ABSTRACT
This Chapter describes a long-term research effort (1992 to the present) on coupled THMC processes in geological systems in the context of the safe geological disposal of radioactive wastes: the DECOVALEX project (DEvelopment of COupled models and their VAlidation through EXperiments). This project is a unique international co-operative research project which was initiated in 1991, officially started in 1992, has continued through a number of phases without interruption since then and is still continuing in the time of preparing this chapter by the authors. The overall objective of this research has been the development, validation and application of numerical modeling methods and techniques for the performance and safety assessments of geological disposal of radioactive waste (GDRW) in underground repositories. The cooperation has been financed by national waste management organizations, regulatory bodies and national research institutes and individual universities in Canada, China, Czech Republic, European Commission, Finland, France, Germany, Republic of Korea, Spain, Japan, Sweden, UK and USA. Over the period of 23 years, the project has made impressive advanced researches in the field of coupled THMC (Thermo-Hydro-Mechanical-Chemical) processes in geological systems, especially in fractured crystalline and sedimentary rocks and buffer/backfill materials, through integrated numerical modeling and laboratory and field experiments. The experiments cover scales ranging from laboratory-sized samples to in situ experiments in underground research laboratories (URLs) in different host rocks in different countries. The work has resulted in an impressive number of major developments, as reported in scientific publications and helped to educate and train younger generations of researchers in this field. This Chapter presents the goals, structure, contents and approaches of the project, as well as achievements and lessons learned during this long-term project, at both the fundamental and application levels.
