05000373/FIN-2013004-01
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Finding | |
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| Title | Failure to Follow Procedure Led to Manual Scram with Complications |
| Description | A self-revealed finding preliminarily determined to be of low-to-moderate safety significance was identified for the licensees failure to follow procedure LOP-CW-10, Dewatering the Circulating Water System, Revision 32, on Unit 2. Specifically, on April 25, 2013, with Unit 2 at 56 percent power, operators appointed to plan and execute the dewatering of the main condenser waterbox did so in a manner inconsistent with procedural guidance by manually adjusting the circulating water isolation valves while condenser manways were still open. The subsequent loss of isolation led to the flooding of the condenser pit and a resultant circulating water pump trip, loss of the normal heat sink, and a reactor scram. The licensee entered this issue into its corrective action program (CAP) as action report (AR) 1506809 and performed a root cause analysis to identify the root and contributing causes of the event, as well as to determine the appropriate corrective actions, such as providing training and revising procedures. The inspectors determined that the licensees failure to follow the prescribed steps of procedure LOP-CW-10 was a performance deficiency warranting a significance determination. The inspectors used Inspection Manual Chapter (IMC) 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power, Exhibit 1, dated June 19, 2012, for the Initiating Events cornerstone. Because the finding caused a reactor trip AND the loss of mitigation equipment relied upon to transition the plant from the onset of the trip to a stable shutdown condition, a detailed risk evaluation was required. The Senior Reactor Analysts (SRAs) used the LaSalle Standardized Plant Analysis Risk (SPAR) model to perform the detailed risk evaluation. In accordance with Risk Assessment of Operational Events Handbook guidance, the initiating event Loss of Condenser Heat Sink was set to 1.0 using the events and condition assessment module of the Systems Analysis Program for Hands-On Integrated Reliability Evaluations (SAPHIRE), Version 8. The calculated conditional core damage probability for the event was 1.6E-6, which represents a finding of low-to-moderate safety significance (White). The finding had a cross-cutting aspect in the area of human performance, decision-making, because the licensee failed to use conservative assumptions when planning and executing the dewatering evolution. Specifically, the incorrect assumption that this evolution performed at-power could be treated the same as when performed during a shutdown condition enabled operators to stray from strict procedure adherence and into knowledge space. |
| Site: | LaSalle  |
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| Report | IR 05000373/2013004 Section 4OA3 |
| Date counted | Sep 30, 2013 (2013Q3) |
| Type: | Finding: White |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71153 |
| CCA | , |
| INPO aspect | DM.2 |
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Finding - LaSalle - IR 05000373/2013004 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (LaSalle) @ 2013Q3
Self-Identified List (LaSalle)
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