05000220/FIN-2017004-02
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Finding | |
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Title | Inadequate Fill and VentProcedure for Control Room Chiller Results in Unplanned LCO Entry |
Description | An NRC-identified Green NCV of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified for Exelons failure to ensure that activities affecting quality were prescribed in a manner appropriate to the circumstances for the Unit 1 control room chiller system. Specifically, Exelon procedure N1-OP-49, Control Room Ventilation System, Revision 03800, Section H.5, Venting of Control Room Chiller Circulating Water Pump 11 and 12 Discharge Piping, led personnel to inadequately fill and vent the 12 control room chiller during system restoration from maintenance, while in a single chiller lineup. As a result, on October 15, 2017, control room chiller 12 tripped on low flow, and due to a prior trip of 11A control room chiller compressor, an unplanned 7-day LCO in accordance with TS 3.4.5.e, Control Room Air Treatment System, was entered due to an insufficient number of available chiller compressors to provide adequate control room cooling. Exelon entered this issue into the CAP as IR 04090200. Corrective actions included generating a procedure change to correct N1-OP-49 Section H.5, which provides instruction for filling and venting when in a single chiller lineup
This finding is more than minor because it is associated with the procedure quality attribute of the Barrier Integrity cornerstone and adversely affected the cornerstone objective of providing reasonable assurance that physical design barriers protect the public from radionuclide releases caused by accidents or events. Specifically, Exelon failed to prescribe an adequate fill and vent procedure for the Unit 1 control room chillers which led to a trip of the 12 chiller on low flow while troubleshooting of chiller compressor 11A was on-going, resulting in an unplanned TS LCO entry. The inspectors evaluated this finding using IMC 0609.04, Initial Characterization of Findings, and Exhibit 3 of IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The performance deficiency did not represent a degradation of the radiological barrier function provided for the control room. Additionally, the performance deficiency did not represent a degradation of the barrier function of the control room against smoke or a toxic atmosphere. Therefore, this finding was determined to be of very low safety significance (Green). This finding has a cross-cutting aspect in the area of Problem Identification and Resolution, Evaluation, because between 2014 and 2017 the inspectors noted over 20 issue reports documenting issues affecting reliability of the control room chiller system. Exelon failed to thoroughly evaluate the issues associated with the chillers to ensure that resolutions address causes and extent of conditions commensurate with their safety significance. Specifically, Exelon failed to effectively evaluate previous chiller trips and to prevent additional trips of the chiller system such as the one that occurred on October 15, 2017. [P.2] (Section 1R12.b.2) |
Site: | Nine Mile Point |
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Report | IR 05000220/2017004 Section 1R12 |
Date counted | Dec 31, 2017 (2017Q4) |
Type: | NCV: Green |
cornerstone | Barrier Integrity |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.12 |
Inspectors (proximate) | M Catts B Sienel P Presby M Patel K Mangan M Hardgrove J Bream F Arner R Rolph G Stock E Miller H Lynn |
Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion V Technical Specification |
CCA | P.2, Evaluation |
INPO aspect | PI.2 |
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Finding - Nine Mile Point - IR 05000220/2017004 | ||||||||||||||||||||||||||||||||||||||||||
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Finding List (Nine Mile Point) @ 2017Q4
Self-Identified List (Nine Mile Point)
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