Patent Number: 046876308
Section: abstract

The hold-down plate of the top nozzle of a fuel assembly is interconnected to the upper extension members of the fuel assembly guide thimbles by an improved joint structure associated with each of a plurality of passageways through the hold-down plate which receives an upper end portion of each one of the guide thimble upper extension members. The improved joint structure includes an internal annular ledge on the hold-down plate within the passageway at a lower portion thereof so as to surround the upper end portion of the extension member, an annular recess on the upper end portion of the extension member, and an annular spring member fitted on the upper end portion of the extension member within the recess. The internal ledge and spring member interfere with one another so as to limit upward movement of the hold-down plate along the guide thimble extension member, while the spring member is resiliently yieldably for absorbing the energy of an impulse load applied to the hold-down plate so as to thereby limit transfer of the load to the guide thimble extension member.