05000317/FIN-2010006-05
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Finding | |
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| Title | Failed to Establish Adequate Procedures for Letdown Restoration |
| Description | A self-revealing NCV of Technical Specification (TS) 5.4.1.a, Procedures was identified for failure to establish adequate procedures for restoration of Chemical and Volume Control System (CVCS) letdown flow. On February 18, 2010, an electrical ground fault caused a Unit 1 reactor trip, loss of the 500 kV Red Bus, and CVCS letdown isolation as expected on the ensuing instrument bus 1Y10 electrical transient. Deficient operating instructions prevented timely restoration of letdown flow following the initial transient. Pressurizer level remained above the range specified in Emergency Operating Procedure (EOP)-1 for an extended period because of the operators\' inability to restore letdown. This ultimately led to exceeding the TS high limit for pressurizer level. CVCS Operating Instruction OI-2A was subsequently revised, providing necessary guidance for re-opening the letdown system excess flow check valve to restore letdown flow. This event was entered into the licensee\'s corrective action program (CR 2010-001378).The finding is more than minor because it is associated with the procedure quality attribute of the Mitigating Systems Cornerstone and affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (Le., core damage). The finding is of very low safety significance because it is not a design or qualification deficiency, did not represent a loss of a safety function of a system or a single train greater than its TS allowed outage time, and did not screen as potentially risk significant due to external events. This finding has a crosscutting aspect in the area of human performance, resources aspect H.2(c), because Constellation did not ensure that procedures for restoring CVCS letdown were complete and accurate. |
| Site: | Calvert Cliffs  |
|---|---|
| Report | IR 05000317/2010006 Section 4OA5 |
| Date counted | Jun 30, 2010 (2010Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 93812 |
| Inspectors (proximate) | D Kern G Dentel J Clifford W Cook |
| Violation of: | Technical Specification |
| CCA | H.7, Documentation |
| INPO aspect | WP.3 |
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Finding - Calvert Cliffs - IR 05000317/2010006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Calvert Cliffs) @ 2010Q2
Self-Identified List (Calvert Cliffs)
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