ML20246H538
| ML20246H538 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/25/1989 |
| From: | Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| MP-13448, NUDOCS 8909010285 | |
| Download: ML20246H538 (2) | |
Text
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g NORTHEAST UTILETIES o.nor.i Ome... s ia.n sir..t. Bornn. Connecticut cs7 Es7 aim'cc5= '
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August 25, 1989 MP-13448 Docket No. 50-423 Re:
10CFR50.36 U.S. Nuclear Regulatory Commission Attn: Document Contrcl Desk Washington, DC 20555 Gentlemen:
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l MillstoneNuclearPowerStation,UnitNed3 Malfunctioning Loose Parts Monitor Channels l
This Special Report is being submitted within 10 days 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 if one or more channels of the " Loose Part Detection System" are inoperable for more than 30 days.
At 0730 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 to be inoperable because they were alarming continuously. Analysis of information recorded by the LPM verified that loose parts did not exist. Further investigation revealed that the alarms l
were caused by malfunctions in LPM equipment located inside the containment building.
Loose part impacts in the Reactor Coolant System (RCS) are detected by l.
accelerometers attached to major RCS components. An impact generates an electrical signal from one or more accelerometers, which triggers the Loose l
Parts Monitor to record information from all channels on a computer disk, 3
and actuate an alarm on the main control board.
The two malfunctioning channels have redundant channels which are operating normally. The malfunctions do not affect other channels. The malfunctioning channels have been turned off, so that valid loose part 3
impact alarms will not be masked.
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- The problems with both channels have been localized to within the containment building and require corrective work in high radiation areas.
For this reason, corrective actions are scheduled for the next reactor Cold Shutdown period.
The LPM was designed and built by Northeast Utilities Service Company.
Connecticut Yankee uses a system based on the same design, but with fewer channels. This design is not used at any other U.S. plant.
The licensee contact for this special report is Robert Conway, who may be contacted at (203) 444-5642.
l Very Truly Yours, NORTHEAST NUCLEAR ENERGY COMPANY I
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Stephen E. Scace Station Superintendent Millstone Nuclear Power Station SES/RDC:lfg cc: W. T. Russell, Region I, Administration D. H. Jaffe, NRC Project Manager, Millstone Unit No. 3 W. J. Raymond, Senior Resident Inspector, Millstone Unit Nos.
1, 2, and 3 I
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