At the end of September and in the beginning of October, several European radioactivity monitoring networks detected ruthenium-106 in the atmosphere. The IRSN (French institute for radioprotection and nuclear safety) then mentioned that the concentration levels “did not entail consequences for human health or the environment”. The Federal Agency for Nuclear Control (FANC) also confirmed that “no increase of ruthenium rates in Belgium had been noticed” by its permanent measuring system Telerad or by any other additional measurements.
The independent analysis carried out by SCK•CEN and KMI/IRM experts used transport and atmospheric dispersion models combined with numeric meteorological data from the European Centre for Medium-Range Weather Forecasts (ECMWF) to determine the origin of ruthenium-106 based on measurements taken across Europe and around the world. The measurements used come from the International Monitoring System (IMS) which is implemented all around the world for inspecting the nuclear test-ban treaty.
“The result of the analysis is shown in the figure below and gives the difference between the measurements and the analysis for each possible region of the northern hemisphere. A low value means that the model and the measurements are strongly linked thus leading to a very possible source region”, explains Pieter De Meutter, in charge of the calculations. “This ruthenium-106, a fission product, probably comes from a region in Russia where many nuclear facilities are located. Yet, it cannot have been released during a nuclear reactor incident. If this was the case, other fission products would have been measured as well, such as noble gases and iodine.“