EC FORGE project: updated consideration of gas generation and migration in the safety case

Abstract

AbstractA safety case for a geological disposal facility (GDF) is a set of claims concerning the environmental safety of the disposal of radioactive waste in a GDF, substantiated by a structured collection of arguments and evidence. Such a safety case needs to address environmental safety at the time of disposal and in the long term, after wastes have been emplaced and the facility has been closed.Waste-derived gas generation and its subsequent migration is an important component of a safety case, and was the focus of research in the integrated, multidisciplinary, European Commission ‘Fate Of Repository GasEs’ project (FORGE) – a pan-European project with links to international radioactive waste management organizations, regulators and academia, specifically designed to tackle the key research issues associated with the generation and movement of repository gases. FORGE was targeted to address gas issues through a series of laboratory- and field-scale experiments, including the development of new methods for upscaling allowing the optimization of concepts through detailed scenario analysis.This paper summarizes the overall understanding on the implications of gas generation and migration for the safety functions of the engineered barrier system (EBS) and the host rock, as informed by the output of the FORGE project. Achievements and recommendations from the FORGE project are noted, emphasizing that FORGE has provided confidence in the basic physical understanding and modelling approaches relevant to GDF-derived gas that can be applied for different concepts – such understanding, and the derived component and system models, can be used in a safety case to address regulatory guidance.