Gas-aerosol Emissions Research Articles

Statistical Computational Model of Fission Products Composition of Irradiated Nuclear Fuel and Their Contribution to Gas-aerosol Emissions of Nuclear Power Plants

Based on the assumption that the radionuclide composition of gas-aerosol emissions from nuclear power plants (NPPs) into the environment is determined by the composition of the fuel in the reactor (but not identical to it), an analysis of the probability of the occurrence of various isotopes in possible emissions is conducted in this paper. It is confirmed that the activity of nuclear fuel, and consequently the emissions, are determined by uranium fission fragments, proving that the decay rate of radionuclides is proportional to the probability of the appearance of radionuclides with certain mass numbers. It is also shown that there is no functional relationship between the mass yield of radionuclides and their atomic mass, as the variability (fluctuations) in the content of radionuclides in VVER-440 reactor fuel and consequently in NPP emissions reaches 20 orders of magnitude, which prevents the application of computational methods for processing the results. This paper proves that, in order to determine the yield of radionuclides from their observable activity, applying a Zipf-Mandelbrot type distribution in “rank - size” coordinates, it is possible to carry out the mathematical modeling based on the appropriate processing of the obtained results.

The Influence of the Radiation Background of City-Forming Settlements with NPPs on Public Health and the Environment

The radioactive decay of elements as a result of a nuclear reaction is a powerful source of energy used in the production of electricity and heat in cities close to NPPs. The problem of using this kind of energy is the danger of radiation exposure. The production of nuclear energy has many advantages, including the profitability of the final product and its low cost; on the other hand, the half-life products of radionuclides in the composition of gas-aerosol emissions from ventilation pipes settle in the environment on the territory of city-forming nuclear power plants. The duality of the problems of the impact of radiation background on the urban areas near NPPs has become the purpose of this study. It is necessary to investigate the negative effect of radioactive waste emissions during the normal operation of nuclear power plants. For this purpose, the method of a project experiment was used, during which, using laboratory monitoring of external radiation safety and an automated radiation monitoring system, indicators of exposure dose capacities were collected from points in the 30-kilometre zone around the NPP. As a result of the monitoring of radiation samples from soil, atmospheric air and precipitation, and reservoirs, it was revealed that the natural radiation background is insignificant; the probability of harm from radiation exposure is small and insufficient for the development of radiation sickness. However, potentially unsafe sources of radiation exposure have been identified, such as natural radiation – the consumption of contaminated food, solar and cosmic radiation from radioactive elements present in the bowels of the earth; radionuclides, whose emissions uncontrollably occur into the atmosphere; radioactive waste, the disposal and storage technology of which is economically costly. Therefore, it is justified to conduct regular design experiments to check the operability of automated radiation monitoring systems. The materials of the study are of practical value for chemists, environmentalists, and ecotechnologists working at NPPs that monitor safety for human health and environmental protection in the field of atomic energy use

Influence of Gas Aerosol Emissions of the Rostov Nuclear Power Plant on the Radiation Background of Southern Waters

Influence of Gas Aerosol Emissions of the Rostov Nuclear Power Plant on the Radiation Background of Southern Waters

Оценка радиационной обстановки в районе расположения АО «ГНЦ НИИАР» до начала эксплуатации ИЯУ МБИР. Часть 2. Водные экосистемы

The analysis of the radiation survey results of freshwater ecosystems of three rivers and the Cheremshansky Bay of the Kuibyshev Reservoir in the vicinity of State Scientific Centre “Research Institute of Atomic Reactors” (SSC RIAR, Institute) before the start of the MBIR fast neutron reactor operation was carried out. The content of natural (K-40, Ra-226, Th-232) and artificial (Sr-90, Cs-137) radionuclides in the main components of freshwater ecosystems: surface and underground waters, bottom sediments, floodplain soils and vegetation, and ichthyofauna was estimated. It has been shown that the specific activity of Cs-137 in the waste water of industrial storm sewerage (PLK-1) of the enterprise is 10-70, Sr-90 2-10 times higher compared to the surface waters of reservoirs of its zone of influence. This is due to the removal of radionuclides from the site of local contamination in the sanitary protection zone of SSC RIAR. In Cheremshansky Bay, downstream, the concentration of radioisotopes decreases by 8-50 times due to dilution processes and their sorption by bottom sediments and hydrobionts. It is noted that the sorption properties of bottom sediments are determined by the presence of organic compounds in their composition. The multidirectional nature of the accumulation of artificial radionuclides in floodplain soils and plants is shown. In some cases, it is determined by the distance from the source of gas-aerosol emissions of radioisotopes and affects the secondary pollution of freshwater ecosystems. Monitoring data demonstrate a stable decrease in the content of artificial radionuclides in surface waters. In Cheremshansky Bay in 2005-2020 for Cs-137 it was 5 times, for Sr-90 it was 3 times. It has been noted that in recent years, the specific activity of artificial radionuclides in sewage of SSC RIAR, surface and underground waters, as well as fish in the zone of enterprise influence is at the level of the regional background and is 1-3 orders of magnitude lower than the current radiological standards. The importance of further radioecological monitoring of freshwater ecosystems in the SSC RIAR location area after the commissioning of the MBIR for assessing the impact of the new reactor on humans and the environment is shown.

