Application Research For VVER Fuel Management Code System

With the development of nuclear power in our country, many types of nuclear power plants come into being. The VVER reactors are pressurized water reactors (PWRs) which employ hexagonal shaped fuel assemblies. The type of VVER-1000 is used in TianWan NPP in Jiangsu Province. So it is necessary to develop the VVER fuel management code packages.Such code package TPFAPHEX/SIMSIX is introduced. The hexagonal assembly homogenization code TPFAPHEX uses transmission probability method combining with the respond matrix method for calculation of neutron flux spatial energy distribution in PWR hexagonal fuel assembly. Core burnup calculations are carried out with the 3D two-group code SIMSIX. TPFAPHEX and SIMSIX are linked by the code LINK. Several feedbacks can be considered such as burnup, core power, the density of coolant, the control rods and Xe.Based on calculations, attention should be paid. First, after modified TPFAPHEX can calculate any form of the fuel pins in the assembly which has two enrichments. Second, cross section-burnup is fitted for three regions. Third, how to take the values of burnup, the density of coolant, etc is summarized.The data of VVER-1000 Kalinin NPP provided by IAEA are used to validate the code package TPFAPHEX/SIMSIX. Comparing with the results provided by some other international organizations, k calculated by TPFAPHEX agrees with that calculated by CASMO-HEX and KASSETA. Most of the variances are less than 1%. The variances of critical boron concentration between calculation and experiment are about 50 ppm. Good agreement is obtained in the calculations from the point of view of assembly power peaking factors as well as from thepoint of view of the location of the assemblies with maximum power. TPFAPHEX/SIMSIX is still on development.