The distribution of radioactive pollutants, such as ^(222)Rn, U, Th and ^(226)Ra in the air, sur- face waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied The mechanical, geoche...The distribution of radioactive pollutants, such as ^(222)Rn, U, Th and ^(226)Ra in the air, sur- face waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied The mechanical, geochemical and biogeochemical processes responsible for the transport and fate of the radioactive elements are discussed based on the monitoring data. The pollutants con- centrations of effluents from the mine tunnels were dependent on pH and SO_4^(2-) which were con- trolled by biochemical oxidation of sulfide in the ore/host rocks. Radon anomalies in air reached 4 km from the tailings pile depending on radon release from the site, topography and climate. ^(238)U and ^(226)Ra abnormities in stream sediments and soil were 40-90 cm deep and 790-800 m away downstream. Anomalies of radioactive contaminants of surface watercourses extended 7.5-13 km from the discharge of effluents of the site mainly depending on mechanical and chemical proc- esses. There were about 2.86 ha rice fields and 1.59 km stream sediments contaminated. Erosion of tailings and mining debris with little or no containment or control accelerated the contamination processes.展开更多
Several previous papers have been published about radioactive contamination in Mexican soil, marine sediments and foodstuffs. Ever since, results have been according to expectation, mainly consisting of natural isotop...Several previous papers have been published about radioactive contamination in Mexican soil, marine sediments and foodstuffs. Ever since, results have been according to expectation, mainly consisting of natural isotopes in small concentration. Continuous research leads with the surprising finding of fission product <sup>137</sup>Cs (t<sub>1/2</sub> = 30 years) in strawberries produced in different states, about 2000 km away from each other. Never before, such contaminant has been observed in foodstuffs, produced in this country. The aim of this work is to report the presence of <sup>137</sup>Cs in Mexican strawberries and compare the activity of such contaminant with the natural radioactivity of <sup>40</sup>K (t<sub>1/2</sub> = 1.28 × 10<sup>9</sup> years), through gamma spectrometry. Eventually, the specific activity of <sup>137</sup>Cs observed in samples FM4, FM5 and FBC is respectively 0.7, 0.8 and 0.3 Bq/kg. The limits established in CODEX-STAN-193-1995 for <sup>137</sup>Cs are 1000 Bq/kg, so all samples meet the recommendation. It’s presence now in vegetables result with enough interest to be known and considered in the near future to measure the possible effect that radioactive contamination could reach after nearly 80 years from second world war, where no nuclear test has been performed, nuclear accident occurred, neither nuclear weapon has ever been used.展开更多
Radioactive contaminants, such as radium, radon, and uranium isotopes are naturally present in drinking water, and gas and oil extraction like hydraulic fracturing can exasperate radionuclide leakage into groundwater....Radioactive contaminants, such as radium, radon, and uranium isotopes are naturally present in drinking water, and gas and oil extraction like hydraulic fracturing can exasperate radionuclide leakage into groundwater. The concentration of radionuclide in drinking water is dependent upon the water source and the underlying lithology within the aquifers. In United States, the Environmental Protection Agency regulates the level of radioactivity in drinking water via the gross alpha test, which is conducted to measure the emitted alpha particles as a result of the radioactive elements’ natural decay. Radionuclides, such as radium and uranium, are known to cause bone cancer and other forms of cancer. Communities with crippling water purification infrastructure may be at a higher risk of being exposed to radionuclides, and this is a significant environmental justice concern. The radionuclide concentrations for the metropolitan or most populated city in each state in the United States and its territories (Puerto Rico, US Virgin Islands and Guam) were analyzed and correlated to the annual household income, to determine any disparities that maybe present. Lower income communities had elevated levels of radionuclides when compared to higher income communities which had lower frequency in elevated radionuclide contaminants.展开更多
