16 Apr (NucNet): A second meeting of a commission set up to investigate increased concentrations of the radioactive isotope ruthenium-106 (Ru-106) in the atmosphere in Europe and Russia last year has been unable to confirm a source of the emissions, the Swedish Radiation Safety Authority (SSM) said today.
SSM said a second meeting of the commission, set up by Russia with Sweden, France, Germany, the UK, Finland and Norway as members, had been held on 11 April 2018, but “available data does not provide sufficient information to verify that the Ru-106 emissions originate from any of the activities that have been assumed to cause the event”.
However, the commission has said its members can continue to analyse the information independently.
SSM said the origin of the emissions is still unknown.
Several countries detected elevated levels of Ru-106 in the atmosphere in September and October 2017.
In November 2017, France’s IRSN, the technical arm of French nuclear regulator ASN, said the contamination originated somewhere in the Urals region of Russia or Kazakhstan. IRSN said it could not pinpoint the location of the release of radioactive material, but based on weather patterns the most plausible zone lay south of the Ural mountains, between the Urals and the Volga river. This could indicate Russia or possibly Kazakhstan, an IRSN official said.
Russia’s meteorological service confirmed “extremely high” concentrations of Ru-106 were found in several parts of the country in late September.
The country’s state nuclear corporation Rosatom said the atmospheric pollution was not related to the activities at the Mayak nuclear facility, which in 1957 was the site of one of the worst nuclear accidents in history when there was an explosion at a building containing nuclear waste. Today Mayak is a reprocessing site for spent nuclear fuel.
Monitoring stations in Germany, Austria, Italy and Switzerland all detected very low levels of Ru-106 from late September 2017.
The Swiss Federal Office of Public Health said at the time measurements indicated “low levels of radioactivity in the air”. The measurements revealed traces of Ru-106 in aerosols taken in Ticino, Switzerland, between 25 September and 2 October. The concentration of Ru-106 amounted to about 40 micro-Bq/m3, which is 17,000 times lower than the limit for air emissions.