Radioecological consequences of radioactive releases due to weapons-grade plutonium production at the ‘Mayak’ facility in the Russian Federation

The process of nuclear weapons production from 1949 to 1987 was accompanied by the generation of a great amount of radioactive waste. Waste processing operations and controls on discharges at this time were not to the same standard as today. Because of this, vast areas of the Urals region of Russia surrounding the Mayak Production Association (MPA) were exposed to routine and accidental radioactive contamination. The greatest contribution to the contamination was gas aerosol emissions from the MPA in the 1950s (total activity 38 PBq, mainly 131I), releases of liquid radioactive waste into the Techa River from 1949 to 1956 (total activity 115 PBq, including long-lived 90Sr and 137Cs) and accidental atmospheric releases as a result of the thermochemical explosion of the storage tank for liquid radioactive waste in 1957 (74 PBq, relatively short-lived radionuclides being the main contributors). Protective measures helped to relieve the pressing problem of population safety in the 1950s and 1960s, but they led to the appearance of new sources of contamination in the territory surrounding the MPA—Lake Karachay (total activity of beta-emitters 4400 PBq) and the Techa Cascade of Reservoirs (TCR; total activity 8 PBq). Owing to natural radioactive decay and rehabilitation measures, the radiation situation in the East Urals Radioactive Trace (EURT) has improved considerably over the years. Economic activity has been partially restored in these territories. Only the most contaminated territory of the East Urals Radioactive Reserve cannot be used for any economic activities up to the present day. Marked non-uniformity of radioactive contamination of the EURT and the Techa River floodplain, as well as radionuclide washout from Lake Karachay and the TCR into the underground waters and the Techa River require on-going radioecological monitoring, management and regulatory supervision.

Natural radioactivity of coal in the context of radioecological safety and rational use

Introduction. Environmental contamination with natural radioactive elements is an urgent ecological problem of the coal industry. Radiation hazard associated with natural radionuclides in coals and enclosing rock is a poorly studied problem requiring special attention. Radionuclides and their combustion products in coals, i. e. ash and slag waste and gas aerosol emissions, released into the biosphere, become the sources of pollution. Radiation monitoring is required in the course of geological prospecting, deposits development and rational use. The research aims to systematize research and analytical material on specific radioactivity of coal and their combustion products, and update the problem of radioecological safety monitoring. Methodology includes studying data on specific radioactivity of coal at various deposits, studying natural radioactivity of coal, enclosing rock and ash and slag waste, describing ash and slag waste and radon as a source of radioactive contamination, assessing potential radon hazard of mine workings, and analyzing ash composition characteristics for toxicologic estimation of ash dumps and their effect on the environment. Results. Generalized data on radionuclide concentration in coal burned at the CHP facilities, slag and fly ash are presented. Radionuclide specific concentration is much higher in ash and slag waste of coal heat power industry than in initial coal. It is caused by the radionuclide concentration in the products of coal combustion. Potential hazard of radon released from rock is revealed, and ash composition is characterised for toxicologic estimation of ash dumps. Conclusions. Uncontrolled coal combustion exacerbates the problem of radioecological safety due to radioactive aerosol emission and the formation of ash and slag waste with increased concentration of natural radionuclides. System monitoring of radioactivity level in the course of geological prospecting, mining, processing and combustion will allow reducing radionuclides entering the fuel cycle and environment.

