Translation. Region: Russian Federation –
Source: International Atomic Energy Agency –
An important disclaimer is at the bottom of this article.
Home
News
What are radioactive sources?
What's what in the nuclear sphere?
Radioactive sources are used to kill bacteria in food, sterilize medical devices and equipment, treat cancer and other diseases, map groundwater sources, test the integrity of mechanical structures, and measure soil density for construction projects.
February 20, 2026
Joanne Liu, Bureau of Public Information and Communications
Radioactive sources like the one pictured are used in a variety of fields, including medicine, agriculture, industry, scientific research, and education. Their size ranges from a few millimeters to several centimeters.
Radioactive sources contain radioactive material, which in turn contains certain radionuclides (unstable forms of a chemical element that emit radiation), the choice of which varies depending on the intended use of the source. These sources emit ionizing radiation, typically in the form of alpha and beta particles, gamma rays, or neutron radiation.
Until the 1950s, it was only possible to use naturally occurring radionuclides, such as radium-226—this isotope of radium is used in the treatment of certain types of cancer. Today, artificial radionuclides produced in nuclear facilities and accelerators are widely used, including cesium-137, cobalt-60, and iridium-192. These radioactive sources are used worldwide for medical, industrial, agricultural, research, and educational purposes.
For example, radioactive sources are used to kill bacteria in food, sterilize medical devices and equipment, treat cancer and other diseases, map groundwater sources, test the integrity of mechanical structures, and measure soil density for construction projects.
Types of radioactive sources
Radioactive sources may contain a wide range of different radionuclides and radioactive materials in varying quantities.
Sealed Source: A radioactive source in which the radioactive material is a) sealed in a permanent capsule or b) is in a chemically bound phase and in a solid state. The radioactive material is sealed or placed in bound form in a capsule that is strong enough to prevent leakage but still allows ionizing radiation to pass through, allowing it to be used in a controlled manner. Concentrated radioactive material is typically supplied in small volume sealed sources – ranging in size from a few millimeters to a few centimeters. Sealed sources can be used in teletherapy machines used to treat cancer, as well as in laboratory equipment such as gas chromatographs, liquid scintillation counters and analytical balances.
Open Source: A radioactive source in which the radioactive material a) is not sealed in a permanent capsule or b) is not in bound form and in a solid state. These types of sources, which can be in the form of powder, liquid or gas, are used in biological research and medicine. In radiotherapy for cancer treatment, ultra-small amounts of open sources are introduced into the body by injection or ingestion to expose specific areas, organs or tissues to radiation. In industry, open sources are used as a radioactive tracer to detect leaks.
Disused source: A radioactive source no longer in use or intended for use in the practice for which official approval was obtained.
Orphan source: A radioactive source that is not under regulatory control because it was either never under regulatory control for various historical and economic reasons, or was abandoned, lost, misplaced, stolen, or transferred without proper official authorization. Previously, there have already been situations where, due to such sources, there were accidents involving radiation exposure.
Safety and security of radioactive sources
Concerns about accidental exposures, including in the metal processing and metallurgy industries and from deliberate unauthorized acts involving radioactive sources, led the IAEA Board of Governors to approve the Code of Conduct on the Safety and Security of Radioactive Sources (Code of Conduct) in 2003. The Code of Conduct, along with its supplementary Guidance on the Import and Export of Radioactive Sources and Guidance on the Management of Disused Radioactive Sources, is a non-binding document that helps countries develop and harmonize policies, laws, and regulations on the safety and security of radioactive sources. Each country is responsible for the regulatory control of radioactive sources, from their initial production to their final disposal.
The purpose of the Code is to help countries reduce the likelihood of accidental exposure to radioactive sources or the malicious use of such sources to cause harm. The Code aims to prevent unauthorized access to or damage to radioactive sources, as well as their loss, theft, or unauthorized transfer.
How to recognize a radioactive source?
The ionizing radiation symbol indicates the presence of ionizing radiation and identifies radioactive sources.
Most radioactive sources are used and housed within larger equipment protected by a powerful shield. Devices or containers containing radioactive sources are typically marked worldwide with a black, purple, or yellow trefoil symbol, or the words "radiation" or "radioactive."
Radioactive sources can look quite harmless—like small metal objects. Examples of radioactive sources can be found here. To confirm the radioactivity of a particular object, radiation detection devices are used.
What should you do if you discover a radioactive source?
Avoid approaching or touching objects marked "radiation." Immediately contact authorities, such as the police. If you feel unwell, seek medical attention immediately and inform them that you were near a potential radiation source. Radiation injuries may look like burns, but unlike burns, they do not heal. Symptoms of radiation overexposure include nausea, diarrhea, and vomiting.
What role does the IAEA play?
Radioactive sources are used in virtually every country in the world. The radiation they emit serves many beneficial purposes in medicine, industry, and agriculture. However, if sources are not properly controlled, they pose a threat to human health and the environment. The IAEA helps countries develop effective, safe, and reliable systems for monitoring their radioactive sources throughout their entire life cycle.
The IAEA provides access to communications and information systems, offers training and information exchange services, and expertise, including comprehensive regulatory assessment services, and helps implement the Code of Conduct on the Safety and Security of Radioactive Sources and its supporting guidance.
The IAEA Incidents and Illicit Trafficking Database (ITDB) contains information on lost or stolen nuclear or other radioactive sources. The range of such data is very wide – from the smuggling and sale of nuclear materials to their unauthorized disposal and detection of lost radioactive substances. Previously, there have been situations where accidents related to radiation exposure occurred due to such sources. The IAEA publishes standards, recommendations and guidance on the safety and security of radioactive sources in the relevant IAEA Safety Standards Series and Nuclear Security Series.
The IAEA assists countries in implementing standards, recommendations and guidance, working in coordination with other bilateral or multilateral initiatives.
The IAEA assists countries in managing disused sealed radioactive sources by providing reference materials and technical guidance, e-learning services, hands-on training and expertise in the safe management of disused radioactive sources.
In addition, the IAEA helps countries implement safe and cost-effective technologies for retrieving, conditioning and storing radioactive sources.
Related resources
Read more
Please note: This information is raw content obtained directly from the source. It represents an accurate account of the source's assertions and does not necessarily reflect the position of MIL-OSI or its clients.