United States Nuclear Regulatory Commission - Protecting People and the Environment
Home > NRC Library > Basic References > Glossary > Radionuclide

Radionuclide

An unstable isotope of an element that decays or disintegrates spontaneously, thereby emitting radiation. Approximately 5,000 natural and artificial radioisotopes have been identified.

Page Last Reviewed/Updated Thursday, November 20, 2014