Alternative fuels to urania

Abstract The fueling of the power reactors happens at relatively long intervals of up to 2 years, which is a convenient way of reducing operation costs by cutting down on fueling shut down periods. To be able to accommodate long runs, the fuels must comply with strict characteristics and properties. Uranium dioxide (UO2) or urania has been used reliably in light water reactors for several decades; therefore newer proposed fuels must meet a high standard to be seriously considered. The nearest term accident tolerant fuel (ATF) is a slight modification of the current urania by doping it with chromia to increase its thermal conductivity and to make it more resistant to crumbling at high irradiation doses. Like the case of the chromium-coated zirconium alloys for cladding, the doped urania fuel may have the easiest and fastest path for regulatory licensing approval. The second family of ATFs considered is called the high uranium density fuel because due to their specific stoichiometry these compounds contain more atoms of uranium per unit mass of fuel than urania. The two most advanced fuels in the high-density family are uranium silicide and uranium nitride. The largest handicap of the two high-density fuels is their high reactivity with water and steam in the case of a cladding breach. Not much is known of their response to an actual nuclear reactor environment. The uranium silicide fuel is currently under irradiation in the advanced test reactor and in a commercial reactor as part of a fuel vendor evaluation.