Radioactive waste is generally classified on the basis of how much radiation it emits and what form of radiation it emits, as well as the length of time for which it will continue to emit radiation. The purpose of this classification system is to ensure that radioactive waste is handled, stored and disposed of in ways that are appropriate to its characteristics.
Radioactive materials are described as low level, intermediate level, or high level depending on how much radiation they emit. Radioactive materials are described as short-lived or long-lived depending on the length of time over which they emit radiation.
Short-lived radioactive materials have a half-life of less than thirty years. This means that half the unstable atoms in short-lived radioactive materials will change into the stable decay product in less than thirty years. Long-lived radioactive materials have a half-life of greater than thirty years. International classification of radioactive waste The International Atomic Energy Agency
classification of radioactive waste is set out in the following table.
| Waste Type | Definition |
|---|
| Low level waste | Contains enough radioactive material to require action for the protection of people, but not so much that it requires shielding during handling, storage or transportation. |
| Intermediate level waste, short-lived | Waste which requires shielding, but needs little or no provision for heat dissipation and contains low concentrations of long-lived radionuclides (less than 4000 Becquerel/gram of alpha-emitters). The radionuclides generally have a half-life of less than thirty years. |
| Intermediate level waste, long-lived | Waste that requires shielding, but needs little or no provision for heat dissipation. The radionuclides generally have a half life of more than thirty years. |
| High level waste | Waste which contains large concentrations of both short- and long-lived radionuclides and is sufficiently radioactive to require both shielding and cooling. The waste generates more than 2 kilowatts of heat per cubic metre. |
Australian classification of radioactive waste
In Australia, radioactive waste is classified into four different categories: A, B, C and S. This classification scheme, developed by the National Health and Medical Research Council (NHMRC) and now administered by the Australian Radiation Protection and Nuclear Safety Agency, can be found in the Code of practice for the near-surface disposal of radioactive waste in Australia
[PDF, 367KB]. This code of practice (known as the NHMRC Code) is based on international recommendations for radioactive waste management, but specifically describes and caters for the types of radioactive waste generated in Australia.
Categories A, B and C- low level and short-lived intermediate level waste
Radioactive waste classified as Category A, B or C is low level or short-lived intermediate level radioactive waste, according to the classifications found in the IAEA Safety Guide on the Classification of Radioactive Waste. The NHMRC Code defines Category A, B and C waste is suitable for near-surface disposal.
Category S - long-lived intermediate level waste
Radioactive waste classified as Category S is long-lived intermediate level radioactive waste, according to the classifications found in the IAEA Safety Guide on the Classification of Radioactive Waste. Category S waste is not suitable for disposal in a near-surface repository, but can be safely stored in a purpose-built, above-ground store.