Development of fuel and materials for fast breader reactor

Among the concept of breeder reactors, that having the possibility of practical use industrially in the world is fast breeder reactor utilizing fast neutron reaction. The present state of the construction of fast breeder reactors and the main particulars of the prototype reactors in the world are shown. In Japan, the experimental reactor Joyo is operated at 75 MW, and the prototype reactor Monju begins the construction in 1980. The materials used for fast breeder reactors are roughly classified into those for core structure elements, coolant, reactor vessels, primary cooling system, secondary cooling system, and steam generators. The state of development of these materials are explained. As the fuel for fast breeder reactors, mixed oxide fuel is used, and sodium is used as coolant, therefore the material with good corrosion resistance to sodium and high temperature strength is required, but there is not much achievement for other materials than austenitic stainless steel. Accordingly austenitic stainless steel is mostly used for core structure elements, neutron shielding, reactor vessels, primary and secondary cooling systems and others. Boron carbide is used for control rods, but europium is promising. Steam generators comprise evaporators and superheaters, and Cr-Mo steel is used for the former, and austenitic stainless steel for the latter. (Kako, I.)