Feasibility of deterministic self-shielding models for Molten Salt Fast Reactor analysis using DRAGON5 code with ENDF/B-Ⅷ.0 data library

摘要

Due to its complex geometry and neutron spectrum, the GenⅣ Molten Salt Fast Reactor was largely studied using the "one-step" calculation scheme, based on the Monte Carlo method. However, for whole-core simulations, this method requires a long computing time to get accurate results. A deterministic "two-step" calculation scheme must be considered and applied to minimize the computational resources. In general, the first step is to obtain multi-group homogenized and condensed cross-sections, while the second step is using those multi-group cross-sections to perform the whole-core simulations. The treatment of the resonance cross-section behavior is one of the biggest problems that affect the accuracy of the multi-group cross-section and handling such a problem is required before proceeding to the second step calculation. So, it is essential to choose a proper and accurate self-shielding model. In this paper, the different self-shielding models are performed with the deterministic code DRAGON5, using ENDF/B-Ⅷ.0 with various energy group libraries on which the self-shielding model is implemented. The infinite multiplication factor K_(inf) and the radial distribution of absorption, nu-fission, and capture rates were calculated at the low temperature to demonstrate the rim effect. To guarantee accurate predictions of the results revealed by the self-shielding models, the temperature was increased in the range 893 K-1123 K, and a series of different parameters, such as K_(inf), average percent error (AVG), root mean square (RMS), and mean relative error (MRE), were calculated as functions of temperature. The calculation's accuracy is determined by comparing the results with the stochastic transport code OpenMC. It was found that the deterministic transport code DRAGON5 can accurately treat the effect of self-shielding behavior in the MSFR; hence, DRAGON5 code can be utilized as a tool to generate the multi-group homogenized cross-sections of MSFR for whole-core calculations.