Some results of developments and investigations of fuel pins with metal fuel for heterogeneous core of fast reactors of the BN-type

RIAR has performed a set of developments and investigations of experimental metal fuel pins as applied to possible use in the BN reactors with heterogeneous oxide-metal core of various types: BEAH (by FA heterogenization), IFAH (intra FA heterogenization), IFEH (intra fuel element heterogenization). This set covers calculated, process, out-of-pile, in-pile and postirradiation examinations of metal fuel, fuel pins and FA of various types and purposes. Main radiation-thermal effects have been studied both in fuel specimens and in fuel pins. Specifically, effect of radiation growth and radiation swelling of metal fuel doped-free and doped uranium, and uranium alloys with plutonium) and physical-chemical interaction between fuel and steel claddings on parameters of the fuel pin reliability during irradiation in reactors MIR, BOR-60 and BN-350 have been investigated. The experiment confirmed the effectiveness of the developed approaches and technique of providing reliability of metal doped-free fuel pins under the conditions similar to possible conditions in the heterogeneous core of the BN type: BEAH, IFAH, IFEH. (author)