Industrial and research applications of radioisotopes and radiation sources

The unique property of radioactivity, namely the spontaneous and repeated emission of radiation at a known rate from a passive source of small mass and dimensions, over an accurately known life-time, allows for wide-ranging and powerful applications. The radiation can be detected with high sensitivity and because of the penetrating power of the gamma component, detection is possible over distances of the order of meters in air and over shorter distances through more dense matter. The rapid advances in solid-state and electronic technology have facilitated the effectiveness of detection apparatus and the ease of data collection and retrieval. All the elements have radioactive isotopes, albeit not all with suitable properties, due to either limited life-time, low-energy emissions or low yield. A radioactive isotope has chemical properties similar to those of the corresponding stable element and can be substituted for the stable analogue, allowing remote observation for study of the behaviour of the particular element in a matrix. Examples of these so-called tracer applications are numerous and some of the more recent applications in the South African industry are presented. The interaction of the radiation with the material through which it travels, is dependent on the physical and chemical properties of this material and therefore allows for the measurement of parameters such as density and atomic number. The application of X-rays and neutron radiation also allows the determination of specific elements and their concentrations. This feature finds application in radiography, level and density gauges, bulk mass determinations, on-line chemical analyses, and a variety of ingenious applications, some of which will be presented. The number of local uses of radioactive sources for industrial applications has increased by 250% over the past decade, to almost 600