ML022130357

Special Report for Nine Mile Point Unit 2 Re Noble Gas Activity Monitoring Instrumentation Inoperable for Greater than 72 Hours

ML022130357
Person / Time
Site:	Nine Mile Point
Issue date:	07/23/2002
From:	Peckham M Constellation Generation Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP2L 2068
Download: ML022130357 (3)

Text

P.O. Box 63 Lycoming, New York 13093 O Clew~

Nine Mile Pbint Nudear Station July 23, 2002 NMP2L 2068 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 RE: Nine Mile Point Unit 2 Docket No. 50-410 NPF-69

Subject:

Special Report, Noble Gas Activity Monitoring Instrumentation Inoperablefor Greater Than 72 Hours Gentlemen:

In accordance with the Nine Mile Point Unit 2 (NMP2) Off-Site Dose Calculation Manual (ODCM), Table D 3.3.2-1, Radioactive Gaseous Effluent Monitoring Instrumentation, items 2.a and 3.a, and section D 3.3.2, Required Action F.2.2, Nine Mile Point Nuclear Station, LLC (NMPNS) is submitting the following Special Report concerning the inoperability of the Gaseous Effluent Monitoring System (GEMS).

ODCM Section D 3.3.2, Required Action F.2.2 requires a special report within 14 days if an inoperable Main Stack Effluent Noble Gas Activity Monitor or an inoperable Radwaste/Reactor Building Vent Effluent Noble Gas Activity Monitor is not restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This Special Report describes two recent events in which both of the aforementioned monitors became inoperable, and have remained inoperable, for longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Description of the events At 1049 hours0.0121 days <br />0.291 hours <br />0.00173 weeks <br />3.991445e-4 months <br /> on July 9, 2002, the Main Stack Effluent Noble Gas Activity Monitor was declared inoperable due to a failed "source check" surveillance. NMPNS's troubleshooting determined that the POLE/ZERO, the electronic reference point for determining the spectral energies, had shifted slightly. Also, a thermal cycle of the noble gas detector was required for proper identification of the isotopic peaks. The POLE/ZERO has been reset, and a thermal cycle has been performed on the noble gas detector.

At 0425 hours0.00492 days <br />0.118 hours <br />7.027116e-4 weeks <br />1.617125e-4 months <br /> on July 12, 2002, the GEMS computer failed, and has remained inoperable. The computer failure has prevented performance of post maintenance testing on the Main Stack Noble Gas Monitoring System, and in addition has caused the

Page 2 NMP2L 2068 Radwaste/Reactor Building Vent Effluent Noble Gas Activity Monitor to be declared inoperable. Initial repairs to the computer have been unsuccessful and, therefore, computer replacement parts are being pursued. Alternatively, NMPNS is searching for a qualified vendor to refurbish the existing computer cards.

At this time, both the Main Stack Noble Gas Monitoring System and the Radwaste/Reactor Building Vent Noble Gas Activity Monitor remain inoperable.

Cause of the events The likely cause of the Main Stack Noble Gas Monitoring System failures is degradation and subsequent failure of the gamma spectroscopy equipment as the result of a lightning strike on June 27, 2002, which was described in a Special Report dated July 10, 2002.

The system was tested and returned to service on July 3, 2002, and no additional transients have occurred which could be suspected to have caused these failures.

The likely cause of the GEMS computer failure can be attributed to a temporary loss of ventilation to the GEMS computer room. The loss of ventilation caused a significant increase in the ambient room temperature, which led to higher temperatures inside the computer, and ultimately to failure of its internal components.

Corrective Actions The following corrective actions have been or are being taken:

1. The GEMS computer room ventilation has been restored.

2. Replacement/refurbishment of the failed computer cards is being pursued.

3. Replacement of GEMS is being evaluated.

No schedule has yet been established for returning GEMS to operable status.

Compensatory actions specified in Section D 3.3.2, Required Action F of the ODCM remain in effect.

Ve y yours, Michael F. Peckham Unit 2 Plant General Manager MFP/IAA/jm

Page 3 NMP2L 2068 cc: Mr. H. J. Miller, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector Records Management