The objective of this paper is to provide information for nuclear field specialists and decision makers on opportunities for minimizing radioactive wastes arising from the decontamination ＆ decommissioning of a CANDU...The objective of this paper is to provide information for nuclear field specialists and decision makers on opportunities for minimizing radioactive wastes arising from the decontamination ＆ decommissioning of a CANDU-6 NPP. The paper proposes a method for selection of appropriate decontamination techniques which may be used at Cernavoda NPP decommissioning, equipped with CANDU heavy water reactors, based on the simulation with ProVision software. The paper has a singular focus on physical decontamination techniques and does not address other aspects of decommissioning. The physical decontamination techniques which are the best for certain areas of the CANDU-6 NPP from point of view of effectiveness and cost were determined. A unit cost for each decontamination technique was determined by relating the total cost to the average surface to be decontaminated. In conclusion, physical techniques will apply more efficiently to concrete surfaces. The chemical decontamination methods, in comparison with physical decontamination methods are. more suitable for non-porous surfaces respectively metal and are less recommended for concrete surfaces.展开更多
The concentrations of natural radionuclides, radium-226, radium-228, and potassium-40, and the artificial radionuclide caesium-137, in river bottom sediments and suspended matter were monitored in the Czech Republic b...The concentrations of natural radionuclides, radium-226, radium-228, and potassium-40, and the artificial radionuclide caesium-137, in river bottom sediments and suspended matter were monitored in the Czech Republic by the Czech Hydrometeorological Institute during the period 2000-2010 and 2001-2010 respectively. The data were used to evaluate the natural background levels of these radionuclides and the impact of human activities on the water environment. For potassium-40 in sediments, the natural background level was estimated to be 570 Bq/kg. To evaluate the background level for radium-226, the river sites affected by human activities (mining and processing uranium ore, coal) were eliminated from the assessment. The average natural background values were 47.8 Bq/kg for radium-226 and 47.2 Bq/kg for radium-228 in sediments and 86.5 Bq/kg for radium-226 and 87.9 Bq/kg for radium-228 in suspended matter. The river sediments were identified as good indicators of radioactive contamination, especially radium-226, which recorded historic contamination due to former uranium mining and milling. The radium-226 contamination rate was assessed using the ratio of radium-226 to radium-228. This ratio was used to classify sediment according to the relative contamination from the uranium industry. The residual contamination of caesium-137 due to the Chernobyl accident in 1986 was also assessed. Average values of caesium-137 were 14.0 Bq/kg in sediments and 25.0 Bq/kg in suspended matter.展开更多
Monitoring the behavior of radioactive contaminants associated with military applications,nuclear power facilities,and interim storage of radioactive waste materials is of significant concern in radiological analysis....Monitoring the behavior of radioactive contaminants associated with military applications,nuclear power facilities,and interim storage of radioactive waste materials is of significant concern in radiological analysis.Four sequential extraction schemes(SES) for fractionation of ^(241)Am were compared using five different types of soils,Vertisol,Cambisol,Chromic Luvisol,Eutric Fluvisol,and mixed urban soil,collected from different parts of Bulgaria.The results for the exchangeable ^(241) Am were in a wide range and depended on the SES used.Soil ^(241)Am varied from 0.5%to 6%in the exchangeable phase,from 0.5%to 35%in the carbonate phase,from0.4%to 36%in the reducible phase(easily reducible and moderately reducible),from 3%to 17%in the oxidizable phase,and from10%to 50%in the residual phase.After 100 d of contamination,around 50%of soil ^(241)Am was permanently fixed in the residual phase.There was strong evidence that the preferable soil phase for ^(241) Am was the carbonate phase.The transfer factor of ^(241) Am in the soil-plant system depended on ^(241)Am in the easily oxidizable phase(fulvic acid(FA)+humic acid(HA) phase).These confirmed the applicability of the National Institute of Standards and Technology(NIST) sequential extraction scheme for fractionation of soil^(241) Am since it includes extraction of FA+HA phase and then the carbonate phase.展开更多
The uptake of Radium-226,Radium-228 and potassium-40 by tomato plants as the effect of irrigation with thermal water was studied as pot experiments.Tomato seedlings were grown in 7 L pots filled with four different so...The uptake of Radium-226,Radium-228 and potassium-40 by tomato plants as the effect of irrigation with thermal water was studied as pot experiments.Tomato seedlings were grown in 7 L pots filled with four different soil textural classes collected from different locations;silt clay soil(SZ1)and sandy clay loam(SZ2)collected from Zara area at Jordan Valley with 226Ra activity 392(SZ2)and 5350(SZ1)Bq∙kg^(-1).Two control soils also were used;clay loamy soil(SW)and sandy soil(SSa)were collected from Amman with 226Ra activity about 20 Bq∙kg^(-1) for SW 8.3 Bq∙kg^(-1).Half of the treatments were irrigated with ther-mal water while the other half were irrigated with non-thermal water.The av-erage Transfer Factor(TF)for 226Ra values ranged from 0.002 to 0.91 in tomato fruits while in vegetative parts ranging from 0.003 to 2.54(stems)and from 0.014,to 4.96(leaves)as a response to irrigation with thermal water.Radium-228 was just detected in tomato leaves that were grown in sandy soil(SSa).High TF was observed for ^(40)K in tomato fruits(8.2 to 133.7)as compared to leaves(1.2 to 16.0)and in stems(1.9 to 11.3).The highest TF values for both 226Ra and ^(40)K were observed in sandy soil.Analysis indicated that source of irrigation water and soil factors affects 226Ra activity in plant tissues while ^(40)K is only af-fected by its concentration in soil.Although the pot experiment offers con-trolled conditions for testing,it does not fully replicate field conditions where root depth,soil heterogeneity,and environmental interactions may influence radionuclide uptake.Therefore,the findings should be interpreted with this limitation in mind.展开更多
