Development of Methodologies for the Safety Analysis of Small Modular Reactors (SMRs) for a European Energy Mix with Low Carbon Emissions

This doctoral study, carried out in the frame of European research initiatives, explores the potential of SMR technology in Hybrid Energy Systems. The characterization of possible Hybrid Energy System layouts is firstly discussed, including preliminary safety considerations for nuclear cogeneration. Afterwards, the study covers CFD analyses on a Light-Water SMR passive safety system, namely the water-wall, following an "engineering approach". These analyses were useful to evaluate the capabilities of numerical codes in dealing with the addressed phenomena and, at the same time, they also provided insights about the effectiveness of such passive systems in dealing with long-term accidents. Additionally, the work contributes to developing a safety assessment methodology for nuclear reactors in hybrid systems by coupling the thermal hydraulic code CATHARE 3 with the dynamic modelling language MODELICA via Functional Mock-up Interfaces adopting a novel fluid coupling approach between primary and secondary side. The code coupling is tested on reference SMR and secondary system models. The resulting methodology was proven functional and used to assess meaningful cogeneration transients, offering valuable insights about the response of the considered nuclear system to events induced by cogeneration.