Decay 05 : Nuclear Energy and Nuclear Disasters. The decrease in the [radiation intensity] of any radioactive material with the passage of time due to the spontaneous emission of radiation from an atomic nucleus
University of California, Riverside, Environmental Health & Safety, Radiation Glossary of Terms, CA, USA 2010. https://apps2.campusservices.harvard.edu/ehs/radia tion/glossary.shtml, (Rad Sfty, Prot and Cont - Amer) {501}
