Deep geological repository

A deep geological repository is a radioactive waste repository excavated deep within a stable geologic environment (typically below 300 m or 1000 feet). It entails a combination of waste form, waste package, engineered seals and geology that is suited to provide a high level of long-term isolation and containment without future maintenance. The Waste Isolation Pilot Plant, under construction in the United States, only accepts transuranic waste for permanent disposition.It is widely accepted that spent nuclear fuel and high-level reprocessing and plutonium wastes require well-designed storage for periods ranging from tens of thousands to a million years, to minimize releases of the contained radioactivity into the environment. Safeguards are also required to ensure that neither plutonium nor highly enriched uranium is diverted to weapon use. There is general agreement that placing spent nuclear fuel in repositories hundreds of meters below the surface would be safer than indefinite storage of spent fuel on the surface. A deep geological repository is a radioactive waste repository excavated deep within a stable geologic environment (typically below 300 m or 1000 feet). It entails a combination of waste form, waste package, engineered seals and geology that is suited to provide a high level of long-term isolation and containment without future maintenance. The Waste Isolation Pilot Plant, under construction in the United States, only accepts transuranic waste for permanent disposition. The most long-lived radioactive wastes, including spent nuclear fuel, must be contained and isolated from humans and the environment for a very long time. Disposal of these wastes in engineered facilities, or repositories, located deep underground in suitable geologic formations is seen as the reference solution. The International Panel on Fissile Materials has said: However, even a storage space hundreds of metres below the ground might not be able to withstand the pressures of one or more future glaciations with thick sheets of ice resting on top of the rock, deforming it and creating internal strains. This is being taken into consideration by agencies preparing for long-term waste repositories in Sweden, Finland, Canada and some other countries that would have to expect a renewed ice age. Common elements of repositories include the radioactive waste, the containers enclosing the waste, other engineered barriers or seals around the containers, the tunnels housing the containers, and the geologic makeup of the surrounding area. The ability of natural geologic barriers to isolate radioactive waste is demonstrated by the natural nuclear fission reactors at Oklo, Gabon. During their long reaction period about 5.4 tonnes of fission products as well as 1.5 tonnes of plutonium together with other transuranic elements were generated in the uranium ore body. This plutonium and the other transuranics remained immobile until the present day, a span of almost 2 billion years. This is quite remarkable in view of the fact that ground water had ready access to the deposits and they were not in a chemically inert form, such as glass. Despite a long-standing agreement among many experts that geological disposal can be safe, technologically feasible and environmentally sound, a large part of the general public in many countries remains skeptical. One of the challenges facing the supporters of these efforts is to demonstrate confidently that a repository will contain wastes for so long that any releases that might take place in the future will pose no significant health or environmental risk. Nuclear reprocessing does not eliminate the need for a repository, but reduces the volume, the long-term radiation hazard, and long-term heat dissipation capacity needed. Reprocessing does not eliminate the political and community challenges to repository siting. Deep geologic disposal has been studied for several decades, including laboratory tests, exploratory boreholes, and the construction and operation of underground research laboratories where large-scale in-situ tests are being conducted. Major underground test facilities are listed below. The pit Asse II is a former salt mine in the mountain range of Asse in Lower Saxony/Germany, that was allegedly used as a research mine since 1965. Between 1967 and 1978 radioactive waste was placed in storage. Research indicated that brine contaminated with radioactive caesium-137, plutonium and strontium was leaking from the mine since 1988 but was not reported until June 2008