Assessment of the impact of the BN-800 reactor operation on the radionuclides content in local foodstuffs in the vicinity of Beloyarsk NPP

The research results are presented as an analysis of long-term data on the effect of gas-aerosol emissions and liquid discharges of Beloyarsk NPP and the Institute of Reactor Materials on the content of artificial radionuclides in local foodstuffs. It was noted that the distance and directions from radiation-hazardous facilities do not significantly affect the accumulation of 90Sr and 137Cs in potatoes and milk. The investigation of a wide range of foodstuffs from the private households of 23 settlements, forests, rivers, and a reservoir of the 30-km zone of the Beloyarsk NPP influence showed that the operation of the BN-800 reactor since 2016 did not lead to a registered increase in the content of artificial radionuclides in agricultural and natural foodstuffs. The maximum specific activities of 90Sr (0.84 Bq/kg) and 137Cs (0.26 Bq/kg) in root vegetables, potatoes, melons and vegetables were noted before the start of operation of the new power unit and were 45 and 300 times, respectively, lower than the current SanPiN standards. The highest content of 90Sr in milk (0.41 Bq/l) was 60 times lower than the requirements of SanPiN, 137Cs (0.11 Bq/l) was 900 times less than the permissible levels. In poultry, the specific activity of 90Sr (0.2-0.3 Bq/kg) and 137Cs (0.13-0.16 Bq/kg) has remained stable low in recent years, and the standardised content of 137Cs in beef (maximum 0.12 Bq/kg) more than 1.5 thousand times lower than the requirements of SanPiN. The highest concentration of 137Cs in wild berries, found in strawberries (1.27 Bq/kg), was 125 times less than SanPiN standards. The content of 90Sr in mushrooms was at the level of 0.1-2.5 Bq/kg, the content of 137Cs is slightly higher than - 0.6-5.8 Bq/kg. The maximum recorded specific activity of 137Cs in mushrooms was more than 80 times lower than the requirements of SanPiN. During the observation period, a decrease of up to 20% or more in the content of artificial radionuclides in samples of 5 fish species was noted; the maximum levels of 90Sr and 137Cs in it were 14 times lower than the strictest SanPiN standards (using fish for baby food). Selective radiation monitoring of foodstuffs of Beloyarsk NPP area aimed at 3H and 14C showed that the content of these radionuclides in foodstuffs was low, close to the background level. In agricultural products, 3H and 14C accumulated to a greater extent in potatoes and milk, and in natural products – in rough boletus and bream. There was noted a need to continue research on the accumulation of 3H and 14C in foodstuffs of Beloyarsk NPP vicinity.

What Formed the North-South Contrasting Pattern of Summer Rainfall Changes over Eastern China?

The south-flood-north-drought pattern of summer rainfall change over eastern China has been attributed to external forcing (greenhouse gas concentration and aerosol emission changes) and a coupled ocean-atmosphere mode (the Pacific Decadal Oscillation; PDO). Here, we investigate the possibility whether the north-south contrasting pattern of summer rainfall change may occur without external forcing and the PDO effect. Analysis of preindustrial and historical climate model simulations and climatological sea surface temperature–forced atmospheric model simulations identified the north-south pattern of summer rainfall changes under constant external forcing and without the PDO signal. This suggests a possible role of atmospheric internal variability. The decadal rainfall change pattern appears as a manifestation of change in the frequency of occurrence of rainfall anomaly distribution from one specific pattern to the other between two neighboring periods. The external forcing and the ocean-atmosphere coupled mode are not necessary conditions for the occurrence of the north-south pattern of summer rainfall changes over eastern China.

