From kanterellaJump to navigation Jump to search
Inadequate Inspection Activities for Emergency Transformer Bus
The inspectors reviewed a self -revealed, non- cited violation of Technical Specification 5.4.1.a for the licensees failure to implement Maintenance Procedure 7.3.41, Examination and High Pot Testing of Non- Segregated Buses and Associated Equipment, Revision 10, during inspection of the emergency station service transformer 4160 V bus bars. Specifically, the inspectors identified a violation of Technical Specification 5.4.1.a for the licensees failure to implement inspection instructions to examine the emergency transformer bus insulation for discoloration and to repair the associated components on March 23, 2015. As a result, the licensee did not properly assess corona -related degradation on the emergency transformer bus, which resulted in an emergency transformer bus fault and a loss of the emergency transformer and the supplemental diesel generator on January 17, 2017. Immediate corrective actions to restore compliance included replacement of the faulted portions of the emergency transformer bus, and extent of condition inspection and cleaning of the remainder of the emergency transformer bus bars . The long term corrective action is replacement of the emergency transformer bus insulation. The licensee entered this issue into the corrective action program as Condition Report CR- CNS -2017- 00223. The licensees failure to implement Maintenance Procedure 7.3.41 to properly assess degradation of the emergency station service transformer bus, in violation of Technical Specification 5.4.1.a, was a performance deficiency. The performance deficiency was determined to be more than minor, and therefore a finding, because it was associated with the equipment performance attribute of the Initiating Events Cornerstone, and affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown, as well as, power operations. Specifically, the finding resulted in the licensees failure to identify and repair indications of corona -related degradation on the emergency station service transformer bus, which resulted in an emergency station service transformer bus fault, and a loss of the emergency station service transformer and supplemental diesel generator on January 17, 2017. Using Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At -Power, dated June 19, 2012, the inspectors determined that the finding required a detailed risk evaluation because it involved the partial loss of a support system that contributes to the likelihood of, or causes, an initiating event (loss -of-offsite power) and 3 the finding affected mitigation equipment (supplemental diesel generator). A senior reactor analyst performed a detailed risk evaluation in accordance with Inspection Manual Chapter 0609, Appendix A, Section 6.0, Detailed Risk Evaluation. The analyst concluded that the finding is of very low safety significance (Green). The performance deficiency had a cross -cutting aspect in the area of problem identification and resolution, associated with evaluation because the licensee failed to thoroughly evaluate emergency station service transformer bus discoloration and high potential test failures to ensure that resolutions addressed the causes and extent of conditions commensurate with their safety significance. Specifically, the licensee failed to thoroughly evaluate emergency station service transformer bus discoloration identified during the 2015 inspection, the hipot testing failures t hat followed the inspection, and the extent of condition of the 2015 testing and inspection deficiencies [P.2].
|Report||IR 05000298/2017012 Section 4OA5|
|Date counted||Dec 31, 2017 (2017Q4)|
|Inspectors (proximate)||P Voss|
|Violation of:||Technical Specification - Procedures|
Finding - - IR 05000298/2017012
Some use of "" in your query was not closed by a matching "".