05000289/FIN-2009006-01
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Finding | |
|---|---|
| Title | Failure to Assess Seismic Qualification of Stop Logs |
| Description | The team identified a non-cited violation of 10 CFR 50, Appendix B, Criterion III, Design Control. The team determined Exelon did not evaluate, in accordance with methodology described in the UFSAR, the suitability of the river water stop logs in the Intake Screen and Pump House (ISPH) structure to ensure they would not fall and block the river water flow path during a seismic event. The team determined that failure of the logs to remain in place would impact the capability of the safety-related nuclear river water, decay river water, and reactor river water pumps to perform their design function following the event. The Updated Final Safety Analysis Report (UFSAR), section 5.1.1, describes the ISPH and the river water systems as Seismic Class I structures, systems and components, and states that this equipment should be evaluated in accordance with the methodologies described in the UFSAR. Following identification Exelon entered the issue into the corrective action program and performed a preliminary analysis which indicated the stop logs would remain in place for all design basis events. This finding is more than minor because it affected the design control attribute of the mitigating systems cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The finding was determined to be of very low safety significance (Green) because the design/qualification deficiency confirmed not to result in loss of operability or functionality. This finding was not assigned a cross-cutting aspect because the underlying cause was not indicative of current performance. (Section 1R21.2.1.7 |
| Site: | Three Mile Island  |
|---|---|
| Report | IR 05000289/2009006 Section 1R21 |
| Date counted | Jun 30, 2009 (2009Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | K Mangan W Sherbin D Orr S Kobylarz J Tifft L Doerflein P Mckenna |
| INPO aspect | |
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Finding - Three Mile Island - IR 05000289/2009006 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Three Mile Island) @ 2009Q2
Self-Identified List (Three Mile Island)
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