Radiation protection of melting of radioactive contaminated metal

An integral component of modern technogenic activities using nuclear energy is the accumulation of radioactively contaminated metals. Solving the issues of recycling or returning these metals to reuse is inextricably linked to ensuring the radiation safety of people and the environment at all stages of the technological cycle using radioactive metal. Possible consequences of the effect of ionizing radiation on the human body are considered, the features of radioactively contaminated metal as a possible source of radiation for production personnel are investigated, as well as the analysis of radiation safety of the utilization of radioactively contaminated metal by its melting using self-deactivation effect. It is noted that an important element of the complex of measures for radiation safety of production personnel is the assessment of the radiation situation, and its main purpose and overall content is indicated. The basic principles of radiation safety are formulated. The choice of rational options for the actions of production personnel in the disposal of radioactive contaminated metal eliminates the exposure of people to radiation levels that exceed standard values. Additional radiation exposure to the environment is also excluded. It is shown that the criterion of radiation safety of a metal is the maximum dose rate of gamma radiation from its surface, which ensures that the limit of the individual annual effective radiation dose is not exceeded. It is reasonable to review the permissible levels of radiation exposure of personnel performing operations with radioactively contaminated metal in accordance with the procedure established by the Ministry of Health of Ukraine. A multistage system for cleaning ventilation emissions from a melting furnace using an electrostatic filter at the last stage, which directly cleans gas aerosol emissions from radionuclides, is proposed. The results of the study can contribute to the return to production of large volumes of radioactively contaminated metal, significantly improve the technical and economic performance of metal production and help to prevent environmental disturbances.

The Leningrad Nuclear Power Plant Primary Annual Gas-Aerosol Emission Analysis

The main radionuclides in gas-aerosol emission of NPPs with power-producing units of RBMK-1000 type were identified in the article. The comparison was made between the specific values of the annual Leningrad NPP gas-aerosol emission of the first stage and the nuclear power plant emissions of the European Union. The annual effective dose to the critical group of the population in the surrounding area of the Leningrad NPP was evaluated.

Structure of the Public Irradiation Dose During Operation of Experimental-Demonstration Power Complex Enterprises

The structure of the public radiation dose resulting from gas aerosol emissions of the experimental-demonstration energy complex incorporating the BREST-OD-300 reactor and fuel fabrication and reprocessing modules is determined. The yearly radiation dose to humans at the point of maximum ground concentration of radionuclides from design basis emissions of the energy complex is formed primarily by 3H,14C, and fission products (0.73, 1.2 2, and 0.9 μSv, respectively) through the peroral pathway as a result of the fallout during the running year of operation of the enterprises. The largest contribution to the irradiation dose is due to the emissions from the spent fuel reprocessing module – 2.33 μSv/yr – and 50% is due to 14C. The radiation dose from the emissions of the BREST-OD-300 reactor is almost completely due to 3H and 210Po (0.73 and 0.17 μSv/yr, respectively). The emissions from the fuel fabrication module have the smallest effect on the public. The dose from fission products is produced by emissions from the reprocessing module approximately in equal amounts in terms of external and internal pathways (0.47 and 0.43 μSv).

Organic Matter in the Surface Microlayer: Insights From a Wind Wave Channel Experiment

The surface microlayer (SML) is the uppermost thin layer of the ocean and influencing interactions between the air and sea, such as gas exchange, atmospheric deposition and aerosol emission. Organic matter (OM) plays a key role in air-sea exchange processes, but studying how the accumulation of organic compounds in the SML relates to biological processes is impeded in the field by a changing physical environment, in particular wind speed and wave breaking. Here, we studied OM dynamics in the SML under controlled physical conditions in a large annular wind wave channel, filled with natural seawater, over a period of 26 days. Biology in both SML and bulk water was dominated by bacterioneuston, and -plankton, respectively, while autotrophic biomass in the two compartments was very low. In general, SML thickness was related to the concentration of dissolved organic carbon (DOC) but not to enrichment of DOC or of specific OM components in the SML. Pronounced changes in OM enrichment and molecular composition were observed in the course of the study and correlated significantly to bacterial abundance. Thereby, hydrolysable amino acids, in particular arginine, were more enriched in the SML than combined carbohydrates. Amino acid composition indicated that less degraded organic matter accumulated preferentially in the SML. A strong correlation was established between the amount of surfactants coverage and -aminobutric acid, suggesting that microbial cycling of amino acids can control physiochemical traits of the SML. Our study shows that accumulation and cycling of OM in the SML can occur independently of recent autotrophic production, indicating a widespread biogenic control of process across the air-sea exchange.

Satellite monitoring of trace gas and aerosol emissions during wildfires in Russia

Peculiarities of the formation of carbon gas and fine aerosol emissions into the atmosphere during wildfires are analyzed. A prompt satellite monitoring system and technique for the assessment of burnt areas and volumes of CO2, CO, and PM2.5 emissions from wildfires are described. The results of satellite monitoring of the Russian Federation and some Russian regions for different months over 2010–2014 are given; burnt areas and volumes of carbon gas and aerosol emissions throughout the entire territory are assessed. The peculiarities of seasonal frequencies of wildfires and volumes of hazardous gas and fine aerosol emissions in the regions under study are identified.

