ML19331C777

LER 80-015/04T-0:on 800721,while Units Were in Cold Shutdown Condition,Actual River Water Temp Exceeded Tech Spec Limits for 6-h.Caused by Inaccurate Compensation for Resistance Temp Detector Lead Resistance During Calibr

ML19331C777
Person / Time
Site:	Three Mile Island
Issue date:	08/14/1980
From:	Mitchell D METROPOLITAN EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19331C772	List: ML19331C771 ML19331C777
References
LER-80-015-04T, LER-80-15-4T, TLL-375, NUDOCS 8008190518
Download: ML19331C777 (2)

Text

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Attachment 2 TLL 376 LICE.3EE EVENT REPORT NARRATIVE REPORT IMI-1 LER 80-015/04T-0 EVENT DATE - JULY 21, 1980 EVENT DESCRIPTION AND CONSE0CENCES This event occurred while both units were in a cold shutdown condition with a minimal need for River Water cooling. Meteorological conditions were such that the ambient river water temperature exceeded 870F which requires additional cooling of discharge River Water (RW) by the Mechanical Uraft Cooling Towers (MDCT). The RWAT was being maintained at about -20F. A discrepancy between IMI-l and TMI-2 indicated RWAT revealed that the TMI-l recorder was indicating 20F higher than the actual RNAT. During approyi=ately0 a.6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> period the RWaT exceeded the -30F limit, reaching a maximum of -5 F, thus the water discharged to the river was actually 320F. This incident did not have any detricental effect on the environment.

EVENT CAUSE AND CORRECTIVE ACTION The cause of the occurrence was inaccurate compensation for the Resistance Temperature Detector (RTD) lead resistance. The RTD are used to monitor river water temperature. The operation of the MDCT was adjested to return the RWAT to within the Technical Specification limits. The RWaI instrumentation was recalibrated by inserting test resistances at the detector end of the leads in lieu of at the cabinet. A revised report will be issued stating the final cause and corrective action by August 15. 1930.

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