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.

A primary standard source of radon-222 based on the HPGe detector.

The present paper describes the prototype of a calibration standard system for radon concentrations to be used in establishing the traceability of radon concentration measurements in dwellings. Radon gas was generated with a radium-226 solid source in a certified volume as a closed system. The activity of the radon that was released in the closed system was determined from the difference between the absolute activity of the standard radium solid source and the residual radon decay products (Bi or Pb).

Prototype of a primary calibration system for measurement of radon activity concentration.

To calibrate measurement devices for monitoring the activity concentration of (222)Rn in air, a prototype of a calibration facility is tested using a solid (226)Ra source and a high-purity germanium (HPGe) detector. An emanation box was mounted on the detector for online gamma measurements. Inside this box, a 32.

Calibration system for radon EEC measurements.

The measurement of radon equivalent equilibrium concentration (EECRn) is very simple and quick technique for the estimation of radon progeny level in dwellings or working places. The most typical methods of EECRn measurements are alpha radiometry or alpha spectrometry. In such technique, the influence of alpha particle absorption in filters and filter effectiveness should be taken into account.

Thoron progeny size distribution in monazite storage facility.

Field experiments in the atmosphere of monazite warehouses with a high content of (220)Rn progeny concentration were conducted. Size distribution of aerosol particles was measured with the combined use of diffusion battery with varied capture elements and cascade impactor. Four (212)Pb aerosol modes were detected-three in the ultrafine region (aerosol median thermodynamic diameters ∼0.