Radiochemistry: Volume 3 (Specialist Periodical Reports - Radiochemistry)

Product description Excerpt. © Reprinted by permission. All rights reserved. Radiochemistry Volume 3A Review of the Literature Published During 1974 and 1975By G. W. A. NewtonThe Royal Society of ChemistryCopyright © 1976 The Chemical SocietyAll rights reserved.ISBN: 978-0-85186-274-3ContentsChapter 1 Industrial Applications of Radioisotopes By J. A. Heslop, Chapter 2 Activation Analysis in Archaeology By G. Harbottle, Chapter 3 Preparation of Radiopharmaceuticals and Labelled Compounds using Short-lived Radionuclides By D. J. Silvester, Chapter 4 Sample Preparation Procedures for Liquid Scintillation Counting By B. W. Fox, Author Index, 133, CHAPTER 1Industrial Applications of RadioisotopesBY J. A. HESLOPThe application of radioisotopes to the study of industrial process and to the measurement and control of those processes is well established. This review will contain little that is radically novel in terms of basic techniques or applications. There exists, however, a basic information gap between the radioisotope applications specialist and the user, be he chemical engineer, R and D scientist, or civil engineer. This gap causes the use of radioisotopes as tracers or in instruments to be considered as a last-gasp effort that is to be used only when all else fails. Experience has shown that the use of radioisotopes can often solve problems much more easily than conventional techniques, and, in cases where the radioisotope specialists are part of the industry or belong to an institute with good industrial contacts, the number of radioisotope applications can show an amazing growth (e.g. the group at TCI Petrochemicals Division who are concerned with the application of radioisotopes within industry complete well in excess of 1000 applications per year). It is hoped that this review will help to bridge the information gap in that it covers recent applications of radioisotopes in industry up to about mid-1975.The field has already been the subject of a number of general reviews which cover the basic principles and certain applications. Specific reviews covering applications in the textile and fibres industry, in plastics, and in the basic metals industry have been published.1 RadiotracersIt has been said that there is no such thing as the perfect tracer, as this material would be indistinguishable from the population as a whole. Isotopes usually provide the nearest approach to the perfect tracer, in that they are, to a good first approximation, chemically and physically indistinguishable from the total population. If they are also radioactive then they possess a useful property (the emission of radiation) which can be related to their concentration in the bulk of the medium under investigation. There are several degrees of sophistication possible in the selection of a tracer. If the medium under investigation undergoes a chemical reaction or a phase change, then a tracer which parallels this behaviour must be selected, and hence the chemical form of the tracer must be identical with the bulk material. If this criterion can be satisfied, then, neglecting any possible isotope effects, the ideal tracer will be used.In the chemical industry, the isotopes which come into this category are usually 14C and 3H, both of which can be readily incorporated into organic materials. These isotopes are far from ideal for use in industry, in that they are both weak β-emitters and hence cannot easily be detected inside process equipment, and sampling is necessary. They both have long half-lives and hence cannot easily be used to study problems in which they would end up in a product which would be sold to the general public. Despite these disadvantages, there are certain problems which can only be solved by the use of 14C or 3H, and, provided the financial incentive is large enough, both isotopes can be used on full-scale plant both efficiently and safely. On smaller scale equipment and in the laboratory 14C and 3H play very important parts in industrial monitoring.In a majority of situations, where the bulk property of a material is being followed, there are no physical or chemical changes, and it is possible to use a physical tracer. This type of tracer will follow the bulk movement of a material, provided that it does not undergo a phase change or a chemical reaction. Similarly, the tracer itself must not be precipitated or in any way lost from the material being traced. It is often sufficient if the material is simply soluble in the medium, as in the use of NH482Br for the tracing of aqueous streams. The use of a physical tracer allows a γ-radiation detector to be used outside the process vessel, and hence removes the need for samples to be taken. This means that short-lived isotopes can be used, thus reducing the problems of radiological protection. Table l is a list of a number of isotopes which have been used in the study of various industrial problems. The isotopes are in general produced in a nuclear reactor and are of