ML030860479
| ML030860479 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/13/2003 |
| From: | Hopkins L Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NMP1L 1721 | |
| Download: ML030860479 (2) | |
Text
P.O. Box 63 Lycoming, New York 13093 Constellation Energy Group Nine Mile Point March 13, 2003 Nuclear Station NMP1L 1721 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Nine Mile Point Unit 1
-Docket No. 50-220 License No. DPR-63 Special Report, Channel #11 and Channel #12 Containment Hydrogen Monitoring System Inoperable Due to Exceeding Environmental Qualification Limits Gentlemen:
In accordance with Action Statements 4a and 4b of Nine Mile Point Unit 1 Technical Specification Table 3.6.11-2, Accident Monitoring Instrumentation Action Statements, Nine Mile Point Nuclear Station, LLC (NMPNS) is submitting the following Special Report concerning the inoperability of Channel #11 and Channel #12 of the Containment Hydrogen Monitoring System.
Description of Event On February 27, 2003, at 1234 hours0.0143 days <br />0.343 hours <br />0.00204 weeks <br />4.69537e-4 months <br />, Channel #11 and Channel #12 of the Containment Hydrogen Monitoring System were declared inoperable when NMPNS determined that twenty-two solenoid operated valves (SOV), eleven in each channel, had exceeded their qualified life for electro-mechanical cycling and that both channels of the Containment Hydrogen Monitoring System were not considered qualified to perform their required post accident functions. In accordance with Technical Specifications, alternate sampling was initiated.
The affected solenoid valves for Channel #12 of the Containment Hydrogen Monitoring System were replaced and post maintenance testing is in progress. Channel #12 is expected to return to service by March 14, 2003. Because of the need to obtain additional SOVs, the return of Channel #11 of the Containment Hydrogen Monitoring System will be delayed. Current plans are to restore Channel #11 by April 30, 2003.
Page 2 NMP1L 1721 Cause of Event Channel #11 and Channel #12 of the Containment Hydrogen Monitoring System were considered inoperable when NMPNS identified that certain SOVs in both channels were being operated beyond their qualification limits for electromechanical cycling. The affected valves are ASCO SOVs, model NP8320. This model of SOV has been qualified by ASCO to a limit of 20,000 cycles.
The Containment Hydrogen Monitoring System was qualified by Teledyne Analytical Instruments and placed into service in 1995. The SOVs in question cycle periodically to change the sampling location. The most limiting cycle frequency is approximately once per 15 minutes, which results in approximately 35,000 cycles per year. The cycling limits of the SOVs were exceeded because:
- The supplier failed to recognize the impact of NMPNS' intended methods for operation of the system on the design of the Containment Hydrogen Monitoring System assembly. This resulted in the qualification documentation failing to reconcile the SOV cycles due to the sample sequencing frequency with the qualification limits of the ASCO SOVs.
- The NMPNS review failed to identify and reconcile this omission.
Corrective Actions
- 1. The affected solenoid valves in Channel #12 were replaced and Channel #12 will be returned to service after completion of post maintenance testing, which is planned to be completed by March 14,2003.
- 2. The affected solenoid valves in Channel #11 will be replaced after receipt of parts.
Completion date for this activity is April 30, 2003.
- 3. The SOV preventive maintenance schedule will be revised by April 25, 2003, to reflect the qualified cycling limit.
- 4. Environmental qualification documentation for the SOVs will be reconciled through the corrective action program via Deficiency Event Report NM-2003-739.
Very truly yours, Lawrence A.
opkins Plant General Manager LAH/KLE/jm cc:
Mr. H. J. Miller, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector