ML022050059
| ML022050059 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 07/10/2002 |
| From: | Conway J Constellation Generation Group |
| To: | Document Control Desk, Office of Nuclear Security and Incident Response |
| References | |
| NMP2L 2066 | |
| Download: ML022050059 (2) | |
Text
P.O. Box 63 Lycoming, New York 13093 Constellation Generation Group Nine Mile Point Nuclear Station July 10, 2002 NMP2L 2066 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 Inoperable for 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. 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 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 />. In the event described below, the Main Stack Effluent Noble Gas Activity Monitor and the Radwaste/Reactor Building Vent Noble Gas Activity Monitor were inoperable from 1416 hours0.0164 days <br />0.393 hours <br />0.00234 weeks <br />5.38788e-4 months <br /> on June 27, 2002 until 1607 hours0.0186 days <br />0.446 hours <br />0.00266 weeks <br />6.114635e-4 months <br /> on July 3, 2002 (approximately 146 hours0.00169 days <br />0.0406 hours <br />2.414021e-4 weeks <br />5.5553e-5 months <br />).
Description of Event On June 27, 2002, at 1416 hours0.0164 days <br />0.393 hours <br />0.00234 weeks <br />5.38788e-4 months <br />, both the Main Stack Noble Gas Activity Monitor and the Radwaste/Reactor Building Vent Noble Gas Activity Monitor were declared inoperable due to damage caused by a lightning strike to the Main Stack structure.
NMPNS's troubleshooting identified that the communications systems in the Main Stack Noble Gas Monitoring System and the Radwaste/Reactor Building Noble Gas Monitoring System had been damaged following the lightning strike. In addition, the programmable logic controller associated with the Main Stack Noble Gas Monitoring System had been damaged. Following troubleshooting, the damaged components in both systems were replaced and the systems tested satisfactorily. The Radwaste/Reactor Building Vent Noble Gas Activity Monitor and the Main Stack Noble Gas Activity Monitor were returned to operable status on July 3, 2002, at 1607 hours0.0186 days <br />0.446 hours <br />0.00266 weeks <br />6.114635e-4 months <br />. During the period of
Page 2 NMP2L 2066 inoperability, compensatory actions stated in ODCM Section D 3.3.2, Required Action F continued to be implemented as required.
Cause of the Event The cause of this event can be directly attributed to a lightning strike on the Main Stack structure. The resulting electrical transient caused damage to several components rendering the above described systems inoperable. These systems have had a prior history of lightning induced failures. Grounding/lightning protection modifications implemented after the earlier failures have proved to be generally effective in maintaining system operability. The event described in this report is considered to be an isolated instance due to the severity of the storm.
Corrective Actions The following corrective actions were taken with respect to the Main Stack Noble Gas Monitoring System and the Radwaste/Reactor Building Vent Noble Gas Monitoring System:
- 1. The damaged communications and control devices were replaced.
- 2. Other electronic devices were thoroughly inspected and tested to verify the absence of any additional damage.
- 3. Channel check surveillances were performed on both Monitors and the Monitors restored to operable status.
Very truly yours, r h T.Conway Site Vice President JTC/IAA/jm cc:
Mr. H. J. Miller, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector Mr. P.S. Tam, Senior Project Manager, NRR (2 copies)
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