Methods and Results of Measurements of 3H and 14C Emission into the Atmosphere during Operation of the RIAR Research Nuclear Facilities

9/17/2026 2026 - #03 Environmental aspects of nuclear power

Rybin A.A. Ryaskova M.V. Serebryakov V.V.

https://doi.org/10.26583/npe.2026.3.11

To protect the environment and ensure the radiation safety of the population, RIAR JSC is improving the methodological aspects of monitoring the composition and activity of radioactive substances in technological media and waste from research nuclear installations and other radiation-hazardous facilities. Here is described the created system for monitoring the activity of genetically and globally dangerous ³H (tritium) and ¹⁴C (carbon-14) in a gas-aerosol mixture discharged through a high-altitude ventilation pipe. The selection of ³H in the form of oxide is carried out on a zeolite sorbent, followed by extraction of tritium moisture in a thermal vacuum desorption unit. The isolation of ¹⁴C in carbon dioxide is carried out by bubbling through an alkali solution and collecting a dry sample of barium carbonate. The selection of gaseous and volatile compounds ³H and ¹⁴C is carried out by the method of preliminary thermocatalytic oxidation inside an electric tubular furnace to tritium dioxide and carbon dioxide, which are immediately trapped from the flow in the adsorber and bubbler. The specific activities of ³H and ¹⁴C in the samples are measured by the liquid scintillation method. Here is presented the developed method of measuring the specific activity of ¹⁴C directly in barium carbonate samples in a liquid scintillator in the form of emulsion, also optimal measurement conditions and metrological properties of loads on a Hidex SL300 radiometer are determined. The extended uncertainty of the results with a minimum measurable activity of 0.2 Bq/g in the BaCO₃ sample does not exceed 23%. Here are given the actual values of ³H and ¹⁴C activity in emissions and the surface air layer at the location of the RIAR research nuclear facilities. The values of tritium emissions into the atmosphere in the previous 20 years ranged from 3.8 to 6 TBq per year, which is less than 1% of the permissible emissions. For the first time the integrated values of ¹⁴C emissions given here over 5 years ranged from 40 to 70 GBq per year.

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tritium carbon-14 radioactivity nuclear research facilities experiment radioactive waste gas-aerosol emissions control methods samples sampling techniques zeolite sorption regeneration radiometry measurement error

Link for citing the article: Rybin A.A., Ryaskova M.V., Serebryakov V.V. Methods and Results of Measurements of 3H and 14C Emission into the Atmosphere during Operation of the RIAR Research Nuclear Facilities. Izvestiya vuzov. Yadernaya Energetika. 2026, no. 3, pp. 154-167; DOI: https://doi.org/10.26583/npe.2026.3.11 (in Russian).