Abstract: A salt waste composed mainly of chlorides, which is generated from the step of a molten salt electrolytic purification in dry reprocessing of a spent metallic nuclear fuel, is reacted with boric acid at high temperature to convert the chlorides in the salt waste into oxides. The resulting oxides of the salt waste are easily vitrifiable, and a vitrification product is obtained by adding a vitrifying additive to the oxides, heat-melting the mixture to form a molten mixture and cooling the molten mixture.

Abstract: According to the present invention, a fibrous material having a property to adsorb radioactive nuclides in the form of ion or molecule onto its surface is added to a cement type hydraulic solidifying material used for a solidifying material, a waste container, a structure in disposal site and a back-filling material used for production of a waste form of radioactive wastes, whereby improvement of long-term endurance of the waste form, the structure and the like and diminishment of leaching of radioactivity from the waste form and the like can be simultaneously attained.

Abstract: A method is disclosed for denitrification of nitrates and nitrates present in aqueous waste streams. The method comprises the steps of (1) identifying the concentration nitrates and nitrites present in a waste stream, (2) causing formate to be present in the waste stream, (3) heating the mixture to a predetermined reaction temperature from about 200.degree. C. to about 600.degree. C., and (4) holding the mixture and accumulating products at heated and pressurized conditions for a residence time, thereby resulting in nitrogen and carbon dioxide gas, and hydroxides, and reducing the level of nitrates and nitrites to below drinking water standards.