This is most often from gamma rays, though beta rays can contribute to dose in the skin and other relatively superficial tissues. Fast reactors can be used to produce more fissile material than they consume. The splitting of the nucleus of an element into fragments. Heavy elements such as uranium or plutonium release energy when fissioned. Any isotope created by the fission of a heavy element.
Fission products are usually radioactive.
The combining of two nuclei to form a heavier one. Fusion of the isotopesof light elements such as hydrogen or lithium gives a large relsease of energy. Gamma rays are similar to X-rays, the latter term being applied usually to electromagnetic waves generated by electron accelerators, as for instance in medical equipment. A unit of absorbed radiation dose equal to 100 rads. The time in which half the atoms of a radioactive substance will have disintegrated, leaving half the original amount.