In September, a cloud of ruthenium-106 spread over Europe. Ruthenium-106 is used in nuclear medicine, and it is extracted from used nuclear reactor fuel. The amounts were tiny – one of the things about radioactive materials is that they can be detected at very, very low concentrations.
There are many atmospheric sampling stations around Europe, and their readings were mapped. The top graphic is the result. The center of the cloud was between the Ural Mountains and the Volga River. The amounts over Europe were not dangerous to health, but the amounts closer to the source might have been. Ruthenium was no longer detected in France after October 13.
The center of the cloud suggests a leak at the Mayak plant near Ozersk, once known as Chelyabinsk-40, one of the Soviet Union’s (and now Russia’s) secret nuclear weapons cities. The plant reprocesses nuclear fuel and has contributed enormous amounts of pollution to surrounding areas. At one time, they just ran the wastes into the nearby lake and river.
The fact that only ruthenium-106 was detected tells us something about what must have happened. If the release had been at a reactor or reprocessing plant, other radionuclides would have been detected as well. The release most likely was from the part of the plant after the reprocessing, where the ruthenium-106 is prepared for medical uses.
Radioisotopes are generally handled in a contained system, with air circulated and filtered before it is released. Most likely a filter broke down. The amount released, as estimated from the atmospheric measurements is between a third of a gram and a gram. The news release gives this in teraBecquerels, which sounds OMG GIGANTIC. I hate Becquerels and think they should never be used in this sort of news release. One Becquerel is one atomic disintegration per second. There are many more than tera atoms in, say, a teaspoonful of material, so you get GIGANTIC numbers for even a small amount of material if you use Becquerels. (Conversion via here and here.)
That said, a release like this of radioactive material is never good. Some cleanup may be warranted in the immediate area of the release, and food grown in the area may be dangerous to eat. So it would be good to know more about it from the organization where the release occurred.
Rosatom, which now operates Mayak, says they are unaware of an accident. The Russian government has said nothing. Mayak is the only likely source of the plume, unless there is another storage or processing site for ruthenium-106 nearby. People at the plant where it occurred must be aware of the breach. The Russian meterological service reports detecting high levels of ruthenium-106 in the Ural Mountains in the same time period. One of the weather stations is about 20 miles from Mayak. The fact that ruthenium-106 is no longer being detected in France indicates that those people have fixed the breach.
It took the Soviet government three days to acknowledge that the Chernobyl reactor had blown up in 1986, while radiation levels climbed over Europe and officials in other countries noted that something was very wrong. That delay was part of what convinced Mikhail Gorbachev to change the way the government operated.
This accident is a infinitesimal echo of Chernobyl. But the Russian government seems to have gone back to the old Soviet ways.
Cross-posted to Balloon Juice.