ENS 47609
ENS Event | |
|---|---|
22:46 Jan 17, 2012 | |
| Title | 24-Hour Report Per Section 2.G of Unit 1 Operating License |
| Event Description | Surveillance Requirement 3.8.4.14 for LCO 3.8.4, "DC Sources - Operating," was performed on 02/10/11 for the 125 VDC Vital Battery 4 (VB4). The recorded capacity was 80.2% and VB4 was declared OPERABLE at that time.
On 06/27/11 VB4 failed the service test as required by SR 3.8.4.13. Prior to the test VB5 was aligned to Vital Battery Board IV. VB5 had previously passed its required SRs within the required surveillance frequency. With VB5 re-aligned to Vital Battery Board IV, the plant was in a configuration that would allow it to meet all design bases events including a four hour station blackout. The eight weakest cells in VB4 were replaced and VB4 re-tested in accordance with SR 3.8.4.13. VB4 passed its acceptance criteria and VB4 was returned to service on 07/06/11. However, on 01/17/12, an independent analysis of the computer generated test data indicated that the actual battery capacity calculated on 02/10/11 was 79.87% which is less than the acceptance criteria of 80%. Therefore, between 02/10/11 and 06/27/11, VB4 was inoperable and the plant was in a condition prohibited by TS. On 01/06/12 a functional test was performed on VB4. The functional test is a service test using a single unit load profile. The single unit load profile consists of Unit 1 loads, common loads, and loads transferred from Unit 2 to Unit 1. VB4 passed the acceptance criterion (105 Vdc) with a terminal voltage of 111.9 Vdc. This test indicates that VB4 was functional from 02/10/11 to 06/27/11. VB4 has been replaced with new battery cells and the acceptance criteria for SR 3.8.4.13 and SR 3.8.4.14 were met. The error in the recorded capacity of 80.2% was discovered during a root cause investigation and attributed to arithmetical rounding errors. The licensee is continuing their investigation to determine extent of condition. The licensee informed the NRC Resident Inspector. |
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+18.43 h0.768 days <br />0.11 weeks <br />0.0252 months <br />) | |
| Opened: | Gregory A. Wallace 17:12 Jan 18, 2012 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Jan 18, 2012 |
| 47609 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 476092012-01-17T22:46:00017 January 2012 22:46:00
[Table view]Other Unspec Reqmnt 24-Hour Report Per Section 2.G of Unit 1 Operating License ENS 468852011-05-14T18:28:00014 May 2011 18:28:00 Other Unspec Reqmnt Violation of License Condition ENS 468392011-05-09T19:18:0009 May 2011 19:18:00 Other Unspec Reqmnt Potential Valve Mispositioning Led to a Condition Prohibited by Technical Specifications ENS 458272010-04-08T04:00:0008 April 2010 04:00:00 Other Unspec Reqmnt Diesel Generators Wired Incorrectly ENS 453312009-09-08T01:20:0008 September 2009 01:20:00 Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition Unusual Event ENS 426902006-07-07T18:45:0007 July 2006 18:45:00 Other Unspec Reqmnt Alternative Report for Non-Declared Emergency Condition in Accordance with Nureg-1022 ENS 414822005-03-11T19:29:00011 March 2005 19:29:00 Other Unspec Reqmnt It Was Determineded That Greater than 1% of Inspected S/G Tubes Must Be Repaired. ENS 402002003-09-26T12:50:00026 September 2003 12:50:00 Other Unspec Reqmnt Greater than 1 Percent of Steam Generators 1,2 & 4 Tubes Inspected Indicate That the Inspected Tubes Require Plugging. 2012-01-17T22:46:00 | |