05000443/FIN-2011010-02
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Finding | |
|---|---|
| Title | Inadequate Operability Determination for Degraded Concrete Structures Housing Safety-Related Equipment |
| Description | The inspectors identified a finding in that NextEra failed to fully evaluate potential structural and seismic response impacts in accordance with the requirements in NextEra procedure EN-AA-1001 after identifying a degraded and nonconforming condition related to degraded conditions for some safety related structures due to Alkali-Silica Reaction (ASR). Specifically, the evaluation did not consider the following effects due to changed properties of concrete, as reflected in reduced values of the modulus of elasticity as measured directly from concrete core samples: 1) building natural frequency in the dynamic response; 2) performance of anchorages and embedment of systems and components attached to the structures; and, 3) shear strength or capacity of affected structures and the dynamic flexural response especially those buildings without corresponding shear reinforcement. The failure to conduct adequate prompt operability determinations per procedure EN-AA-203-1001 for degraded and nonconforming conditions associated with ASR was a performance deficiency relative to a self imposed standard. Specifically, the prompt operability determinations conducted following the identification of ASR in safety-related structures did not completely analyze the effects of the reduced modulus of elasticity on the dynamic and flexural response of the structures to seismic events for certain conditions. This performance deficiency was associated with the design control aspect of the Mitigating Systems cornerstone; and, based on a comparison to Example 3.i of Appendix E of IMC 0612, it was determined to be more than minor. Specifically, the failure to conduct adequate operability determinations adversely affected the Mitigating Systems cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences because it required an additional evaluation to confirm that the design bases was met. The issue was evaluated using IMC 0609, Significance Determination Process, and was determined to be of very low safety significance (Green). Specifically, when evaluated under IMC 0609, Attachment 4, the performance deficiency was a design or qualification deficiency confirmed not to result in an actual loss of safety function. The finding had a cross cutting aspect in the area of problem identification and resolution, P.1(c), related to ensuring that issues potentially impacting nuclear safety are thoroughly evaluated. Specifically, NextEra did not fully evaluate conditions adverse to quality, including evaluating the effects of the reduced concrete modulus of elasticity for impact on operability of the affected structures. |
| Site: | Seabrook  |
|---|---|
| Report | IR 05000443/2011010 Section 4OA5 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | Finding: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | A Shaikh G Thomas M Modes R Conte S Chaudhary W Raymond |
| CCA | P.2, Evaluation |
| INPO aspect | PI.2 |
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Finding - Seabrook - IR 05000443/2011010 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Seabrook) @ 2011Q4
Self-Identified List (Seabrook)
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