Short-lived isotopes used as tracers in industry (with special reference to Swedish industry)

Abstracts of paters darkrooms, microcurie laboratories, animal house, biological and chemical laboratories, low-background counting room, lecture theatre and a library. It is expected that the research will extend over many scientific and technological disciplines; a good proportion of the work *ill involve short-lived radioisotopes and typical projects are described. Some Techniques for Isolating and Using ShortLived Radioisotopes.* F. NELSON and K. A. KR~ZUS, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A. Radioisotopes of a large number of elements have been used extensively at Oak Ridge National Laboratory in ion exchange, solubility and other physicalchemical studies. The use of short-lived radioisotopes in such studies has necessitated development not only of rapid methods of preparing and purifying radioisotopes but also of special techniques.for obtaining pertinent information in a relatively short time, often within a few minutes. Some recently developed methods are described for preparing and purifying short-lived isotopes, particularly those originating from neutron-irradiated materials, including fissionable elements. The latter, of course, are convenient sources of a number of useful short-lived radioisotopes, e.g. Mogg, Te132, and methods are described for rapidly isolating these and other fission products in a carrier-free state by ion Methods of separating short-lived exchange. daughter activities from long-lived parents by “milking” techniques in which the parent is strongly adsorbed on organic or inorganic ion exchange materials are also described and typical examples discussed, e.g., milking of 1.7 hr Inu3 (from Snu3) and 2.6 min Bar3’ (from Cs13’). Two applications involving use of short-lived tracers in chemical studies are described. The first is for rapidly measuring a “packed bed” technique solubilities of sparingly soluble salts which have been tagged with tracers. Some recent results obtained by the method on the solubility of LaF, in HCl and HClO, solutions are described. The second is a rapid method for measuring diffusion coefficients in liquid systems. Thin, porous porcelain frits are saturated with solution containing a radioisotope, then rapidly rluted with solution not containing tracer. Diffusion coefficients may be calculated from the decrease of counting rate of the frit with time, after calibration with a material of known diffusion rate. Because of the short diffusion path used, the measurements may be completed in substantially less time by this method than by conventional techniques, e.g. diaphram cell or capillary tube methods. * SM-32111.

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Application of the P-Decay of Tel32 for the Preparation of 1132-Labelled Molecules.* J. -P. ADLOFF and M. BACHER, Centre de recherches nucltaires de Strasbourg, France The principal advantage of iodine-l 32 in biological and medical applications, and in uses as a radioactive tracer, lies in its short half-life (T = 2.30 hr), which, however, represents a serious drawback for the synthesis of labelled molecules. The paper shows that it is possible to take advantage of the chemical reactivity of “nascent” iodine, formed during B-decay of tellurium- 132, for rapidly preparing labelled species with a high specific activity. This reactivity comes partly from the sudden change of the atomic number during the decay which in turn releases a highly excited iodine atom, and partly from the internal conversion of the y-ray following the B-emission. Iodine-132 has to be formed within the medium to be labelled: the most convenient chemical form for the parent compound is tellurium-132 tetrachloride, which is soluble in a number of organic liquids. Several systems have been studied (aromatic hydrocarbons and derivatives, alcohols, etc.) After a few hours of contact, the organic solution is analysed by gaseous phase radiochromatography, and the separation of the various labelled species formed by radiosynthesis can be effected by distillation after addition of carriers. The labelled products may be the results of isotopic exchange or hydrogen abstraction and fragmentation reactions. Near-specific labelling can be achieved in some cases by the use of a suitable organic medium. Short-Lived Isotopes Used as Tracers in Industry (With Special Reference to Swedish Industry).t L. G. ERWALL, H. G. FORS~ERC and K. LJUNGGREN, Isotoptekniska Laboratoriet, Stockholm, Sweden Radioactive tracer methods are rapidly being recognized as a valuable means in industrial research and control. They have already been used with great advantage in trouble shooting, in investigations of the characteristics of process units and as an aid in designing such units. This review comprises typical examples of applications of short-lived tracers, which can be produced in medium neutron fluxes, e.g. Naz4, C13*, K42, Mn56, BrB2, La140, and Aulg8: Studies of the transport of solids through process unitsrotary kilns, blast furnaces, cellulose digesters, bleaching towers, dorr-thickeners; * SM-32/12. t SM-32/13.

