Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.202
Filtrar
1.
Chemosphere ; 253: 126683, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32278920

RESUMO

In this study, the distribution and migration of 237Np and 239+240Pu in soils in the vicinity (<5 km) of Qinshan and Tianwan Nuclear Power Plants in China were studied, which is the first specific study of global fallout 237Np in Chinese soils. The 237Np and 239+240Pu concentrations in surface soils showed large spatial inhomogeneity. A remarkable 239+240Pu concentration (4.783 mBq/g) was observed in a surface soil near Qinshan NPP and stands for the ever reported highest value in the Chinese soils. The inventories of 239+240Pu in two Qinshan and Tianwan soil cores were estimated to be 128.8 Bq/m2 and 121.0 Bq/m2, respectively; while the 237Np inventories were 0.039 Bq/m2 and 0.035 Bq/m2 at these sites, respectively. The 240Pu/239Pu atomic ratios in these soils indicated that the global fallout is the main source of Pu in these regions. However, the non-isotopic 237Np/239Pu atomic ratio in environmental soil is not a sensitive indicator for source identification. Furthermore, we conducted pilot study on the migration behaviors of 237Np and 239+240Pu in soil core at Qinshan site with the Convection-Dispersion Equation (CDE) model. The obtained apparent dispersion coefficients of 237Np (2.82 ± 2.06 cm2/y) was 5 times higher than that of 239+240Pu (0.57 ± 0.16 cm2/y), proving that 237Np has stronger migration ability than Pu isotopes in the Qinshan soil. Finally, we predicted that with the increase of migration time, both 237Np and 239+240Pu concentration in the soil will gradually become more evenly distributed among different soil layers due to the dominant dispersion effects.


Assuntos
Netúnio/análise , Monitoramento de Radiação , Cinza Radioativa/análise , Poluentes Radioativos do Solo/análise , China , Centrais Nucleares , Projetos Piloto , Plutônio/análise , Solo
2.
Chemosphere ; 252: 126524, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32217409

RESUMO

129I released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been observed in the atmospheric, terrestrial and oceanic environments, and it also entered the marine sediments via dispersion by sea water movement and deposition around Japan. However, there have been few studies of marine sediment cores in contrast to the large number of studies on seawater. In this work, a sediment core collected near FDNPP was analyzed for 129I. It is observed that the 129I/127I atomic ratios in this sediment core are comparable to those in the seawater and sediments collected from offshore Fukushima after the accident, but 2 orders of magnitude higher than those in seawater in this region before the accident, suggesting the significant amount of 129I has been transferred and incorporated to the offshore shallow sediments. The difference in environmental behavior between 129I and 137Cs is discussed based on their depth distributions in the sediment core in comparison with the grain size distribution of sediments. The peak concentrations of iodine isotopes were found in a relatively deeper layer than radiocesium. Radiocesium follows the distribution of fine grains in the sediment core, implying its high association to fine grains.


Assuntos
Acidente Nuclear de Fukushima , Radioisótopos do Iodo/análise , Monitoramento de Radiação , Poluentes Radioativos da Água/análise , Radioisótopos de Césio , Sedimentos Geológicos , Japão , Centrais Nucleares , Oceanos e Mares , Água do Mar , Movimentos da Água
3.
J Environ Radioact ; 217: 106213, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32217245

RESUMO

Vertical and horizontal distributions are fundamental for sampling and in-situ gamma spectrum measurement strategies. The distributions of 137Cs were investigated for paved surfaces affected by the Fukusima Dai-ichi Nuclear Power Plant accident. Additionally, the effects of the distributions on the measurement uncertainties of in-situ spectrometry were evaluated. Relaxation mass depth, representing the depth profile of 137Cs, was estimated to be less than 0.23 g cm-2. Variation in the relaxation mass depth, of 0.1-0.23 g cm-2, led to a minor error (less than 5%) in the spectral analysis of the137Cs inventory (activity per unit area, kBq m-2). The 137Cs inventory, within a 20 × 20 m square of 400 cells each measuring 1 m2, showed an uneven distribution with large variation; coefficient of variation ranged from 54 to 136% of geometric average inventory of 424 kBq m-2. Increasing the grid size decreased 137Cs inventory variation among cells, revealing the relationship between instrument field of view and the spatial uncertainty of the results of in-situ gamma spectrometry.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Radioisótopos de Césio , Japão , Centrais Nucleares , Poluentes Radioativos do Solo , Espectrometria gama
4.
Artigo em Inglês | MEDLINE | ID: mdl-32037370

