Near-Field Modelling for the Safety Assessment of French High-Level Waste Repositories

In assessing the safety of a French high-level waste repository, the fluxes of radionuclides released by the near-field into the geosphere are modelled by the CONDIMENT source code. This code describes the corrosion of the vitrified waste and the transport of elements released by the waste into the engineered barrier. In developing CONDIMENT, the Commissariat a l'Energie Atomique adopted the following approach: the different near-field degradation processes were first investigated in the laboratory and finely modelled (corrosion of nuclear glass, weathering of environmental materials, migration of radionuclides in these materials). The long-term extrapolation of these models then serves to determine the degradation mechanisms liable to condition the long-term evolution of the near-field, and which must accordingly be taken into account in CONDIMENT.