[en] Site characterization is the process of field and laboratory investigation by which a knowledge and understanding are obtained of the geological setting; the potential paths of fluid flow and waste migration through the rock; the mechanisms of thermal, mechanical and hydrological response of the rock mass that might either affect the construction and operation of the repository or alter the potential paths of fluid flow and waste migration; and the mechanisms of waste migration and retention along the potential paths. (author) 5 figs., 7 refs