Nowadays the concept of closed nuclear fuel cycle (CNFC) for fast neutron reactors (FR) is developed in Russia. CNFC can be implemented for FR with sodium coolant using mixed uranium-plutonium oxide (MOX) fuel and for reactors with lead coolant using mixed U-Pu-(Np-Am) nitride (MINT) fuel.
By “PRORYV” Project the combined “РН-technology” was proposed as the technology for reprocessing of MOX and MINT fuel . This technology combines pyrochemical and hydrometallurgical methods of SNF reprocessing.
To work on the hydrometallurgical part of “РН-technology” the full-scale crystallization purification test bench was made at JSC “Siberian Group of Chemical Enterprises” . This test bench consists of such steps as SNF extraction, reductive striping of Pu, U stripping, concentration of striped Pu-Np mixture and crystallization refining of U-Pu-Np mixture.
At present time according to current industrial SNF technologies Pu is separated, transferred into oxide form and then at the stage of fuel fabrication added to uranium. However the crystallization process due to the similarity of U(VI) and Pu(VI) properties allows to recover them simultaneously as uranyl and plutonyl nitrate hexahydrates that is much in line with concept of non-proliferation of nuclear materials.[3,4]
The crystallization experiments of pure uranyl nitrate hexahydrate and mixture of uranyl and plutonyl nitrate hexahydrates were performed with the use of the full-scale crystallization purification test bench. The crystallization purification experiments of uranyl nitrate showed that such elements as Се, Nd and La don’t co-crystallize with U and mostly get into the mother-washed solution that allows increasing the level of purification by the factor of 1-2. During the experiments of uranyl and plutonyl nitrate hexahydrates co-crystallization the co-crystallization coefficient range from 0,7 to 0,8 according to the process conditions.
Achieved results have confirmed not only earlier successfully proven possibility of combined separation of U(VI) and Pu(VI) from nitric acid solution as uranyl and plutonyl nitrate hexahydrates, but also showed the ability of using crystallization process for SNF reprocessing in industrial scale.
1. A.Yu. Shadrin, K.N. Dvoeglazov, A.G. Maslennikov, V.A. Kashcheev, S.G. Tret’yakova, O.V. Shmidt, V.L. Vidanov, O.A. Ustinov,V.I. Volk, S.N. Veselov, V.S. Ishunin, Radiokhimiya, 2016, Vol. 58, No. 3, pp. 234–241.
2. S.G. Terentiev, S.A. Cheshuyakov, A.Yu. Shadrin, K.N. Dvoeglazov,Full-Scale Refining Extraction-Crystallization Stand to Prove Out the Technology for Reprocessing SNF from Fast Breeder Reactors – First Test Findings, International Conference on Fast Reactors “FR17” - Ekaterinburg, Russia, 2017.
3. Shibata A., Ohyama K., Yano K., et al. Experimental Study on U-Pu Cocrystallization Reprocessing Process., J. of Nucl. Scien. Technol. 2009. Vol. 46. № 2. P.204-209
4. V.I. Volk, S.N. Kruglov, S.N. Veselov, Е.V. Zenchenko, L.V. Arseenkov, K.N. Dvoeglazov, S.A. Cheshuyakov, А.Yu. Shadrin. Co-Crystallysation of uranyl and plutonyl nitrate hexahydrates. Atomic energy, 2017, in print.