Effect of the Heat Transfer Correlation Choice on the Coupled Assessment of Energy Release and Stress-Strain State of an Elementary Supercritical Fuel Rod Under Nuclear Heating Conditions

Abstract The paper presents a multiphysics procedure for estimating the parameters of a fuel channel under nuclear heating conditions. The idea of the approach is to determine the multiplying properties of an elementary fuel rod in the 4-group diffusion approximation, together with the estimation of the temperature field of both the supercritical coolant and the structural elements of the fuel rod. Group constants are prepared on the basis of a precision code that takes into account the design features of the reference fuel assembly. Several dozen different correlations are implemented into the procedure to calculate heat transfer. A concept of parametric energy release functions is proposed, which can be useful, for example, when modeling the core using CFD. The concept is based on the analysis of the influence of parametric temperature profiles (according to the classification of heat transfer regimes) on the effective multiplication factor. The paper presents the results of assessments of the fuel rods temperature state and thermal power depending on the selected reactivity margin and the selected HTC correlation. The stress-strain state of fuel rods was analyzed for each calculation option. The developed approaches are fast and can be used to optimize design decisions.