ML20212B908

Special Rept:On 990901, 12 Containment Hydrogen Monitoring Sys Was Declared Inoperable for Planned Maint.Caused by Planned Maint Being Performed as Corrective Action.Check Valves with O Rings Were Replaced

ML20212B908
Person / Time
Site:	Nine Mile Point
Issue date:	09/14/1999
From:	Rich Smith NIAGARA MOHAWK POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NMP1L-1466, NUDOCS 9909210053
Download: ML20212B908 (2)

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• A NiagarahMohawk' September 14,1999 NMPIL 1466 U. S. Nuclear Regulatory Commission Attn: Document Control Desk )

Washington, DC 20555 /

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RE: Nine Mile Point Unit 1 Docket No. 50-220 DPR-63

Subject:

Special Report Gentlemen:

In accordance with Nine Mile Point Unit 1 Technical Specification Table 3.6.11-1, " Accident Monitoring Instrumentation," and associated Action Statement 4.a, Niagara Mohawk Power ,

Corporation is submitting the following special report concerning the inoperability of the #12 i Containment Hydrogen Monitoring System.

Description of Event l l l l On September 1,1999, at 0917 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.489185e-4 months <br />, with the reactor mode switch in the "RUN" position during normal operations, control room operators declared #12 Containment Hydrogen Monitoring System inoperable for planned maintenance. This planned maintenance replaced two check valves in the #12 Containment Hydrogen Monitoring System. As described in Special Reports dated July 29,1999 (NMPIL 1452) and February 8,1999 (NMPIL 1400),

corrective actions included replacing all check valves having "O" rings with an installed life ,

greater than eight years. After replacing the check valves, the #12 Containment Hydrogen l Monitoring System was satisfactorily tested and returned to service on September 4,1999 at 1620 hours0.0188 days <br />0.45 hours <br />0.00268 weeks <br />6.1641e-4 months <br />.

Cauw of Event f%

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The #12 Containment Hydrogen Monitoring System was inoperable for planned maintenance.

This planned maintenance was being performed as corrective action for Special Reports dated July 29,1999 (NMPIL 1452) and February 8,1999 (NMPIL 1400).

9909210053 990914 PDR ADOCK 05000220 g PDR I

Nine Mile Point Nuclear Station, RC. Box 63, Lycoming. New York 13093 0063

• 315.343.2110

• www...;mo.com L-

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i.,j Page 2 Corrective Acilanc

'All check valves with "O" rings with an installed life greater than eight years have been replaced and the preventive maintenance database has been changed to ensure that the valves are replaced every eight years, 1

Very truly yours,  !

Robert G. Smith

' Plant Manager .NMP1 RGS/CES/jb xc: Mr. H. J. Miller, Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector Records Management 1

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