Development of technologies for production of fuel with minor actinides

Highlights: • The full use of the energy potential of uranium raw materials. • R&D program to involve MA in mixed nitride. • Production of mixed nitride fuel with MA – homogeneous option. • Production of mixed nitride fuel with MA – intra-pin heterogeneity. • Development of fuel for intra-FA heterogeneity of MA transmutation. The main results and plans for the future in the framework of R&D on the involvement of americium, neptunium (MA) in mixed nitride fuel of fast reactors are presented. Depending on the method and amount of MA introduced into the mixed nitride, R&D is carried out in three directions: homogeneous introduction of minor actinides; intra-fuel pin heterogeneity and intra-fuel assembly (FA) heterogeneity of minor actinides. At the first stage, the technology of homogeneous transmutation is being tested using dismountable FA (OU) in the BOR-60 reactor. Each OU includes 7 fuel pins. An intermediate unloading of fuel pins is planned with the corresponding additional loading of new ones and irradiation prolongation. The irradiation parameters of subsequent experimental fuel pins with MA will be specified after determining the characteristics of fuel pellets of mixed nitride with MA. In order to study the effect of MA additives on the cladding corrosion from the first batches of pellets, at the end of 2018, three experimental fuel pins with Np and Am with pellet density of ~10 g/cm³ in OU-16 were manufactured and loaded in BOR-60. Upon reaching the maximum fuel burn-up of 1.36 at% and a dose of 10.7 displacements per atom (dpa) OU-16 was unloaded for intermediate examination of fuel pins with MA. To minimize the loss of Am at the stage of fuel pellets sintering, the method of high-voltage electric impulse consolidation for pellets with Am is considered.