Definition of "strontium 90" []

• The strontium isotope with mass 90, having a half-life of 28 years, used for its high-energy beta emission in certain nuclear electric power sources and constituting a radiation hazard in fallout. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.