What can we learn from a radioactive cloud over Europe?

ruthenium crystals
CC BY 3.0 Periodictableru

The accident probably occurred in the last days of September. Perhaps it was an explosion. Or a gas under high pressure hissing out of a pipe. Maybe it was a chemical cloud over a crashed truck.

In early October, monitoring stations across the Eastern European Union countries sounded alarm: an elevated level of radioactive ruthenium-106 (Ru-106, for short) was detected in the air.

The authorities launched into action, increasing monitoring and communicating results along a network of agencies cooperating to keep all citizens safe in the event of industrial incidents. Although the levels detected were low – 17,000 times less than the action level – there was nothing to indicate the origin of the contamination nor whether it would increase before it ceased.

The ruthenium-106 found spreading over the European continent is one of many different isotopes – ruthenium has 7 stable isotopes and 34 known radioactive isotopes*, of which Ru-106 is the most common. No other radioactive elements were found, so an accident at a nuclear power could be ruled out. Most likely, the radioactive ruthenium was purified, intended for one of its most common uses: in medical treatments. Or perhaps it was released from a nuclear fuel processing facility.

Levels continued to be monitored, and over the next days into mid-October, reports continued to be generated, tracking the Ru-106 as it was carried westward on the breeze.

Finally this weekend, researchers from the French Institute for Nuclear Security (ISRN) reported that they have traced the ruthenium-106, working backwards along the path of the cloud and factoring in weather conditions prevailing at the time, to a probable incident in the southern Ural Mountains, where Russia borders Kazakhstan.

Russian authorities have denied any incidents of this sort, and European authorities have little contact with the responsible authorities in Kazakhstan. In spite of the fact that the pollution so easily crossed many national borders, there is no legal instrument in place to force countries to share information about such incidents. Our further knowledge about how many workers might have been injured or what was done and is being done to prevent and manage such an industrial accident is limited.

So what can we learn from the strange case of the radioactive ruthenium cloud?

First, take a moment to be fascinated by the wonders of this metal. The hard, silver-white metal ranks below gold but above palladium in abundance in the earth’s crust. It forms beautiful crystals (pictured), but is most often sold in the form of powder for ease of industrial handling or as metal ingots. Ruthenium helps certain alloys perform to high-tech standards (for example, the single-crystal superalloy TMS-138A contains 3.8% ruthenium), and ruthenium oxide serves a role in swimming pool disinfection plants.

Of the radioactive isotopes, ruthenium-106 is the most common and has the longest half-life of almost a year (half-life measures the time required for half of the radioactive substance to decay). The radioactive Ru-106 is useful in medical treatments, especially for melanoma of the uvea, which consists of layers of cells that encircle the eyeball. But it may be a real miracle medicine because it sits just above iron on the periodic table so it can use some of the body’s natural mechanisms to its advantage when it is delivered as a drug.

Second, we learn about the amazing technologies that work to balance the risks of these industrial and medical chemicals so that we can benefit from their unique properties. The fact that authorities were alerted when the exposure levels to the radioactivity of the Ru-106 for a full week was still 100,000 times less than the background radiation we get from natural sources in an hour underlines the incredible sensitivity of the monitoring network, which is designed to detect potential releases early, giving responding authorities the maximum amount of time to issue warnings and implement safety measures for the population.

Finally, this is a reminder that pollution doesn’t stop at national borders. Although this incident posed no threat to the health of people, lots of pollution issues that do pose risks for our health, safety, and security need to be addressed by trans-national and global cooperation. No country is an island, not even the islands, in our interlinked planet’s ecosphere.

*Did you ever wonder what an isotope is? If you remember back to your chemistry class: atoms are made from a center of protons and neutrons, with electrons circulating around the outer edges of the atom. The identity of an atom, e.g. ruthenium, is established by the number of protons. In isotopes, the number of protons remain the same while the number of neutrons varies.

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