Abstract: The present invention relates to a process to dissolve plutonium or a plutonium alloy, by placing it in contact with an aqueous dissolution mixture, wherein said dissolution mixture comprises nitric acid, a carboxylic acid with complexing properties with respect to plutonium, and a compound comprising at least one —NH2 radical such as urea. The invention also relates to a process to convert plutonium or a plutonium alloy into plutonium oxide and to manufacture nuclear fuel from said oxide. The invention particularly applies to the dismantling of plutonium contained in nuclear weapons with a view to its use in civilian nuclear reactors, particularly in the form of MOX fuel.

Abstract: This invention relates to an electrolytic method for the selective recovery and recycling of silver from a nitric acid solution containing it in the form of Ag(I), this method comprising successive steps of electro-deposition of the silver in the form of silver metal Ag(0), and then of redissolution of the deposited silver Ag(0), to give a final solution of Ag(I) in which the step of electro-deposition is carried out at a prescribed current and the successive steps of electro-deposition of the silver and of redissolution of the deposited silver are carried out in the same apparatus. The invention is applicable particularly to the selective recovery of Ag(I) by reduction to Ag metal from nitric acid solutions arising from the processing of plutonium containing waste in plants for the reprocessing of nuclear fuels and to the redissolution of the silver metal to form Ag(I) with the purpose of recycling it to an upstream point of the method.

Abstract: The invention relates to a process for the electrochemical oxidation of Am(III) to Am(VI), usable for separating americium from spent nuclear fuel reprocessing solutions.The process consists of adding to the aqueous nitric solution (17) containing the Am(III) a) heteropolyanion able to complex the americium, such as potassium phosphotungstate and b) the Ag(II) ion for oxidizing Am(III) being converted into Ag(I), and subjecting the solution to an electrolysis under conditions such that electrochemical regeneration takes place of the Ag(II) ion from the Ag(I) ion obtained during said oxidation.After oxidizing Am(III) to Am(VI), it is possible to extract the latter in an appropriate organic solvent.

Abstract: The invention relates to a process for recovering the plutonium contained in the solid waste, such as process, technological and laboratory waste.The waste is contacted with aqueous nitric acid solution having a nitric acid concentration of 2 to 8 mole/l, which contains a compound of Ag.sup.2+ soluble in the solution, for oxidizing the plutonium present in the waste and for dissolving same in the nitric solution.Preferably, contacting takes place in an electrolytic cell having an anode and a cathode, by applying a potential difference between anode and cathode which is sufficient to continuously regenerate the Ag.sup.2+ ions used for oxidizing the elements present in said waste.