ML041810515

Revised Special Report for Nine Mile Point, Unit 1 Re Channel #12 of the Containment Hydrogen Monitoring System Inoperable

ML041810515
Person / Time
Site:	Nine Mile Point
Issue date:	06/18/2004
From:	Hopkins L Constellation Energy Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP1L 1842
Download: ML041810515 (2)

Text

Constellation Energy- RO. Box 63 Nine Mile Point Nuclear Station Lycoming, New York 13093 June 18,2004 NMP1L 1842 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Nine Mile Point Unit 1

_. _ __-DocketiNo.-50-220 License No. DPR-63 Revised Special Report, "Channel #12 of the Containment Hydrogen Monitoring System Inoperable" Gentlemen:

By letter dated May 4, 2004 (NMP1L 1833), Nine Mile Point Nuclear Station, LLC (NMPNS),

submitted a special report required by Action 4.a of Nine Mile Point Unit 1 Technical Specification Table 3.6.11-2. In that submittal, NMPNS committed to revise the special report when the cause of the event wasdetermined. .  ;

The revised special report is'attached. Changes to the previously submitted report are marked with revision bars.

Very truly yours, Lawrence A. Hopkins Plant General Manager LAH/RF/bjh Attachment cc: Mr. H. J. Miller, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector

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Attachment

.Revised Special Report "Channel #12 of the Containment Hydrogen Monitoring System Inoperable" Descrptionof Event On April 21, 2004, at approximately 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> Channel #12 of the Containment Hydrogen

- Monitoring (CHM) System became.inoperable due.to intermittentindications of elevated ___-

hydrogen concentrations in the torus.

The redundant Channel #11 of the CHM System was verified to be in service prior to removing Channel #12 from service.

Cause of Event Channel #12 of the CHM System was declared inoperable due to indications of irregular changes in hydrogen concentrations. Settings of the thermoelectric cooler of Channel #12 of the CHM System were found to be improper, which resulted in less cooling provided to the sample stream and moisture intrusion into the system's detector.

On February 16, 2004, preventive maintenance was performed on Channel #12 of the CHM System. The Preventive Maintenance Procedure contained multiple actions in one step, which resulted in a human performance error. Specifically, the thermoelectric cooler settings were not reset to their proper operating values.

CorrectiveActions The inoperability of CHM System Channel #12 has been resolved through the Corrective Action Program. The thermoelectric cooler settings were reset properly and the moisture was removed from Channel #12 of the CHM System. Subsequently, Channel #12 of the CHM System was operated for approximately 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> and after confirming stable operation, declared operable on May 10, 2004 at 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br />.

The Preventive Maintenance Procedure involved was revised to enhance barriers to prevent potential human performance errors.

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