Cherenkov radiation usually occurs when radioactive materials are immersed in water. The nuclear materials that make up radioactive materials can be used for peaceful purposes (such as energy production), but also for the manufacture of nuclear weapons.
The IAEA’s mandate includes ensuring that nuclear materials and facilities are used for peaceful purposes. States communicate to the IAEA the location, quantity, chemical composition, physical form and use of nuclear material in their possession, in accordance with their safeguards agreements, and the IAEA ensures that the information provided are complete and correct.
Specialized equipment, such as Next Generation Cherenkov Observation Devices (XCVDs) or Digital Cherenkov Observation Devices (DCVDs), which capture emitted light, allows inspectors to analyze nuclear material at nuclear facilities and elsewhere and compare this data with information provided by States. For example, inspectors can measure Cherenkov radiation in nuclear reactor spent fuel storage ponds and determine if the state has declared the correct amount. They can thus verify whether part of the nuclear materials in the spent nuclear fuel has been diverted from peaceful uses.