Development and optimization of the reactivity control system of the XSMR in design at NAAREA

To study the behavior of the reactor that NAAREA is designing, codes and models have been developed during this master thesis through an internship. The XSMR in conception at NAAREA is a GEN IV reactor which requires the implementation of several calculation codes to simulate the overall behavior in nominal, incidental or accidental conditions. Hence, a first model that couples neutronics and thermal hydraulics has been developed in Python language. It has been adapted for the MSRE, a reactor built by the ORNL in the 60's, since data are widly available. Some accidental situations (reactivity insertion, pump coasts-down) have been simulated and compared to the experimental data and other results from litterature. In the meantime, a model of the XSMR core has been implemented in DYMOLA, a 0D-1D object-oriented simulation tool, using the ORNL TRANSFORM library. The extracted power from the chosen heat exchanger model has been found first. Then, a coolant pump coast-down has been simulated to see the overall behavior of the model.