Nuclear fuel assembly with a lock-support spacer grid

摘要

An improved grid for a nuclear reactor fuel assembly that has an egg-crate base grid as the primary support structure with each support cell of the base grid that supports a fuel rod having a lock-support sleeve that is rotatable within the support cell between a first and second orientation. In the first orientation the lock-support sleeve fits loosely within the support cell of the base grid and respectively, loosely receives the fuel rods that are loaded therein. The lock-support sleeves are then rotated to a second orientation that locks the fuel rods axially within the support cells.

主权项

1. A fuel assembly for a nuclear reactor comprising:
a parallel array of a plurality of elongated nuclear fuel rods supported between a lower nozzle and an upper nozzle and having an axial length along the elongated dimension of the nuclear fuel rods; a plurality of spaced support grids arranged in tandem along the axial length of the fuel rods, between the upper nozzle and the lower nozzle, at least partially enclosing an axial portion of the circumference of each fuel rod within a support cell of the support grids to maintain a lateral spacing between fuel rods, at least one of the support grids comprising;an egg-crate base grid having a plurality of orthogonal intersecting straps that define the support cells at the intersection of each four adjacent straps that surround the nuclear fuel rods, a length of each strap between the intersections of the four adjacent straps forming a wall of the corresponding support cell, and
a lock-support sleeve configured to fit within at least one of the support cells and in a first orientation loosely receive the nuclear fuel rod therethrough and in a second orientation place a transverse pressure on the fuel rod to restrain the fuel rod axially, the lock-support sleeve being rotatable within the at least one of the support cells between the first orientation and the second orientation.