The large amount of radioactive waste generated by the rapid development of nuclear energy is in urgent need of disposal.Metal chalcogenide ion-exchangers(MCIEs)are newly developed in recent years that show great pote...The large amount of radioactive waste generated by the rapid development of nuclear energy is in urgent need of disposal.Metal chalcogenide ion-exchangers(MCIEs)are newly developed in recent years that show great potential in the field of removing radionuclides.This is a comprehensive review of the latest research progress on the removal of key radioactive ions(e.g.,radioactive Cs^(+),Sr^(2)+,UO_(2)^(2+),lanthanide ions,and actinide ions)by MCIEs.The structure and ion-exchange properties of MCIEs are summarized emphatically.The ion-exchange mechanism of MCIEs is discussed and the structure-function relationship is preliminarily revealed.Easily exchangeable cations in the interlayer/channel,appropriately sized interlayer/channel/window spaces,flexible open framework,and the strong affinity of the Lewis soft base S^(2−)/Se^(2−)sites in the framework for soft or relatively soft metal ions,are the keys to the excellent selectivity and fast adsorption kinetics of MCIEs for radioactive ions.Finally,future research directions of metal chalcogenides for radioactive ions removal are foreseen.It is hoped that the review will provide a reference for the design of new metal chalcogenide ion-exchangers with practical application prospects for radioactive waste treatment and point to new directions for environmental radioactive contamination control.展开更多
Emphasizing its potential for environmental sustainability,this review investigated how biochar—a carbon-rich material obtained from biomass pyrolysis—might be used into nuclear science and technology.High surface a...Emphasizing its potential for environmental sustainability,this review investigated how biochar—a carbon-rich material obtained from biomass pyrolysis—might be used into nuclear science and technology.High surface area,porosity,and functional groups give biochar special adsorption capacity,which qualifies it as a potential instrument for radiation cleanup and improving energy economy in nuclear uses.From the historical development of nuclear physics to the creative application of biochar in nuclear waste management and radiation shielding as well as its contribution to sustainable nuclear energy,the study covers several spheres.Biochar presents amazing efficiency in adsorbing and immobilizing radionuclides in the field of nuclear waste management,therefore establishing itself as a viable substitute for more traditional approaches.Its uses cover handling of high-level radioactive materials as well as treating low-level radioactive effluents.The paper also looks at using biochar as radiation shielding since its carbonaceous character produces strong,light-weight protective barriers.Using controlled pyrolysis and later changes,the paper addresses advanced manufacturing processes for customizing nuclear-grade biochar for particular uses.Within the nuclear industry,economic studies emphasize the affordability and possible financial gains of biochar,as well as its market potential and commercialization techniques.Lifetime analysis helps to evaluate environmental effects and sustainability by stressing the part of biochar in carbon sequestration and lowering of ecological footprints.The paper discusses safety and regulatory issues,how artificial intelligence and machine learning might be used for material optimization,and the limits and difficulties in using biochar.Practical case studies highlight its success in nuclear environments.The study ends by placing biochar as a major component in creating sustainable nuclear technology,which calls for continuous research,cooperation,and creativity.展开更多
The scintillation properties of a CdMoO4 crystal have been investigated experimentally.The fluorescence yields and decay times measured from 22 K to 300 K demonstrate that CdMoO4 crystal is a good candidate for an abs...The scintillation properties of a CdMoO4 crystal have been investigated experimentally.The fluorescence yields and decay times measured from 22 K to 300 K demonstrate that CdMoO4 crystal is a good candidate for an absorber for a bolometer readout,for both heat and scintillation signals.The results from Monte Carlo studies,taking the backgrounds from 2ν2β of^100 42Mo ^116 48Cd） and internal trace nuclides ^214Bi and ^208Tl into account,show that the expected sensitivity of a CdMoO4 bolometer for neutrinoless double beta decay experiments with an exposure of 100kg·years is one order of magnitude higher than those of the current sets of the limT1/2^0νββ of ^100 42Mo and ^116 48Cd.展开更多
