Radioactive cloud over Europe associated with experiments at the Russian plant Mayak

From September 29 to October 4, 2017 severalEuropean stations tracking radioactive background recorded an increased concentration of radioactive substances - the ruthenium isotope-106 in the atmosphere. Fortunately, the concentration of the substance in the air was very low to threaten the health of people or the environment. Nevertheless, scientists said that the emission of radiation was significant. The Commission of Experts on Radiation Threats for two years tried to determine the source of this release. Recently, the staff of the French Institute for Radiation Protection and Nuclear Safety, who were also members of the commission, published a report on the results of this work. In it, scientists indicate that the cause of the release of a radioactive isotope, most likely, could be an incident that occurred at the Russian enterprise “Mayak”.

Where is the "lighthouse"?

Enterprise "Mayak" is located in Chelyabinskarea in the city of Ozersk. It is under the control of the state corporation Rosatom. It was founded in 1948 and is engaged in the production of components of nuclear weapons, isotopes of radioactive elements, storage and processing of spent nuclear fuel from nuclear power plants and submarines, as well as other types of radioactive waste. In the history of the station has already been a major accident. For example, one occurred in 1957 and was named the Kyshtym disaster. As a result of an exploded tank with radioactive waste, several dozens of tons of radioactive substance spilled onto the ground. In the first days of the accident, about 200 people died. And the total number of victims of the accident was 270 thousand. This radioactive catastrophe is considered the third in severity after the Chernobyl and the accident at the Japanese nuclear power plant Fukushima-1.

When did the release of a radioactive substance occur?

The first at the beginning of October 2017 reportedThe increased background level of ruthenium in the atmosphere is the staff of the Ro5 (Ring of Five) scientific network. The network was created in the mid-80s by scientists from five countries: Finland, Sweden, Germany, Denmark and Norway. The organization is engaged in monitoring and sharing data on the distribution of radioactive substances in the atmosphere. Over time, it was joined by experts from other countries. Now this organization includes research laboratories from a couple of dozen European countries.

The first emission of ruthenium 106 was discovered by European stations in Romania.

Assumption that isotope releaseruthenium-106 could have happened at the Russian “Mayak”; European scientists put forward even in the first days after its discovery. However, representatives of the company from the very beginning rejected these statements. According to Kommersant, the Mayak management still denies involvement in the leak. The information service of the Ozersky Combine states that ruthenium-106 was not used in 2017 and, in general, the production of ionizing radiation sources on its basis has not been carried out at the plant for many years.

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Russian scientists from Rosatom at the time of autumn2017 also argued that no accidents at the Russian nuclear enterprises at that time did not occur. However, research stations in the Chelyabinsk region recorded an increased background radiation. But he was 10,000 times lower than the maximum allowable rate. It was noted that there is no danger to the life and health of people. Nevertheless, these data indirectly confirm the conclusion of a new international study.

To the conclusion that it is “Mayak” that isThe most probable source of ruthenium-106 emission, an international commission of scientists from 32 countries, came after studying more than 1,100 atmospheric measurements of radioactive background collected by several dozen European monitoring stations.

In addition, the researchers also compared thesedata with the results of computer simulation of the movement of air masses, taking into account the weather conditions available at the time of the recorded increased background radiation. Based on this, the scientists were able to calculate the probable coordinates of the ruthenium-106 emission, as well as the approximate leak time. The study showed that the release could occur in the period from September 25 to September 26, 2017, a few days before its effects were first recorded on the European territory by Romanian monitoring stations.

What caused the leakage of ruthenium-106 radioactive isotope?

During the investigation, scientists examined severalversions that could lead to a release. Most of them were eventually rejected. For example, the commission excluded the possibility of an accident at the plant’s reactor. It is explained that in this case, in addition to ruthenium-106, an increased concentration of other radioactive elements would be detected in the atmosphere.

Also during the study was rejected versionthat ruthenium-106 isotope could have been released as a result of a leak of spent radioactive fuel. Experts found out the age of radioactive particles in the atmosphere. The data showed that they are much younger than the analogs of the isotope, which is usually contained in spent nuclear fuel.

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Also, the version about the fall of the satellite,on board which could be a battery with a radioactive source. This version at the time of the incident was very popular in the media. Experts noted that the data on the vertical distribution of ruthenium-106 in the atmosphere did not correspond to the data that would be expected when a spacecraft was destroyed. If it were a satellite, then ruthenium-106 would have been detected in the higher layers of the atmosphere.

The most likely cause of leakage of ruthenium-106An international commission calls an unsuccessful attempt to produce another radioactive substance, the cerium-144 isotope. According to Science News, it is produced from spent nuclear fuel, which contains various radioactive isotopes, including ruthenium-106. Apparently, cerium-144 from a Russian company was to be used for the Italian Borexino experiment to search for particles of the so-called sterile neutrino. It is indicated that this experiment was canceled in December 2017, that is, a couple of months after the leak at Mayak. Science News, citing Italian scientists, reports that some unexpected problems have occurred during the cleaning of the material.

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