Among the most recent designs of water-moderated Small Modular Reactors (SMR), several concepts are characterized by natural convection in the primary circuit during normal and abnormal operation, with the aim of increasing the inherent safety of the design. The absence of primary pumps in this type of SMRs significantly complicates the start-up and power increase ramps. This requires the development of specific start-up procedures to heat up the primary water circuit and enable the reactor to reach its nominal conditions, in accordance with safety requirements. These kinds of procedures rely on simulations using validated models to understand the reactor behavior during these phases and define the accessible parameters domain.
The goal of this PhD project is to develop a numerical model capable of simulating the startup of an SMR operating in natural convection, and to contribute to the validation of this model. The PhD study also aims at developing a methodology for reactor control systems optimization, to attain a fast startup while remaining within the prescribed safety criteria.
The analysis of the reactor startup procedure entails two disciplines: thermal-hydraulics and neutronics, which requires the development of multi-physics coupled simulation tools. Three scientific calculation tools in particular will be coupled in the framework of the PhD study: CATHARE3 (reactor system thermal-hydraulics), FLICA5 (core thermal-hydraulics) and APOLLO3 (neutronics).
The PhD student will work in a team of neutron physicists and thermohydraulic engineers at the IRESNE Institute (CEA Cadarache). He/she will develop skills in nuclear reactor physics and modeling.