Sealed sources are solid materials, usually metal or plastic, that encapsulate a core of radioactive material. While sealed sources emit radiation, they are designed so that the radioactive material stays within, minimizing the chance of contamination.  However, sealed and plated sources may present an external exposure hazard, depending on the properties of the radioisotope and the activity present. Sealed source activities require a Sealed Source Use Authorization. Most sealed sources are stand-alone sources used to calibrate or check instrumentation, to irradiate materials, or for experiments in student science labs.  Laboratory equipment, such as gas chromatographs, liquid scintillation counters, analytical balances and static eliminators, may contain sealed sources.  The persons responsible for such equipment should be aware of the presence of sealed sources. 

Generally licensed devices are instruments that require a radioactive component in order to function properly. Examples of these include static eliminators, exit signs and some gas chromatographs and liquid scintillation detectors.  In addition to requiring a Sealed Source Use authorization, these devices must be licensed with the Iowa Department of Public Health. 

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