Numerical tools for molten salt reactors simulation

paper 9207International audienceEssentially, because the salt is the moderator, the coolant and the fuel, the study of Molten Salt Reactor are specific. There are strong coupling between neutronics, and other part of physic field like the chemistry for instance. The system presented in this paper is called Molten Salt Fast Reactor which is a molten salt reactor with no moderator inside the core with a salt composition which leads to a fast neutron spectrum. Previous studies showed that this concept (previously called Thorium Molten Salt Reactor – Non moderated) has very promising characteristics. We tried to explain computational problems due to the study of this concept, especially the coupling with the reprocessing and with the chemistry. Indeed, the reprocessing is done little by little in situ, so we have to consider it in our studies. We also show that the redox properties changes during operation because fissions change the salt chemistry (it is a reductive process). Our program is a coupling between MCNP and a home made evolution code called REM. It was validated for thermal neutron and epithermal neutron spectrum but not for fast neutron spectrum, so a brief study with ERANOS of the MSFR is also presented here