ML20082K528

Special Rept:On 950316,loose Part Monitoring Sys (Lpm) Channel 5,SG a Lower Failed.Cause of Lpm Channel 5 Failure Isolated to in-containment Cabling/Accelerometer.Cable & Accelerometer Replacement Planned for Next Refueling Outage

ML20082K528
Person / Time
Site:	Millstone
Issue date:	04/11/1995
From:	Miller D NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
MP-95-118, NUDOCS 9504190328
Download: ML20082K528 (2)

Text

,p .

• h Northeast nope Ferry ad. (Route 156), Waterford, cT 06385 Nuclear Energy Millstone Nuclear Power Station g' Northeast Nuclear Energy Company 9

• P.O. Box 128 Waterford, CT 06385-0128 (203) 447 - 1791 Fax (203) 444-4277 The Northeast Utilities System April 11, 1995 MP-95-118 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Millstone Nuclear Power Station, Unit No. 3 Loose-Part Detection System Channel Fallure 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 0 3eration) or Mode 2 (Startup), outlining the cause of the malfunction and the plans "or restoring the channel (s) to operable status.

On March 16,1995, at 1305, with the plant in Mode 1 (Power Operation) at 100% power, 2250 psia, and 586 degrees Fahrenheit, the Loose Parts Monitoring System (LPM) was declared inoperable. Channel 5, Steam Generator A Lower, failed. Subsequent troubleshooting and corrective action has been unable to restore channel 5. Channel 8, Steam Generator D Lower, had previously failed on October 24,1994, and was reported by Special Report dated November 15,1994. The remaining 10 channels, including the redundant Steam Generator D channel and the redundant Steam Generator A channel, are restored, fully functional and capable of detecting a loose part.

Loose parts impacts in the Reactor Coolant System (RCS) are detected by accelerometers attached to major RCS components. An impact generates a signal from one 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 5 failure has been isolated to the in-containment cabling / accelerometer. Cable and accelerometer replacement is planned for the next refueling outage (currently scheduled to commence April 14,1995).

This Special Report is conservatively submitted in advance of any Technical Specification requirement. Channel 5 is not expected to be Inoperable for more than the 30-day Technical Specification for Mode 1 or Mode 2, because the refueling outage will commence before 30 days elapse. Although the subsequent 10-day ,

Special Report is not required, it is submitted in advance for information purposes. )

I i

.f b 7 gn"EPc0 SkP p' i

04/11/95, MP-95-118

\

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

Very truly yours, NORTHEAST NUCLEAR ENER Y O ANY onald B. iller, Jr.

Senior Vice President - Millstone Station DBM:IJs cc: T. T. Martin, Region i Administrator R D. Swetland, Senior Resident inspector, Millstone Unit Nos.1,2, and 3 V. L. Rooney, NRC Project Manager, Millstone Unit No. 3 ,

l 1

l l

l l-l

,