ML20077A425
| 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) | |
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Northeast Nuclear Energy Company P.O. Box 128 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 t
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