Tracer is a detectable substance added to a chemical, biological, physical or industrial system by means of some injection or labelling technique in order to study and evaluate the characteristics and the dynamic behaviour of such a process.

Leak detection and leak location are the most widespread radiotracer applications in industrial plants. Any undesirable interconnection between isolated parts of a same system or between two different systems may be a leak. A leak is suspected if there is any abnormal behaviour of a system such as loss of pressure, contamination of product or loss of process efficiency. Detection of a leak, if any, is unambiguously achieved by injecting a radiotracer into the suspected part and measuring for the tracer in the part that should be isolated. Radiotracers are especially useful when the leak is located in underground pipelines since in such cases there is no needs of performing excavations.

Mixing processes are operations which reduce non-uniformities in compositions, properties or temperature in bulk materials. Often, mixing processes take a long time and if the operation conditions are unknown this time becomes much longer than needed making the production costs grow up. This conclusion is valid not only for continuous mixing but also for batch processes. Radiotracers are excellent tools for evaluation of mixing efficiency in liquid grease, colloid, mud, gas or solid phases contributing to the optimisation of mixing processes.

Flow rate measurement is also among the more frequent radiotracer applications in industry due to the good applicability of radiotracer techniques for convenient and accurate measurements and the lack of other competing methodologies. Its main application fields are flow meter calibration, pump efficiency evaluation and flow rate measurement in rivers, channels or drainages.

Mass balance is another radiotracer technique successfully applied for inventory of materials and for evaluation of process efficiency in many branches of industry. The dilution principle is the basis of this technique whose main application is mercury inventory in electrolytic cells.

Finally, some words on radiotracer application for determination of residence time distribution (DTR). It is probably the most important tracer technique from the point of view of the valuable information that can be got from it. As a matter of fact, its application makes it possible not only to determine if a process is working properly according to its design parameters but also to interpret its behaviour by means of mathematical models of different complexity. This is the only technique able to get a complete and reliable information about the dynamics of any process. More information ...