Radioactive waste disposal is the final and most critical step in the management of nuclear waste. The goal is to safely and permanently isolate radioactive materials from the environment and human populations for the thousands of years required for their radioactivity to decay to safe levels. The approach to disposal depends on the type of waste, which is generally categorized into low-level, intermediate-level, and high-level waste.

Low-level waste (LLW), such as contaminated clothing and tools from nuclear facilities, typically has a short half-life and can be disposed of in near-surface disposal facilities. These sites often use a combination of natural and engineered barriers to ensure containment. High-level waste (HLW), which includes spent nuclear fuel, is far more complex and requires a long-term solution. The international consensus is that deep geological disposal is the safest and most effective method for HLW. This involves burying the waste deep underground in stable geological formations, such as clay, salt, or granite, which can provide containment for millennia. The waste is placed in highly durable canisters and sealed within the repository, creating a multi-barrier system that provides multiple layers of protection against the release of radionuclides.