Thermal hydraulic analysis of research reactors with plate-type fuel

As well as nuclear power plants, research reactors are subject to a strict licensing process, requiring different studies to certify that the project is capable to safely withstand transients, without radiological consequences for people or environment. Thus, this work aims to develop a computational tool to investigate the behavior of MTR research reactors, including the Brazilian Multi-Purpose Reactor (RMB), by using a numerical-analytical approach for coupled thermohydraulic and neutronic analysis in a cooling subchannel. The modeling consists of the heat conduction equations on a fuel plate, the coolant energy transport equation in the subchannel and point kinetics equations with six groups of delayed neutrons. 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 the finite difference method. The resulting system of ordinary differential equations is solved numerically by using the NDSolve function of the Mathematica software. The code is verified against the IAEA MTR 10 MW benchmark problems, showing good agreement with literature data. The Serpent 2 Monte Carlo code is employed to calculate the RMB kinetic parameters of the NPK equations and the steady state power distribution. The analysis results demonstrates that RMB operates safely under the events of loss of flow and reactivity insertion. (author)