high-level waste (HLW)

High-level waste (HLW) refers to the highly radioactive materials produced from nuclear reactors, primarily used fuel that has been irradiated. This waste contains a mix of hazardous isotopes that can remain dangerous for thousands of years. Due to its radioactivity and heat generation, HLW requires special handling, storage, and disposal methods to protect human health and the environment. It is typically stored in pools of water for cooling before being moved to secure facilities, like deep geological repositories, designed to safely isolate it from the surrounding environment for the long term.