Safety/risk assessment methodologies of deep geological facilities: results from a cross-national comparison

Any geological disposal/storage facility must prove its safe performance prior to licensing, regardless of whether the compound is solid radioactive waste (RW) or gaseous carbon dioxide (CO<SUB align="right"><SMALL>2</SMALL></SUB>). The disposal/storage facility is considered safe if it meets the relevant safety standards and proves its reliable safe performance over defined timescales. This paper presents a cross-national comparison of the safety/risk assessment aspects of ultimate disposal facilities for RW and CO<SUB align="right"><SMALL>2</SMALL></SUB> in the Czech Republic, Switzerland, India, and Bulgaria, completed in an international project. In both fields, the main goal of safety assessments is to create a reliable evaluation of the disposal system performance over long timescales. The procedures are based on the following scheme: system description - system development description - model development - consequence analyses. Due to the long temporal and large spatial effects of the substances disposed of, a call for the introduction of a broader range of safety indicators has emerged in both fields. The main emphasis of this study is on reliable models and data.