ML20055D024

Special Rept:On 890716,2 of 12 Loose Parts Monitor Channels Declared Inoperable When Alarms Received Due to Malfunction of Equipment in Containment Bldg.On 900519,loose Parts Channel Alarmed Continuously.Channels Turned Off

ML20055D024
Person / Time
Site:	Millstone
Issue date:	06/22/1990
From:	Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
MP-90-614, NUDOCS 9007030104
Download: ML20055D024 (2)

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N t#TILITIES: a.nor.i Oriic . . s.io.n si,..t. a rnn. conn.ciicui EiIrUb v't:INeo* P.O. BOX 270 HARTFORD. CONNECTICUT 06141-0270 k k J [.,((m m,'n,[e ew[one.L (203) 665-5000 June 22, 1990 MP-90-614 Docket No. 50-423 Re: 10CTR50.36 U.S. Nuclear Regulatory Comdssion Attn: Document Control Desk' Washington, DC' 20555

References:

(1) Special Report, Stephen E. .Scace Letter (MP-13448) to U.S. Nuclear Regulatory Commission, Millstone Nuclear Power Station, Unit No. 3, Malfunctioning Loose Parts Monitor Channels, dated August 25, 1989 (2) Special Report, Stephen E. Scace/ Carl H. Clement Letter (MP-13906) to U.S. Nuclear Regulatory Comission, Millstone Nuclear Power Station, Unit No. 3, Malfunctioning Loose Parts Monitor Channels, dated January 2, 1990 Gentlemen:

11111 stone Nuclear Power Station, Unit No. 3 Malfunctionina Loose Parts Monitor Channel This.Special Report is being submitted pursuant to Millstone Unit 3

. Technical Specification 3.3.3'.8.a: Loose Part Detection System. Plant Technical Specification 3.3.3.8.a requires a Special Report be submitted to

,. the NRC 10 days following one or mere channels of the Loose Part Detection System inoperable for more than 30 days. This Special Report also supplements the August- 25, 1989 and January 2, 1990 Special Reports on e Malfunctioning Loose Parts Monitor Channels (referenced above) .

On July 16,.1989 with the plant in Mode 1, at 48% power, 2250 psia, and 586 degrees Fahrenheit, two of twelve Loose Parts Monitor (LPM) . channels were ,

declared inoperable. Data analysis verified that loose part impacts were not occurring. Further investigation revealed that the alarms were caused by malfunctions in' LPM equipment located inside the containment building.

For this reason, corrective actions were scheduled for the next reactor Cold Shutdown period.

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Millstone Unit ~3 was in Cold Shutdown from November 29, 1989 to

- December 5,1989 to replace the "C Pressurizer Code Safety Valve, as reported by Licensee Event Report 89-031-00. -During this time, the malfunctioning LPM channels were investigated further and exact locations of failed components were identified. Replacement of the components would have required extending the outage by several days to remove and reinstall

. mirror insulation on the reactor head and the affected steam generator, but would not-have increased plant safety since redundant LPM channels

-monitoring these locations were operating satisfactorily. For these reascas, the component replacement was scheduled for the next refueling outage.

Millstone Unit 3 was shutdown from May 10, 1990 to May 20, 1990 to perform improvements to the intake structure. On May 16, 1990 the malfunctioning channels were repaired and returned to service, On May 19, 1990 with the plant in Mode 3 (Hot Standby), 0% power, 585 degrees' Fahrenheit, and 2250 psia, one LPM channel was placed out of service was alarming continually but data analysis data showed there were no associated impact events. This channel is not one of the two which w:re returned to service on May 16, 1990. The malfunctioning channel has a redundant channel which is operating normally. Other channels are not affected. To prevent valid loose part impact alarms from being masked, the malfunctioning. channel has been turned off. This channel will be repaired during the next refueling outage.

The licensee contact for this special report is Robert Conway,-who may be contacted at (203) 444-5442.

Very Truly Yours, NORTHEAST NUCLEAR ENERGY COMPANY a *1 W Stephen E. cace irector, Millstone Station

-SES/RDC:bjo cc: T. T. Martin, Region I, Administrator W. J. Kaymond, Senior Resident Inspector, Millstone Unit Nos. 1, 2, and 3 D. H. Jaffe, NRC Project Manager, Millstone Unit No. 3 l

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