Increasing burn-up of KLT-40S fuel by introduction of neptunium

Abstract

A floating nuclear power plant (FNPP) is one of the varieties of small nuclear power plants. Among mobile small nuclear power plants, floating power units with KLT-40S reactors, developed on the basis of reactor technologies already mastered in nuclear shipbuilding, deserve special attention. The involvement of protactinium and neptunium in the fuel compositions can significantly increase fuel burn-up in light-water reactor. The chains of nuclide transformations, starting with protactinium and neptunium, are characterized by a gradual improvement of the multiplying properties, which ensures an increased fuel burn-up. Due to limited reserves of protactinium and neptunium, their use in large-scale nuclear power plants may not proper. In this paper, the use of neptunium (as a more accessible material compared to protactinium) as burnable absorber in order to increase burn-up of KLT-40S fuel is considered. For neutron-physics calculations, GETERA and SKETCH-N software packages are used. Particular attention is paid to ensuring favourable values of fuel and coolant temperature reactivity coefficients.