RESUMO

Responding to the radiation-related concerns of parents/guardians with infants/small children is an important public health issue for regional recovery after radioactive contamination. This study summarizes the results of a systematic internal contamination screening of infants/small children, aged 0-6 years, using BABYSCAN and individual counselling sessions with physicians about radiation concerns from 2014 to 2018 in Minamisoma City. Of 3,114 participants, no one was found to have internal contamination with radioactive caesium with a detection limit of 50 Bq/body. The questionnaire survey showed a decreasing trend of concerns about food contamination and playing outside as possible causes of internal contamination over time. Because people's concerns were diverse in counselling sessions, individual responses are required. This study showed that examinations using BABYSCAN provide an opportunity for direct dialogue between the parents/guardians of infants/small children and experts. This can be considered a model case for risk communication conducted by the local government after a radioactive contamination incident.


Assuntos
Radioisótopos de Césio/análise , Contagem Corporal Total/estatística & dados numéricos , Criança , Pré-Escolar , Exposição Ambiental/estatística & dados numéricos , Feminino , Contaminação Radioativa de Alimentos/estatística & dados numéricos , Acidente Nuclear de Fukushima , Humanos , Lactente , Recém-Nascido , Japão , Masculino , Centrais Nucleares , Monitoramento de Radiação/estatística & dados numéricos , Liberação Nociva de Radioativos/estatística & dados numéricos , Fatores de Risco , Inquéritos e Questionários
5.
PLoS One ; 15(2): e0228549, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023299

RESUMO

The effect of age and gender in risk estimates related to long-term residence in areas contaminated by nuclear power plant fallout was evaluated by applying the lifetime attributable risk (LAR) concept to an existing exposure model that was previously used for cumulative effective dose estimates. In this study, we investigated the influence of age distribution on the number of cancer cases by applying five different age distributions from nuclear power-producing countries (India, Japan, South Korea, and the United States), and Egypt because of intentions to develop nuclear power. The model was also used to estimate the effective dose and gender-specific LAR as a function of time after fallout for the offspring of the population living in 137Cs fallout areas. The principal findings of this study are that the LAR of cancer incidence (excluding non-fatal skin cancers) over 70 y is about 4.5 times higher for newborn females (5.4% per MBq m-2 of initial 137Cs ground deposition) than the corresponding values for 30 y old women (1.2% per MBq m-2 137Cs deposition). The cumulative LAR for newborn males is more than 3 times higher (3.2% versus 1.0% per MBq m-2 137Cs deposition). The model predicts a generally higher LAR for women until 50 y of age, after which the gender difference converges. Furthermore, the detriment for newborns in the fallout areas initially decreases rapidly (about threefold during the first decade) and then decreases gradually with an approximate half-time of 10-12 y after the first decade. The age distribution of the exposed cohort has a decisive impact on the average risk estimates, and in our model, these are up to about 65% higher in countries with high birth rates compared to low birth rates. This trend implies larger average lifetime attributable risks in countries with a highly proportional younger population. In conclusion, the large dispersion (up to a factor of 4 between newborns and 30 y olds) in the lifetime detriment per unit ground deposition of 137Cs over gender and age in connection with accidental nuclear releases justifies the effort in developing risk models that account for the higher radiation sensitivity in younger populations.


Assuntos
Radioisótopos de Césio/análise , Modelos Estatísticos , Neoplasias Induzidas por Radiação/etiologia , Centrais Nucleares/estatística & dados numéricos , Cinza Radioativa/efeitos adversos , Medição de Risco/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Carga Corporal (Radioterapia) , Criança , Pré-Escolar , Egito/epidemiologia , Feminino , Humanos , Incidência , Índia/epidemiologia , Lactente , Recém-Nascido , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Neoplasias Induzidas por Radiação/epidemiologia , Doses de Radiação , Monitoramento de Radiação , República da Coreia/epidemiologia , Fatores de Risco , Estados Unidos/epidemiologia , Adulto Jovem
6.
J Environ Radioact ; 214-215: 106173, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32063291

