05000331/FIN-2011002-03
From kanterella
Jump to navigation
Jump to search
Finding | |
|---|---|
| Title | Licensee-Identified Violation |
| Description | The licensee identified a finding of very low safety significance (Green) and an associated NCV of 10 CFR 50, Appendix B, Criterion III, Design Control, for the failure to ensure the seismic qualification of the SBLC system test tank. Specifically, the licensee completed engineering analyses that concluded the SBLC test tank may not withstand a DBE when filled greater than three-fourths full of water. This condition had the potential to cause the failure of other safety-related SBLC equipment, rendering the system inoperable. Immediate corrective actions included draining the test tank. The licensee also revised applicable procedures to ensure that the test tank was drained prior to restoring SBLC system operability following maintenance or surveillance activities. The licensee documented the issue and associated corrective actions in CR 0594231. The failure to ensure the seismic qualification of the SBLC system test tank during a DBE was a performance deficiency. The performance deficiency was more than minor since it was similar to IMC 0612, Appendix E, Example 3j. The seismic qualification deficiencies were significant enough to require compensatory measures and procedural changes to ensure seismic qualification of the SBLC system test tank. The inspectors determined the finding could be evaluated using the SDP in accordance with IMC 0609, Significance Determination Process, and affected the Mitigating Systems Cornerstone. According to IMC 0609, Attachment 0609.04, Table 4a, the finding screened as potentially risk significant due to a postulated seismic event and the Region III Senior Risk Analyst (SRA) performed an SDP Phase 3 risk-assessment of the performance deficiency. The Duane Arnold SBLC system is used as a backup for reactivity control and thus the SRA evaluated the risk impact for failure to scram (anticipated transient without scram) events. The Phase 3 analysis assumed that, given a seismic-induced functional failure of the SBLC system and the control rod drive and hydraulic units, the core damage probability was 1.0. The SRA used generic seismic fragility information and plant-specific seismic hazard information from the Risk-Assessment Standardization Project (RASP) Handbook. Using Table 4A-1 from the RASP Handbook, the frequency of various seismic events was determined. Using this information and assuming a conditional core damage probability of 1.0, the seismic core damage frequency for this issue was below 1E-6. The SRA also reviewed the licensees risk evaluation, which reached the same conclusion. This result showed that the change in core damage frequency for this issue was of very low safety significance (Green). |
| Site: | Duane Arnold  |
|---|---|
| Report | IR 05000331/2011002 Section 4OA7 |
| Date counted | Mar 31, 2011 (2011Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | L Haeg M Mitchell R Murray A Wilson B Cushman K Riemer |
| INPO aspect | |
| ' | |
Finding - Duane Arnold - IR 05000331/2011002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Duane Arnold) @ 2011Q1
Self-Identified List (Duane Arnold)
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||