Controlled porosity reactor fuel

Thermally stable UO2 reactor fuel pellets have been obtained using volatile additive pore formers and high activity powders. Various additives, including uranyl and ammonium salts, have been studied, nearly all of which appear similar in effect. Due to the inherently small percentage of fine pores (<2μm dia.) present and large grain size of pellets made by this process, it is expected that the fuel will exhibit excellent irradiation stability. Density can be controlled reproducibly by varying the amount of pore former such that fuels suitable for either LWR's or fast reactors can be prepared. The size fraction of additive does not effect the thermal response of the pellet. The size distribution of the pores can be controlled within fine limits. (Auth.)