The distribution of radioactive pollutants, such as ^(222)Rn, U, Th and ^(226)Ra in the air, sur- face waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied The mechanical, geoche...The distribution of radioactive pollutants, such as ^(222)Rn, U, Th and ^(226)Ra in the air, sur- face waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied The mechanical, geochemical and biogeochemical processes responsible for the transport and fate of the radioactive elements are discussed based on the monitoring data. The pollutants con- centrations of effluents from the mine tunnels were dependent on pH and SO_4^(2-) which were con- trolled by biochemical oxidation of sulfide in the ore/host rocks. Radon anomalies in air reached 4 km from the tailings pile depending on radon release from the site, topography and climate. ^(238)U and ^(226)Ra abnormities in stream sediments and soil were 40-90 cm deep and 790-800 m away downstream. Anomalies of radioactive contaminants of surface watercourses extended 7.5-13 km from the discharge of effluents of the site mainly depending on mechanical and chemical proc- esses. There were about 2.86 ha rice fields and 1.59 km stream sediments contaminated. Erosion of tailings and mining debris with little or no containment or control accelerated the contamination processes.展开更多
Objective:To assess the thorium exposure of the mine workers and the public to a typical rare earth mine and estimate the resultant committed effective dose to them.Methods:A total of 79 volunteers were selected in th...Objective:To assess the thorium exposure of the mine workers and the public to a typical rare earth mine and estimate the resultant committed effective dose to them.Methods:A total of 79 volunteers were selected in this survey,including 69 mine workers and 10 local residents living about 4 km away from the mine site.Urinary samples were collected from 79 volunteers,with 65 hair samples from 57 workers and 8 local residents.The thorium concentrations in urinary and hair samples were determined by using inductively coupled plasma mass spectrometry.The committed effective doses were estimated based on the urinary samples collected and the parameters as recommended by ICRP Publication 137.Results:Thorium concentrations in the samples from the workers ranged from 19.0 to 2388.8 ng/g in hair with median of 149.8 ng/g,and in urine 18.3–906.1 ng/L with median of 59.6 ng/L,respectively.The median values of thorium concentrations were 11.8 ng/g in hair and 32.40 ng/L in urine for the public respectively.The thorium concentrations in urinary and hair samples of the workers were not only higher than those of the residents in the local area,but also than those of non-occupationally exposed populations as reported.The median values of committed effective dose were estimated to be 1.51 mSv for the workers and 781μSv for the local residents,respectively.Conclusions:The residents in the local area,and especially the workers,have been subject to long term thorium exposure.More attention should be paid to the radiological hazards of thorium to the workers and local residents.展开更多
The decision by Japan to begin discharging the Fukushima wastewater into the ocean on August 24,2023 was followed by protests from several countries,including China,Russia,Korea,Vietnam,and deep concerns from the inte...The decision by Japan to begin discharging the Fukushima wastewater into the ocean on August 24,2023 was followed by protests from several countries,including China,Russia,Korea,Vietnam,and deep concerns from the international community.This decision is related to the aftermath of the Fukushima Daiichi nuclear disaster that occurred in 2011,which destroyed the cooling system of the nuclear power plant and caused the reactor cores to overheat.Much water was used to cool down the reactors fuel rods;about 1.3 million cubic meters contaminated water with highly radioactive material was generated,which can fill more than 500 Olympic swimming pools[1].In order to reduce the levels of radioactivity,an Advanced Liquid Processing System(ALPS)was used to remove most radioactive contaminants from water.ALPS works by circulating water through a system of tanks and filters,which removes specific contaminants such as cesium and strontium,using a multi-step process that includes coagulation,flocculation,ion exchange,and absorption[1].Japan's government and some scientists have argued that the ALPS-treated water is safe for release into the ocean.According to their claims,the discharged water poses minimal risk to human health and the environment.However,concerns about the long-term effects of this discharge remain in scientists′minds.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.49832005)the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of Ministry of Education,China.
