05000316/FIN-2012008-09
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Finding | |
|---|---|
| Title | Computer Program Used for Operability Evaluation Was Not Benchmarked |
| Description | The inspectors identified a finding of very low safety significance and associated Non-Cited Violation of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, for failure to establish procedures for reduced inventory operations that were appropriate to preclude air entrainment into Residual Heat Removal (RHR) and Reactor Coolant Systems (RCS). Specifically, a procedure allowed operation of RHR while in reduced inventory operations with a minimum RCS level and maximum pump flowrate combination that was determined to result in air-entrainment vortices. The finding was entered into the licensee s corrective action program to place an administrative hold to the procedure until proper documentation is revised and updated and to revise the procedure to require stricter use of high accuracy level instrumentation. The performance deficiency was determined to be more than minor because it was associated with the initiating event cornerstone attribute of procedure quality and affected the cornerstone objective of limiting the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown operations. The finding screened as of very low safety significance (Green) using a Phase II evaluation. The inspectors did not identify a cross-cutting aspect associated with this finding because the finding was not confirmed to reflect current performance due to the age of the performance deficiency. The licensee used Flow-3D Version 9.0 for a past-operability evaluation of a gas void found in the containment recirculation sump suction piping. Specifically: Calculation ALION-CAL-AEP-4462-04, D.C. Cook Recirculation Containment Sump Hydraulic Analysis Task 4 Results, was performed in the early development of the GSI-191 response effort to postulate an air pocket venting from the CS and RHR suction lines into the recirculation sump. This analysis was performed to evaluate the necessary transition period to avoid air entrainment in the pumps and the pressure transients as they impact the recirculation sump strainers. This analysis was not used for any design basis or engineering modification; however, it was used as a tool for a past-operability evaluation of a gas void found in the sump suction piping. Calculation ALION-CAL-AEP-7354-02, D.C. Cook Unit 1 Operability Analysis to Evaluate Gas Void in ECCS Sump Suction Piping, was performed for a void evaluated in the same location as the one evaluated by ALION-CAL-AEP-4462-04. However, this analysis was performed to evaluate the past-operability of the void volume found in January 2009 as oppose to a postulated volume. Specifically, an air pocket was discovered downstream of the Unit 1 sump isolation valve (i.e., 1-ICM-306) in the B train suction pipe. This discovery was captured in the CAP as AR 00844125. The licensee did not own or maintain a license for Flow-3D. These analyses were performed by an outside contractor under the contractor s Quality Assurance Program and were accepted by the licensee through their Owner s Acceptance Review Process. However, when the inspectors questioned if the computer code was verified against test data, the contractor informed the licensee that no benchmark flow modeling was conducted for these software applications. The licensee did not own or maintain a license for Flow-3D. These analyses were performed by an outside contractor under the contractor s Quality Assurance Program and were accepted by the licensee through their Owner s Acceptance Review Process. However, when the inspectors questioned if the computer code was verified against test data, the contractor informed the licensee that no benchmark flow modeling was conducted for these software applications. NRC Regulatory Issue Summary (RIS) 2005-20, Revision 1, Revision to NRC Inspection Manual Part 9900 Technical Guidance, Operability Determinations and Functionality Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality or Safety, informed licensees that the NRC had revised NRC Inspection Manual Part 9900. Guidance provided in Appendix C, Section C.4 of the inspection manual stated the use of any analytical method must be technically appropriate to characterize the SSCs involved, the nature of the degraded or nonconforming condition, and specific facility design. It further stated that general considerations for establishing this adequacy include, in part, acceptable alternative methods such as the use of best estimate codes, methods, and techniques. The inspection guidance also stated that in these cases, the evaluation should ensure that the SSC s performance is not over-predicted by performing a benchmark comparison of the non-current licensing basis (CLB) analysis methods to the applicable CLB analysis methods. The inspectors consulted with NRR and determined the operability evaluation relied on a computer code that has not been demonstrated to be technically appropriate for the intended applications. Specifically, the computer code had not been qualified by benchmarking against test or plant data to demonstrate its applicability to the type of analyses being conducted. This issue is unresolved pending licensee past-operability evaluation and determination of NRC courses of action for resolution of the issue. |
| Site: | Cook  |
|---|---|
| Report | IR 05000316/2012008 Section 4OA5 |
| Date counted | Sep 30, 2012 (2012Q3) |
| Type: | URI: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | C Tilton N Feliz Adornoa Dunlopj Lennartz J Laughlin J Ellegood R Walton N Feliz-Adomo P Laflamme E Sanchez-Santiagor Waltonn Feliz P Laflamme M Phalen J Lennartz J Ellegood |
| INPO aspect | |
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Finding - Cook - IR 05000316/2012008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Cook) @ 2012Q3
Self-Identified List (Cook)
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