What caused Europe’s 2017 radiation cloud?
Release of ruthenium 106[edit | edit source]
On October 11, 2017, authorities in Germany announced slightly elevated levels of radioactive ruthenium-106 (Ru-106) had been detected at European monitoring stations beginning on September 29, 2017. Those readings ranged between just a few microbecquerel up to 5 millibecquerel (mBq) per cubic meter of air. While these dissipated concentrations posed no threat, European authorities said it is likely an evacuation would have been required at the source, if that source was identified in the West.
Germany’s radiation protection agency, the Bundesamt für Strahlenschutz (BfS), said elevated Ru-106 levels were recorded at six national monitoring stations. France, Switzerland, Austria and Norway were among the European nations all reporting elevated Ru-106 readings beginning in late September, as were Finland and Greece. Even Russia – the suspected culprit in the release – reported levels of Ru-106 in St. Petersburg it said were four times below a safe threshold, according to the Roshydromet service.
Ruthenium, bearing the Latin name for Russia, was first discovered in the 1800s by scientists studying platinum and named in 1825 after research on samples taken from the Ural Mountains. The discovery was verified in 1840 by Karl Klaus at the University of Kazan. It is considered one of the rarest metals on earth, now sought-after in the solar energy and chemical industries. The relatively stable Ru-106 isotope is not found in nature, and scientists say the release was unusual. So unusual, in fact, that Ru-106 was last seen more than 30 years ago during the Chernobyl accident in Ukraine. Yet an accident at a nuclear reactor was ruled out by international agencies because that would have released other isotopes too.
Russia denies leak[edit | edit source]
Rosatom, the Russian nuclear energy agency, said no facilities had any radiation situations above normal level. “The claim that the contamination had a Russian origin is unfounded,” the agency said in October. Outside of St. Petersburg there were no reports of elevated readings elsewhere in the country, although there were low levels in the Chelyabink region where the Maïak nuclear complex, with its own history of a secret 1957 nuclear accident, is located. Rosatom does produce Ru-106 through JSC Isotope, an entity of the state corporation headquartered in Moscow, but that’s for medical uses. An accident at a Russian nuclear reactor was ruled out by European agencies because it would have released other isotopes too.
European response[edit | edit source]
German officials conducted an investigation and said the reason for the Ru-106 release remains unclear, as did the origin. The BfS calculations on atmospheric dispersion of the release pointed to the southern Ural Mountains during the last week of September, without ruling out other geographic possibilities in southern Russia. “Considering that Russia must be assumed to be the region of origin of radioactive release,” the BfS said, Germany expected “responsible Russian authorities, and IAEA, to provide robust information as soon as possible in order to help clarify the causes of the increased ruthenium readings.” The German agency worked closely with France’s Institut de Radioprotection et de Sûreté Nucléaire (IRSN) to determine a geographic location of the Ru-106 leak and any possible cause.
On November 9, 2017, the IRSN released a map of calculations based on Ru-106 readings across France from September 27 through October 13, when the last of the lingering contamination was recorded. The IRSN also gathered data from other European nations, nearly all of which were affected. “Based on the meteorological conditions provided by Météo France and the measurement results available in European countries, IRSN carried out simulations to locate the release zone, to assess the quantity of ruthenium released, as well as the period and the duration of the release,” the French agency said.
The IRSN map was based on 368 readings from 28 countries with Ru-106 release simulations carried out across a geographic grid. The most likely source of the release, with more than 60 percent confidence, was somewhere between the Ural Mountains and the Volga River in Russia, although researchers point to the possibility of Kazakhstan as the source as well. Kazakhstan's Nuclear Physics Institute in Almaty said on November 10 that there were no nuclear leaks there in September and October, while the Kazakh Institute of Radiation Security said the country has no facilities that could cause this accident.
Potential health hazards[edit | edit source]
The IRSN corroborated its research findings with international experts, all with good agreement. France’s research also found the most likely reason for the Ru-106 leak was either in nuclear fuel cycle facilities or a radioactive medicine source. The IAEA assisted with ruling out the possibility of a satellite powered by Ru-106 releasing the contamination on re-entry; there were no such timely occurrences.
Europeans were not placed at health risk by the release, but IRSN said it was a major release at the unknown location that, had it occurred in France, would have required evacuation at a distance of several kilometers from the source for health reasons. It also would have exceeded France’s safe levels of exposure for food for tens of kilometers from the source location; however, import controls were not indicated. The Ru-106 cloud dissipated a month earlier and had not recurred, leaving Europeans safe.
What is not safe, though, is the failure of the responsible nation to explain the Ru-106 leak to its international neighbors. Jean-Christophe Gariel, IRSN director for health, said that responsibility for identifying the source now lies with the Russians or Kazakhs. If they fail to identify where the contamination came from, the matter could be referred to the United Nations.