文摘The distribution of radioactive pollutants, such as ^(222)Rn, U, Th and ^(226)Ra in the air, sur- face waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied The mechanical, geochemical and biogeochemical processes responsible for the transport and fate of the radioactive elements are discussed based on the monitoring data. The pollutants con- centrations of effluents from the mine tunnels were dependent on pH and SO_4^(2-) which were con- trolled by biochemical oxidation of sulfide in the ore/host rocks. Radon anomalies in air reached 4 km from the tailings pile depending on radon release from the site, topography and climate. ^(238)U and ^(226)Ra abnormities in stream sediments and soil were 40-90 cm deep and 790-800 m away downstream. Anomalies of radioactive contaminants of surface watercourses extended 7.5-13 km from the discharge of effluents of the site mainly depending on mechanical and chemical proc- esses. There were about 2.86 ha rice fields and 1.59 km stream sediments contaminated. Erosion of tailings and mining debris with little or no containment or control accelerated the contamination processes.
文摘Several previous papers have been published about radioactive contamination in Mexican soil, marine sediments and foodstuffs. Ever since, results have been according to expectation, mainly consisting of natural isotopes in small concentration. Continuous research leads with the surprising finding of fission product <sup>137</sup>Cs (t<sub>1/2</sub> = 30 years) in strawberries produced in different states, about 2000 km away from each other. Never before, such contaminant has been observed in foodstuffs, produced in this country. The aim of this work is to report the presence of <sup>137</sup>Cs in Mexican strawberries and compare the activity of such contaminant with the natural radioactivity of <sup>40</sup>K (t<sub>1/2</sub> = 1.28 × 10<sup>9</sup> years), through gamma spectrometry. Eventually, the specific activity of <sup>137</sup>Cs observed in samples FM4, FM5 and FBC is respectively 0.7, 0.8 and 0.3 Bq/kg. The limits established in CODEX-STAN-193-1995 for <sup>137</sup>Cs are 1000 Bq/kg, so all samples meet the recommendation. It’s presence now in vegetables result with enough interest to be known and considered in the near future to measure the possible effect that radioactive contamination could reach after nearly 80 years from second world war, where no nuclear test has been performed, nuclear accident occurred, neither nuclear weapon has ever been used.
文摘Radioactive contaminants, such as radium, radon, and uranium isotopes are naturally present in drinking water, and gas and oil extraction like hydraulic fracturing can exasperate radionuclide leakage into groundwater. The concentration of radionuclide in drinking water is dependent upon the water source and the underlying lithology within the aquifers. In United States, the Environmental Protection Agency regulates the level of radioactivity in drinking water via the gross alpha test, which is conducted to measure the emitted alpha particles as a result of the radioactive elements’ natural decay. Radionuclides, such as radium and uranium, are known to cause bone cancer and other forms of cancer. Communities with crippling water purification infrastructure may be at a higher risk of being exposed to radionuclides, and this is a significant environmental justice concern. The radionuclide concentrations for the metropolitan or most populated city in each state in the United States and its territories (Puerto Rico, US Virgin Islands and Guam) were analyzed and correlated to the annual household income, to determine any disparities that maybe present. Lower income communities had elevated levels of radionuclides when compared to higher income communities which had lower frequency in elevated radionuclide contaminants.
