Calculation and Analysis of Neutronic and Kinetic Parameters in NuScale Small Modular Reactor

Abstract: Since the neutronic calculation of a nuclear reactor is a basis for designing other parameters such as thermal hydraulic, safety, etc., thus, in this work the neutronic and kinetic parameters of the next generation SMR reactor called NuScale have been calculated and analyzed. These parameters include the effective multiplication factor (keff), neutron flux, axial and radial power peaking factor, effective delayed neutron fraction and prompt neutron lifetime. Moreover, the burn up calculation is performed to find the mass changes in fissile isotopes such as 235U and 239Pu, burnable poison material and some of important fission fragments. The acid boric concentration in the coolant has been found about 1.8 g/kg in the criticality condition. Also, the average values of thermal, epithermal and fast neutron fluxes are obtained about 1.85×1013, 8.79×1013 and 3.67×1013□(n/(〖cm〗^2.s)), respectively. In addition, the values of neutronic and kinetic parameters are decreased in the present of acid boric. The results show that in the beginning of cycle (BOC) the keff value is decreased suddenly due to Xe production and then the neutron absorption by Gd burnable poison. Afterwards, this parameter is increased due to the production of fission fragments and the spatial self-shielding property of Gd fuel rods. Finally, we can see that Gd burnable poison causes increasing of the value of keff parameter in during the cycle.