Fuel assembly or control assembly with releasable locking between the

Abstract

An fuel or control assembly for a nuclear reactor includes an elongated case having a longitudinal axis, side walls extending parallel to the axis and defining an interior with a polygonal cross section, two ends, a rim, and at least one case opening being surrounded by the rim at one of the ends. The side walls have inner surfaces with a groove-like profile being machined therein and extending at a predetermined distance from the rim. A bundle of rods parallel to the axis or an elongated absorber body is disposed in the interior of the case. An end part has lateral surfaces extending parallel to the axis and being adapted to the polygonal cross section of the interior. The end part has corners disposed between the lateral surfaces being rounded and shaped in the axial direction to form dovetail-like protrusions. The end part is rotatable into a first position relative to the case in which the end part is insertable axially from outside into the opening in the case during installation and in which the end part is axially displaceable outwardly during disassembly. The end part is rotatable into a second position relative to the case for operation of the nuclear reactor. The lateral surfaces of the end part are opposite the side walls of the case in the first position, and the dovetail-like protrusions engage the groove-like profile and are locked to the side walls of the case as soon as the end part is rotated about the axis into the second position.