NEW CONTROL AND PROTECTION SYSTEM FOR SD-TMSR

The current work introduces a reliable safety system based on control rods in addition to the online feed system reactivity control in the Single-fluid Double-zone Thorium-based Molten Salt Reactor (SD-TMSR). The reactivity of the SD-TMSR core is controlled through two systems of control assemblies: (1) the Control Safety Devices (CSD) and (2) the Diverse Safety Devices (DSD). In the present work, the control rods are natural B4C and B4C-90 (with 90% weight content of the main absorbing 10B isotope). Since the numbers and distribution of control assemblies in SD-TMSR have not been studied previously, we proposed a unique distribution as a starting point for this analysis. The distribution of these 25 fuel assemblies with control rods in the SD-TMSR core and their numbering scheme were presented in this paper. Additionally, excess reactivity, control rod worth, and shutdown margin were calculated using Monte Carlo code Serpent2. Analysis results showed that the proposed placement of the control rods will make it possible to compensate for excess reactivity during fuel burnout and emergency shutdown of the reactor.