05000454/FIN-2007009-02
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Finding | |
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| Title | Failure to Implement Timely Corrective Actions for Degraded Sx Riser Piping |
| Description | The team identified an apparent violation of 10 CFR 50 Appendix B, Criterion XVI, Corrective action, associated with the licensees failure to take timely corrective actions after identification of the corroded essential service water system riser pipes. Specifically, the licensee failed to take timely actions to remove the external corrosion layer present on the riser pipes to support sufficient wall thickness measurements to assess the significance of the pipe wall loss. Consequently, the licensee operated the plant for an extended period of time with a substantial loss of pipe wall on the essential service water riser piping while corrosion proceeded to the point that a through-wall leak developed on the 0C essential service water riser pipe. The cause of this apparent violation was related to the Decision Making Component (Item H.1(b) of IMC 305) for the cross-cutting area of Human Performance, because the licensee failed to make conservative assumptions in decisions affecting the integrity of the essential service water riser piping. The presumption of pipe integrity was not based on sufficient information to be able to demonstrate that the proposed action/decision to leave these risers in service was safe. The licensee subsequently completed a plant shutdown and replaced the degraded portions of these essential service water system riser pipes. The finding associated with this apparent violation was greater than minor because the degraded essential service water piping condition resulted in an increase in the likelihood of the loss of the essential service water system due to pipe failures, which directly affected the Initiating Events Cornerstone. It was also associated with the Equipment Performance attribute of the Mitigating Systems Cornerstone and affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e., core damage). The finding associated with this apparent violation was assessed using a Phase 3 analysis in accordance with NRC Inspection Manual Chapter 0609 Appendix M, Significance Determination Process Using Qualitative Criteria, and is preliminarily determined to have low to moderate safety significance (White) |
| Site: | Byron  |
|---|---|
| Report | IR 05000454/2007009 Section 4OA3 |
| Date counted | Mar 31, 2008 (2008Q1) |
| Type: | Violation: White |
| cornerstone | Initiating Events, Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | C Moore D Hills J Mcghee L Kozak M Holmberg T Bilik V Meghanib Kemkerj Jacobson R Skokowskij Heckp Lougheed S West |
| CCA | H.14, Conservative Bias |
| INPO aspect | DM.2 |
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Finding - Byron - IR 05000454/2007009 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2008Q1
Self-Identified List (Byron)
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