05000321/FIN-2009006-03
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Finding | |
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| Title | Non-Interruptible Essential Instrument Air Header Check Valves for Units 1 and 2 |
| Description | The team identified an Unresolved Item (URI) regarding non-interruptible essential instrument air header check valves for Units 1 and 2. The licensee had not performed periodic maintenance or testing that demonstrated the capability of the check valves to prevent back-flow during a loss of instrument air event. During a loss of instrument air event, the back-up nitrogen system automatically pressurizes the non-interruptible essential air system with nitrogen. Then on-interruptible essential air header is designed with check valves that function as a boundary between instrument air and non-interruptible essential air. The boundary check valves prevent the loss of back-up nitrogen through postulated breaks in the instrument air system. The team noted that emergency operating procedures utilize the back-up nitrogen system for operation of the hardened containment vent, which is a dominant contributor to the plants overall core damage frequency risk profile, during loss of instrument air events. The licensee scoped the function of the non-interruptible essential air system into the maintenance rule program as documented in the Performance Criteria dated June 19, 1998. Since initial plant start-up of Units 1 and 2, the licensee had not performed periodic maintenance or testing that demonstrated the capability of the check valves to prevent back-flow during a loss of instrument air event. The team determined that the lack of periodic maintenance or testing resulted in a lack of reasonable assurance that the valves could perform their design function if called upon. The licensee initiated CR2009105109 for this issue and provided interim guidance to operators for responding to a loss of instrument air event. This issue is unresolved pending further inspection and interface with the licensee to determine the extent of condition and impact from the lack of periodic maintenance or testing of the non-interruptible essential instrument air header check valves. (URI 05000321/2009006-03 and 05000366/2009006-03, Non-Interruptible Essential Instrument Air Header Check Valves for Units 1 and 2 |
| Site: | Hatch  |
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| Report | IR 05000321/2009006 Section 1R21 |
| Date counted | Sep 30, 2009 (2009Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | C Smith C Baron D Jones G Skinner R Lewis J Hamman B Desai R Williams J Eargle A Senguptab Caballerod Jones E Morris G Macdonald J Eargle P Niebaum S Shaeffer |
| INPO aspect | |
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Finding - Hatch - IR 05000321/2009006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Hatch) @ 2009Q3
Self-Identified List (Hatch)
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