05000413/FIN-2009005-01
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Finding | |
|---|---|
| Title | Inadequate 50.59 Evaluation for the DCS Modification |
| Description | The inspectors identified an unresolved item (URI) regarding the licensees 10 CFR Part 50.59 evaluation for a new process DCS. Additional inspection would be required to determine if the licensees 50.59 evaluation properly addressed whether the modification resulted in more than a minimal increase in the likelihood of occurrence of a malfunction of an SSC important to safety previously evaluated in the UFSAR. The licensee replaced their Westinghouse 7300 analog control system with a Westinghouse Ovation DCS. The licensee was committed to follow NEI 96.07 to complete the 10 CFR 50.59 evaluation. The licensee concluded that the systems described in ED 78871 and EC 78914 have design functions described in the UFSAR. The licensee further concluded that the new DCS had several inherent risks. The inspectors questioned whether the licensee had adequately addressed some of the risks associated with the DCS upgrade. The inspectors identified a potential increase in risk of fault propagation in the DCS system from common mode fault mechanism triggers. Other potential risks not addressed by the licensee included complete DCS failure across all systems, inaccurate scaled data across all four system channels, and different combinations of systems and channels failing at the same time. The inspectors concluded that additional inspection would be required to understand both if the licensees 50.59 evaluation properly addressed whether the modification resulted in more than a minimal increase in the likelihood of occurrence of a malfunction of an SSC important to safety previously evaluated in the UFSAR and the potential impact to the plant. The inspectors did not identify an immediate safety concern because the safety system(s) required to safely shutdown the plant during an event were unaffected by the modification. This issue was identified as URI 05000413/2009005-01, Review of 50.59 Evaluation for the DCS Modification |
| Site: | Catawba  |
|---|---|
| Report | IR 05000413/2009005 Section 1R17 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.17 |
| Inspectors (proximate) | A Sengupta N Karlovich M Riches J Bartley F Ehrhardt R Rodriguez S Walker R Cureton R Fanner A Hutto C Kontz R Williams P Braxton T Fanellij Bartleyr Rodriguez R Cureton A Hutto |
| INPO aspect | |
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Finding - Catawba - IR 05000413/2009005 | |||||||||||||||||||||||||||||||||||||||||||
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Finding List (Catawba) @ 2009Q4
Self-Identified List (Catawba)
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