Published 19.02.2008 , updated: 27.10.2009, 14:51
For the most common sources, such as Cobalt-60, Cesium-137, Americum-241 and Krypton-85, approval is required at activity levels of 10 GBq. For Promethium-147, the level is 10 TBq. The reader is however urged to consult the Regulations on Radiation Protection.NRPA should also receive written notification in the event of name changes and when the radioactive source is handed in/disposed off. When turning in sources it should be kept in mind that both the transport and waste disposal of radioactive source are closely regulated.What is an industrial radionuclide gauge?Radionuclide gauges are devices used for taking measurements or for process control with the help of radioactivity from one or more sealed radioactive sources. Such devices normally consist of a housing containing a radioactive source and a detector.How is the source housing constructed?A source housing ensures shielding from radiation in all directions except that towards which the radioactive source is to be directed. For sources emitting high energy gamma radiation, lead is a common shielding material because of its great density. For radioactive sources that emit low energy gamma or beta radiation, other metals of lesser density offer sufficient shielding. The source housing normally comes with a closing mechanism that allows the user to open and close the device to the primary radioactive field. The source housing usually comes with a closing mechanism allowing the user to open or close for the primary beam (useful beam). Examples of radioactive sources in use:In the paper industry, promethium-147, which is a beta emitter, is used as a source for measuring the thickness of paper. The paper can pass freely between the units in such apparatuses and measurements may be made continually. Pictured here is a Cesium-137 source which is used to measure the dry matter in liquids. Both the source housing to the right and the detector on the left are attached tightly with clamps around the pipe from which the measurements are to be taken.