05000317/FIN-2010003-02
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Finding | |
|---|---|
| Title | Inadequate Design Control Reviews of the Turbine Control System and the Nuclear Steam Supply System |
| Description | The inspectors identified an NCV of 10 CFR Part 50, Appendix B, Criterion III, \\\"Design Control,\\\" because Constellation did not perform adequate design reviews associated with modifications to the turbine control system and the nuclear steam supply system (NSSS). Specifically, Constellation did not adequately evaluate the potential adverse impacts of removal of the power load unbalance (PLU) turbine trip on safety related systems, structures, and components (SSCs) such as the main steam safety valves (MSSVs) and pressurizer power operated relief valves (PORVs). In addition, during significant changes to plant design such as steam generator replacements and power uprates, Constellation did not conduct an adequate evaluation to determine if the turbine bypass valve (TSV) and the atmospheric dump valve (ADV) design specification of opening within 3 seconds after receiving the quick open signal would still be sufficient to prevent lifting MSSVs. Immediate corrective actions included entering these issues into their corrective action program (CAP) and performing an immediate operability determination and a probabilistic risk analysis. This finding is more than minor because it affected the Initiating Event cornerstone attribute of design control and affects the cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the removal of the PLU turbine trip and the modifications to the NSSS could challenge prirnary and secondary overpressure protection devices and result in a stuck open MSSV or PORV. The inspectors evaluated this finding using an SDP phase 2 analysis and deterrnined that the issue is of very low safety significance. This finding has a cross-cutting aspect in the area of hurnan performance, decision rnaking, because Constellation did not adequately make safetysignificant decisions using a systematic process when faced with uncertain or unexpected plant conditions, to ensure safety is maintained. (H.1.a of IMC 0310). |
| Site: | Calvert Cliffs  |
|---|---|
| Report | IR 05000317/2010003 Section 1R18 |
| Date counted | Jun 30, 2010 (2010Q2) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.18 |
| Inspectors (proximate) | K Mangan S Pindale G Dentel S Kennedy R Rolph J Hawkins R Montgomery M Osborn |
| CCA | H.13, Consistent Process |
| INPO aspect | DM.1 |
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Finding - Calvert Cliffs - IR 05000317/2010003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Calvert Cliffs) @ 2010Q2
Self-Identified List (Calvert Cliffs)
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