Information on nuclear waste

Radioactive waste means a material, item or structure that contains radioactive substances, has no use and which, due to its radioactivity, must be rendered harmless.

Typically, radioactive waste cannot be disposed of; rather, it must be isolated from living environments and habitats in a reliable manner. The activity of the waste nevertheless diminishes by itself through radioactive decay, and the requirements set for the isolation of waste depend, in addition to the activity level, on the half-life of the prevalent radionuclides.

The use of nuclear energy and the production of nuclear weapons generate large amounts of radioactive waste, referred to as nuclear waste according to its origin. In Finland, nuclear waste is primarily generated in the nuclear power plants in Loviisa and Olkiluoto. Small amounts are also generated in the research reactor located in Otaniemi. Given that the Otaniemi research reactor is being decommissioned, it is generating decommissioning waste. Nuclear waste is subject to nuclear energy legislation.

Other radioactive waste accumulates in the context of extraction operations, the industrial sector, healthcare and in research facilities which use sources of radiation. The quantities and activity of such waste are minor compared to nuclear waste, with the exception of excavation wastes where the quantities may be high. They are subject to radiation legislation.

Radioactive waste

Radioactive waste is categorised into high-, intermediate- and low-level waste. Radioactive waste arising from the use of nuclear energy is subject to the Nuclear Energy Act and waste arising from any other use of radioactive substances is subject to the Radiation Act.

For the purpose of processing and storage of radioactive waste, it is appropriate to categorise waste according to the activity level into the following categories

1. High-level waste requires very efficient radiation protection arrangements and usually also cooling. In this case, the activity concentration of the waste is higher than 10 GBq/kg. In Finland, spent fuel from nuclear reactors is categorised as high-level waste.
2. The processing of intermediate-level waste requires efficient radiation protection arrangements, and the activity concentration of such waste is more than 1 MBq/kg but not more than 10 GBq/kg. For example, ion-exchange resin used for cleaning the primary circuit in a nuclear power plant is intermediate-level waste.
3. Low-level waste can be can be processed without any special radiation protection arrangements, and the activity concentration in such waste is not more than 1 Mbq/kg. For example, mixed solid waste accrued during maintenance outages in nuclear power plants (so-called maintenance waste) is mainly low-level waste.

For final disposal purposes, radioactive waste is often categorised into short- and long-lived waste. In short-lived waste, the half-life of the predominant radioactive material is not more than about 30 years (for example, strontium-90 and cesium-137 are included here). Their activity level is reduced to a safe level within a few hundred years. Low and intermediate-level radioactive waste arising from the operation of nuclear power plants is usually short-lived. Long-lived waste, such as spent fuel, contains substantial concentrations of radioactive materials, with a half-life of more than 30 years.