Reactor materials study of EBR-II and BN350

Abstract

The objective of this research is to go through the technical review of how the body of information relating to the in-reactor behavior of structural materials of Experimental Breeder Reactor-II (EBR-II) and BN350 are associated. Such an effort would lead to reviewing and combining the data from both sides as it concerns important issues for the Light Water Reactor (LWR) and fast reactor communities. The most important issue is the applicability of the BN350 and EBR-II data for the studies on prolonging the lifetime of LWRs. EBR-II and BN350 are sodium cooled fast reactors that had operated for more than twenty-five years. Studies to review and compile the existing reactor materials data for the purpose of this thesis were completed both in the U.S. and in Kazakhstan. The compilation, comparison and combination of the data was done by developing several databases using SQL software. The BN350 data on ultimate tensile strength and total elongation depending on swelling have been shown. The BN350 data is over a large swelling range (0-15 %) and reveals total consumption of ductility and strength as the amount of swelling reaches high values. The BN350 data is an important example supporting other studies that show a dominant correlation between swelling and mechanical property loss in the high swelling range (>10 %). Different forms of axial strain data from both reactors, which could be of use in reactor control and decommissioning studies, are presented, as well. The swelling formulations developed for Russian and American austenitic steels before reaching steady-state conditions are compared, and possible applications of the formulation for Russian steels to some compositionally similar American steels have been discussed. The effects of slight composition and metallurgical condition differences on swelling are stated to explain the possible differences between the data points of American steel and the predictions for the corresponding Russian steel. Some of the compiled data on ferritic/martensitic steels are presented showing their better mechanical property and swelling behaviors in the EBR-II and BN350 exposure conditions.