Study on dynamic characteristics of fission products in 2 MW molten salt reactor

In this study, a numerical flow model of the fission products (FPs) in the primary loop system of a molten salt reactor (MSR) was established and solved using Mathematica 7.0. The simulation results were compared with those of the ORIGEN-S program in the static burnup mode, and the deviation was found to be less than 10%, which indicates that the results are in good agreement. Furthermore, the FPs distribution in the primary loop system under normal operating conditions of the 2 MW MSR was quantitatively analyzed. In addition, the distribution phenomenon of the FPs under different flow rate conditions was studied. At the end of life, the FPs activity in the core region (including active region, and upper and lower plenum regions) accounted for 77.3%, and that in the hot leg #1, main pump, hot leg #2, heat exchanger, and cold leg region accounted for 1.2%, 16.15%, 0.99%, 2.5%, and 1.9%, respectively, of the total FPs in the primary loop under normal operating conditions. The proportion of FPs in the core decreased with the increase in flow rate in the range of 2.24–22,400 cm 3 s −1 . The established analytical method and conclusions of this study can provide an important basis for radiation safety design of the primary loop, radioactive source management design, thermal–hydraulic safety analysis, and radiochemical analysis of FPs of 2 MW MSRs.