Validation of 3D Depletion Model of the Parcs–Paths Program for WWER-440 Type Reactors

Within the framework of a three-dimensional model, the burnup process of the core of the WWER-440 reactor was studied using measurements of the operating cycles of the Armenian NPP (ANPP). Simulation results showed that a model study that takes into account only the temperature dependence of the thermal conductivity of the PATHS (PARCS Advanced Thermal Hydraulic Solver) fuel leads to discrepancies with the measured values of the boron concentration as the cycle time increases. However, taking into account the dependence of thermal conductivity on burnup significantly improved the agreement between the results of PARCS–PATHS (Purdue Advanced Reactor Core Simulator) and measurements. Taking into account the heat transfer of the fuel rod gap further improved the agreement between the simulation and measurement results. For the non-peripheral fuel assemblies, the relative difference between the predicted PARCS–PATHS and measured thermocouple results meet the acceptance criteria (≤10%). For peripheral assemblies that are in contact with the reflector by three faces, the relative error exceeds the acceptance criteria (15%) by 1–2%.