Current state and trends of development of structural materials for fast reactor cores

The problems are discussed related to radiation and corrosion damage to fuel element cladding and assembly cans, due to neutron radiation and liquid sodium. The aims are formulated of the development of suitable materials with increased resistance to radiation damage and of ways of protecting fuel elements against corrosion by sodium, this for fast reactors with a neutron flux density of up to 1016 cm-2s-1. The basic trends are summed up of the research and development of these materials in the USSR, the USA, the FRG, France and Great Britain. The analysis shows that a suitable material has not yet been found for fast reactor fuel element cladding whose volume growth by pore development would be smaller than 5%. The best prospects with regard to resistance against volume growth are shown by chromium nickel austenitic steels (40 to 50% Ni), with regard to sodium corrosion by refractory metals, namely Mo. (J.C.)