCW System radiation monitor alerted the operators to the possibility.of a Primary Coolant-1 System leak. A RCS leak test was initiated and, at 1244 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.73342e-4 months <br />, RCS leakage was verified and. determined to be 2.37 gpm.-

At 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br />;the pressurizer liquid sample line isolation valves, which are normally opened during day shift operations for sampling, were.promptly closed.-

A second RCS leak test was performed and, at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the RCS leak ~

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rate was-determined to'be essentially zero. No further increase in CCW surge tank level or CCW radiation monitor readings occurred follow-ing the closure of the sample line isolation valves. The leak path i

was subsequently identified as being'from the pressurizer liquid space throup the sample line into the sample cooler and into the CCW System via a leaking tube bundle in the cooler. The leakage experienced was in excess of the limits allowed by Technical Specification Section 3.1.5.2 and is reportable in accordance with Technical Specification-6.9.2.b(2).

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The cause of the event was the sampic cooler tube bundle. leakage. The tube bundle leakage is attributed to normal wear.

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- Since the RCS leakage ^was totally contained within the CCW System,_

which is a closed radioactive system, there.was no threat to either.

the plant or to the public health or safety.

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Corrective Action

The sample line isolation valves were closed ~to eliminate further leakage as immediate corrective action.

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Corrective Action to Prevent Further Occurrence The sample cooler tube bundle was removed and replaced. A review of' maintenance records on this~and other similar sample coolers was performed to' determine if any generic. problems could.be identified which would indicate a need for further corrective' action..This i

review revealed that all sample coolers.have operated'in a reliable manner and no generic problems were identified Specifically,'since the beginning of operation, only three cooler tube bundle _ftilures have occurred for six sample coolers (i.e.,:three separate failures in approximately 60 tube bundle years of operation) and ru) cooler l-tube bundles have failed more than once.

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Therefore, the sample cooler operation is' considered to be sufficiently-j reliable'and no further corrective action is deemed necessary, i

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