• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1176-1179
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• 2019

Measurements of activity concentrations of radionuclides in atmospheric releases were performed in 2017-2018 at vent stacks of seven Russian nuclear power plants. The selected instruments and research methods, with detection limits significantly lower than the existing detection limit of Russian NPPs routine control, allowed to reliably determine up to 26 radionuclides. Analysis of experimental data allows to determine the list of radionuclides for calculation the effective dose rates to public and the permissible annual discharge levels for each Russian NPP. Radiocarbon is determined as major contributor for the dose from the atmospheric releases of LWGR reactors - up to 98% for EGP-6 and RBMK-1000 (Smolensk NPP) reactors. For PWR reactors (VVER) radionuclides contribution to the annual dose from atmospheric releases is more complicated, but, in general, dose is formed by tritium, $^{14}C$ and noble gases. The special monitoring results with ranking of measured radionuclides according to their contribution to the effective dose makes it possible to optimize the list of controlled radionuclides in airborne releases of Russian NPPs from 94 to 8-16 for different NPPs.

• Journal of Radiation Protection and Research
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• v.8 no.2
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• pp.41-46
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• 1983

Annual collective dose within 50 miles radius of Ko-ri I reactor site due to normal airborne effluent discharges in 1979 has been estimated by AIRDOS-EPA computer code. Gaussian plume equation is used for estimation of both horizontal and vertical dispersion of radionuclide release into the atmosphere. Also, radionuclide concentrations in meat, milk, and fresh produce consumed by near-by population are estimated by coupling the output of the atmospheric transport models with the USNRC terrestrial food chain models. Annual collective doses are found to be $3.348{\times}10^{-1}$ whole body manrem and 84.95 thyroid manrem. Whole body manrem calculated by AIRDOS-EPA computer code do not differ greatly from that calculated by GASPAR computer code, but value for thyroid manrem have been estimated lower than that calculated by GASPAR computer code.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2107-2111
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• 2023

The aim of the study is the activity concentration measurements of organic and inorganic ¹⁴C in the discharges of JSC "Institute of Nuclear Materials" (INM). In INM the research water-water reactor "IVV-2M" is operating. Collecting of ¹⁴C species was performed using a ¹⁴C sampler with a chromium oxide and platinum catalysts at different temperatures: 400, 550 and 700 ℃. The measurements of ¹⁴C activity were performed using a liquid scintillation counter. The share of organic ¹⁴C in emissions ranged from 0.30 to 0.84 and depends on the temperature of the catalyst, core structure and reactor operating mode.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.696-706
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• 2023

Consequences of an anticipated Beyond Design Basis Accident (BDBA) Long-Term Station Blackout (LTSBO) event with complete loss of grid power in the VVER-1200 reactor of Rooppur Nuclear Power Plant (NPP) of Unit-1 are assessed using the RASCAL 4.3 code. This study estimated the released radionuclides, received public radiological dose, and ground surface concentration considering 3 accident scenarios of International Nuclear and Radiological Event Scale (INES) level 7 and two meteorological conditions. Atmospheric transport, dispersion, and deposition processes of released radionuclides are simulated using a straight-line trajectory Gaussian plume model for short distances and a Gaussian puff model for long distances. Total Effective Dose Equivalent (TEDE) to the public within 40 km and radionuclides contribution for three-dose pathways of inhalation, cloudshine, and groundshine owing to airborne releases are evaluated considering with and without passive safety Emergency Core Cooling System (ECCS) in dry (winter) and wet (monsoon) seasons. Source term and their release rates are varied with the functional duration of passive safety ECCS. In three accident scenarios, the TEDE of 10 mSv and above are confined to 8 km and 2 km for the wet and dry seasons, respectively in the downwind direction. The groundshine dose is the most dominating in the wet season while the inhalation dose is in the dry season. Total received doses and surface concentration in the wet season near the plant are higher than those in the dry season due to the deposition effect of rain on the radioactive substances.

• Journal of Radiation Protection and Research
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• v.46 no.2
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• pp.58-65
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• 2021

Background: The evaluation of skyshine distribution, release of airborne radioactive nuclides, and soil activation and groundwater migration were required for radiological assessment of the impact on the environment surrounding In-Flight (IF)-system facility of the RAON (Rare isotope Accelerator complex for ON-line experiment) accelerator complex. Materials and Methods: Monte Carlo simulation by MCNPX code was used for evaluation of skyshine and activation analysis for air and soil. The concentration model was applied in the estimation of the groundwater migration of radionuclides in soil. Results and Discussion: The skyshine dose rates at 1 km from the facility were evaluated as 1.62 × 10^-3 μSv·hr^-1. The annual releases of ³H and ¹⁴C were calculated as 9.62 × 10^-5 mg and 1.19 × 10^-1 mg, respectively. The concentrations of ³H and ²²Na in drinking water were estimated as 1.22 × 10^-1 Bq·cm^-3 and 8.25 × 10^-3 Bq·cm^-3, respectively. Conclusion: Radiological assessment of environmental impact on the IF-facility of RAON was performed through evaluation of skyshine dose distribution, evaluation of annual emission of long-lived radionuclides in the air and estimation of soil activation and groundwater migration of radionuclides. As a result, much lower exposure than the limit value for the public, 1 mSv·yr^-1, is expected during operation of the IF-facility.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.1
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• pp.33-42
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• 1989

Nowadays, nuclear power production plays a principal role in the electrical energy supply. However, a nuclear power plants emit small amounts of radio-activity due to mostly fission product gases to the local environment during their normal operation. They may release considerably more radioactivity when accidents occur. It is quite necessary to be able to calculate the radiation doses to the general public from such radioactivity releases in order to evaluate the environmental impact of the normally operating nuclear power plant, to assure that this is within acceptable radiation standards, and to ascertain the radiological consequences of nuclear reactor accidents. Such computations also play an important role in determining the acceptability of a proposed nuclear reactor site. Before radiation dose calculations can be carried out, therefore, it is necessary to determine how the concentration of the radioactive effluents is distributed in the environment following their emissions into the atmosphere. This matter is considered and radiation dose calculations are mentioned in conclusions.