According to the State Specialized Enterprise EcoCentr, which provides continuous radiation monitoring of the lowest atmospheric layer in the Chornobyl Exclusion Zone by air sampling with the help of stationary aspiration installations, increase in the activity concentration of iodine-131 (131I) within 2.1-3.3 x 10-6 Bq/m3 was recorded at four monitoring stations during 18-23 February 2018.
The detected content of artificial iodine-131 is above the minimum detected level of measuring devices, and these concentrations do not pose risks to safety of the public and the environment and prove the ability of current radioecological monitoring systems to record insignificant changes and fluctuations in radiological conditions.
According to the prompt message of the Ukrainian Hydrometeorological Center of the State Emergency Service of Ukraine (SESU), traces of iodine-131 were not detected at the air monitoring stations in Kyiv.
At the air monitoring stations in the Ukrainian NPP observation areas, the activity of iodine-131 on 18-27 February 2018 was below the minimum detected values: 8.5 x 10-7 Bq/m3.
The SNRIU jointly with the Ukrainian Hydrometeorological Center of the SESU, EcoCentr of the State Agency of Ukraine on Exclusion Zone Management (SAEZ) and Energoatom NPPs continues to analyze the situation.
Reference: iodine-131 is a beta and gamma emitter with a half-life of 8.04 days. Man-made sources of this isotope may be plants for irradiated nuclear fuel reprocessing, NPPs and nuclear explosions.
According to NRBU-97 (Annexes D 2.1, D.2.2), allowable concentration of iodine-131 in the air for category C (the public) is 4 Bq/m3.
According to the SNRIU