Formation of Radon Situation in Buildings of Educational Institutions of Lermontov Town

Purpose: To determine the levels of indoor radon EEC of educational institutions in Lermontov city, to estimate the doses due to radon, to establish the causes of increased radon activity concentration in the indoor air and the patterns of its change.

Material and methods: measurements of radon EEC in cold and warm seasons were performed using the SSNTD (TRACK-REI_1M equipment), the content of natural radionuclides in building materials and soils using the Progress-2000 scintillation gamma spectrometer based on NaI(Tl) detector, the radon exhalation rate, using the Camera-01 charcoal complex, and radon continuous monitoring was carried out with the Radon Eye and Radex MR107. A total of 19 buildings were surveyed.

Results: It was found that the territory is characterized by a high geogenic radon, the average radium-226 content is 103 Bq/kg (range from 45 to 230 Bq/kg), the average value of radon exhalation is 263 mBq/(m²s) (range from 31 to 2730 mBk/(m²s)). The indoor radon EEC values of the 1st floors of educational institutions ranged from 12 to 1347 Bq/m³. Exceeding the permissible levels was found in all surveyed buildings, except for one kindergarten, where basement reliably protect against radon entering buildings. There are no clear seasonal patterns in the distribution of indoor radon, as well as a significant decrease in radon concentrations on the upper floors of buildings, which is apparently explained by intense convective mixing of air between floors. The main source of radon in buildings is its release from the soil. The entry of radon into buildings is caused by the convective transfer of radon through leaky tie-ins of communications and other defects in basement. The ineffectiveness of the radon mitigation measures is highlighted in all buildings where they were carried out. This is due to the inefficient allocation of responsibilities and the lack of competence and experience of the construction organisations carrying out this work.