ENS 45460
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ENS Event | |
|---|---|
20:34 Oct 23, 2009 | |
| Title | Plant Shutdown Due to Excess Letdown Heat Exchanger Tube Leak and After-The-Fact Unusual Event |
| Event Description | On 10/23/09 at 1633, North Anna Unit 1 was placing Excess Letdown in service per 1-OP-8.5 due to a small unquantifiable throughwall leak on 1-CH-TV-1204B. At 1634 [the licensee] entered action of TS 3.4.13 due to what appears to be an Excess Letdown Heat Exchanger tube leak. The Component Cooling Water Head Tank [level] increased from 59% to 79% and the VCT [Volume Control Tank] level dropped 20 % indicating approximately 260 gallons of RCS had flowed into the Component Cooling Water System. At 1638 Excess Letdown was removed from service and the leak was terminated. At 1718 [the licensee] commenced ramping Unit 1 from service [TS Required Shutdown] to comply with TS 3.6.1, 'Containment Integrity' due to the throughwall leak on 1-CH-TV-1204B.
The licensee has placed the normal letdown system back in service while the plant is being shut down. The throughwall leak on 1-CH-TV-1204B is relatively small and unquantifiable compare to the tube leak on the excess letdown heat exchanger. The licensee plans to proceed to Mode 5 to repair both the Letdown valve and the Excess Letdown Heat Exchanger tube leak. The licensee will notify the NRC Resident Inspector.
The licensee determined that it exceeded EAL SU6.1, Unidentified or Pressure Boundary Leakage greater than 10 gpm, for 4 minutes but currently does not meet the EAL Criteria. This requires the licensee to make a 1-hour notification that it has classified the event after-the-fact as an unusual event but did not actually declare the unusual event . The licensee will notify the NRC Resident Inspector and has notified the Virginia Department of Emergency Management. |
| Where | |
|---|---|
North Anna  Virginia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+-3 h-0.125 days <br />-0.0179 weeks <br />-0.00411 months <br />) | |
| Opened: | Robert Counts 17:34 Oct 23, 2009 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Oct 23, 2009 |
| 45460 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 546522020-04-09T05:00:0009 April 2020 05:00:00
[Table view]10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Reactor Coolant System Pressure Boundary Leakage ENS 521372016-07-30T15:52:00030 July 2016 15:52:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Technical Specification Required Shutdown Due to Unisolable Reactor Coolant System Boundary Leakage ENS 507002014-12-23T03:30:00023 December 2014 03:30:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Unit 1 Technical Specification Shutdown Due to Rcs Pressure Boundary Leakage ENS 474972011-12-05T13:47:0005 December 2011 13:47:00 Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition - Unusual Event ENS 466972011-03-24T18:00:00024 March 2011 18:00:00 Other Unspec Reqmnt Non-Compliance with Nuhoms Technical Specification ENS 461532010-08-05T17:55:0005 August 2010 17:55:00 Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition Meeting Unusual Event Criteria ENS 460942010-07-14T23:34:00014 July 2010 23:34:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Tech Spec Shutdown Due to Through Wall Flaws in S/G Sample Line, Secondary Side ENS 454602009-10-23T20:34:00023 October 2009 20:34:00 Other Unspec Reqmnt, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Plant Shutdown Due to Excess Letdown Heat Exchanger Tube Leak and After-The-Fact Unusual Event ENS 450132009-04-22T09:00:00022 April 2009 09:00:00 Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition - Alert - Due to Fire Damage to Safety-Related Breaker ENS 431952007-02-28T00:47:00028 February 2007 00:47:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Failed Surveillance Testing ENS 403282003-11-17T16:50:00017 November 2003 16:50:00 Other Unspec Reqmnt Significant Leak in Fire Protection Header 2020-04-09T05:00:00 | |
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