Dependence of mechanical properties on swelling in austenitic steels

The effect of swelling on the behavior of reactor materials is an important concern for the performance and lifetime extension issues of nuclear reactors. Austenitic steels are the main structural material in fast reactors and they are widely employed also in light water reactor systems. Material property data concerning austenitic steels of EBR-II and BN350 fast reactors has been compiled. The Russian austenitic steels show strong correlation of ultimate tensile strength and total elongation with swelling over a large swelling range. Some assemblies from BOR-60 reactor also support these findings (1). For American steels, the changes in the strength and ductility with neutron exposure and swelling have been investigated in some detail. However, most of these studies are confined to modest amounts of swelling where there may be only limited correlation with mechanical properties (2,3). Therefore, the data on Russian austenitic steels is of great importance to understand the mechanical property behavior of austenitic steels over a large range of swelling (or dose) and to apply these findings to the light water reactor systems considering exposure temperature, dose rate and neutron energy spectrum differences. (author)