05000259/FIN-2009003-04
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Finding | |
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Title | Inadequate Scoping of Risk Significant Systems For Online Risk Assessment |
Description | The inspectors identified an issue associated with the possible omission of certain risk significant systems from the licensees routine assessment of online risk that was required by 10 CFR Part 50.65 (a)(4), Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants. This issue is being characterized as an unresolved item (URI). Several systems identified as risk significant by the licensees MR Program, and listed in Table 2, Initiators and System Dependency, of the Risk Informed Inspection Notebook for Browns Ferry Nuclear Plant Units 1 and 2, did not appear to be considered as part of the licensees routine online risk assessment. The inspectors observed that the following risk significant systems identified in Table 2 did not appear to be evaluated for on-line risk impact by the licensee: Raw Cooling Water (RCW), Fuel Oil Transfer, Emergency Diesel Generator (EDG) Room Ventilation (i.e., exhaust fans), Plant Control Air, Drywell Control Air, and Containment Ventilation. Furthermore, examples of risk significant systems identified as risk significant by the licensees MR Program that did not appear to be assessed for online risk were as follows: RCW, EDG Room Ventilation, EDG Starting Air, and the Fuel Oil Transfer system. To address the inspectors concern regarding the assessment of online risk for all risk significant systems the licensee initiated PER 169904. As part of the corrective actions for PER 169904, the licensee committed to review Table 2 of risk significant systems against the list of risk significant systems as determined by the new Browns Ferry PRA model that was being developed, once it has been peer reviewed and approved. At which point the licensees maintenance rule and on-line risk management tools would be updated accordingly. This issue of concern requires additional information from the licensee. Such as, whether the MR and Table 2 designations of risk significant systems are appropriate, and how the current online risk assessment tools do or do not scope or bound the impact on risk associated with the unavailability of the aforementioned systems. Consequently, pending additional information from the licensee and further review by the NRC, this issue will be identified as URI 05000259, 260, 296/2009003-04, Inadequate Scoping of Risk Significant Systems for Online Risk Assessment |
Site: | Browns Ferry ![]() |
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Report | IR 05000259/2009003 Section 4OA2 |
Date counted | Jun 30, 2009 (2009Q2) |
Type: | URI: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71152 |
Inspectors (proximate) | R Hamilton W Loo H Gepford E Guthrie K Korth R Williamsc Stancilt Ross H Gepford E Guthrie L Miller K Korth |
INPO aspect | |
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Finding - Browns Ferry - IR 05000259/2009003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Browns Ferry) @ 2009Q2
Self-Identified List (Browns Ferry)
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