Sodium-cooled fast reactors: void coefficient and waste minimization. Neutronic studies using MURE

paper 9205; International audience; The future of nuclear energy may require breeding and optimized waste management. Innovative technologies have to be explored, in order to reduce considerably the ore consumption and the associated waste production. Sodiumcooled fast reactors seem to be the most achievable technology in the coming decades, and can play an important role to launch the generation 4 technologies. However, the standard sodium-cooled reactors face to the problem of the positive void reactivity and a major Minor Actinides (MA) production if transmutation is not considered. In this context, we perform neutronic studies on innovative (or evolutive) sodium-cooled reactors. These studies are based on MURE (MCNP Utility for Reactor Evolution), a C++ object-oriented evolution code that couples the Monte-Carlo transport code MCNP with a fuel depletion code under given conditions. Firstly, a “reference” case, a SFR without recycling MA, is presented and a propagation of statistical error is shown during the whole evolution. Then, different configurations of a fast sodium cooled reactor (SFR, with a total power of 1.45 GWe) are investigated. A self-breeding Th/U configuration has been found, using thorium blankets, which allows reducing significantly sodium void reactivity. Comparisons of produced wastes in different systems (Th/U or U/Pu fuel) are presented.