The UK system classifies waste based on activity concentration:
| Category | Definition | Key Properties |
|---|---|---|
| Exempt Waste | Below thresholds defined in legislation (Environmental Permitting Regulations 2016) | Does not require radioactive substances permit for disposal |
| Out of Scope Waste (formerly Very Low Level Waste / VLLW) | Waste below the threshold values in EPR 2016 Schedule 23, not requiring a radioactive substances permit. The former VLLW category was effectively replaced by the “out of scope” concept under the Environmental Permitting Regulations 2016. | Can be disposed of at permitted landfill sites or with normal waste |
| Low Level Waste (LLW) | Radioactive content not exceeding 4 GBq/te of alpha activity or 12 GBq/te of beta/gamma activity | Suitable for disposal in near-surface engineered facilities (e.g. LLWR Drigg); mainly lightly contaminated paper, plastic, metal, soil, building materials |
| Intermediate Level Waste (ILW) | More radioactive than LLW but does not generate enough heat for this to be taken into account in storage or disposal | Arises mainly from reprocessing of spent fuel and general operations; includes fuel cladding, reactor components, graphite, sludges |
| High Level Waste (HLW) | Radioactive enough for decay heat to significantly increase its temperature and surroundings; heat generation must be accounted for in design | Includes liquid residue from reprocessing of spent fuel; this residue once solidified; or any other waste with similar radiological characteristics |
| Higher Activity Waste (HAW) | Broad term covering all HLW and ILW, plus certain LLW not suitable for existing LLW disposal facilities | Destined for the GDF programme |