Near and far field thermal calculations for nuclear spent fuel disposal in deep geological formations

This article presents the results from thermal analyses pertaining to the disposal of nuclear spent fuel in deep geological formations. The analyses have been carried out at two different scales, in order to evaluate the sensibility of the temperature field to different parameters essential to the definition of the repository, either at the scale of one container (near field), or at the scale of the repository (far field). The finite difference code FLAC(3D) has been used to solve the general equations of heat transport and obtain the temperature evolution with time for a heat-decaying source. Owing to the flexibility of the FISH language available in FLAC(3D), the influence of several parameters could be easily investigated, such as storage time, spacing between galleries and containers within each galleries, thermal characteristics of the materials, influence of radiative heat transfer between container and buffer due to non perfect contact. Future work should be carried out to investigate the mechanical effects induced by temperature changes.