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Hautes Energies
Dr. Axel LAUREAU - "Simulation tools and models based on hybrid Monte Carlo approaches for safety studies and reactor physics"
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Europe/Paris
Description
In the context of today's societal choices, the study of nuclear reactors is a rapidly evolving research field. Producing sustainable energy with reactors able to breed their fissile fuel and to burn nuclear waste while ensuring a high level of safety is a strong public expectation. To design and study such complex systems where many physics are interacting together, the development of full core simulations is under progress, given the difficulty of measuring specific or isolated phenomena in experimental reactors, or of validating their representativeness on a large-scale core. These multiphysics simulations have to cover very large scales in energy (from 1 meV up to 20 MeV for the neutronics), space (from the nucleus size of some fermis to the core size of some meters) and time (from some micro-seconds for the neutron generation time to some hundreds seconds for the reactor global behaviour during a transient, i.e. the modification of the operation conditions). This requires precise calculations with a reasonable calculation time, which is possible with the computer capacities available now associated to the development of new simulation codes based on optimized physical models.
During this seminar, I will detail such a new physical approach, developed for neutronic simulations. This approach is hybrid between full Monte-Carlo and deterministic resolutions, by condensing the Monte Carlo response into Green functions to characterise the system response. Its validation on numerical benchmarks and on experimental measurements will be presented, together with its application to the study of various nuclear systems, illustrating that this approach is very efficient, reliable and generic, and can be used to elaborate new calculation schemes. Studies performed on the Molten Salt Fast Reactor (MSFR) developed by the CNRS, on the sodium fast reactor ASTRID developed by the CEA and on the Pressurized Water Reactors (PWR) operated by EDF highlight the capability of this approach to express the physics associated to the neutron transport. This provides reference solutions to identify the advantages and weak points of these reactors and to optimize them.