文摘The objective of this paper is to provide information for nuclear field specialists and decision makers on opportunities for minimizing radioactive wastes arising from the decontamination ＆ decommissioning of a CANDU-6 NPP. The paper proposes a method for selection of appropriate decontamination techniques which may be used at Cernavoda NPP decommissioning, equipped with CANDU heavy water reactors, based on the simulation with ProVision software. The paper has a singular focus on physical decontamination techniques and does not address other aspects of decommissioning. The physical decontamination techniques which are the best for certain areas of the CANDU-6 NPP from point of view of effectiveness and cost were determined. A unit cost for each decontamination technique was determined by relating the total cost to the average surface to be decontaminated. In conclusion, physical techniques will apply more efficiently to concrete surfaces. The chemical decontamination methods, in comparison with physical decontamination methods are. more suitable for non-porous surfaces respectively metal and are less recommended for concrete surfaces.
文摘The concentrations of natural radionuclides, radium-226, radium-228, and potassium-40, and the artificial radionuclide caesium-137, in river bottom sediments and suspended matter were monitored in the Czech Republic by the Czech Hydrometeorological Institute during the period 2000-2010 and 2001-2010 respectively. The data were used to evaluate the natural background levels of these radionuclides and the impact of human activities on the water environment. For potassium-40 in sediments, the natural background level was estimated to be 570 Bq/kg. To evaluate the background level for radium-226, the river sites affected by human activities (mining and processing uranium ore, coal) were eliminated from the assessment. The average natural background values were 47.8 Bq/kg for radium-226 and 47.2 Bq/kg for radium-228 in sediments and 86.5 Bq/kg for radium-226 and 87.9 Bq/kg for radium-228 in suspended matter. The river sediments were identified as good indicators of radioactive contamination, especially radium-226, which recorded historic contamination due to former uranium mining and milling. The radium-226 contamination rate was assessed using the ratio of radium-226 to radium-228. This ratio was used to classify sediment according to the relative contamination from the uranium industry. The residual contamination of caesium-137 due to the Chernobyl accident in 1986 was also assessed. Average values of caesium-137 were 14.0 Bq/kg in sediments and 25.0 Bq/kg in suspended matter.
文摘Monitoring the behavior of radioactive contaminants associated with military applications,nuclear power facilities,and interim storage of radioactive waste materials is of significant concern in radiological analysis.Four sequential extraction schemes(SES) for fractionation of ^(241)Am were compared using five different types of soils,Vertisol,Cambisol,Chromic Luvisol,Eutric Fluvisol,and mixed urban soil,collected from different parts of Bulgaria.The results for the exchangeable ^(241) Am were in a wide range and depended on the SES used.Soil ^(241)Am varied from 0.5%to 6%in the exchangeable phase,from 0.5%to 35%in the carbonate phase,from0.4%to 36%in the reducible phase(easily reducible and moderately reducible),from 3%to 17%in the oxidizable phase,and from10%to 50%in the residual phase.After 100 d of contamination,around 50%of soil ^(241)Am was permanently fixed in the residual phase.There was strong evidence that the preferable soil phase for ^(241) Am was the carbonate phase.The transfer factor of ^(241) Am in the soil-plant system depended on ^(241)Am in the easily oxidizable phase(fulvic acid(FA)+humic acid(HA) phase).These confirmed the applicability of the National Institute of Standards and Technology(NIST) sequential extraction scheme for fractionation of soil^(241) Am since it includes extraction of FA+HA phase and then the carbonate phase.
