The International Atomic Energy Agency (IAEA) said on 2 July that the recent detection of slightly elevated levels of radioisotopes in northern Europe is likely related to a nuclear reactor that is either operating or undergoing maintenance, when very low radioactive releases can occur. The geographical origin of the release has not yet been determined.

Basing its technical assessment on data reported by member states, IAEA reiterated that the observed air concentrations of the particles were very low and posed no risk to human health and the environment.

Estonia, Finland and Sweden had previously measured levels of ruthenium and caesium isotopes which were higher than usual. They also reported the detection of some other artificial radionuclides. The three countries said there had been no events on their territories that could explain the presence of the radionuclides, as did more than 40 other countries that voluntarily provided information to IAEA.

Seeking to help identify their possible origin, the IAEA on 27 June contacted its counterparts in the European region and requested information on whether the particles were detected in their countries, and if any event there may have been associated with the atmospheric release.

In response, 37 member states in the European region (Albania, Austria, Belgium, Bosnia and Herzegovina, Bulgaria, Republic of Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Netherlands, North Macedonia, Norway, Poland, Portugal, Romania, Russian Federation, Republic of Serbia, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, Ukraine and United Kingdom) had voluntarily reported to the IAEA that there were no events on their territories that explained the release. They also provided information about their own measurements and results.

In addition, ten countries which were not asked for such information – Algeria, Canada, Georgia, Japan, Kuwait, Morocco, Qatar, Tajikistan, United Arab Emirates and USA – also voluntarily reported to the IAEA.

Based on the IAEA’s technical analysis of the mix of artificial radionuclides that were reported, the agency said the release was likely related to a nuclear reactor, either in operation or in maintenance. The IAEA ruled out that the release was related to the improper handling of a radioactive source. It was also unlikely to be linked to a nuclear fuel processing plant, a used fuel pool or to the use of radiation in industry or medicine.

Based on the data and information reported to the IAEA, no specific event or location for the dispersal of radionuclides into the atmosphere has yet been determined. To do this, the IAEA said it depends on receiving such information from a country where the release occurred.