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522

seminar on short-liced

Determination of jlow rates for liquids in tubes and oj~en strenms, to measure for example the total water consumption in a plant; Deter-mination of residence times, hold-back, and blocked z~olume for liquids in difierent procrss units in e.g. the pulp and paper industry; “ W’eighing” by means of isotope dilution techniques for determination of e.g. the amount of slag in openhearth furnaces ; LIetermination

of the origin of12on-lnetallicinclu.rionri~lsteel

to find better lining materials and to optimize pouring techniques ; Lnbelling fx qualiv iclentz$cution--experiment steel baths and specific material in thr iron and steel industry are being identifird with absolute certainty; Deteunination

of the &iency

of

mixet-s

in the concrete

radioisotojm

was studied. For measuring distribution and residence time of liquids in reactors, injections of labellrd solutions were made into aqueous, organic Similar mrthods wcrc and organometallic media. applied for the determination of mixing time and contents of storage containers, for leak detrction and an rxamination of dyestulf washing in a filter press. ‘l-he activities required were produced mainly b) irradiation in FRF, the 50 k\Y homogeneous reactor of Frankfurt University. ;\a an example of the application of an isotope generator in thr chemical process industries. an extraction drvicc for the repeated preparation of several millicuries of Ba137m (2.6 min) in a highboiling organic solvent is described.

indztt~y ; i2fai)biug

of joflom in receii,ei-s for

sezeagr

or tejaste

rmlatei-

to find the best point for thr outlet of such liquids; Detection and localixtion of leaks. ‘To minimize the contamination of the final products, the availability of short-lived tracers has been essential in many of thesr stud&. &lost cases are of the physical tracing type, with a variety of possible trarrrs. Thus a tracer can be chosen which has a suitable half-lift and radiation characteristics. If the radioactive nuclidc used has a large neutron activation cross section:which is thr casefor theabovemc-ntioned nuclides, a rcscarch reactor has nuflicicnt neutron flux for the production of quantities of cvcn curies of the tracers. providing that high specific activit)- is not a requisite. In S\vedrn a joint industrial institutr, the Isotope ‘I’cchniqucs Laboratory. \vas formed in 1960 to make research and development work and to assist the industrial enterprises with advice. personnel and necrssay in industrial radioisotope instruments appliration.

Studies with Short-Lived Radioisotopes in the K, FI
Studies of Powder Mixing with Short-Lived Radioisotopes.* I. BJERLE, ~l’he Stockholm Siporex blanufdcturing Company. Sddertalje 2. Sweden and H. G. I’orsbcrg Isotope Techniques Laborator),, Stockholm ii, Sweden Many industrial processes involvr the mixing of If the mixing powders to form homogenous products. conditions are not well established the mixing units will not bc use-d to their best advanta%gr. hIany mixing problems can be studies by means of chemical analysis. but a series of such analvscs is rxpcnsivc in comparison with the fast and rhrap mcasurcment of radioactivity. I;or this reason radioisotopes are often used in determining optimum ‘The statistical nature of racliomixing conditions. activr dcca); also simplifies the treatment of the data obtairlctl. The thcor) and application of some usc_fLrl statistical methods are described. .\a an example. the mixing of light concrctr from cement powder, aluminium powder. sand and water is dcscribcd. ‘l’his is a severe mixing problem as mixing must occur bcforc the reaction bctwccn water and aluminirun. \vhich gives the typical li%ght-concrete structure. takes place to any considerable cxtrnt. Samples of aluminium powder and cement powdrr are activated in a reactor and are thrn used as radioactive tracers for the 5m3 batchrs of mixture. ‘IX: brhaviour of the aluminium po”dcr is studied using the nuclide hIn5’j which is produced from manganese impurities in the aluminium. If certain precautions are taken, it is possible to use this nuclidc in spite of its short half-life (2.6 hri. In the case of cement powder, use is made of the nuclidrs Na2” and K”” which are formed in this material. -

* SM-32/14.

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* Sbl-32/15.

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