The main risks associated with nuclear energy have to do with health hazards of radiation poisoning. This isn’t the same type of radiation we’re talking about with light and microwaves (that type is electromagnetic radiation). The radiation associated with nuclear energy involves subatomic particles, like neutrons, given off from nuclear decay processes. Exposure to this type of radiation can cause cancer or genetic defects, among other problems. Since the fission processes used to generate energy are normally well controlled, though, nuclear energy is generally one of the cleanest energy sources available. Nuclear reactors only become dangerous in the event of a meltdown or other disaster, but the chances of these happening are extremely small. Modern nuclear power plants are built with a series of fail-safes such that a series of multiple, extremely unlikely events would have to happen, one after another, for a meltdown to occur.