Persistent northward North Atlantic tropical cyclone track migration over the past five centuries.

Accurately predicting future tropical cyclone risk requires understanding the fundamental controls on tropical cyclone dynamics. Here we present an annually-resolved 450-year reconstruction of western Caribbean tropical cyclone activity developed using a new coupled carbon and oxygen isotope ratio technique in an exceptionally well-dated stalagmite from Belize. Western Caribbean tropical cyclone activity peaked at 1650 A.D., coincident with maximum Little Ice Age cooling, and decreased gradually until the end of the record in 1983. Considered with other reconstructions, the new record suggests that the mean track of Cape Verde tropical cyclones shifted gradually north-eastward from the western Caribbean toward the North American east coast over the last 450 years. Since ~1870 A.D., these shifts were largely driven by anthropogenic greenhouse gas and sulphate aerosol emissions. Our results strongly suggest that future emission scenarios will result in more frequent tropical cyclone impacts on the financial and population centres of the northeastern United States.

Identification of the Main Dose-Forming Radionuclides in NPP Emissions

The results of an analysis of gas-aerosol emissions from the ventilation tubes of European NPP are presented. An assessment is made of the contribution of the controlled radionuclides in the exposure of the public to the radiation from NPP emissions of five types of reactor facilities: AGR, BWR, LWGR, PWR, and CANDU. The radionuclides forming the 95% dose in the critical group of the population are determined for each type of NPP.

Near-linear response of mean monsoon strength to a broad range of radiative forcings

Theoretical models have been used to argue that seasonal mean monsoons will shift abruptly and discontinuously from wet to dry stable states as their radiative forcings pass a critical threshold, sometimes referred to as a "tipping point." Further support for a strongly nonlinear response of monsoons to radiative forcings is found in the seasonal onset of the South Asian summer monsoon, which is abrupt compared with the annual cycle of insolation. Here it is shown that the seasonal mean strength of monsoons instead exhibits a nearly linear dependence on a wide range of radiative forcings. First, a previous theory that predicted a discontinuous, threshold response is shown to omit a dominant stabilizing term in the equations of motion; a corrected theory predicts a continuous and nearly linear response of seasonal mean monsoon strength to forcings. A comprehensive global climate model is then used to show that the seasonal mean South Asian monsoon exhibits a near-linear dependence on a wide range of isolated greenhouse gas, aerosol, and surface albedo forcings. This model reproduces the observed abrupt seasonal onset of the South Asian monsoon but produces a near-linear response of the mean monsoon by changing the duration of the summer circulation and the latitude of that circulation's ascent branch. Thus, neither a physically correct theoretical model nor a comprehensive climate model support the idea that seasonal mean monsoons will undergo abrupt, nonlinear shifts in response to changes in greenhouse gas concentrations, aerosol emissions, or land surface albedo.

Wildland fire emissions, carbon, and climate: Modeling fuel consumption

Fuel consumption specifies the amount of vegetative biomass consumed during wildland fire. It is a two-stage process of pyrolysis and combustion that occurs simultaneously and at different rates depending on the characteristics and condition of the fuel, weather, topography, and in the case of prescribed fire, ignition rate and pattern. Fuel consumption is the basic process that leads to heat absorbing emissions called greenhouse gas and other aerosol emissions that can impact atmospheric and ecosystem processes, carbon stocks, and land surface reflectance. It is a critical requirement for greenhouse gas emission inventories. There are several fuel consumption models widely used by scientists and land managers including the First Order Fire Effects Model, Consume, and CanFIRE. However, these models have not been thoroughly evaluated with an independent, quality assured, fuel consumption data set. Furthermore, anecdotal evidence indicates the models have limited ability to predict consumption of specific fuel bed categories such as tree crowns, deep organic layers, and rotten logs that can contribute significantly to greenhouse gases. If we are to move forward in our ability to assess the contribution of wildland fire to greenhouse gas to the atmosphere, our current fuel consumption models must be evaluated and modified to improve their predictive capabilities. Finally, information is lacking on how much black and brown carbon from wildland fire is generated during the combustion process and how much remains on site becoming sequestered in soils, partially offsetting greenhouse gas emissions. This synthesis focuses on the process and modeling of fuel consumption and knowledge gaps that will improve our ability to predict fuel consumption and the resulting greenhouse gas emissions.

