05000458/FIN-2008002-03
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Finding | |
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Title | Improper Design Control for Evaluating Emergency Diesel Generator Turbocharger Combustion Air Pipe Stresses (Section 1R19.3) |
Description | The inspectors identified a noncited violation of Title 10 CFR Part 50, Appendix B, Criterion III, \"Design Control,\" for failure to incorporate accurate design information into a calculation to determine emergency diesel generator turbocharger discharge combustion air pipe stresses. This resulted in pipe failure. Specifically, a calculation assumed nonconservative pipe wall thicknesses and process air temperatures, treated pipe end points as rigid anchors and failed to use stress intensification factors. This resulted in low calculated pipe stresses. With appropriately calculated pipe stress values, Entergy personnel could reasonably have been expected to adequately modify the combustion air piping to preclude subsequent failures. This issue was entered into the licensees corrective action program as Condition Report RBS-2008-2869. This issue was determined to be more than minor because it affected the mitigating systems cornerstone objective and was similar to Manual Chapter 0612, Appendix E, Example 3.j because the errors were considered more than a minor calculation error in that the deficiency failed to identify the high pipe wall stresses that significantly reduced the overall allowable material strength margin. Later pipe and weld flaws developed at the intercooler adapter and turbocharger end connections that rendered the emergency diesel generator Division 2 inoperable. Using the Manual Chapter 0609, \"Significance Determination Process,\" Phase 1 worksheet, the inspectors determined that the issue was of very low safety significance (Green) because it did not screen as risk significant due to a seismic, flooding, or severe weather initiating event (Section 1R19.3). |
Site: | River Bend ![]() |
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Report | IR 05000458/2008002 Section 1R19 |
Date counted | Mar 31, 2008 (2008Q1) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.19 |
Inspectors (proximate) | R Deese G Guerra R Kopriva P Alter G Larkin D Bollock B Correll |
INPO aspect | |
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Finding - River Bend - IR 05000458/2008002 | |||||||||||||||||||||||||||
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Finding List (River Bend) @ 2008Q1
Self-Identified List (River Bend)
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