Modeling and calculation of the three-dimensional reactor core and comparative analysis of various homogenization schemes for asymmetrical fuel assemblies based on BEAVRS 2.02

Abstract

BackgroundThe two-step approach, as the major method in reactor numerical calculation, faces the challenge of accuracy in calculating high-fidelity models because of limitations imposed by simplified assumptions such as assembly homogenization and the core diffusion calculation.PurposeThis study aims to validate the applicability of the two-step method in high-fidelity numerical simulation calculations and homogenization scheme of asymmetrical assemblies.MethodsBased on the Benchmark for Evaluation And Validation of Reactor Simulations Rev.2.0.2 (BEAVRS 2.02), the deterministic codes DRAGON5 and DONION5 were used to calculate the BEAVRS benchmark in the hot zero-power state. Firstly, a transport calculation was performed with DRAGON5 on the fuel assemblies. Then, the complete core calculation was done with DONJON5 using diffusion theory. Finally, the calculation errors of traditional homogenization, one-time multi zone homogenization, and multiple multi zone homogenization schemes were compared.ResultsThe results show that these calculations are comparable to the accuracy of the benchmark, with the deviation of critical boron concentration being less than 5×10-5 and the error of the control rod value calculation being within 5×10-4. Comparison results of the fission rate indicate that the average deviation of the assemblies near the asymmetric fuel assemblies is reduced from 5.62% to 3.345% using one-time multi zone homogenization scheme.ConclusionsThis study verifies the applicability of the two-step approach in high-fidelity numerical simulation calculations.

Keywords

• two-step approach
• beavrs
• homogenization techniques
• dragon/donjon
• simulation