Patent Number: 052079805
Section: abstract

A replacement guide pin assembly is provided for aligning a nuclear fuel assembly with an upper core plate of a nuclear reactor core. One embodiment of the guide pin assembly includes an elongated guide pin body, a ferrule, and a lock screw. The guide pin body has a lower expandable base insertable within a hole in the top nozzle, and capable of expanding radially outwardly relative to a longitudinal axis of the guide pin body to provide an interference fit with the top nozzle. The ferrule is insertable within the top nozzle hole, interfitted with the guide pin body, and capable of imparting a radially and outwardly directed force on its lower expandable base to expand it within the hole of the top nozzle and thereby secure the guide pin body to the top nozzle in response to a predetermined displacement of the ferrule relative to the guide pin body along its longitudinal axis. The lock screw is insertable within the top nozzle hole, interfitted with the ferrule and threaded into the guide pin body so as to produce the predetermined displacement of the ferrule. Another embodiment of the guide pin assembly includes a guide pin body, an expandable insert body, and a ferrule. The guide pin body has a lower attachment base insertable within the top nozzle hole. The expandable body is insertable within the top nozzle hole, interfitted about the lower attachment base of the guide pin body, and capable of expanding radially outwardly relative to a longitudinal axis of the guide pin body to provide an interference fit with the top nozzle. The ferrule is insertable within the hole in the top nozzle, interfitted with the expandable body, and threaded with the lower attachment base of the guide pin body to produce a predetermined displacement of the ferrule relative to the guide pin body along its longitudinal axis sufficient to impart a radially and outwardly directed force on the expandable body to produce expanding thereof within the hole of the top nozzle into the interference fit with the top nozzle and thereby secure the guide pin body to the top nozzle.