Process for the separation and recovery of plutonium and neptunium from a nitric acid solution

摘要

A method of separating and recovering Pu and Np from a Pu- and Np-containing nitric acid solution. The method comprises the steps of subjecting a nitric acid solution containing Pu and Np to valence adjustment by adding a reducing agent consisting of hydroxylamine nitrate and hydrazine to said nitric acid solution so as to reduce Pu and Np in said nitric acid solution to Pu (III) and Np (IV), respectively; adjusting a nitric acid concentration of said nitric acid solution after said valence adjustment to 6 to 8 M; bringing said nitric acid solution after said nitric acid concentration adjustment into contact with a strong basic anion exchange resin so as to cause Np to be selectively adsorbed by said resin and to separate and recover Pu as a plutonium nitrate solution; and eluting said adsorbed Np (IV) by using diluted nitric acid of 1 M or below so as to recover Np as a neptunium nitrate solution. The valence adjustment step may be carried out by subjecting the Pu- and Np-containing nitric acid solution to electrolytic reduction instead of using the reducing agent.