05000346/FIN-2009003-01
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Finding | |
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| Title | Loss of Switchyard J Bus |
| Description | The inspectors determined that an unresolved item (URI) existed concerning the loss of the 345 KV switchyard J Bus. The J Bus was de-energized upon a catastrophic failure of the J Bus phase B capacitive coupled potential device (CCPD) at 12:49 a.m. on June 25, 2009. The event required the licensee to declare one offsite AC source inoperable and enter TS LCO 3.8.1(a) requiring restoration of one offsite circuit within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. During the event, a spread of fire was reported in the switchyard. The licensees fire brigade was able to extinguish the fire within 33 minutes. As a conservative measure, the assistance of Carroll Township was requested, but was not needed to put out any fires. A temporary modification was issued to remove the CCPDs from all three phases of the J Bus until a bus outage could be scheduled to replace the potential devices. At 11:05 p.m. on June 26, the licensee safely restored the J Bus to an energized and operable condition, which was required to meet TS 3.8.1 and exit the 72-hour shutdown requirement. At the time of the failure, the licensee evaluated the Emergency Action Levels (EALs), but did not make an emergency declaration at that time. However, upon further review the following morning, the licensee determined that the failure of the CCPD met the definition of an explosion as defined in emergency procedure RA-EP-02840, Explosion. A reportability notification was made to the NRC at 11:44 a.m. on June 26, 2009. The NRC is continuing to inspect this aspect of the event. The switchyard maintenance strategy template requires a critical potential device to be replaced after 25 years. After two non-catastrophic failures of CCPDs, occurring in December 2007, and January 2008, the licensee identified that these components were installed beyond the 25-year life expectancy. At that time, a walkdown of the switchyard revealed eight CCPDs that were beyond 25 years and needing replacement. Replacement was scheduled to begin in the fall of 2009 and spring of 2010. The CCPD that caused the loss of the J Bus had been installed beyond 25 years. The cause of the catastrophic failure of the CCPD is not known at this time. Condition Report 09-61025 documented the equipment failure. A root cause evaluation was assigned to determine the cause of the failure, to identify equipment, organizational and programmatic factors involved in the failure and to develop actions to prevent recurrence. The root cause evaluation of the event was not available for the inspectors review before the end of the inspection period. Therefore, this issue is considered an unresolved item (URI 05000346/2009003-01) pending completion of the inspectors review |
| Site: | Davis Besse  |
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| Report | IR 05000346/2009003 Section 1R13 |
| Date counted | Jun 30, 2009 (2009Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.13 |
| Inspectors (proximate) | M Marshfield J Rutkowski A Wilson D Kimble T Go J Cameron P Vossj Rutkowskid Jones A Wilson J Cameron P Voss |
| INPO aspect | |
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Finding - Davis Besse - IR 05000346/2009003 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Davis Besse) @ 2009Q2
Self-Identified List (Davis Besse)
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