The amount of dangerous high-level radioactive waste is much smaller than the amount of low-level waste.

Waste that contains high levels of radioactive substances. Radioactive waste is produced by a wide range of human activities, including the operation of nuclear power plants, the use of radioisotopes in medicine, agriculture, and scientific research. Radioactive waste can be hazardous to human health and the environment and must therefore be handled with care. Its advantage is that, compared to toxic waste, its radioactivity and therefore its harm decrease with time. Radioactive waste may be classified according to its radioactivity level as low-level, intermediate-level, or high-level radioactive waste and according to its state as solid, gaseous, or liquid waste. Each type requires a different method of processing and storage.