ENS 45827
ENS Event | |
|---|---|
04:00 Apr 8, 2010 | |
| Title | Diesel Generators Wired Incorrectly |
| Event Description | Action F of LCO 3.8.1, 'AC Sources - Operating,' was entered at 20:57 EDT April 7, 2010 for the 2A-A and the 2B-B diesel generators (DGs) being inoperable. Action F has a two hour allowed outage time (AOT). The DGs were determined to be inoperable due to incorrectly implemented wiring changes made by personnel performing construction work on Watts Bar Unit 2. The impact of the change is that during [an] actual or simulated ESF actuation signal, if the diesel is in test mode, and the output breaker is closed in parallel with the board supply breakers, the DG would not return to a 'ready to load' state meaning the output breaker would not have opened as designed for this condition. This function is tested as required on an 18 month frequency as a part of Surveillance Requirement (SR) 3.8.1.17.
The wiring changes which affected the DGs were made in accordance with Unit 2 Work Order (WO) 09-954447 and 09-954448. The WOs as developed would not have an impact on Unit 1 operations. A review of the Unit 1 Operator Logs from January 1, 2010 to present, did not find any entries establishing the Unit 2 work had been authorized by Unit 1. The proper technical specification entry would have been Action 8 of LCO 3.8.1 for this activity. Entry into Action B of LCO 3.8.1 requires the implementation of several actions including a verification of the operability of the offsite circuits. Since these Technical Specification required actions were not complied with, WBN is providing this 24-hour notification in accordance with Section 2.G of the Watts Bar Unit 1 Facility Operating License. During the review of work performed by Unit 2 it was identified that the wiring was initially lifted on January 6. 2010. At the time of this report, actions have been taken to restore the wiring to its appropriate configuration on both of the DG circuits. 2B-B DG wiring was restored at 22:18 on April 7, 2010 and the 2B-B DG was declared operable. Action F of LCO 3.8.1 was exited at this time and Action B was entered for the 2A-A DG (14 day AOT). 2A-A DG circuitry was restored at 00:37 on April 8, 2010, and all LCO actions were exited. This event has been entered into TVA's corrective action program and actions are being initiated to establish the reason the leads were incorrectly lifted and to verify that no other similar wiring issues exist. The licensee notified the NRC Resident Inspector.
The Watts Bar Nuclear Plant (WBN) Unit 2 diesel generators (DGs) were not inoperable. The Unit 2 DGs were initially declared inoperable because of an inappropriate wiring change that disabled a DG output breaker trip in the event of an actual or simulated ESF actuation signal while the DG is in test mode and the output breaker is closed in parallel with the board supply breakers. Because Surveillance Requirement (SR) 3-8.1.17 required verification of this function for the Unit 1 DGs, and TVA was uncertain of the impact of the loss of this function to the Unit 2 DGs, TVA conservatively declared the Unit 2 DGs inoperable because they would not be able to meet this SR. Upon review TVA determined that it was proper to exclude this surveillance requirement for the Unit 2 DGs. Since SR 3.8.1.17 only applies to Unit 1 DGs, inability of Unit 2 DGs to meet this requirement is not a basis for inoperability. TVA has concluded that the Unit 2 DGs and offsite power sources were operable, and WBN was in compliance with its Technical Specifications throughout the period that the wiring change was installed. Therefore, this event was not reportable under WBN License (NPF-90) Condition 2.G, 10 CFR 50.72, or 10 CFR 50.73. The licensee notified the NRC Resident Inspector. Notified R2DO (O'Donohue). |
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+13.43 h0.56 days <br />0.0799 weeks <br />0.0184 months <br />) | |
| Opened: | Newton Lacy 17:26 Apr 8, 2010 |
| NRC Officer: | Charles Teal |
| Last Updated: | May 10, 2010 |
| 45827 - 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 | |