For very low level waste, low level waste and short-lived intermediate level waste, there is international consensus that this can be safely disposed of in near-surface facilities at a depth of no more than 30 m. The underlying assumption is that deposited radioactive waste will decay to background levels before institutional control is lost (within about 300 years).
Before being placed in the facility, the radioactive waste must be treated and conditioned. At present, different technologies and installations for the treatment, conditioning, storage and disposal of short-lived low and intermediate level waste exist.
For example, it may be compacted to reduce its volume, or solidified if it is a liquid. Usually, it is placed in metal or concrete containers and then embedded in concrete. For very low level waste, less robust packaging may be used.
Near surface facilities may be simple trenches or may comprise an array of reinforced concrete cells. Once filled, these the trenches or cells may be closed with a concrete slab and then sealed with an impermeable sheath. Finally, the trench or cell will be capped with a layer of clay several metres thick, to ensure the long-term confinement of the waste.
In Europe, repositories of this type exist in France, Hungary, Slovakia, Spain and the United Kingdom. In Finland and Sweden low level waste and short-lived intermediate level waste are disposed of in mined facilities at up to 100m depth.
In addition to these seven countries, other member states with nuclear power plants as well as a number without nuclear power are at various stages of implementation of low-level waste repositories, from conception through to final construction. By 2020 it is likely that all the states with nuclear power plants will have an operational repository for this type of waste, with the exception of the Netherlands.
