Behaviour of fuel assemblies and fuel elements under irradiation in the fast neutrons reactor BN-350

The efficiency of all types of assemblies and fuel elements of the reactor BN-350 is in detail considered. The factors limiting the efficiency are indicated. The behaviour of assemblies with stainless steels duct is studied. It is studied. It is shown that the efficiency is restricted in this case by shape and dimensional changes of hexagonal ducts due to radiation swelling creep of structural materials. The problem of dimensional changes of ducts was solved for cores of reactor BN-350 and BN-600 after testing in BN-350 of experimental assemblies with ducts made of ferric-martensitic steel 12Cr13Mo2NbVB. For fuel elements of second type of loading with cladding made of stainless steel 0Cr16Ni15Mo3Nb the efficiency is limited by depletion of nuclear fuel of 13% h.a. and damage doze of 80 dpa. To increase depletion of nuclear fuel the core of the BN-350 is supplied by assemblies of modernized type with elements having a large gas plenum and cladding made of stainless steel 0Cr16Ni15Mo2Mn2TiVB which has a good resistance to irradiation. The efficiency of fuel elements of modernized assemblies in the reactor BN-350 core condition is provided up to 15% h.a. and damage dose 105 dpa