Experience of mixed nitride uranium-plutonium fuel fabrication at the siberian chemical plant js']jsc site

The "Proryv" project is significant for the Russian Federation and relates to the activity that has been assigned the status of "especially important" for the Rosatom State Corporation. It is planned to develop a new generation of nuclear energy technologies based on the closed nuclear fuel cycle of fast neutron reactors with a lead coolant and mixed nitride uranium-plutonium nuclear fuel as a part of this direction (hereinafter - MNUP fuel). The first method for MNUP fuel producing was the direct synthesis of nitrides from starting metals and alloys of uranium and plutonium (hydrogenation-nitration), implemented in laboratory conditions. The disadvantage of this method is its explosion and fire hazard. A method for carbothermal reduction in the atmosphere of nitrogen from the initial oxides of uranium and plutonium is proposed for the production of MNUP fuel on an industrial scale. According to the results of the literature data analysis of considered above methods, carbothermic reduction in a nitrogen atmosphere from the starting oxides of uranium and plutonium is the most optimal for the industrial production of MNUP fuel. Based on the foregoing as part of the "Proryv" project the concept of MNUP fuel production by the carbothermic synthesis method was adopted as the main method at the site of Siberian Chemical Plant (Joint stock company). For this purpose in 2012 a set of experimental facilities (a unique platform for the pilot industrial production of fuel components (from pellets to fuel assemblies) of fast reactors) was created. During this period for the first time in the world at the set of experimental facilities full-scale nuclear fuel assemblies based on MNUP fuel composition were made, data for verifying the technological model of the processes for manufacturing MNUP fuel were prepared, using experimental models of the equipment a complex technological process with experimental scaling of the manufacturing technology of MNUP fuel was developed, an automatic algorithm sorting of tablets and systems for providing and controlling the parameters of the box atmosphere was developed, as well as construction materials of furnaces for the synthesis and sintering of nitride fuel were tested. In total, 24 nuclear fuel assemblies - more than 1000 fuel elements of various designs with different shells - were transferred for loading into the BN-600 reactor. Successfully completed irradiation of 21 nuclear fuel assemblies.