05000382/FIN-2014008-06
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Finding | |
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| Title | Feedwater System Vibrations |
| Description | The inspectors identified an unresolved item concerning the design control aspect of main feedwater vibrations that began after steam generator replacement during refueling outage 18. Title 10 CFR Part 50, Appendix B, Criterion III, Design Control requires, in part, that design control measures shall be established to provide for verifying or checking the adequacy of design, such as by the performance of design reviews, by the use of alternate or simplified calculational methods or by the performance of a suitable testing program. Description. The licensee experienced elevated main feedwater vibrations after installing replacement steam generators during refueling outage 18 in 2012. In its cause analyses, the licensee determined that these vibrations caused or contributed to several equipment failures. The licensee determined vibrations to be: the possible cause of unintended feedwater regulating valve closure and subsequent plant trip (CR-WF3-2013-00445), a contributing cause to a loss of operability of emergency feedwater isolation valve (twice in one month) (CR-WF3-2013-04433 and -04670), the apparent cause of a loss of operability of emergency feedwater containment isolation and backup flow control valve EFW-229A (CR-WF3-2013-00883), and the apparent cause of damage to several main feedwater pipe supports both inside and outside of containment (CR-WF3-2014-02135). Damaged component supports included degraded feedwater hangers inside of containment, a completely failed constant support hanger rod inside of containment, a cracked weld on a snubber trunnion support, several snubber bench test failures due to high drag loads, and a completely locked snubber inside of containment. During refueling outage 19 in early 2014, the licensee repaired vibration-damaged components and supports and hardened the main feed system such that it is less susceptible to vibration-induced failure. The licensee evaluated the component support failures in Condition Report CR WF3-2014-2135. The licensee performed an analysis to demonstrate the structural integrity of the main feedwater piping over the past operating cycle. It is indeterminate whether the vibration-induced failures were the result of inadequate design review practices. Therefore, the team was unable to determine whether a performance deficiency exists. This issue is unresolved pending further NRC review: URI 05000382/2014008-06, Feedwater System Vibrations. |
| Site: | Waterford  |
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| Report | IR 05000382/2014008 Section 4OA2 |
| Date counted | Jun 30, 2014 (2014Q2) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | G Miller P Jayroe S Crane A Sanchez C Speer E Rueschd Merzke E Ruesch F Ramirez G George M Hayes T Hipschma |
| Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - Waterford - IR 05000382/2014008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Waterford) @ 2014Q2
Self-Identified List (Waterford)
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