LAUSR

Abstract Dynamical behavior of the Brazilian Multipurpose Reactor (RMB) is investigated by using the coupled neutronics and thermal hydraulics code NTHC1, which consists of the neutron point kinetics (NPK) equations with six groups of delayed neutrons, the heat conduction equations in a fuel plate, and the energy transport equation in a coolant subchannel. The Serpent 2 Monte Carlo code is employed to calculate the RMB kinetic parameters of the NPK equations and steady state power distribution. Improved lumped formulations are adopted for heat conduction in the transversal direction of the fuel and cladding, while the fluid energy equation is discretized along the subchannel by finite difference method. The resulting system of ordinary differential equations is solved by numerical method. The NTHC1 code was verified against the IAEA 10 MW MTR benchmark problems, showing good agreement with literature data. The simulation results demonstrated that RMB operates safely under the postulated initiating events (PIE) of loss of flow and reactivity insertion.