GB1402197A - Combinations of nuclear reactor fuel rods and spacers therefor - Google Patents

Abstract

1402197 Fuel elements SIEMENS AG 23 March 1973 [24 March 1972] 14265/73 Heading G6C Each fuel rod 2 of an assembly has at least two parallel-flanked ribs 5 disposed at intervals of less than 180 degrees about its periphery and projecting into parallel-flanked slots 6 situated in a spacer 4, the fuel rod thereby being tangentially supported. The slots 6 are each defined by a pair of projections 7, 8 on the spacer 4. Each fuel rod 2 comprises pellets of fissile material stacked within a stainless steel cladding 1. The spacer 4 is either assembled from sheet-metal strips disposed on edge or produced from a solid plate by spark erosion, the latter method being particularly suitable with metallic materials which are difficult to work, e.g. non-rusting Ni alloys. There are preferably three ribs 5 spaced apart by 120 degrees about each fuel rod 2. Any increase in diameter of the cladding 1 during operation merely has the result that the ribs 5 penetrate further into the slots 6. The fuel rods 2 are securely held fast against turning and lateral movement is positively limited to an amount necessary to permit thermal expansion. The slots 6 around each hexagonal cell of the frame 4 are formed alternately in its inner and outer surfaces. The ribs 5, as well as the projections 7, 8 defining the slots 6, are bevelled at their ends to facilitate the introduction of the fuel rods 2 into the frame 4. In an alternative, but less desirable construction, the slots are formed in the cladding and the ribs on the frame.