Ro5 Researchers Indicate Radioactive Readings in 2017 Due to Unreported Nuclear Plant Accident; Major Nuclear Releasehttps://phys.org/news/2019-07-ro5-radioactive-major-nuclear.htmlAfter the Chernobyl accident in 1986, scientists in Europe realized that a network of radiation monitoring stations was the best way to detect and alert the public to fallout from nuclear accidents. Scientists in five countries, Finland, Sweden, the Federal Republic of Germany, Denmark and Norway, set up such a network, which they called the Ro5. Scientists from other European countries have joined the network over the years, but the name has remained.
Two years ago, members of the network began reporting higher-than-normal levels of ruthenium 106 (106Ru). The levels were not high enough to be considered dangerous, but the area of detection was large enough to suggest something unusual had happened—some suspected a nuclear accident at a facility in Russia. But Russian officials insisted the levels were due to a release from a disintegrating satellite. In this new effort, 69 researchers from across Europe together found evidence that very strongly suggests the radioactivity they observed came from a Russian nuclear power plant in a southern part of the Urals—likely Majak.Research by the team consisted of combining and compiling 1,100 atmospheric readings and 200 readings taken on the ground.
The researchers were able to conclude that the radioactivity was not from a satellite. They further report that levels of radioactivity varied widely, from tenths of µBq·m−3 to over 150 mBq·m−3. They also found that the widespread nature of the readings suggested an unprecedented release of 106Ru. By looking at the data placed over a map, they were able to trace it back to its source—in the Southern Urals in Russia. HYSPLIT-based 240-h backward trajectories ending at the Romanian monitoring station in Zimnicea (black star) (43.666 N, 25.666 E), every 3 h on September 30, 2017, from 2 AM to 11 PM UTC. The green circle indicates the position of the Mayak industrial complex. The altitude of the air parcels is given in meters above ground level (AGL). The green circle in the altitude sections of the trajectories ending at 3 PM and 5 PM UTC (maps surrounded by red frames), respectively, indicates the time and altitude (approximately 500 m) the air parcels were in closest proximity to the Mayak area.The researchers suggest the evidence indicates that there was likely an unreported nuclear plant accident.... On September 29, 1957, a chemical explosion took place in a radioactive waste storage tank at the Mayak nuclear complex, causing a massive release of radionuclides. The accident became known as the “Kyshtym accident.” In the course of this accident, about 2,700 TBq of 106Ru (together with various other radionuclides) were released into the environment, causing a significant contamination in a more than 100-km-long strip that has been termed the East Urals Radioactive Trace (23).
Although such incidents have become rare events in recent years,
106Ru was released from nuclear reprocessing facilities in the past on multiple occasions.
On September 26, 1973, following an exothermic reaction at the Windscale reprocessing plant (United Kingdom), 35 workers were contaminated through an atmospheric release of 106Ru estimated at 0.37 TBq (25). On April 6, 1993, an explosion at the reprocessing plant of the Tomsk-7 nuclear complex (Siberia, Russian Federation) led to the release of approximately 0.52 TBq of
106Ru among other fission products and actinides (26, 27). About 200 km2 were contaminated. On May 18, 2001 and October 31, 2001, a failure in the vitrification shops at the La Hague reprocessing plant (France) led to an atmospheric release of
106Ru. Based on aerosols sampled at 200 km downwind from the stack and grass sampled in the vicinity, the first release was estimated between 0.005 and 0.05 TBq, while the second was estimated to range between 0.0005 and 0.02 TBq (28). Significant atmospheric releases also occurred from the early Hanford operations that were linked to United States nuclear weapons production, with
106Ru (14 TBq from 1944 to 1972) being a relatively minor constituent (compared with 2.7 EBq
131I in the same time span) (29).
For comparison, the present, undeclared accident released an estimated activity of 250 TBq at once.Open Access: O. Masson et al.
Airborne concentrations and chemical considerations of radioactive ruthenium from an undeclared major nuclear release in 2017,
Proceedings of the National Academy of Sciences (2019)
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See also: https://en.wikipedia.org/wiki/Kyshtym_disaster------------------------
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