ML20216J925
| ML20216J925 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/30/1999 |
| From: | Conway J NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NMP1L-1474, NUDOCS 9910060345 | |
| Download: ML20216J925 (2) | |
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' Jolut T. Conway Phone: 315.349.4213 Vics President Fax: 315.349.2605 Nuclear Generation September 30, 1999 NMPIL 1474 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 RE:
Nine Mile Point Unit 1 Docket No. 50-220 DPR-63
Subject:
Supplement to the Special Report, dated July 2,1999 Gentlemen:
In accordance with Nine Mile Point Unit 1 Technical Specification Table 3.6.11-1, " Accident Monitoring Instrumentation," Action Statement 4.a., Niagara Mohawk Power Corporation submitted Special Reports dated July'2,1999, concerning the inoperability of the #11 Containment Hydrogen Monitoring System. At the time of that report, the cause of the chart recorders indicating below normal operating range had not been determined. This supplement report describes that cause, and additional corrective actions to make the pumps less
- susceptible to excessive wear.
Descm(ption af Event
- On June 21,1999, at 0441 hours0.0051 days <br />0.123 hours <br />7.291667e-4 weeks <br />1.678005e-4 months <br />, with the reactor mode switch in the "RUN" position during
- normal operations, Nine Mile Point Unit 1 operators identified that the #11 Containment Hydrogen Monitoring System chart recorder was indicating below normal operating range.
Operators investigated and found that the sample pump appeared to be operating improperly and at 0506 hours0.00586 days <br />0.141 hours <br />8.366402e-4 weeks <br />1.92533e-4 months <br /> on June 21,1999, declared the #11 Containment Hydrogen Monitoring System inoperable.
\\,0 r-~ of Event l
l The downscale chart recorder indication was an actual low flow condition. The cause of the i
bypass pump's inability to maintain adequate flow was a result of excessive wear on the valve L
dody and discs of the bypass pump.
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8-Nine Mile Point Nuclear Station RO. Box 63, Lycoming, New York 13093-0063 +
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. Page 2 e-Carredive Artinns 1.
- The sample pump was replaced and the bypass pump was rebuilt. The #11 Containment Hydrogen Monitoring System was declared operable on July 14, 1999.
2.
' Subsequent investigation into long-standing concerns with the Containment Hydrogen Monitoring System revealed that redesigned pump parts will make the pumps less susceptible to wear. ; Sample and bypass pumps for the #12 Containment Hydrogen Monitoring System were rebuilt using redesigned parts.
3.;
Work Order 99-04831 has been written to perform identical maintenance on #11 Containment Hydrogen Monitoring System. This maintenance is scheduled to start on October 10,1999.
Very truly yours, T
John T. Conway Vice President Nuclear Generation JTC/CES/jb
- xc:
Mr. H. J. Miller, Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector Records Management}