05000455/FIN-2013005-05
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Finding | |
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Title | Reactor Vessel Design Documents Not Updated to Reflect Unit 2 Missing Head Stud |
Description | The inspectors identified a finding of very low safety significance and an associated NCV of 10 CFR 50, Appendix B, Criterion III, ?Design Control,? when licensee personnel failed to maintain reactor vessel design specifications and analyses up-to-date for the 53 stud vessel head configuration applicable to Unit 2. Specifically, the reactor vessel Design Specification and Design Analysis did not reflect a modified and stuck stud number 11. The licensee entered this issue into their (CAP) as Issue Report (IR) 01578285, ?Design Documentation is Not in Compliance with ASME [American Society of Mechanical Engineers]. The inspectors determined that the performance deficiency was more than minor because it was associated with the Design Control attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective of limiting the likelihood of those events that upset plant stability and challenge critical safety functions. The inspectors also answered ?Yes? to the more-than-minor screening question, ?If left uncorrected, would the performance deficiency have the potential to lead to a more significant safety concern?? Specifically, the inspectors determined that this issue was more than minor because, if left uncorrected, the failure to maintain the Unit 2 reactor vessel design specification and analysis caused them to be inaccurate and if these documents were subsequently relied on for future design changes, the vessel design may not be adequate to maintain structural integrity during design basis events resulting in a loss-of-coolant-accident (LOCA). The inspectors performed a Phase 1 Significance Determination Process (SDP) screening and evaluated this issue by application of Questions 1 and 2. Questions 1 and 2 asked: ?If after a reasonable assessment of degradation, could the finding result in exceeding the reactor coolant system leak rate for a small LOCA or could the finding have likely affected other systems used to mitigate a LOCA resulting in a total loss of their function (e.g., Interfacing System LOCA)?? In this case, the degradation prompting the reduction in the number of head studs and the licensee?s failure to maintain the design analysis had not yet affected the ability of the reactor vessel to perform its design functions, so the inspectors answered these questions ?No? and this issue screened as having very low safety significance. The
inspectors determined that this finding was not indicative of current performance, and therefore no cross-cutting aspect was assigned. |
Site: | Byron |
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Report | IR 05000455/2013005 Section 1R18 |
Date counted | Dec 31, 2013 (2013Q4) |
Type: | NCV: Green |
cornerstone | Initiating Events |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.18 |
Inspectors (proximate) | C Thompson D Jones E Duncan J Cassidy J Laughlin J Mcghee J Robbins M Holmberg M Jones N Feliz Adorno R Ng S Sheldon B Bartlett B Palagi |
Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
CCA | H.14, Conservative Bias |
INPO aspect | DM.2 |
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Finding - Byron - IR 05000455/2013005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2013Q4
Self-Identified List (Byron)
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