One curie is 37 billion atoms undergoing decay each second. Hanford released an estimated 739,000 curies of iodine-131 from 1944 to 1972. In contrast, the 1979 accident at the Three Mile Island nuclear power plant in Pennsylvania released an estimated 15 curies of iodine-131. This term is used because a radiation dose to one part of the body does not have the same potential health effect as a dose to another part. The EDE is used to put different types of radiation doses on an equivalent basis in terms of their potential for causing damage.
Equivalent dose is measured in rems.
The term refers to radiation, such as gamma rays and X-rays, that can penetrate human skin and thus cause biological damage from outside the body. Gamma rays are photons, or electromagnetic waves, that come from the nucleus of the atom. Gamma rays are uncharged and pass through humans at the speed of light. As gamma rays pass through the body, they may damage cells. Cobalt-60 is a source of gamma radiation.