RESUMO

A series of accidents at the Fukushima Dai-ichi Nuclear Power Plant (1F NPP) following the Great East Japan Earthquake and tsunami of 11 March 2011 resulted in the release of radioactive materials to the ocean. We used the Regional Ocean Model System (ROMS) to simulate the 137Cs activity in the oceanic area off Fukushima, with the sources of radioactivity being direct release, atmospheric deposition, river discharge, and inflow across the domain boundary. The direct release rate of 137Cs after the accident until the end of 2016 was estimated by comparing simulated results with measured 137Cs activities adjacent to the 1F NPP. River discharge rates of 137Cs were estimated by multiplying simulated river flow rates by the dissolved 137Cs activities, which were estimated by an empirical function. Inflow of 137Cs across the domain boundary was set according to the results of a North Pacific Ocean model. Because the spatiotemporal variability of 137Cs activity was large, the simulated results were compared with the annual averaged observed 137Cs activity distribution. Normalized annual averaged 137Cs activity distributions in the regional ocean were similar for each year from 2013 to 2016. This result suggests that the annual averaged distribution is predictable. Simulated 137Cs activity attributable to direct release was in good agreement with measurement data from the coastal zone adjacent to the 1F NPP. Comparison of the simulated results with measured activity in the offshore area indicated that the simulation slightly underestimated the activity attributable to inflow across the domain boundary. This result suggests that recirculation of subducted 137Cs to the surface layer was underestimated by the North Pacific model. During the study period, the effect of river discharge on oceanic 137Cs activity was small compared to the effect of directly released 137Cs.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Radioisótopos de Césio , Japão , Centrais Nucleares , Oceano Pacífico , Rios , Poluentes Radioativos da Água
7.
Sci Total Environ ; 717: 137094, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32062259

RESUMO

Marine biogenic materials such as corals, shells, or seaweed have long been recognized as recorders of environmental conditions. Here, the bivalve Cerastoderma edule is used for the first time as a recorder of past seawater contamination with anthropogenic uranium, specifically 236U. Several studies have employed the authorized radioactive releases, including 236U, from nuclear reprocessing plants in La Hague, France, into the English Channel, and Sellafield, England, into the Irish Sea, to trace Atlantic waters and to understand recent climate induced circulation changes in the Arctic Ocean. Anthropogenic 236U has emerged over recent years as a new transient tracer to track these changes, but its application has been challenged owing to paucity of fundamental data on the input (timing and amount) of 236U from Sellafield. Here, we present 236U/238U data from bivalve shells collected close to La Hague and Sellafield from two unique shell collections that allow the reconstruction of the historical 236U contamination of seawater since the 1960s, mostly with bi-annual resolution. The novel archive is first validated by comparison with well-documented 236U discharges from La Hague. Then, shells from the Irish Sea are used to reconstruct the regional 236U contamination. Apart from defining new, observationally based 236U input functions that will allow more precise tracer studies in the Arctic Ocean, we find an unexpected peak of 236U releases to the Irish Sea in the 1970s. Using this peak, we provide evidence for a small, but significant recirculation of Irish Sea water into the English Channel. Tracing the 1970s peak should allow extending 236U tracer studies into the South Atlantic Ocean.


Assuntos
Centrais Nucleares , Água do Mar , Urânio , Poluentes Radioativos da Água
8.
J Environ Radioact ; 217: 106191, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32063555

