05000361/FIN-2011010-01
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Finding | |
|---|---|
| Title | Inadequate Assessment of Seismic Qualification of Emergency Diesel Generator Buried Fuel Oil Tanks |
| Description | The team identified a Green noncited violation of 10 CFR 50, Appendix B, Criterion III, Design Control, which states in part: Measures shall be established to assure that applicable regulatory requirements and the design basis are correctly translated into specifications, drawings, procedures, and instructions. Specifically, from initial construction until July 22, 2011, the licensee had not properly evaluated the seismic qualification of the buried emergency diesel generator fuel oil storage tanks, to ensure that the tanks structures would not fail during a seismic event. The calculation did not accurately reflect the actual installed condition of the fuel oil tanks. The team determined that failure of the tanks to remain intact would impact the capability of the safety related emergency diesel generators to perform their design function following the event. This finding was entered into the licensees corrective action program as Nuclear Notification NN-201548802. The team determined that the failure to have an adequate seismic calculation for emergency diesel generator fuel oil storage tanks was a performance deficiency. The finding was more than minor because it was associated with the mitigating systems cornerstone attribute of design control, and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the inadequate design analysis of these components could have resulted in structural failure, preventing continued operation of the emergency diesel generators after an earthquake. In accordance with Inspection Manual Chapter 0609, Attachment 4, Phase 1 Initial Screening and Characterization of Findings, the team determined that the finding was of very low safety significance (Green) because it did not represent a design issue resulting in the loss of function, did not represent an actual loss of a system safety function, did not result in exceeding a Technical Specification allowed outage time, and did not affect external event mitigation. Specifically, the licensee performed a preliminary re-evaluation of the tank shell stresses due to the concrete structures, and determined that the tank stresses were still within the American Society of Mechanical Engineers (ASME) Code allowable stresses following a Safe Shutdown Earthquake (SSE). The team reviewed the evaluation, and concurred that the stresses were below those allowed by ASME Boiler and Pressure Vessel Code. This finding did not have a crosscutting aspect because the most significant contributor did not reflect current licensee performance |
| Site: | San Onofre  |
|---|---|
| Report | IR 05000361/2011010 Section 1R21 |
| Date counted | Sep 30, 2011 (2011Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | J Watkins R Kopriva S Pindale T Farnholtz W Sherbin S Kobylarz |
| INPO aspect | |
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Finding - San Onofre - IR 05000361/2011010 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (San Onofre) @ 2011Q3
Self-Identified List (San Onofre)
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