Results of Research and Optimization for the Third-Generation Fuel Assemblies PK-3 VVER-440
Construction of VVER-440 fuel assemblies was being continuously modernized throughout the whole period of these reactors’ operation. The interest in further increasing the fuel cycle efficiency has currently resulted in the technical proposal of a third-generation assembly, which incorporates the following improvements:
• replacement of working assembly shroud with stiffening angles;
• reduced fuel element diameter (higher water-uranium ratio);
• reduced fuel cladding thickness from the inside (a possibility to load more uranium);
• increased diameter of fuel pellet with exclusion of its central hole (increased mass of uranium in the fuel assembly);
• replacement of several fuel elements in the working assembly with displacers of various kinds;
• increased fuel enrichment – up to 4.95% of uranium-235.
The paper summarizes the results of calculations of the basic neutron physics parameters for various configurations of VVER-440 third-generation RK-3 fuel assemblies, the results of computer exploration of fuel loads with various RK-3 options and the results of computer analyses of fuel element’s behaviour in RK-3 fuel assemblies. The paper also provides a technical and economic assessment of fuel cycles with different RK-3 fuel assembly options for VVER-440.