Abstract: An easily dismountable fuel assembly for a nuclear reactor comprising a bundle of parallel fuel slugs held spaced apart by cross-pieces transverse to the slugs and by assembly bearing tubes which take the places of some of the slugs, the tubes being longer than the slugs and being secured at each end to a respective plate for maintaining the fuel assembly rigid. Each tube is secured to at least one end plate by a cylindrical sleeve comprising a connection complementary with a corresponding connection borne by the respective end of the tube and formed with a profile for engagement by a tool for rotating the sleeve around its axis in one direction for securing it to the tube and clamping the tube to the end plate in the axial direction, and in the other direction for releasing the tube from the plate.