radiation
The main concern over the use of nuclear energy is the risk of radiation. Accidents at nuclear power plants can release harmful radiation that endangers people and other living things. Even without accidents, the used fuel that is left after nuclear fission reactions is still radioactive and very dangerous. It takes thousands of years for it to decay until it no longer releases harmful radiation. Therefore, used fuel must be stored securely to protect people and other living things. You can learn more about the problem of radioactive waste at this URL: http://www. youtube. com/watch?v=OPQ97LVRuuM.