View of the reactor

The facts & the project

A reactor with the best safety standards to demonstrate sustainable management of nuclear material resource and radioactive waste... It is the specification of ASTRID, the technology demonstrator at industrial scale currently investigated by the CEA. This innovative reactor prefigures the next generation of nuclear plants, belonging to the sodium-cooled fast neutrons reactor line (RNR-Na).

Making these reactors as safe as possible requires in particular to know precisely their behavior should a major accident occur. It is exactly the everyday life of the research team from the Laboratoire de Physique et de Modélisation des Accidents graves (LPMA) of CEA in Cadarache, in the South of France.

The results

“Modelling a major accident, from its initial phase to the severe and global deterioration of the core of the reactor, is an ambitious objective”, Laurent Trotignon and Pierre Gubernatis, researchers at LPMA, said. “Because there is at work the coupling, at different scales, of many phenomena: thermalhydraulics, multiphase physics (sodium, steel, nuclear fuel under liquid and/or vapor state), neutronics and mechanics”.

For working on this very complex physics, thus better describing and quantifying the whole phenomena that could affect the core of the reactor, “the need of supercomputers is imperative”, the researchers underlined. They perform their simulations with a new computation workflow, called SEASON and developed within the framework of an international cooperation, including in particular the Japan Atomic Energy Agency (JAEA). Their final goal: To improve the robustness of the safety demonstration for RNR-Na and to assess the performance of prevention and mitigation systems foreseen in ASTRID, as for example devices directing molten fuel towards a core catcher.