Modular nuclear fission waste conversion reactor

A small nuclear fission reactor designed to operate for a decade or longer without refueling, which reactor comprises:

• a reactor vessel,
• a central core within said vessel for creating heat via fission reactions in said core, which core includes a plurality of initial fissile sections located in a plurality of vertically spaced apart horizontal regions, and flanking conversion sections, said a plurality of initial fissile sections remaining an active, integral part of a critical core region throughout the lifetime of the central core,
• a helium circulation system for extracting heat from said core by the circulation of helium into and out of said vessel to maintain the core temperature between about 700° C. and 1000° C. and to generate power from said heated helium exterior of said vessel,
• said a plurality of initial fissile sections of said core comprising fuel elements in the form of silicon carbide containers which contain sintered fuel bodies comprising carbide fissile and fertile nuclides, the silicon carbide containers having a thickness of at least about 1 mm, and
• a system for continuously withdrawing volatile fission products from said fuel elements during normal operation, the fission products being removed in a flow path separate from the helium circulation system.