Incore thimble tube wear analysisElmer, I am no longer with the Plant, but Salem put a modification (designed by CE) in to the lower internals to install inserts into the core plate in incore locations in the mid 1980s. These were about 20 " long and were rolled into place during a refuel outage working from the manip crane bridge. The upper part was larger than the tube and had flow slots cut into the sides. This closed the tolerance and provided some protection from cross flow at the area between the core plate and the fuel assy. You may want to get in touch with Paul Lippie at Salem to evaluate its effectiveness (been ~ 20 yrs in service) and see if this would be cost effective to eliminate the testing and replacement of thimbles. ----- Original Message ----- From: Lehmann Elmer E To: pwrrm@keffective.com Sent: Friday, March 24, 2006 9:13 AM Subject: [Pwrrm] Incore thimble tube wear analysis
Hopefully this email will get to all the Westinghouse pwr Reactor Engineers for them to reply.
Wolf Creek is currently putting together the paperwork for an application to the NRC for Plant Life Extension. We currently track and evaluate incore thimble tube fretting wear in our lower internals, fuel assembly bottom nozzle, and lower core plate using a spreadsheet we have developed that has an input from Eddy Current Test results that are obtained every refueling outage. The group set up for gathering information for Plant Life Extension indicates the NRC requires a procedure instead for the analysis and actions taken as a result of the analysis.
1) Do any of you use such a procedure, and if you do, could you supply me a copy to model one after to use at Wolf Creek?
2) If any of you have been approved for Plant Life Extension, did the NRC require such a procedure for your plant in order to be approved.
3) How do you account for wear scars that may extend into the area of repositioned thimble tube,i.e., a repositioning of 2 inches still is in the wear area and the next ECT shows large amount of wear in one cycle of operation.
I would appreciate the above information so that if I need to write a procedure for analysis, it is very similar to procedures at other plants so it will not be used to ratchet other plants to revise their procedure or NOT get approved for Plant Life Extension.
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