ML20077A425

Special Rept:On 941024,LPMS Declared Inoperable Due to Failure of Lpms Channel 8.Cause of Lpms Channel 8 Failure Isolated to in-containment Cabling/Accelerometer.Cable & Accelerometer Replacement Planned for Next Refueling Outage

ML20077A425
Person / Time
Site:	Millstone
Issue date:	11/15/1994
From:	Miller D NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
MP-94-635, NUDOCS 9411230167
Download: ML20077A425 (1)

Text

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t Nordierist nope Ferry ad. (aoute 156), waterford, cr 06385 Niicletir Eiieray-e Ministone Nuclear Power Station Northeast Nuclear Energy Company ,

P.O. Box 128

1. . waterford, Cr 06385-0128 (203)447 - 1791 Fax (203) 444-4277 The Northeast Utilities System Docket No. 50-423 RE: 10CFR50.36 ,

November 15, 1994 U.S. Nuclear Regulatory Commission MP-94-635 Attention: Document Control Desk Washington, D.C. 20555 .

Millstone Nuclear Power Station, Unit No. 3 Loose-Part Detection System Channel Failure 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 to the NRC 10 days following one or more channels of the Loose-Part Detection System being declared inoperable for more than 30 days while in Mode 1 (Power Operation) or Mode 2 (Startup), outlining the cause of the malfunction and the plans for restoring the channel (s) to operable status.

On October 24,1994, at 0806, with the plant in Mode 1 (Power Operation) at 100%

power,2250 asia, and 587 degrees Fahrenheit, the Loose Parts Monitoring System (LPM) was c eclared inoperable. Channel 8, Steam Generator D Lower, failed.

Subsequent troubleshooting and corrective action has been unable to restore channel 8. The remaining 11 channels, including the redundant Steam Generator l D channel, era restored, fully functional and capable of detecting a loose part.

Loose pMs impacts in the Reactor Coolant System (RCS) are detected by accetr romnters attached to major RCS components. An impact generates a signal from t.,,., or more accelerometers and triggers a High Alarm annunciator on the Main Control board. The High Alarm signal causes information to be recorded from 12 channels onto a computer disk.

The cause of the LPM channel 8 failure has been isolated to the in-containment cabling / accelerometer. Cable and accelerometer replacement is planned for the next refueling outage (currently scheduled for Spring 1995). ,

The Ucensee contact for this Special Report is Michael Watson, who may be contacted at (203) 447-1791 (x6578).

Very truly yours, c 9 g ., "c p' NORTHEAST NUQgAR EN Y f0MPANY

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Donald B. Miller, Jr.

Senior Vice President - Millstone Station cc: T. T. Martin, Region I Administrator ,

P. D. Swetland, Senior Resident inspector, Millstone Unit Nos.1, 2, and 3 V. L. Rooney, NRC Project Manager, Millstone Unit No. 3 941123o167 941115 PDR ADOCK 05o00423 "

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