Abstract: The powdered form of nuclear fuels such as uranium dioxide and plutonium dioxide are dispersed in an about 3N aqueous nitric acid solution, and irradiated by UV rays at a wavelength of approximately 300 nm in order to improve a dissolving rate of the nuclear fuels. This enables easy and efficient dissolution of the nuclear fuels.

Abstract: In a method of coextracting neptunium and plutonium, a nitric acid solution containing a mixture of neptunium and plutonium is oxidized by irradiation of ultraviolet light. As a result, different valences of neptunium are adjusted all into the valence 6, which can remain in water, and in the meantime, valences of plutonium are adjusted into the valence 4 or 6, which can be extracted in the organic phase. It is therefore possible to coextract neptunium and plutonium without difficulty. The coextracted neptunium and plutonium can be used in forming mixed fuel by blending at least a portion of at least one of neptunium and plutonium which neptunium and plutonium have been formed by separating a nitric acid solution containing neptunium and plutonium by exposing the solution and a reducing agent to ultraviolet radiation to adjust the valences, and extracting the solution using an organic phase to extract plutonium from the solution into the organic phase.

Abstract: In a method of separating neptunium and plutonium, a nitric acid solution containing a mixture of neptunium and plutonium is oxidized by irradiation of ultraviolet light in the presence of a reducing agent. As a result, different valences of neptunium are adjusted all into the valence 5, which can remain in water, and in the meantime, valences of plutonium are adjusted into the valence 4 or 6, which can be extracted in the organic phase. It is therefore possible to separate neptunium and plutonium from each other without difficulty.