Unstable Nucleus 1 : a nucleus that contains an uneven number of protons and neutrons and seeks to reach equilibrium between them through radioactive decay (i.e., the nucleus of a radioactive atom). See also stable nucleus
James M. Smith, Ph.D. & Marie A. Spano, M.S., Interim Guidelines for Hospital Response to Mass Casualties from a Radiological Incident, Glossary of Radiological Terms & Acronyms, Division of Environmental Hazards and Health Effects, National Center for Environmental Health (and Centers for Disease Control and Prevention CDC Radiation Emergencies), USA 2003. http://www.bt.cdc.gov/radiation/pdf/masscasualties guidelines.pdf, (Rad - Amer) {934}