HBK project high temperature reactor fuel cycle. HTR Fuel Performance. Presentations at the 89th Meeting of the American Ceramic Society

Compilation of two papers presented at the 89. Meeting of the American Ceramic Society held in Pittsburgh in 1987: ''IRRADIATION BEHAVIOR OF ADVANCED FUEL ELEMENTS FOR THE HIGH TEMPERATURE REACTOR'' - Following the development, testing and utilization in AVR and THTR of mixed oxide Thorium/High Enriched Uranium Fuels, the German HTR program has concentrated on Low Enriched UO₂ (LEU) fuels. A series of irradiation tests have been completed with these fuels. These experiments have shown in-pile failure fractions below 2x10^-5 and fission product release orders of magnitude lower than in previous HTR fuels. ''FAILURE OF TRISO FUEL PARTICLES AT VERY HIGH TEMPERATURES'' - The fuel particle for the High-Temperature Gas-Cooled Reactor, which is coated with multiple layers of pyrolytic carbon and silicon carbide, fulfills the functional requirements of a fuel element in retaining fission products. Irradiated and unirradiated fuel particles have been evaluated for their high temperature (2000- 2500°C) performance and failure mechanisms in multi-national laboratory heating tests. A phenomenalistic failure model, which incorporates the SiC failure mechanisms of corrosion by fission products and SiC thermal decomposition, as well as diffusion of fission products in the pyrocarbon, is fitted to the data.