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The main results of a study of regimes for dissolution of plutonium oxide and mononitride powders, obtained by the pyrochemical method from weapons plutonium, in acids for subsequent extraction removal of gallium, americium, and ballast impurities and obtaining ceramic-type plutonium oxide powder suitable for fabricating mixing oxide fuel are presented. It is established experimentally that plutonium oxide and mononitride obtained by the pyrochemical method dissolve rapidly in the acid mixture HNO 3 12 moles/liter and HF 0.1 moles/liter. Plutonium extraction into solution reaches >99%.Americium must be removed from oxide fuel which is to be used in thermal reactors. This operation can be combined with the removal of gallium and ballast impurities by the Purex process, which by now has been well-perfected. The properties of plutonium dioxide which is obtained by oxidizing plutonium hydride or nitride have been little studied. Specifically, there are no data on the behavior of plutonium oxide and plutonium mononitride, obtained by the pyrochemical method, in solutions of nitric acid.For this reason the following were done: 1) the dissolution of plutonium dioxide and mononitride in solutions of nitric acid and mixtures of nitric and hydrofluoric acids was studied to determine the optimal technological parameters (the concentration of the nitric acid, the volume/mass ratio, the solution temperature, the composition of the gas phase, undissolved residue);2) the possibilities were determined of the formation of pyrophoric compounds in the undissolved residues after plutonium dioxide and nitride have dissolved; and3) the regimes of plutonium leaching from undissolved residues were perfected. The present work is devoted to studying the combined process which incorporates the pyrochemical synthesis of plutonium oxide or mononitride powder from weapons plutonium, their dissolution in acids, obtaining plutonium solutions for the standard extraction purification and preparation of plutonium dioxide powders (Fig. 1). A previous study of the dissolution of mixed uranium and plutonium mononitride and monocarbide pertained to compact fuel kernels with density 85-95% of the theoretical value [1,2].

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