Radioactive waste needs to be managed (see e.g., SSR‑5 IAEA 2011a). It can, in principle, be safely stored in surface facilities. However, because these facilities need maintenance and care, their safety is inevitably reliant on continued societal stability. Societal stability may, for example, be linked to political or financial stability, uncertainties which are far greater than those associated with the evolution of conditions deep underground in geological formations that are suitable to host a repository.
As a long-term waste management option, deep geological disposal has the positive attribute that, if the site and design are chosen appropriately, neither the societal stability needed for governmental and regulatory control, nor any specific controls on activities occurring at the surface of the Earth are prerequisites for post-closure safety. In fact, geological disposal provides long-term passive safety. Passive safety means that safety does not require any active measure to be undertaken following closure of the repository. Thus, no burden is placed on future generations to maintain and control the repository once it has been closed, although such control is certainly possible if society decides in favour of it.
Geological disposal contains the waste for a prolonged period while its associated radioactivity decays naturally. It is designed to prevent radioactivity from reaching the surface environment in amounts that could cause harm to humans or the environment. Placing the waste in a deep rock formation also enhances security in that it reduces the possibility of sabotage or theft.
The proof of existence of suitable rock formations, together with the findings of safety assessments conducted for a wide range of sites and designs world-wide (see, e.g., OECD/NEA 2017), lend support to the feasibility of safe geological disposal.