Safety enhancement in the molten salt fast reactor (MSFR)

This thesis presents a new modification for the cooling circuit design of the Molten Salt Fast Reactor MSFR to solve the problem of high temperatures in the hot spots regions that affect the reactor safety. These high-temperature regions appear as a result of the salt recirculation of the liquid fuel. There is also a problem of delayed neutron fraction decrease. This decrease in β_eff. reduces the safety of the reactor because it shifts it closer to the prompt critical state. The new modification depends on distributing the flow between the side and the centre by adding a coolant circuit that passes through the core centre from the bottom to the top.At the end of this study, we see that this new design moderated the hot spots and reduced the maximum temperature to about 1094 k. This value is greater than the core outlet temperature by about 67 k and smaller than the maximum temperature of the benchmark design by about 190 k. The design also reduced the salt velocity from the benchmark value of 3.9 m/s to the value of 2.38 m/s. The core calculations of the MSFR were done using different codes. KENO (one of the SCALE package), WIMS, and MCNP5 nuclear codes were used in the beginning to calculate the multiplication factor Ke_fff or the benchmark design for work verification. After that, WIMS and TRITON (one of the SCALE package) were used to find the nuclear constants and use them in the multi-physics code COMSOL to model the reactor and calculate the neutron flux Eigenvalues of the neutron diffusion equation and then calculate the multiplication factor K_eff and get the neutron flux distribution. This distribution was used to make a coupling between the neutronic and the thermal-hydraulic of the reactor. The study showed the differences between the multiplication factor values from each code and compared them with the values from old reference studies and reflected the effect of the selection of the data libraries and the code on the results.