05000424/FIN-2012005-04
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Finding | |
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Title | Licensee-Identified Violation |
Description | TS 3.0.3 requires, in part, that when a limiting condition of operation (LCO) is not met and the associated actions are not met, an associated action is not provided, or if directed by the associated actions, the unit shall be placed in a mode or other specified condition in which the LCO is not applicable. TS 3.7.14 require that two engineered safety feature (ESF) room cooler and safety-related chiller trains shall be operable. Contrary to the above, on August 17, 2012, at approximately midnight, the unit 1 shift supervisor failed to enter the required action statement for TS LCO 3.7.14, Condition A when the unit 1A ESF chiller condenser purge pressure was noted to be out of specification high. Inoperability of the chiller was not recognized until August 26, 2012, and the LCO entered at 1437. Further, during the extended period during which the 1A ESF chiller was inoperable (albeit unrecognized as inoperable), opposite train supported components as well as redundant room coolers on the train B ESF Chiller and room cooler train were removed from service for unrelated activities which resulted in two occasions during which TS 3.0.3 should have been applied. The licensee documented this event in their corrective action program as CR 507143. Using IMC 0609, dated June 19, 2012, Attachment 4, Table 2, the inspectors verified that the finding affected the mitigation systems cornerstone. IMC 0609 Attachment 4 Table 3 directed the inspectors to use IMC 0609 Appendix A to characterize the finding. Because the finding represented an actual loss of function of one train of ECCS for greater than its TS Allowed Outage Time, a detailed risk evaluation was required. A detailed risk evaluation was performed by a regional senior reactor analyst in accordance with IMC 0609 Appendix A guidance using the NRC Vogtle SPAR model and the Saphire 8 risk analysis code. An Event/Condition Analysis module in Saphire was run with the unit 1A train ESF chiller failed with no recovery allowed for a 9 day exposure period. The dominant sequence was a loss of offsite power with success of reactor trip and emergency power with late failure of feedwater and failure to implement feed and bleed cooling due to failure of the Unit 1B train chiller and loss of the safety related switchgear. The detailed risk evaluation determined that the risk due to the performance deficiency was an increase in core damage frequency of <1E-6/year, a GREEN finding of very low safety significance. The risk was mitigated by the availability of alternate train components and the short exposure period. |
Site: | Vogtle ![]() |
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Report | IR 05000424/2012005 Section 4OA7 |
Date counted | Dec 31, 2012 (2012Q4) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | Licensee-identified |
Inspection Procedure: | |
Inspectors (proximate) | A Nielsen F Ehrhardt A Vargas-Mendez J Laughlin M Cain B Caballero T Chandler R Williams C Dykes W Pursley |
INPO aspect | |
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Finding - Vogtle - IR 05000424/2012005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Vogtle) @ 2012Q4
Self-Identified List (Vogtle)
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