UNATTACHED 212PB FRACTION IN THE WORKER'S BREATHING ZONE AT HIGH THORON CONCENTRATIONS.

Classical aerosol physics predicts that it is impossible to observe noticeable values of the unattached fraction of decay products of thoron at typical concentrations of aerosol particles. The experimental data have shown that the unattached fraction of the thoron decay products in a monazite storage facility is in the range 0.3-0.

Determination of radionuclide composition of the Russian NPPs atmospheric releases and dose assessment to population.

Original data on radionuclide activities in air emissions of Russian NPPs are presented based on direct on-site measurements in vent stacks of NPPs during an extensive survey in 2017-2018. For the first time, the detailed inventories of radionuclides in the air releases were directly measured for all types of nuclear reactors, employed in the Russian NPPs. Based on the results of measurements, annual doses for local populations around the Russian NPPs were estimated.

Anomalously high unattached fraction of Rn decay products in the atmosphere of monazite storage facility.

High levels of the unattached Pb fraction of the Rn decay products in the atmosphere of the monazite storage facility were found: f = 0.3-0.5 at the aerosol concentration of 20 000 cm and 0.

Comparison of radioactive aerosol size distributions (Activity, number, mass, and surface area).

Information regarding the number, mass, and specific surface area distributions of aerosols is extremely important for assessments of exposure to radiation due to the intake of radioactive aerosols by inhalation. In this study, these distributions were compared with the activity size distributions for radon decay products. The experiments were conducted in a radon chamber under controlled conditions for the aerosol concentrations and with size distributions in the range from 5 nm to 10 µm.

ULTRAFINE AEROSOL INFLUENCE ON THE SAMPLING BY CASCADE IMPACTOR.

Cascade impactors based on inertial deposition of aerosols are widely used to determine the size distribution of radioactive aerosols. However, there are situations where radioactive aerosols are represented by particles with a diameter of 1-5 nm. In this case, ultrafine aerosols can be deposited on impactor cascades by diffusion mechanism.