Radioisotopes-Byproducts of the Uranium Cycle with Commercial Applications

Abstract

Radioactivity, or the spontaneous disintegration of an atomic nucleus, was first observed by Becquerel in 1896. During the next 40 years the potentially useful proper ties of naturally occurring radioisotopes such as radium, were identified, but perhaps the most important developments that led to widespread application of radioactivity and radioisotopes were the discovery of fission by Hahn and Strassman, the invention of the cyclotron by Lawrence in the 1930's, and the start-up on 1947 July 22 of the NRX reactor at Chalk River Nuclear Laboratories. When NRX's high neutron fluxes and large irradiation volumes became available, large quantities of a wide range of radioisotopes could be produced for the first time. Research leading to clinical or commercial applications of reactor produced radioisotopes dominated the next 25 years, whereas it is only during the last 15 or so years that cyclotron isotopes have seen widespread usage. Reactor produced isotopes can be categorized into two groups - those which are direct products of the nuclear fuel cycle itself such as fission products or transuranics and those which are produced by exposure of a deliberately inserted target to the reactor's neutron flux.