The leak was 100 times worse than Fukushima. Photo / 123RF
The leak was 100 times worse than Fukushima. Photo / 123RF
One by one, dozens of nuclear detection stations across Europe began reporting massive amounts of atmospheric radiation over a period of several days in late 2017.
A lab in Italy raised the alarm on October 2, with subsequent detections flagged in the Czech Republic, Norway and Austria later that day.
Further alarming reports were made by authorities in Poland, Austria, Sweden, Greece and Switzerland in coming days.
The levels of the radioactive material ruthenium were so significant it prompted panic that some catastrophe had occurred on the scale of Fukushima or Chernobyl.
It was indeed 100 times more radiation released into the atmosphere than during the Japanese nuclear disaster in 2011, and the first time ruthenium had been detected in large quantities since Chernobyl in 1986, reports news.com.au.
But no one put their hand up to report an accident at their nuclear facilities. Just as quickly as the huge radiation cloud swept across the continent, it dissipated.
The Institute for Radioprotection and Nuclear Security in Paris released this map summarising the detection levels across Europe. Photo / Supplied
Preliminary modelling mapped the cloud's origin back to the southern Eurasian border region, somewhere around the Ural Mountains, between the East European and West Siberian plains.
And while the radiation itself was not hazardous, the real cause for concern was the denials from Russia that one of its plants was responsible for the spill.
Now, a team of researchers has examined more than 1300 radioactivity monitoring stations across Europe and crosschecked their results with weather and airflow patterns.
The results, published this week in the scientific journal PNAS, reveals the source of the leak.
For weeks after the detections in October 2017, Russia sat quietly and in denial of a problem, before its nuclear agency eventually acknowledged the existence of the radiation cloud.
At that stage, it offered its own theory.
The ruthenium was likely caused by a satellite burning up during re-entry into Earth's atmosphere, it said.
Russia insisted it wasn't the cause of the radiation cloud and said soil testing at its facilities had come back clear.
A map of detection stations that reported the large radiation cloud. Photo / Supplied
The new research has examined a wealth of data in an attempt to get to the bottom of not just where the radiation came from, but what occurred.
"Based on time series of detections at various locations in Central Europe, the event was characterised as a short release," the research found.
"The (cloud) duration lasted about (one to three days) on average, depending on the location, with the exception of a few areas."
At the time, the Institute for Radioprotection and Nuclear Security in Paris plotted the cloud and concluded that its most probable source was between the Volga river and Ural mountains in Russia.
The area is home to the Mayak nuclear facility, a massive site that includes reactors and a plant to process spent nuclear fuel.
It has a dark history, having been home to the world's third-worst nuclear accident in 1957, which was unknown to the world for almost two decades.
A Google Maps satellite image of the Mayak facility taken in 2010. Photo / Google
"The Mayak Production Association was one of the first and largest nuclear facilities of the former Soviet Union and spearheaded the Soviet nuclear weapons program," researchers said.
"In the Cold War era, it hosted a total of 10 nuclear reactors, mainly for the production of weapons-grade plutonium."
Despite the disaster in 1957, Mayak continues to operate today on an industrial scale and employs an estimated 12,000 workers.
It has two reactors for isotope production as well as nuclear material storage facilities and a nuclear fuel reprocessing facility, the research report said.
After looking at the detection timelines, "a back trajectory analysis" and the type of radiation found, researchers concluded that Mayak was the source of the leak in 2017.
A radioactive cloud which blanketed parts of Europe in 2017 has been traced back to a nuclear power plant in Russia. Picture: Institute for Radiological Protection and Nuclear Safety. Photo / Supplied
While exactly what happened remains a mystery, but an accidental leak that lasted a short time is the likely culprit.
A major incident, such as a nuclear accident, would've resulted in the release of a number of different radioactive materials, rather than just one.
And researchers stumbled upon a fact that shines further light on the incident.
They discovered that a nuclear research facility in Italy had ordered materials from Mayak just before the detection.
"There are several indications that the release of ruthenium-106 was linked to this order," the report concluded.
