Radioactive sources in industry
Artificial radioelements are often used in industry, e.g. for inspecting welding or measuring the thickness of materials using gauges that contain a source of radiation. Depending on the half-life of the radioelement in question, their limited service life makes some sources unusable after a few months or years. There is a special monitoring system for tracking all sealed sources and their movements. The most common type of smoke detector uses a small americium-241 source. It is estimated that between 6 and 8 million of these smoke detectors are installed.