September-October 2018 NPJ

Ibrahim Ezzi Ibrahim M. Ezzi leads Westinghouse’s reactor internals guide tube guide card wear related projects. He has worked in roles of Designer, Analyst and Project Manager on several reactor internals related projects and is a recipient of George Westinghouse Signature Award for Technical Excellence. He enjoys working closely with customers, understanding their needs and providing solutions accordingly. Mr. Ezzi has been with Westinghouse since 2007. He moved to Pittsburgh from Hyderabad, India, after completing his graduation in Mechanical Engineering. Mr. Ezzi holds a patent disclosure and has published a technical paper on the guide card wear subject for the Internal Conference on Nuclear Engineering (ICONE). He is a certified project management professional and also a graduate of Leadership Pittsburgh Inc.’s Leadership Development Initiative program. Mr. Ezzi holds a M.S. degree in Industrial Engineering from University of Pittsburgh and is currently pursuing his M.B.A. at Carnegie Mellon University. Allowing More Operation Cycles Owners of Westinghouse nuclear steam supply system-design reactors wanting more operational service from their 17x17 A, AS or AXLR style guide tubes now have options to postpone their replacement with innovative solutions. The first solution – called a thicker special guide plate – has already been successfully extending guide tube opera- tional service for at least two refueling (or fuel) cycles in a plant. The second, longer term solution – called a continuous spe- cial guide – will be qualified in 2019 to move to the subsequent phases of manu- facturing and installation; it is expected to extend guide tube operation for six to nine fuel cycles. Both of these solutions evolved following a guide card wear measurement campaign conducted in 2009 at a nuclear power plant in Spain and were established mainly due to the aggressive guide card wear observed at this plant. Normal wearing of the guide card surfaces – which are the areas of the guide openings for the control rods to move through – occurs primarily due to impact- fretting of the rodlets. In Westinghouse design reactors, guide tubes are located in the upper internals to provide guidance of the rod cluster control assemblies above the core fuel assemblies. Each guide tube houses one rod cluster control assembly, which is made up of 16 to 24 long, slender rodlets that are commonly attached to a drive rod by a coupling fixture called a spider. There are typically 25 to 33 guide tubes in a two- loop reactor and 45 to 57 guide tubes in three-loop and four-loop reactors. Guide cards are spaced along the length of the guide tubes to keep the rodlets of the rod cluster control assemblies aligned during movement. Since 2009, Westinghouse has performed more than 30 guide card wear measurement campaigns globally. The findings at the plant in Spain were not consistent with findings at other plants and led Westinghouse to issue Nuclear Safety Advisory Letter (NSAL) NSAL-10-1, “Rod Control Cluster Assembly Guide Card Wear.” While it was not considered a substantial safety hazard pursuant to the requirements delineated in 10 CFR Part 21, “Reporting of Defects and Non Compliance,” the NSAL informs industry of the findings, of plants that may be affected and of recommended actions. In 2015, another plant in Europe reported similar findings, which ledWestinghouse, with the support of the utility, to conduct an inspection of a plant in the U.S. and ultimately to conclude that additional plants using the 17x17 A, AS and AXLR guide tube designs could be affected. Westinghouse subsequently issued NSAL 17-1, “Guide Tube Guide Card Wear Attributed to Ion Nitride Rod Cluster Control Assembly,” to notify industry. At the time of the original NSAL, only the guide cards at the nuclear power plant in Spain needed to be addressed. Because the guide card wear at that plant was aggressive and occurring in the guide cards of several guide tubes, the options to replace the guide tubes, or innovate an alternative solution were considered. Replacing worn guide tubes with new ones is a very expensive approach, especially considering the complexities of their disposal. Additionally, procuring new guide tubes requires a lead time of a few years. Depending on the model, there are 10 to 12 guide cards in the guide tubes of 17x17 A, AS and AXLR guide tube designs. Each guide card has 24 holes to guide the individual rodlets, and slots to allow the spider vanes of the rod cluster control assembly, to which the rodlets are attached, to pass through. The Westinghouse guide tube wear measurement criteria for 17x17 A, AS or AXLR guide tubes allows for six consecutive guide card holes to break out before a guide tube is deemed 36 NuclearPlantJournal.com Nuclear Plant Journal, September-October 2018 Continuous Special Guide By Ibrahim Ezzi, Westinghouse Electric Company.