05000353/FIN-2016003-01
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Finding | |
|---|---|
| Title | Inadequate Design Control of Plant Processing Computer Modification |
| Description | A self-revealing finding of very low safety significance (Green) was identified when Exelon did not implement their engineering design control procedures during the plant processing computer (PPC) modification. Specifically, Exelon did not fully address effects of the modification on other plant systems and did not establish a testing boundary that encompassed all components whose operation was altered by the modification. As a result, the PPC modification had a wiring design error that resulted in the trip of both reactor recirculation pumps (RRPs) which required a manual reactor trip of Unit 2. In response to this issue, Exelon initiated IR 2676712, investigated the cause of the trip, fixed the wiring design error, performed a root cause evaluation, and performed an extent of condition review. This issue is more than minor because it adversely affected the design control attribute of the initiating events cornerstone to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the PPC modification process had a wiring design error that resulted in the trip of both RRPs which required a manual reactor trip of Unit 2. The issue was evaluated in accordance with IMC 0609, Appendix A, "Significance Determination Process for Findings At-Power, using Exhibit 1, "Initiating Events Screening Questions, Section B, Transient initiators. The finding was determined to be of very low safety significance (Green) because the finding did not cause 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. The inspectors determined that this finding has a cross-cutting aspect in the area of Human Performance, Challenge the Unknown, because LGS staff did not stop when faced with uncertain conditions, and risks were not evaluated and managed before proceeding. Specifically, Exelon did not stop and reevaluate the risks and effects on plant systems when changes were made to the PPC design modification package. [H.11] |
| Site: | Limerick  |
|---|---|
| Report | IR 05000353/2016003 Section 4OA3 |
| Date counted | Sep 30, 2016 (2016Q3) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | D Schroeder J Nicholson M Fannon M Patel R Nimitz S Barber S Hammann S Rutenkroger |
| CCA | H.11, Challenge the Unknown |
| INPO aspect | QA.2 |
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Finding - Limerick - IR 05000353/2016003 | |||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Limerick) @ 2016Q3
Self-Identified List (Limerick)
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