05000259/FIN-2009008-02
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Finding | |
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Title | Violation of 10CFR50, Appendix B, Criterion V for Inadequate Procedure for Emergency Equipment Cooling Water System Flow Balancing |
Description | The inspectors identified a Green non-cited violation (NCV) of 10 CFR 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, for the failure to provide adequate guidance in existing procedures utilized for flow balancing of the emergency equipment cooling water (EECW) system. The EECW system provided the heat sink for station safety-related heat loads including cooling for the residual heat removal (RHR) and core spray (CS) room coolers. The installed strainers on the EECW system are capable of filtering debris greater than 1/8 inch (.125 inches), potentially allowing debris less than 1/8 inch to pass through and clog downstream throttle valves. A clog in the throttle valves would prevent adequate flow from reaching safety-related heat exchangers unless procedural guidance or limitations prevented throttling valves to disk-to-seat clearances of less then 1/8 inch. The existing EECW flow balance procedure was inadequate in that it made no provision in the acceptance criteria to limit or evaluate minimum throttle valve seat/disc clearance, and the subsequent potential for increased flow obstruction, resulting from system flow balancing. This finding was entered into the licensees corrective action program as problem evaluation reports (PERs) 208374 and 208636. Planned corrective actions included a revision to EECW flow balancing procedures. The inspectors verified and discussed with the licensee existing indications that are available to alert the operator of potential clogging. This finding is more than minor because it affects the Mitigating Systems cornerstone objective of ensuring the availability, reliability, and operability of the RHR and CS pump room coolers to perform the intended safety function during a design basis event and the cornerstone attribute of Procedure Quality, i.e. Maintenance and Testing (Pre-event) Procedures. The team assessed this finding using the Significance Determination Process (SDP) and determined that the finding was of very low safety significance (Green) because the inspectors found no documented history of an actual loss of safety system function. This finding was reviewed for cross-cutting aspects and none were identified |
Site: | Browns Ferry ![]() |
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Report | IR 05000259/2009008 Section 1R21 |
Date counted | Dec 31, 2009 (2009Q4) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.21 |
Inspectors (proximate) | J Leivo R Aiello R Berryman H Campbell C Even R Patterson B Desai J Kent |
INPO aspect | |
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Finding - Browns Ferry - IR 05000259/2009008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Browns Ferry) @ 2009Q4
Self-Identified List (Browns Ferry)
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