Core neutronic characterization of a large molten‐salt cooled thorium‐based solid fuel fast reactor

Abstract

Thorium is three to four times as abundant as uranium, providing a potentially large, reliable long-term supply of clean energy, if it is exploited. In high temperature nuclear systems, molten salts have many attractive advantages as a coolant. Prior work of homogenous core model indicated that the liquid-salt-cooled solid-fuel fast reactor (LSFR) could achieve a self-sustained core based on thorium fuel with exciting neutronic performance. To further explore this concept, a fuel assembly design and a heterogeneous LSFR reference reactor core model were put forward in this study. The aim of this study was to inspect more closely the LSFR self-sustaining core and deeply investigate the neutronic characteristics with fine burnup computational model. One of the benefits of using fine burnup computation model for heterogeneous core was that the detailed physical information in each assembly could be obtained. The leakage rate at End of Equilibrium Cycle (EOEC) comprised 4.93% of 3100 MWth LSFR heterogeneous active core model and 3.00% of prior homogenous active core model. Besides this, the LSFR core neutronic characteristics were in good consistency with that of homogenous model. The characteristics of thorium-based LSFR reference core are (a) a high discharge burnup ~20% FIMA; (b) small reactivity swing during the reactor lifespan; and (c) the negative reactivity temperature coefficients for all cases.