ML20042A683

LER 82-006/03L-0:on 820207,power Range Nuclear Instrumentation Channel N 43 Indicated High & Then Became Erratic.Cause Not Given.Channel Returned to Normal During Operation.Instrumentation to Be Closely Monitored

ML20042A683
Person / Time
Site:	Indian Point
Issue date:	03/09/1982
From:	Mooney J CONSOLIDATED EDISON CO. OF NEW YORK, INC.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20042A678	List: ML20042A677 ML20042A683
References
LER-82-006-03L, LER-82-6-3L, NUDOCS 8203230679
Download: ML20042A683 (3)

Text

U.S. NUCLEAR REGULATORY COMMISSION NRC FORM 166*

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ATTACHMENT I Docket No. 05000247 Consolidated Edison Co. of N. Y., Inc.

LER # 82-006-03L-0 Indian Point Station, Unit 2 NI CH43 Failures - Sequence Of Events Saturday, February 6, 1982 Plant at hot shutdown CH 43 indicated high. While no specific cause of the event was found, evidence indicated a possible problem with isolation amplifier NM 306 (output to OTDT protection system) .

This isolation amplifier was replaced with spare. Type N200-3 isolation amplifier manufactured by HYBRID SYSTEMS CORP.

Sunday, February 7, 1982 During normal start up at approximately 2% power CH 43 indicated high and then became erratic. While trouble shooting, the problem cleared up.

Monday, February 8, 1982 Plant at 100% Power, CH 43 indicated down scale - Nuclear.Instru-ment (NI) procedures were implemented and power was reduced to less than 70%. Problem was determined to be high voltage power, but specific cause could not be determined. Both H.V. power supply and cable / detector were separated and tested satisfactory. When restored to normal, channel was functioning properly. High voltage power supply replaced with spare manufactured by Power Designs Inc. Model (UPMD X 54W High Voltage Regulated DC Source

+ 300 to 1500 VDC 0-15MA)

A containment entry was made for a general inspection in the vicinity of the detector. No unusual conditions were observed.

Tuesday, February 9, 1982 Plant at 100% Power, CH 43 indicated up scale for a short duration then returned to normal. N.I. procedures implemented and power reduced to less than 70t; exact cause of failure could not be determined. Decision made to replace entire Drawer B Assembly.

Thursday, February 11, 1982 Plant at 100% Power CH 43 operation normal since 2/9/82. Replaced Drawer B Assembly. - DRG # 6051D53601 Date of Manufacturer 9/68 Contract NY 77207ARKN - Westinghouse Electric Corp. Nuclear Instrumentation and Control Department. Calibrated Drawer assemblies and returned channel to normal service.

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Friday, February 19, 1982 Plant at 100% Power, CH 43 indicated a brief down scale spike. N.I.

procedures were implemented and power reduced. Channel problem was short in duration and exact cause'could not be determined. A test recorder was added'to monitor the H.V. power in order to detect any fluctuations of H.V. power.

Monday, February 22, 1982 Plant at 100% Power, during Surveilance tests, Technicians observed high voltage fluctuations when high voltage cable was moved. Re-working the high voltage Anphenol triaxial connector eliminated the fluctuations.

Thursday, March 4, 1982 Plant at 100% power - CH 43 experienced a momentary perturbation and immediately returned to normal operation.

The instrument continues to be closely monitored to assure proper operation.

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