05000498/FIN-2016007-08
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Finding | |
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| Title | Failure to Ensure Sufficient Capacity and Capability of Mitigating Systems during a Station Blackout Event |
| Description | The team identified a Green, non-cited violation of 10 CFR 50.63(a)(2) which states, in part, The reactor core and associated coolant, control, and protection systems, including station batteries and any other necessary support systems, must provide sufficient capacity and capability to ensure that the core is cooled and appropriate containment integrity is maintained in the event of a station blackout for the specified duration. Specifically, since September 12, 2013, the battery sizing and load profile calculations of the channel I (A train) direct current battery bus failed to include proper design data for expected loads and possible worst case load currents. In response to these issues, the licensee determined the battery bus was operable and the licensee initiated actions to analyze the effects of the change in calculation methodology, as well as to account for the additional loads. This finding was entered into the licensee's corrective action program as Condition Reports CR 16-1794, CR 16-2197, and CR 16-2236. The team determined that the failure to ensure the capacity and capability of protection systems to provide support for core cooling and containment integrity maintenance in the event of a station blackout was a performance deficiency. The performance deficiency was more than minor, and therefore a finding, because it was associated with the equipment performance attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. In addition, if left uncorrected, the performance deficiency would have the potential to lead to a more significant safety concern. Specifically, if the channel I emergency safety features direct current bus were required to support loads for the four hour coping period, the licensee may subject components used to ensure core cooling and containment integrity to conditions that were not assumed in their station blackout analysis. In accordance with Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At- Power, dated June 19, 2012, Exhibit 2, Mitigating Systems Screening Questions, the issue screened as having very low safety significance (Green) because it was a design or qualification deficiency that did not represent a loss of operability or functionality; did not represent an actual loss of safety function of the system or train; did not result in the loss of one or more trains of non-technical specification equipment; and did not screen as potentially risk significant due to seismic, flooding, or severe weather. This finding had a cross-cutting aspect in the area of human performance associated with procedure adherence because the licensee failed to follow process, procedures, and work instructions. Specifically, the licensee did not follow the calculation change process procedures to complete an impact review of pertinent licensing information associated with station blackout when the battery load assumptions were revised in the station blackout coping calculation [H.8]. |
| Site: | South Texas  |
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| Report | IR 05000498/2016007 Section 1R21 |
| Date counted | Mar 31, 2016 (2016Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21M |
| Inspectors (proximate) | C Baron C Stott G Gardner J Kirkland M Williams S Hedger T Fanelli T Farnholtz |
| Violation of: | 10 CFR 50.63 |
| CCA | H.8, Procedure Adherence |
| INPO aspect | WP.4 |
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Finding - South Texas - IR 05000498/2016007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (South Texas) @ 2016Q1
Self-Identified List (South Texas)
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