Heavy water nuclear reactor

An improved design is proposed of fuel channels and assemblies of rod-type fuel elements for a heavy water reactor. Fuel assembly mantles are made from normal structural material and are slidably connected in the axial direction to fuel element assemblies. The fuel channels are provided with stops for retaining the assembly mantles above the reactor core during reactor fueling. Thermal shields in the form of bushings manufactured from a material having a small neutron capture cross section are provided inside the fuel channels in the core area. Thus, thermal insulation bushings from expensive material are fixed and need not be replaced in each refueling. (M.S.)