Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA

Numerical study of the THM effects on the near-field safety of a hypothetical nuclear waste repository—BMT1 of the DECOVALEX III project. Part 1: Conceptualization and characterization of the problems and summary of results

11 pagesInternational audienceGeological disposal of the spent nuclear fuel often uses the concept of multiple barrier systems. In order to predict the performance of these barriers, mathematical models have been developed, verified and validated against analytical solutions, laboratory tests and field experiments within the international DECOVALEX III project. These models in general consider the full coupling of thermal (T), hydraulic (H) and mechanical (M) processes that would prevail in the geological media around the repository. For Bench Mark Test no. 1 (BMT1) of the DECOVALEX III project, seven multinational research teams studied the implications of coupled THM processes on the safety of a hypothetical nuclear waste repository at the near-field and are presented in three accompanying papers in this issue. This paper is the first of the three companion papers, which provides the conceptualization and characterization of the BMT1 as well as some general conclusions based on the findings of the numerical studies. It also shows the process of building confidence in the mathematical models by calibration with a reference T–H–M experiment with realistic rock mass conditions and bentonite properties and measured outputs of thermal, hydraulic and mechanical variables