Uranyl nitrate pouring solution for producing nuclear fuel particles and

Abstract

Sorbitol, or another polyalcohol such as erythritol, dulcitol or xylitol, is added to a solution containing uranyl nitrate which may also contain another heavy metal, such as throium or plutonium, prior to preneutralization with ammonia in order to provide a highly viscous solution that can be preneutralized to a great extent without premature precipitation of uranium. The high viscosity makes possible the formation of favorably large drops when the solution is dripped into an ammonia containing bath for external gelification of the drops. According to the pouring apparatus used, the particles after washing, drying and sintering have a diameter between 0.6 and 1.5 mm. The polyalcohol is added to a hydrosol containing from 1.5 to 2 moles per liter of heavy metal, the polyalcohol being added until concentration of one-third mole of polyalcohol per mole of heavy metal is reached. In certain cases up to four moles of ammonium nitrate per liter are added. The solution so produced can be preneutralized with up to 90% of the amount of ammonia stoichiometrically necessary for the separation of uranium without the formation of any precipitate, preferably by first adding ammonia gas under strong stirring and then adding ammonium bicarbonate in excess, which decomposes to liberate ammonia to an extent determined by the temperature, which is to be precisely controlled. It is possible to obtain this way a solution of predetermined viscosity from which the excess ammonium bicarbonate can readily be separated.