RESUMO

In March 2011, an earthquake caused the shutdown of the active reactors at the Fukushima Daiichi Nuclear Power Plant (NPP), with the succeeding tsunami resulting in the release of radioactively contaminated water into the adjacent Japanese coastal waters. Marine biota selected from various trophic levels were collected in Korean coastal waters throughout 2014 and 2015 and their plutonium levels were measured to evaluate the radioactive contamination levels in the marine organisms that constitute the primary seafood diet in the Republic of Korea (ROK). The results showed that the activity concentrations of 239,240Pu in plankton, macroalgae, mollusks, crustaceans, and cephalopods ranged from 13 to 58, 0.64 to 0.80, 0.94 to 5.40, 0.06 to 0.50, and 0.26 mBq kg-1 of wet weight (w.w.), respectively. The activity concentrations of 239,240Pu measured in the muscles of fish varied from 0.09 to 0.30 mBq kg-1 (w.w.), relatively low values compared to those in other groups regardless of fish species, size, and sampling area. The concentration characteristics of 239,240Pu in the various organs in the respective marine products revealed that the internal organs showed higher concentrations than the muscle or skin (or exoskeleton). The highest concentration of 239,240Pu was measured in the viscera of an abalone, which had an activity concentration of 6.31 mBq kg-1 (w.w.). The concentration factors (CFs) in the >300-µm fraction of plankton and in anchovy, shrimp, and mackerel ranged 67-84% of the International Atomic Energy Agency (IAEA)-recommended values, although the CF in macroalgae was much lower at approximately 5% of IAEA values, suggesting a wide range of 239,240Pu CF in macroalgae. The mean transfer factor (TF) between macroalgae (0.6-0.8 mBq kg-1) and abalone (5.4 mBq kg-1) was estimated to be 7.5, implying that effective Pu transfer occurred between the two species. These figures equate to annual effective doses of 239,240Pu to Koreans through consumption of macroalgae, shellfish, and fish of 1.8 × 10-6, 1.4 × 10-6, and 7.1 × 10-7 mSv yr-1, respectively, and a total dose of 3.9 × 10-6 mSv yr-1, values that are negligible compared to the annual effective dose limit of 1 mSv yr-1.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Animais , Radioisótopos de Césio , Japão , Centrais Nucleares , Oceanos e Mares , Plutônio , República da Coreia , Poluentes Radioativos da Água
9.
J Environ Radioact ; 216: 106178, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32056787

RESUMO

The intent of minimizing the impact of the large amount of radioactive material potentially released into the atmosphere in a nuclear event implies preparedness activities. In the early phase and in absence of field observations, countermeasures would largely rely on a previous characterization of the transport and dispersion of radioactive particles and the potential levels of radioactive contamination. This study presents a methodology to estimate the atmospheric transport, dispersion and ground deposition patterns of radioactive particles. The methodology starts identifying the main airflow directions by means of the air mass trajectories calculated by the HYSPLIT model, and, secondly, the dispersion and the ground deposition characteristics associated with each airflow pattern by running the RIMPUFF atmospheric dispersion model. From the basis of these results, different products can be obtained, such as the most probable transport direction, spatial probability distribution of deposition and the geographical probability distribution of deposition above certain predefined threshold. The method is trained on the HYSPLIT trajectories and RIMPUFF simulations during five consecutive years (2012-2016) at the Almaraz Nuclear Power Plant, in Spain. 3644 forward air mass trajectories were calculated (at 00 and 12 UTC, and with duration of 36 h). Eight airflow patterns were identified, and within each pattern, the persistent days, i.e. those days in which trajectories at 00 and 12 UTC grouped into the same airflow pattern, were extracted to simulate the atmospheric dispersion and ground deposition following a hypothetical ISLOCA accident sequence of 35 h. In total, 833 simulations were carried out, in which ground contamination was estimated at cell level on a non-homogeneous geographical grid spacing up to 800 km from Almaraz. The corresponding outcomes show a large variability in the area covered and in deposition values between airflow patterns, which provide comprehensive and oriented information and resources to decision makers to emergency management.


Assuntos
Monitoramento de Radiação , Poluentes Radioativos do Ar , Emergências , Modelos Teóricos , Centrais Nucleares , Liberação Nociva de Radioativos , Espanha
10.
J Environ Radioact ; 216: 106188, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32056792