文摘The uptake of Radium-226,Radium-228 and potassium-40 by tomato plants as the effect of irrigation with thermal water was studied as pot experiments.Tomato seedlings were grown in 7 L pots filled with four different soil textural classes collected from different locations;silt clay soil(SZ1)and sandy clay loam(SZ2)collected from Zara area at Jordan Valley with 226Ra activity 392(SZ2)and 5350(SZ1)Bq∙kg^(-1).Two control soils also were used;clay loamy soil(SW)and sandy soil(SSa)were collected from Amman with 226Ra activity about 20 Bq∙kg^(-1) for SW 8.3 Bq∙kg^(-1).Half of the treatments were irrigated with ther-mal water while the other half were irrigated with non-thermal water.The av-erage Transfer Factor(TF)for 226Ra values ranged from 0.002 to 0.91 in tomato fruits while in vegetative parts ranging from 0.003 to 2.54(stems)and from 0.014,to 4.96(leaves)as a response to irrigation with thermal water.Radium-228 was just detected in tomato leaves that were grown in sandy soil(SSa).High TF was observed for ^(40)K in tomato fruits(8.2 to 133.7)as compared to leaves(1.2 to 16.0)and in stems(1.9 to 11.3).The highest TF values for both 226Ra and ^(40)K were observed in sandy soil.Analysis indicated that source of irrigation water and soil factors affects 226Ra activity in plant tissues while ^(40)K is only af-fected by its concentration in soil.Although the pot experiment offers con-trolled conditions for testing,it does not fully replicate field conditions where root depth,soil heterogeneity,and environmental interactions may influence radionuclide uptake.Therefore,the findings should be interpreted with this limitation in mind.
基金financial supports from the National Natural Science Foundation of China(22325605,U21A20296,22076185 and 21771183)the Natural Science Foundation of Fujian Province(2020J06033).
文摘The large amount of radioactive waste generated by the rapid development of nuclear energy is in urgent need of disposal.Metal chalcogenide ion-exchangers(MCIEs)are newly developed in recent years that show great potential in the field of removing radionuclides.This is a comprehensive review of the latest research progress on the removal of key radioactive ions(e.g.,radioactive Cs^(+),Sr^(2)+,UO_(2)^(2+),lanthanide ions,and actinide ions)by MCIEs.The structure and ion-exchange properties of MCIEs are summarized emphatically.The ion-exchange mechanism of MCIEs is discussed and the structure-function relationship is preliminarily revealed.Easily exchangeable cations in the interlayer/channel,appropriately sized interlayer/channel/window spaces,flexible open framework,and the strong affinity of the Lewis soft base S^(2−)/Se^(2−)sites in the framework for soft or relatively soft metal ions,are the keys to the excellent selectivity and fast adsorption kinetics of MCIEs for radioactive ions.Finally,future research directions of metal chalcogenides for radioactive ions removal are foreseen.It is hoped that the review will provide a reference for the design of new metal chalcogenide ion-exchangers with practical application prospects for radioactive waste treatment and point to new directions for environmental radioactive contamination control.
文摘Emphasizing its potential for environmental sustainability,this review investigated how biochar—a carbon-rich material obtained from biomass pyrolysis—might be used into nuclear science and technology.High surface area,porosity,and functional groups give biochar special adsorption capacity,which qualifies it as a potential instrument for radiation cleanup and improving energy economy in nuclear uses.From the historical development of nuclear physics to the creative application of biochar in nuclear waste management and radiation shielding as well as its contribution to sustainable nuclear energy,the study covers several spheres.Biochar presents amazing efficiency in adsorbing and immobilizing radionuclides in the field of nuclear waste management,therefore establishing itself as a viable substitute for more traditional approaches.Its uses cover handling of high-level radioactive materials as well as treating low-level radioactive effluents.The paper also looks at using biochar as radiation shielding since its carbonaceous character produces strong,light-weight protective barriers.Using controlled pyrolysis and later changes,the paper addresses advanced manufacturing processes for customizing nuclear-grade biochar for particular uses.Within the nuclear industry,economic studies emphasize the affordability and possible financial gains of biochar,as well as its market potential and commercialization techniques.Lifetime analysis helps to evaluate environmental effects and sustainability by stressing the part of biochar in carbon sequestration and lowering of ecological footprints.The paper discusses safety and regulatory issues,how artificial intelligence and machine learning might be used for material optimization,and the limits and difficulties in using biochar.Practical case studies highlight its success in nuclear environments.The study ends by placing biochar as a major component in creating sustainable nuclear technology,which calls for continuous research,cooperation,and creativity.
