GB1071411A - Improvements in or relating to fuel elements for nuclear reactors - Google Patents

Abstract

1,071,411. Forging. CENTRAL ELECTRICITY GENERATING BOARD. Jan. 29, 1964 [Jan. 29, 1963], No. 3694/63. Heading B3H. [Also in Division G6] A nuclear reactor fuel element is formed by completely enclosing a rigid rod of fissile material in an integral can. The enclosing is carried out in a die by means of a high-speed, highenergy process, utilizing for example high or low explosives, electro-hydraulic or electromagnetic discharge, or a stored energy pneumatic process. The fuel rod may be solid, e.g. uranium, or composted powder. The canning is preferably a magnesium alloy, but a composite canning billet may be employed to give different properties along the can; the wall thickness may also be varied. The can may also be powdered metal, composted either before or during the coming process. The canning material may be preheated, before or after being placed in the die. Referring to Fig. 1, the billet 12 is placed in the die 10 and the fuel rod 11 and former 14 forced into the billet and die respectively, thus totally enclosing the rod as seen in Fig. 2. The grooves 17 are to prevent ratchetting; the combination of the forming pressure and temperature difference (hot canning billet) results in excellent heat transfer across the interface. Canning may be carried out in a vacuum, or non-oxidizing atmosphere. The die may include longitudinal recesses for forming baffles and splitters (e.g. 26 in Fig. 8, not shown). Fig. 7 shows a fuel element machined from Fig. 2 and including a stabilizing spider 23, the fins may alternatively be of herring-bone pattern. In an alternative method of canning (Fig. 3, not shown), a tubular billet of canning metal is placed in a die having both ends open, and a clearance fit fuel rod placed in it; formers are forced into both ends of the die simultaneously. Helium gas, or a radioactive clathrate compound can be included in the can for leak detection purposes.