RESUMO

Environmental radiocarbon (14C) monitoring is gaining importance in China due to the recent rapid development of the nuclear industry. In this study, synthetic benzoic acid samples with the fingerprint of environmental 14C were generated by using the synthesis method, and the specific activity of 14C was determined using the liquid scintillation counting (LSC) method. The ultra-performance liquid chromatography (UPLC) analysis was performed in chemical properties test and results showed that the mean assay and yield of synthetic benzoic acid were 91.8% ± 2.4% and 84.5% ± 2.0%, respectively. Under adopted LSC counting conditions, the minimum detectable activity (MDA) of 64 Bq/kg C was achieved in our laboratory. The method's linearity was examined using a series of spiked samples, along with the 14C-free samples. The results showed a wide linear range up to 2000 Bq/kg C. Reproducible results were obtained from three batches of experiments with deviations in the intra-group and inter-group of 0.38%-3.06% and 1.24%-3.55%, respectively. Long-term evaluation of the system was found to be very stable (over 5 months storage) with the relative standard deviations of <1%. In addition, field applications in the vicinity of a nuclear power plant demonstrated that 14C data measured by our method was consistent with the accelerator mass spectrometry (AMS) method, suggesting the method's precision can meet the requirement of 14C monitoring near the nuclear facility. This is the first study to report the use of synthetic benzoic acid in environmental 14C monitoring, and it provides a new approach for improving the environmental 14C monitoring network.


Assuntos
Monitoramento de Radiação , Ácido Benzoico , Radioisótopos de Carbono , China , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas , Centrais Nucleares
11.
J Environ Radioact ; 216: 106190, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32056793

RESUMO

The 1986 accident at the Chernobyl Nuclear Power Plant led to large-scale changes in the environmental situation. The purpose of our study was to conduct a comparative analysis of the morphological states of the dentition of individuals living in regions exposed to radiation to determine the groups at risk for the main classes of dental anomalies. We believe our results will support the development of a differentiated system for dental rehabilitation and follow-up of individuals exposed to radiation. The prevalence rate of dental anomalies was studied in 1,889 patients of both sexes divided by age in accordance with dentition formation stages and by regions of residence in accordance with the 137Cs soil-contamination level. A statistically significant decrease was observed in the number of patients with normal dentition for their age among those who had been exposed to prenatal radiation. A sharp increase in combined dental anomalies was revealed in patients who lived in regions with a137Cs soil-contamination level ranging from 555 to 1665 GBq/km2; concomitantly, multidirectional fluctuations were observed in the numbers of tooth and occlusion anomalies. Among the examined population, the most severe pathology of the oral organs was found in prenatally irradiated patients (born between April 26, 1986, and April 30, 1987). The prevalence of dental anomalies is interrelated not only with the level of radioactive contamination in the soil of the dwelling area, but also with the age of the surveyed individuals at the moment of the accident.


Assuntos
Monitoramento de Radiação , Acidente Nuclear de Chernobyl , Feminino , Humanos , Masculino , Centrais Nucleares , Gravidez , Prevalência , Solo , Poluentes Radioativos do Solo , Ucrânia
12.
Mar Pollut Bull ; 151: 110860, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32056642

RESUMO

Following the Fukushima Daiichi nuclear power plant accident in 2011, some marine radionuclide monitoring studies report a lack of evidence for contamination of Japanese coastal waters by U and Pu, or state that marine contamination by them was negligible. Nevertheless, Fukushima-derived U and Pu were reported as associated with Cs-rich microparticles (CsMPs) found in local soil, vegetation, and river/lake sediments. Over time, CsMPs can be transported to the sea via riverine runoff where actinides, as expected, will leach. We recommend establishing a long-term monitoring of U and Pu in the nearshore area of the Fukushima Prefecture using marine bivalve mollusks; shells, byssal threads and soft tissues should all be analyzed. Here, based on results from Th biosorption experiments, we propose that U and Pu could be present at concentrations several times higher in shells with a completely destroyed external shell layer (periostracum) than in shells with intact periostracum.


Assuntos
Bivalves , Acidente Nuclear de Fukushima , Plutônio/análise , Monitoramento de Radiação , Poluentes Radioativos da Água , Animais , Japão , Centrais Nucleares , Urânio/análise
13.
J Environ Radioact ; 213: 106138, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31983447