基金Supported by National Natural Science Foundation of China(11275199)
文摘The scintillation properties of a CdMoO4 crystal have been investigated experimentally.The fluorescence yields and decay times measured from 22 K to 300 K demonstrate that CdMoO4 crystal is a good candidate for an absorber for a bolometer readout,for both heat and scintillation signals.The results from Monte Carlo studies,taking the backgrounds from 2ν2β of^100 42Mo ^116 48Cd） and internal trace nuclides ^214Bi and ^208Tl into account,show that the expected sensitivity of a CdMoO4 bolometer for neutrinoless double beta decay experiments with an exposure of 100kg·years is one order of magnitude higher than those of the current sets of the limT1/2^0νββ of ^100 42Mo and ^116 48Cd.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 30170866)
文摘The distribution of radioactive pollutants, such as ^(222)Rn, U, Th and ^(226)Ra in the air, sur- face waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied The mechanical, geochemical and biogeochemical processes responsible for the transport and fate of the radioactive elements are discussed based on the monitoring data. The pollutants con- centrations of effluents from the mine tunnels were dependent on pH and SO_4^(2-) which were con- trolled by biochemical oxidation of sulfide in the ore/host rocks. Radon anomalies in air reached 4 km from the tailings pile depending on radon release from the site, topography and climate. ^(238)U and ^(226)Ra abnormities in stream sediments and soil were 40-90 cm deep and 790-800 m away downstream. Anomalies of radioactive contaminants of surface watercourses extended 7.5-13 km from the discharge of effluents of the site mainly depending on mechanical and chemical proc- esses. There were about 2.86 ha rice fields and 1.59 km stream sediments contaminated. Erosion of tailings and mining debris with little or no containment or control accelerated the contamination processes.
文摘Objective:To assess the thorium exposure of the mine workers and the public to a typical rare earth mine and estimate the resultant committed effective dose to them.Methods:A total of 79 volunteers were selected in this survey,including 69 mine workers and 10 local residents living about 4 km away from the mine site.Urinary samples were collected from 79 volunteers,with 65 hair samples from 57 workers and 8 local residents.The thorium concentrations in urinary and hair samples were determined by using inductively coupled plasma mass spectrometry.The committed effective doses were estimated based on the urinary samples collected and the parameters as recommended by ICRP Publication 137.Results:Thorium concentrations in the samples from the workers ranged from 19.0 to 2388.8 ng/g in hair with median of 149.8 ng/g,and in urine 18.3–906.1 ng/L with median of 59.6 ng/L,respectively.The median values of thorium concentrations were 11.8 ng/g in hair and 32.40 ng/L in urine for the public respectively.The thorium concentrations in urinary and hair samples of the workers were not only higher than those of the residents in the local area,but also than those of non-occupationally exposed populations as reported.The median values of committed effective dose were estimated to be 1.51 mSv for the workers and 781μSv for the local residents,respectively.Conclusions:The residents in the local area,and especially the workers,have been subject to long term thorium exposure.More attention should be paid to the radiological hazards of thorium to the workers and local residents.
文摘The decision by Japan to begin discharging the Fukushima wastewater into the ocean on August 24,2023 was followed by protests from several countries,including China,Russia,Korea,Vietnam,and deep concerns from the international community.This decision is related to the aftermath of the Fukushima Daiichi nuclear disaster that occurred in 2011,which destroyed the cooling system of the nuclear power plant and caused the reactor cores to overheat.Much water was used to cool down the reactors fuel rods;about 1.3 million cubic meters contaminated water with highly radioactive material was generated,which can fill more than 500 Olympic swimming pools[1].In order to reduce the levels of radioactivity,an Advanced Liquid Processing System(ALPS)was used to remove most radioactive contaminants from water.ALPS works by circulating water through a system of tanks and filters,which removes specific contaminants such as cesium and strontium,using a multi-step process that includes coagulation,flocculation,ion exchange,and absorption[1].Japan's government and some scientists have argued that the ALPS-treated water is safe for release into the ocean.According to their claims,the discharged water poses minimal risk to human health and the environment.However,concerns about the long-term effects of this discharge remain in scientists′minds.
