05000455/FIN-2008002-03
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Finding | |
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Title | Unit 2 Notice Of Unusual Event Due To Loss Of Both System Auxiliary Transformers |
Description | On March 25, 2008, Unit 2 SAT 242-2 de-energized upon receipt of a C phase to ground relay actuation. As designed the upstream switchyard breakers opened de-energizing both SAT 242-1 and 242-2. Also as designed the downstream breakers opened resulting in a fast transfer of the 6.9KiloVoltage buses to the Unit Auxiliary Transformers and the transfer of the 4KiloVoltage buses to the emergency diesel generators which had automatically started. The licensee entered a Notification of Unusual Event and the NRC entered the Monitoring Mode. The licensee subsequently transferred the 4KiloVoltage loads to the Unit 1 SATs and began troubleshooting efforts. Following verification that a fault did not exist on the SAT 242-1 circuit all Unit 2 house loads were transferred to SAT 242-1. Subsequently the licensee exited the Unusual Event and the NRC exited the Monitoring Mode. The inspectors reviewed the plants and the operators responses to the loss of both unit SATs to determine if the responses were appropriate and in accordance with design, procedures and training. At the close of the inspection period additional information was required to determine if the loss of the SAT was a finding, or if it constituted a deviation or violation. The additional information needed was the results of the licensees root cause evaluation and proposed corrective actions. Based on the root cause of the fault a possible performance deficiency existed and the root cause analysis would assist the inspectors in making such a determination. Documents reviewed are listed in the Attachment. (URI 05000455/2008002-03 |
Site: | Byron |
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Report | IR 05000455/2008002 Section 4OA3 |
Date counted | Mar 31, 2008 (2008Q1) |
Type: | URI: |
cornerstone | No Cornerstone |
Identified by: | NRC identified |
Inspection Procedure: | IP 71153 |
Inspectors (proximate) | B Bartlett C Acosta C Thompson C Zoia D Jones J Cassidy J Jacobson N Feliz _Adorno R Jickling R Ng R Russell R Skokowski T Bilik V Meghanir Ng C Thompson B Bartlett J Cassidy R Skokowski C Scott |
INPO aspect | |
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Finding - Byron - IR 05000455/2008002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2008Q1
Self-Identified List (Byron)
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