RESUMO

Atmospheric air samples were collected at 9 monitoring stations (A1 to A9) less than 2 km from the Paks Nuclear Power Plant (Paks NPP) and a background station (B24). The monthly integrated CO2 and total carbon (CO2+hydrocarbons (CnHm)) samples were collected to determine the excess 14C activity at the vicinity of the NPP. The measurements providing the 14C/12C ratio of the monthly integrated samples were carried out on a MICADAS type AMS at HEKAL. Due to the relatively low 14CO2 emission of PWR type Paks reactors and the local Suess effect, there was negligible excess 14C activity at the investigated stations in the pure CO2 fraction during the investigated 2 years period (2015-2016). On the contrary, there was a detectable (although minor) excess at every station in the CnHm fraction. In case of CO2, the average Δ14C excess was 3.8‰ and the highest measured value was 91.2‰ at the A3 station in February 2015. In case of CnHm, the average excess was 31.1‰ and the highest measured value was 319.1‰ at the A4 station in February 2016. We applied PC-CREAM 08 modelling to investigate the observed excess 14C activity at the environmental sampling stations, which depends on the distance from the NPP and the meteorological conditions, such as wind direction and wind speed. Meteorology data was collected at the operating area of the Paks NPP in a meteorology tower. The direct C-14 emission through the 120 m high stacks was measured in the NPP by liquid scintillation counting. These emission data and our model calculations explain the excess activity in the CnHm fraction at the A4 station, which is located only 915 m far from the NPP's stacks in the prevailing wind direction. The excess activity at A3 station (the farthest unit) probably came from the nearby NPP wastewater discharge point. The recently observed average excess and highest excess data is similar to the published data in former studies (Molnár et al., 2007; Veres et al., 1995) on Paks NPP, the highest 14CO2 and 14CnHm excess are just a little higher than it was in the earlier studies, but in these former studies, the A3 station was not equipped with a radiocarbon monitoring unit and the level of radiocarbon emission was almost invisible from the wastewater discharge point.


Assuntos
Centrais Nucleares , Monitoramento de Radiação , Poluentes Atmosféricos , Monitoramento Ambiental , Hungria , Vento
15.
Environ Pollut ; 256: 113386, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31706761

RESUMO

After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, radionuclides released by this event were observed in the Pacific Ocean. Models predicted that these radionuclides would be transported to the Bering Sea; however, limited evidence currently reveals the transportation of these radionuclides to the Arctic Ocean. Here, we provide the first direct observation showing that FDNPP-derived 134Cs and 137Cs were present in subarctic regions and the Arctic Ocean (Chukchi Sea) in 2017. Furthermore, we conclude that these radionuclides were transported from the Pacific Ocean into the Bering and Chukchi Seas by ocean currents. Additionally, the 137Cs activity concentrations in the Bering Sea exceed those in all previous reports. Due to the continuous leaking of radionuclides from the FDNPP, we hypothesize that FDNPP-derived radionuclides will be continuously transported to the Arctic Ocean in the next several years. Our results suggest that though far away from Fukushima, the accident-derived anthropogenic radionuclides also influenced the Arctic Ocean by ocean currents.


Assuntos
Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Monitoramento de Radiação/métodos , Poluentes Radioativos da Água/análise , Regiões Árticas , Japão , Centrais Nucleares , Oceanos e Mares , Oceano Pacífico
16.
Chemosphere ; 241: 125019, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31610456

RESUMO

The abundance and distribution of highly radioactive cesium-rich microparticles (CsMPs) that were released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) during the first stage of the nuclear disaster in March 2011 are described for 20 surface soils collected around the FDNPP. Based on the spatial distribution of the numbers (particles/g) and radioactive fraction (RF) of the CsMPs in surface soil, which is defined as the sum of the CsMP radioactivity (in Bq) divided by the total radioactivity (in Bq) of the soil sample, three regions of particular interest have been identified: i.) near-northwest (N-NW), ii.) far-northwest (F-NW), and iii.) southwest (SW). In these areas, the number and RF of CsMPs were determined to be 22.1-101 particles/g and 15.4-34.0%, 24.3-64.8 particles/g and 36.7-37.4%, and 0.869-8.00 particles/g and 27.6-80.2%, respectively. These distributions are consistent with the plume trajectories of material released from the FDNPP on March 14, 2011, in the late afternoon through to the late afternoon of March 15, 2011, indicating that the CsMPs formed only during this short period. Unit 3 is the most plausible source of the CsMPs at the beginning of the release based on an analysis of the sequence of release events. The lower RF values in the N-NW region indicate a larger influence from subsequent plumes that mainly consisted of soluble Cs species formed simultaneously with precipitation. The quantitative map of the distribution of CsMPs provides an important understanding of CsMP dispersion dynamics and can be used to assess risks in inhabited regions.


