The uranium fuel cycle: Some aspects of the physics, chemistry and measurement of radon and thoron daughters

Abstract

AbstractMuch effort has been devoted world‐wide towards minimizing exposure to radon and thoron daughters in the exploitation of nuclear energy. In this work, the behaviour of radon and thoron daughters after formation from their gas precursors is discussed, together with optimally designed measurement and dosimetry methods for assessing alpha radiation exposure in uranium mines and mills, in buildings and in the environment. The interaction of radon and thoron daughters with aerosol particles, which is very important in determining the fate of the airborne radioactivity, can be described better in terms of activity‐size distributions than by use of the commonly applied concepts of “attached” and “unattached” fractions. Further, the properties of the aerosol‐daughter system are shown to depend upon humidity and the presence of trace gases, which serve as electron sources to neutralize the newly‐formed positive daughters. Finally, the mechanisms of release of radium and radon from ore and soil are discussed. The significance of the various conclusions to practical situations is emphasized.