TOP NOZZLE ASSEMBLY HAVING DOUBLE HOLDDOWN SPRING IN NUCLEAR FUEL ASSEMBLY

摘要

A top nozzle assembly having a double hold down spring in a nuclear fuel assembly is provided to stably fix a position of the nuclear fuel assembly and prevent the nuclear fuel assembly from being bent by providing a proper pushing force for a length change of the nuclear fuel assembly. A top nozzle assembly having a double hold down spring in a nuclear fuel assembly includes a pushing plate(11), an outer guide post(12), a supporting unit(10), a central guide post(14), and an elastic body(20). The elastic body has a spring which provides an elastic force to the nuclear fuel assembly. The outer guide post is vertically connected between the pushing plate and a flow field plate. The central guide post is vertically protruded to the flow field plate in parallel with the outer guide post in the pushing plate direction. The elastic body has first and second springs which have different elastic coefficient and are penetrated by the outer guide post. The first and second springs are connected to each other in series. A plate is installed between the first spring and the second spring of the elastic body.