Enhanced Central European summer precipitation in the late 19th century: a link to the Tropics

AbstractIn Central Europe, an unusually large number of floods were recorded in the summers and autumns of the late 19th century, causing considerable damage. Different factors contributing to the recurrence of these floods have been discussed in the literature, including the unusually high precipitation anomalies recorded at the time. Based on the frequency and spatial pattern of these floods, previous studies suggest that changes in the large‐scale circulation may have played a relevant role. Here, we use an atmospheric global climate model forced with observed sea surface temperatures (SSTs) and atmospheric forcings (greenhouse gas concentrations and aerosol emissions) to test this hypothesis and identify the causes for the associated atmospheric circulation pattern.We find that our model is able to reproduce the high summer precipitation anomalies observed in Central Europe in the late 19th century, and we show that between 1875 and 1890, transient SSTs, as opposed to climatological ones, are the primary driver for this precipitation increase. Using a series of numerical experiments, we find that the SST variability in the central and eastern tropical Pacific Ocean (associated with the El Niño–Southern Oscillation region) was the primary driver for these anomalies. In addition, SST variability in the Indian Ocean as well as increasing anthropogenic aerosol emissions substantially enhanced European precipitation.The atmospheric circulation anomalies associated with this precipitation increase show a Pacific North American (PNA)‐like pattern over North America and a substantially weakened mid‐troposphere westerly flow over Europe and the North Atlantic, as well as increased pressure over Greenland and reduced pressure over Europe, resembling the negative phase of the summer North Atlantic Oscillation (NAO).

Remote monitoring of emission activity level from NPP using radiofrequencies 1420, 1665, 1667 MHz in real time

The Fukushima nuclear accident showed the importance of timely monitoring and detection of radioactive emissions released from enterprises of the nuclear fuel cycle. Nuclear power plants (NPP) working continuously are a stationary source of gas–aerosol emissions which presented in a ground surface layer persistently. Following radioactive emission, untypical effects can be observed, for example: the occurrences of areas with increased ionization, and increased concentration of some gases caused by photochemical reactions. The gases themselves and their characteristic radiation can be markers of radioactivity and can be monitored by a passive method. Hydrogen atom (H) and hydroxyl radical (OH) are formed in a radioactive plume by radiolysis of water molecules and other hydrogen-containing air components by the high energy electrons from beta-decay of radionuclides. The hydrogen atom and hydroxyl radical can spontaneously radiate at 1420 MHz and 1665–1667 MHz respectively. The passive method of remote monitoring of radiation levels using radio-frequencies of H and OH from radioactive emissions of NPP is described. The model data is indicative of the monitoring of radiation levels using these frequencies.

Bone mineral density in residents of radioactive territories of Chelyabinsk Region

Operation of the Mayak plutonium production association resulted in radioactive contamination of a part of Chelyabinsk Region in the 1950–1960s. Significant gas-aerosol emission of 131I occurred since 1948; in 1957, a radiation accident resulted in 90Sr contamination of large territories. This paper presents comparison of the bone mineral density of persons who lived on territories with different levels of 90Sr-soil contamination with that of a control group. It was found that in 1970–1975, the bone mineral density, estimated from the mineral content in bone samples, in residents of contaminated areas born in 1936–1952 was significantly lower compared to the control group. For persons born in 1880–1935, such differences were not found. It was shown that the decrease in the bone mineral density was not related to 90Sr exposure of osteogenic cells in the dose range from 0.1 to 1300 mGy: the coefficient of correlation between individual 90Sr doses and bone mineral contents is not significant. The decrease in bone mineral density of persons born in 1936–1952 may be associated with exposure of the thyroid and parathyroid glands (systemic regulators of calcium metabolism) to 131I from gas-aerosol emissions from Mayak. The highest levels of gas-aerosol emissions occurred in 1948–1954 and coincided with the growth and development of the thyroid gland, characterized by intensive accumulation of 131I, and with the growth and maturation of the skeleton of persons born in the given calendar years.