05000498/FIN-2011003-02
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Finding | |
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| Title | Inadequate Risk Assessment for Switchyard Activities |
| Description | The inspectors reviewed a self-revealing noncited violation of 10 CFR 50.65(a)(4) for the failure to perform an adequate risk assessment to manage the increase in risk of performing activities in the switchyard. On September 26, 2010, the licensee removed 345 kVac circuit breaker Y530 from service for planned replacement. The replacement activities were performed by a contractor, however, the details of the work package were not provided to the licensee nor were they discussed. As a result of incorrect terminations, on September 30, 2010, when the work was completed and the contractors were performing testing, a false differential condition was sensed resulting in all the north bus breakers opening. This resulted in a loss of power to the standby transformer for Unit 1, de-energizing the train B engineered safety features bus. The loss of offsite power to the train B bus resulted in an engineered safety features actuation that started the train B standby diesel generator and actuated train B safety-related equipment. The licensees corrective actions included: (1) revising the switchyard management procedure to provide more detailed instructions for utilizing the switchyard coordinator in providing oversight and directing of switchyard activities; (2) specific instructions as to points of contact, details of switchyard work to be performed; and (3) specifying coping strategies and integrating the work control process with the management of switchyard activities. This finding was more than minor because it affected the Initiating Events Cornerstone attribute of protection against external factors and affected the cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during power operations. This deficiency directly resulted in loss of offsite power to the train B engineered safety features bus. The inspectors performed the significance determination using NRC Inspection Manual Chapter 0609.04, Phase 1 - Initial Screening and Characterization of Findings, dated January 10, 2008, because it affected the Initiating Events Cornerstone while the plant was at power. Because the finding affects the licensees assessment and management of risk the Phase 1 worksheet sent the inspectors to Attachment K, Maintenance Risk Assessment and Risk Management Significance Determination Process, dated May 19, 2005. This finding was determined to be of very low safety significance because it only impacted performance of risk managed actions not taken and the incremental core damage probability risk assessment increase of 6.3 E-13 was less than the 1 E-6 threshold. In addition, this finding had human performance cross-cutting aspects associated with work practices in that the licensee did not ensure supervisory and management oversight of work activities, including contractors, such that nuclear safety is supported. |
| Site: | South Texas  |
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| Report | IR 05000498/2011003 Section 1R13 |
| Date counted | Jun 30, 2011 (2011Q2) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.13 |
| Inspectors (proximate) | J Dixon K Clayton B Tharakan W Walker P Jayroe J Dykert M Brooks |
| CCA | H.2, Field Presence |
| INPO aspect | LA.2 |
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Finding - South Texas - IR 05000498/2011003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (South Texas) @ 2011Q2
Self-Identified List (South Texas)
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