| Term | Definition |
|---|---|
| Design life | The expected effective lifespan of a nuclear facility. Nuclear facilities are designed to operate within a specific range of conditions for a specific amount of time. |
| Disposal | Disposal is the process of permanently placing waste into suitably engineered facilities. |
| Disused sealed source |
When the radioactivity of a sealed source decays to a certain level that is no longer useful for its intended purpose, we consider it to be disused. Most sealed sources will become radioactive waste unless they can be reused or recycled. We collected information on short-lived and long-lived sealed sources in separate categories in our 2021 report. We’ve now combined this information. |
| Exempt waste (EW) | Exempt waste contains very low levels of radioactivity that do not require radiation protection safety measures. It can be safely disposed of in the same way as non-radioactive waste. |
| Existing waste | Waste generated from past and current nuclear activities, like medical applications, space research and industrial processes. |
| Half-life |
The half-life (t1/2) is the time needed for half of the unstable nuclei in a sample to decay. Each radionuclide has a unique half-life, which can range from fractions of a second to billions of years. (Source: IAEA) Generally, short-lived radionuclides have half-lives of less than 30 to 40 years, while long-lived radionuclides have half-lives longer than 40 years. |
| Intermediate-level radioactive waste (ILW) |
ILW usually contains larger amounts of long-lived radionuclides. Intermediate-level waste:
ILW generally needs purpose-built containers that provide shielding during transport or storage. This type of waste may also need additional shielding in a storage facility. ILW also needs to go through treatment and conditioning processes before disposal. |
| Low-level radioactive waste (LLW) |
Low-level waste:
LLW needs to go through treatment and conditioning processes, such as compaction or mixing with cement, before disposal. Large and bulky items, such as decommissioning rubble, may need larger containers such as shipping units. There are no exact thresholds to determine what is LLW or ILW. The waste classification depends on whether it is being stored or disposed of. |
| Naturally occurring radioactive material (NORM) |
Naturally occurring radioactive material (NORM) is the term used to describe any radioactive substance that exists naturally in the environment. (Source: EPA) A few organisations reported NORM in their inventories. Examples include ore and mineral samples held by research organisations, schools or universities. |
| Nuclear materials |
Nuclear materials are uranium, plutonium and thorium, with only limited exceptions. In Australia, the Nuclear Non-Proliferation (Safeguards) Act 1987 regulates nuclear materials and associated items (such as nuclear facility equipment) for nuclear security and safeguards purposes. The Australian Safeguards and Non-Proliferation Office (ASNO) ensures Australia’s compliance with this Act. Although waste streams from different waste categories can contain nuclear materials, we assume that waste containing nuclear material will be managed alongside ILW streams. |
| Radioactivity | Radioactivity is the term used to describe disintegration of atoms. We describe an atom by the number of protons in the nucleus. Some natural elements are unstable, so their nuclei disintegrate or decay and release energy in the form of radiation. (Source: IAEA) |
| Radioactive decay | Radioactive decay is the process where unstable atomic nuclei release energy and particles to become more stable. This process is spontaneous and unpredictable for individual atoms, but the rate the decay occurs at is predictable for a large sample of atoms. (Source: IAEA) |
| Radioactive waste | Radioactive waste is radioactive material that has no further use. Read more about radioactive waste in Australia. |
| Radionuclide | A radionuclide is an unstable atom, or an unstable form of an element. It emits radiation as it decays to a more stable state. (Source: IAEA) |
| Sealed source |
Sealed sources:
|
| Storage | Storage involves temporarily holding safely contained radioactive waste in a facility until future disposal. |
| Waste category | Radioactive waste is usually categorised by radiological properties like their radioactivity level and half-life. |
| Waste characterisation | A process that uses measurements, computer modelling, lab analysis or historical data to understand the physical, chemical and radiological properties of radioactive waste. Waste characterisation is a crucial part of managing radioactive waste. |
| Waste holders |
Waste holders are organisations that are currently managing and storing radioactive waste. They include:
|
| Waste regulators | The radiation protection regulators in each state and territory, as well as the Australian Government nuclear safety regulator ARPANSA, are also waste holders. These regulators manage radioactive waste that comes from their research and regulatory activities. The Australian Safeguards and Non-Proliferation Office (ASNO) also regulates waste containing nuclear materials for nuclear security and safeguards purposes. ASNO is not a waste holder. |
| Waste stream | A waste stream is a collection of radioactive waste that has similar radiological, chemical and physical properties. All wastes in a waste stream are likely to have the same or similar origin. |
| Waste treatment |
Radioactive waste treatment involves converting radioactive materials into forms suitable for safe handling, storage, and eventual disposal. This process typically includes treatment to modify the waste's characteristics and conditioning to solidify it in a stable form. Treatment might involve compaction, filtration or other techniques to reduce volume or remove radionuclides. Conditioning often involves cementation or vitrification to create a stable, insoluble solid. (Sources: IAEA, World Nuclear Association) |