High level waste

Radioactive waste with a high activity concentration of both short- and long- lived radionuclides typically in the range of 10⁴ to 10⁶ TBq/m³. It generates significant quantities of heat from radioactive decay and normally continues to generate heat for several centuries. This waste requires a high degree of containment isolation from the environment to ensure long-term safety.

ICRP Glossary entry - May 2019