Assuntos
Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Centrais Nucleares , Material Particulado/análise , Poluentes Radioativos/análise , Japão , Tamanho da Partícula , Monitoramento de Radiação , Radioatividade , Solo/química
17.
Chemosphere ; 242: 125175, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31675583

RESUMO

A review is presented of data on solid-liquid distribution coefficients (Kd-s) of the main radiologically important radionuclides of the Chernobyl release within geological deposits at the Chernobyl Nuclear Power Plant (ChNPP) Site. The Kd values for Sr, Cs and Pu for Quaternary sandy deposits that form sedimentary cover at Chernobyl fall within the range of parameters reported in international sorption databases. In agreement with general knowledge on radionuclide geochemical behavior and affinity to soils, Kd-s increase in the sequence: Sr < Cs < Pu. Alluvial and fluvioglacial sandy deposits are characterized by larger Kd values then deposits of eolian genesis due to higher content of clay minerals in fine fractions. For Sr, laboratory batch tests have given Kd values that are in a reasonable agreement with in situ measurements. At the same time, the 90Sr Kd-s obtained from groundwater transport model calibrations were noticeably lower than experimentally determined values, thus showing potential limitations of the Kd-approach. Monitoring data on mobility of 90Sr, 137Cs and 239,240Pu in groundwater in the Chernobyl zone on a whole are consistent with the radionuclide Kd-s summarized in this article. The highest concentrations in groundwater (based on data for 2012-2014) were observed for 90Sr, while orders of magnitude lower concentrations were observed for 137Cs and 239,240Pu. At the same time, detection of 137Cs and 239,240Pu in groundwater at sites with a relatively deep groundwater table suggests the possibility of facilitated transport of small amounts of these radionuclides in the form of non-retarded colloids or complexes.


Assuntos
Radioisótopos de Césio/análise , Acidente Nuclear de Chernobyl , Centrais Nucleares , Plutônio/análise , Radioisótopos de Estrôncio/análise , Sedimentos Geológicos/análise , Água Subterrânea/análise , Monitoramento de Radiação/métodos , Poluentes Radioativos do Solo/análise , Poluentes Radioativos da Água/análise
18.
J Environ Radioact ; 213: 106109, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31756642

RESUMO

The time-dependence of 137Cs in new shoots of tea (Camellia sinensis (L.) Kuntze) following a137Cs-deposition was analyzed and quantified in terms of effective half-lives. The underlying monitoring studies were performed after the accidents in the Chernobyl and the Fukushima Daiichi nuclear power plants for tea plants growing in Japan. The major transfer route for atmospherically deposited radiocaesium to the first new shoots sampled after the accidents were different: for the Fukushima accident, it was mainly translocation of radiocaesium deposited onto old leaves and twigs to the new growth, while direct deposition on the new leaves was the major source after the Chernobyl accident. The effective half-lives in new tea leaves representing the fast and slow components of the decline did not significantly differ between these accidents. Geometric means (ranges) of fast and slow effective half-lives of 137Cs after the Chernobyl accident were 66 d (25-125 d) and 902 d (342-15900 d), respectively, and those after the Fukushima accident were 50 d (26-105 d) and 416 d (222-1540 d), respectively. From these results, 137Cs declines in new tea leaves were similar although contamination conditions were different for these two accidents.


Assuntos
Camellia sinensis , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Chá , Radioisótopos de Césio , Japão , Centrais Nucleares
19.
Accid Anal Prev ; 134: 105351, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31715548

