Criticality Properties and Control Rod Worth of the Critical Experiment Device for MSR Research

Zero-power experiments are very important parts in design verification for all reactor types. In the 1970s, in China, at the Shanghai Institute of Applied Physics (then, Shanghai Institute of Nuclear Research), a Critical Experiment Device (cold) was established for research on the physics characteristics of the molten salt reactor (MSR), and a series of zero-power experiments was successfully performed; related experimental results were obtained later. The device consisted mainly of graphite moderator and powdered BeF2 – UF4 / ThF4 fuel and could achieve a maximum power of 200 W. The current work is focused on criticality properties with various core configurations and fuel arrangements of this device and the worths of the cadmium rods used in the device. Evaluations on the agreement of calculation results with experimental data showed good results. Discrepancies between the calculation results and the experimental data might be primarily caused by the simulated outermost fuel element positions not being exactly the same as the experimental arrangements and the unmodeled instruments used in the experiments. The findings in this work can be considered a step of verification of simulation methods and calculations for a cold MSR.