Atomic reactor: Same as nuclear reactor.
Background radiation: Natural radiation due to cosmic rays, and due to radioactive substances in the earth, in the atmosphere, and in our own bodies.
Beta ray (particle): An energetic electron or positron emitted by some radioactive nuclei. Practically all of the fission products are beta (electron) emitters.
Blast wave: Same as shock wave.
Cesium¹³⁷: A radioactive fission product. It emits a 0.5 million volt beta ray and a 0.7 million volt gamma ray with a half-life of 30 years. The daughter nucleus is stable barium¹³⁷.
Chain reaction: Self-maintained sequence of fissions. Neutrons released by the fission of one nucleus are used to induce fission in another nucleus.
Chromosome: A small irregularly shaped body found in cells. Chromosomes carry the genes, which are responsible for heredity.
Clean bomb: A nuclear bomb which produces heat and blast, but only a negligible amount of radioactivity. The energy of such a bomb is derived almost entirely from the fusion process.
Cobalt⁶⁰: Radioisotope—decays into nickel⁶⁰ with the emission of a weak beta ray. The half-life for this decay is 5.3 years. The nickel⁶⁰ immediately ejects two gamma rays with a total energy of 2.5 million electron-volts.
Cobalt bomb: A radiological bomb which produces a large quantity of cobalt⁶⁰.