RESUMO

INTRODUCTION: Mindful organizing (also known as collective mindfulness) is a team level construct that is said to underpin the principles of high-reliability organizations (HROs), as it has shown to lead to almost error-free performance. While mindful organizing research has proliferated in recent years, studies on how to measure mindful organizing are scarce. Vogus and Sutcliffe (2007) originally validated a nine-item "Mindful Organizing Scale" but few subsequent validation studies of this scale exist. The present study aimed to validate a Spanish version of the Mindful Organizing Scale. METHOD: The sample included 47 teams (comprising of a total of 573 workers with an average team size of 12.19) from a Spanish nuclear power plant. A confirmatory factor analysis (CFA), reliability analysis, and an analysis of aggregation indices were carried out. A correlation analysis and CFA were used to further validate the scale in terms of its distinctiveness from, and relationship with, other team-related variables such as safety culture, team safety climate, and team learning. Finally, evidence of criterion-related validity was collected by testing the incremental validity of the mindful organizing scale in the association with various workplace safety outcomes (safety compliance and safety participation). RESULTS: The results confirmed a unidimensional structure of the scale and indicated satisfactory internal consistency. Aggregation of the scores to the team level was justified while significant positive correlations between mindful organizing and other team-related variables (safety culture, team safety climate, team learning) were found. Moreover, mindful organizing showed distinctiveness from safety culture, team safety climate and team learning. Finally, incremental validity of the scale was supported, as it shows to be associated with safety compliance and safety participation above and beyond other related constructs. CONCLUSIONS: The Spanish version of the Mindful Organizing Scale has shown to be a valid and reliable scale that can be used to measure mindful organizing. CONTRIBUTIONS: The validation of the unidimensional Spanish version of Vogus and Sutcliffe's (2007) Mindful Organizing Scale provides researchers and practitioners with a reliable and valid tool to use in Spanish speaking organizations to measure mindful organizing, which has been shown to result in more reliable performance. Theoretically, this study offers four contributions. Firstly, it validates a scale that operationalizes the 'mindful organizing' construct in a traditional high-reliability organization (nuclear power plant) which has never been done before. Secondly, it offers evidence that a mindful organizing scale can be validated in a new cultural context and language (Spanish) to any of the previous studies done before it. Thirdly, it adds to our understanding of mindful organizing's nomological network by distinguishing it from other team and safety-related variables. Lastly, it builds on current research showing sound psychometric properties of a one-dimensional, quantitative measure of mindful organizing.


Assuntos
Atenção Plena , Gestão da Segurança/organização & administração , Inquéritos e Questionários/normas , Adulto , Análise Fatorial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Centrais Nucleares/organização & administração , Psicometria , Reprodutibilidade dos Testes , Traduções
20.
J Environ Radioact ; 211: 106082, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31707255

RESUMO

The construction of Akkuyu Nuclear Power Plant (NPP) was launched in 2018 and the plant is expected to be operative by the year 2023. Being situated in the Mediterranean coastline, Akkuyu NPP will be the first nuclear power generation facility in Turkey. The plant will have four Russian VVER-1200 type pressurized water reactors with a total installed capacity of 4800 MW. In this study, atmospheric dispersion and ground level deposition of Cs-137 and I-131 released from a possible accident in Akkuyu NPP was estimated using a Lagrangian particle dispersion model, FLEXPART, for different time periods representing relatively extreme meteorological conditions for Mersin. The source term used in simulations was assumed the same with that of the Chernobyl NPP accident that occurred in 1986. In addition, cumulative dose and risk values were calculated from FLEXPART output datasets considering potential exposure pathways such as inhalation, ground-shine exposure and cloud-shine exposure. The results were further analyzed with python codes and dose and risk maps were created for local and regional scales. According to results of the study, it was found that the vicinity of Mersin and Central Anatolia were simulated to be the most significantly affected areas from the accident under both scenario conditions. The northern and western parts and all coastlines of Turkey were simulated to be more contaminated in the simulations conducted under December 2009 conditions, whereas southern and western parts of Turkey and some parts of Middle East countries like Syria, Iraq and Lebanon were simulated to be comparatively more contaminated under August 2010 conditions. The results indicated that radioactivity levels exceeding 100 kBq/m2 were observed near the accident site under both scenario conditions. Values exceeding 10 kBq/m2 level were simulated in western Turkey in the first scenario whereas similar values were found in eastern Turkey in the second scenario. Furthermore, the results indicated 7-day thyroid dose values ranging between 0.10 mSv and 10.0 mSv in western and eastern parts of Mediterranean region for the first and the second scenario, respectively. Similarly, 1-year effective dose of only Cs-137 ranged between 0.1 mSv and 1.0 mSv around Akkuyu NPP site in both scenarios. The results revealed that meteorological conditions were among the most important parameter for the fate and transport of radioactivity originating from such a catastrophic event.


Assuntos
Centrais Nucleares , Monitoramento de Radiação , Radioisótopos de Césio , Radioisótopos do Iodo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA