Feasibility Study of 24-month Refueling for VVER

In order to reduce the number of refueling overhauls within the service life of VVER, improve the unit capacity factor, and increase annual power generation, this paper studies the feasibility of realizing the 24-month refueling cycle of VVER by increasing the average ²³⁵U enrichment of fuel assemblies and the number of refueling batches using KASKAD software package, so as to design a long and short alternative 24-month long cycle core refueling scheme. The analysis of the calculation results of this scheme shows that the duration of cycle is 633.5 EFPD (effective full power days) or 667.1 EFPD, respectively, and each core characteristic parameter meets the design limit requirements and has a large margin. Compared with the current 18-month core refueling cycle scheme, this scheme has good economic benefits. When the international natural uranium purchase price does not exceed 60 dollars/pound, each unit will bring at least 12 million yuan of income per year. Therefore, the core loading scheme of the 24-month refueling equilibrium cycle studied in this paper has good safety, economy and flexibility, and has very good engineering application value.