05000263/FIN-2010007-01
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Finding | |
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| Title | HELB Analysis Potentially Non-Conservative |
| Description | As part of the review of the ACE for an adverse trend in double disc gate valve (DDGV) local leak rate testing (LLRT) performance documented in CAP 1202466, the inspectors noted that the ACE had determined that the valves performance degradation did not prevent the valves from performing their safety function. The ACE only addressed the valves safety function of providing containment isolation. The inspectors questioned if the safety function of the high pressure coolant injection (HPCI), reactor core isolation cooling (RCIC) and reactor water cleanup (RWCU) steam supply valves to close after detection of a HELB should have been considered. The licensee responded that the ACE did not need to consider the effect of the valves increased leakage on the HELB analyses because any leakage would not impact the alternate shutdown path. The inspectors reviewed the assumptions and acceptance criteria of the HELB calculations for HPCI, RCIC and RWCU line breaks and identified potential inconsistencies between the calculations assumptions with Technical Specifications and UFSAR allowed values for valve closure times, incorporation of delay actuations, and isolation initiation signals. The licensee entered the NRC concerns with these potential inconsistencies into the CAP by initiating CAP 01252363 on October 1, 2010. The licensee stated that the calculations were appropriate and provided the inspectors with some original licensing documents for the HELB analyses; however, additional questions remained. This issue will be tracked as URI 05000263/201007-01 pending further NRC review of the licensee responses and the HELB analyses and determination of the original and current licensing bases. |
| Site: | Monticello  |
|---|---|
| Report | IR 05000263/2010007 Section 4OA2 |
| Date counted | Dec 31, 2010 (2010Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | K Riemer M Mitchell S Thomas J Bozga P Voss A Scarbearyn Shahk Riemer M Phalen C Scott D Sand |
| INPO aspect | |
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Finding - Monticello - IR 05000263/2010007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Monticello) @ 2010Q4
Self-Identified List (Monticello)
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