| Film badge: Dosimetry monitoring device that uses photographic film to measure a person’s radiation dose. Fissile material: Any material in which neutrons cause a fission reaction. Fission: The splitting of a nucleus into at least two fragments, accompanied by the release of neutrons and energy. Fission of a nucleus may be initiated by absorption of a neutron or, in some materials, can happen spontaneously. Fusion: The joining together of two or more less stable nuclei into one more stable nucleus. | 
