Engineering and physical fundamentals for the plasma processing technology of MNUP and MOF spent nuclear fuel of fast neutron reactors

Abstract

One of the urgent tasks of the nuclear power industry today is reprocessing of spent nuclear fuel (SNF) and radioactive waste (RW), which is necessary to switch to a closed fuel cycle in order to use the reactor fuel resources to more extent by separating minor actinides for reuse of refabricated fuel. Another equally important driver for the creation and implementation of such technology is the environmental requirements aimed at reducing the disposal of radioactive waste and the scope of high-level waste transportation. It should be noted that any civil technology for SNF reprocessing must meet the requirement of non- proliferation of nuclear weapons, i.e. is obliged to prevent the release of plutonium, including by changing the operating modes of the equipment. There are promising hydrometallurgical and pyrochemical technologies developed at present day, as well as plasma processing methods. This report presents the engineering and physical fundamentals of plasma separation of SNF and RW. The potential advantages of plasma technologies for SNF or RW processing include a small amount of additional waste, the ability to adapt to different types of SNF and RW, and a possibility of implementing the technology into existing and designed material processing cycles and varying the processing scale from on-site to plant-size ones within large facilities. An important feature of plasma methods, i.e. insufficient selectivity for the separation of minor actinides from each other, shall also be mentioned. It is precisely such “crude” approach that ensures acceptable civilian processing technology, which satisfies the conditions for non-proliferation of nuclear weapons. The paper proposes an approach aimed to use the accelerating potential to overcome the energy and angular distribution of plasma ions at the entrance to the separation area and a potential well for the spatial separation of ions of different masses. It considers the physical principles of the plasma separation method and its main stages. There are provided experimental results achieved so far at a pilot facility for testing the plasma separation method. The results of calculations of ion trajectories and energy cost estimates are shown, demonstrating the prospects of the plasma method for process application. The process flow diagram of plasma processing and the steps to be taken to develop the technology are also discussed.