Project description:Here we present the first report of a carbon-γ-Fe₂O₃ nanoparticle composite of mesoporous carbon, bearing COOH- and phenolic OH- functional groups on its surface, a remarkable and magnetically separable adsorbent, for the radioactive material emitted by the Fukushima Daiichi nuclear power plant accident. Contaminated water and soil at a level of 1,739 Bq kg(-1) ((134)Cs and (137)Cs at 509 Bq kg(-1) and 1,230 Bq kg(-1), respectively) and 114,000 Bq kg(-1) ((134)Cs and (137)Cs at 38,700 Bq kg(-1) and 75,300 Bq kg(-1), respectively) were decontaminated by 99% and 90% respectively with just one treatment carried out in Nihonmatsu city in Fukushima. Since this material is remarkably high performance, magnetically separable, and a readily applicable technology, it would reduce the environmental impact of the Fukushima accident if it were used.
Project description:We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Plant accident on the testis from 2 bulls. Estimated dose of internal exposure in one bull was 0.7-1.2 mGy (¹³⁴Cs) and 0.4-0.6 mGy (¹³⁷Cs) and external exposure was 2.0 mGy (¹³⁴Cs) and 0.8 mGy (¹³⁷Cs) (196 days). Internal dose in the other was 3.2-6.1 mGy (¹³⁴Cs) and 1.8-3.4 mGy (¹³⁷Cs) and external dose was 1.3 mGy (¹³⁴Cs) and 0.6 mGy (¹³⁷Cs) (315 days). Sperm morphology and spermatogenesis were within normal ranges. ¹³⁴,¹³⁷Cs radioactivity was detected but Cs was not detectable in the testis by electron probe microanalysis. Thus, adverse radiation-induced effects were not observed in bull testes following chronic exposure to the above levels of radiation for up to 10 months. Since we could analyse a limited number of testes, further investigation on the effects of ionizing radiation on spermatogenesis should be extended to more animals.
Project description:The environmental surface contamination by radioactive elements following a nuclear research reactor hypothetical accident is evaluated employing the hotspot code, IAEA safety guide, and NRC guidelines. Gaussian plume depositions of radioactive contaminants are calculated under very conservative assumptions for a worst-case accident scenario, and site most probable wind speed and metrological conditions. Results reveal that the contamination strongly decreases with distance, dropping seven orders of magnitude from 2.2E+09 kBq/m2 at the reactor site to 9.5E+2 kBq/m2 60 km from the reactor at the plume centerline. In rainy weather, the wet deposition is depleted to 6.0E+2 kBq/m2 after 50 km, limiting the spread of contaminants to a much smaller area. Although the results of this work tend to overestimate the surface deposition of radionuclides, they present a clear insight into the radiological consequences of nuclear accident worst-case scenario. Thus, it assists with the development of a comprehensive emergency preparedness program by identifying all areas with potential risk to contamination.
Project description:The diffusion process of the treated Fukushima nuclear accident contaminated water to be discharged into the Pacific Ocean from 2023 is analyzed by two analysis models from macroscopic and microscopic perspectives. Results show that the tritium will spread to the whole North Pacific in 1200 days, which is important to formulate global coping strategies.
Project description:Large quantities of radionuclides released by the Fukushima nuclear power plant accident entered terrestrial and marine ecosystems. The resulting radioactive contamination of large omnivorous wild mammals such as wild boar (Sus scrofa) and Asian black bear (Ursus thibetanus) varied greatly depending on location, season, and time after the accident. Quantitative modeling of how such factors influence radionuclide burdens in these species is important for enhancing current knowledge of chronic radionuclide exposure consequences in mammalian populations, and for assessing potential human risks from consumption of contaminated animal meat. Here we modeled the time course of radioactive cesium (134Cs + 137Cs) concentrations in boar and black bears from Fukushima Prefecture over ~ 7 years after the accident, using nonlinear robust and quantile regressions and mixed-effects modeling. To estimate predictive performance, models fitted to the full data set were compared with those fitted only to the first 3.5 years of data, and tested on the last 3.5 years of data. Ecological half-lives for radioactive cesium, and magnitudes and phase shifts for sinusoidal seasonal oscillations in cesium burdens, were estimated by each analysis method for each species. These results can improve the understanding and prediction of radionuclide concentrations in large mammals that inhabit radioactively contaminated areas.
Project description:Decreasing the transfer of radioactive cesium (RCs) from soil to crops has been important since the deposition of RCs in agricultural soil owing to the Fukushima nuclear power plant accident of 2011. We investigated the genotypic variation in RCs accumulation in 234 and 198 hexaploid wheat (Triticum spp.) varieties in an affected field in 2012 and 2013, respectively. The effects of soil exchangeable potassium (ExK) content to RCs accumulation in wheat varieties were also evaluated. A test field showed fourfold differences in soil ExK contents based on location, and the wheat varieties grown in areas with lower soil ExK contents tended to have higher grain RCs concentrations. RCs concentrations of shoots, when corrected by the soil ExK content, were positively significantly correlated between years, and RCs concentrations of shoots were significantly correlated with the grain RCs concentration corrected by the soil ExK content. These results indicated that there were genotypic variations in RCs accumulation. The grain to shoot ratio of RCs also showed significant genotypic variation. Wheat varieties with low RCs accumulations were identified. They could contribute to the research and breeding of low RCs accumulating wheat and to agricultural production in the area affected by RCs deposition.
Project description:Although the influence of nuclear accidents on the reproduction of top predators has not been investigated, it is important that we identify the effects of such accidents because humans are also top predators. We conducted field observation for 22 years and analysed the reproductive performance of the goshawk (Accipiter gentilis fujiyamae), a top avian predator in the North Kanto area of Japan, before and after the accidents at the Fukushima Daiichi nuclear power plant that occurred in 2011. The reproductive performance declined markedly compared with the pre-accident years and progressively decreased for the three post-accident study years. Moreover, it was suggested that these declines were primarily caused by an increase in the air dose rate of radio-active contaminants measured under the nests caused by the nuclear accidents, rather than by other factors. We consider the trends in the changes of the reproductive success rates and suggest that internal exposure may play an important role in the reproductive performance of the goshawk, as well as external exposure.
Project description:Six years after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, data for 236U and 236U/238U have remained limited to a few heavily contaminated samples. In the present study, activities of 236U, 239Pu, and 240Pu, along with other U isotopes in 46 soil samples both heavily and lightly contaminated by this accident were measured by inductively coupled plasma-mass spectrometry (ICP-MS) and triple-quadrupole ICP-MS. The 236U activities and 236U/238U atom ratios in these soil samples were in the range of (0.469-24.4) × 10-5 Bq kg-1 and ((0.099-1.35) × 10-7), respectively. Higher 240Pu/239Pu atom ratios (0.245-0.312) and 238Pu/239+240Pu activity ratios (0.859-1.62) indicated Pu contamination originated from this accident and global fallout in some samples. For those soil samples along with black substances collected along roads in Fukushima Prefecture, high linear correlations were presented between 236U activities and 239+240Pu activities (Pearson's r = 0.755, p < 0.01), and between 236U activities and 238Pu activities (Pearson's r = 0.844, p < 0.01). The analysis of these soil samples confirmed the release of 236U, although in trace amounts, during the FDNPP accident.
Project description:The Reggane region, where the first French atmospheric nuclear tests were conducted in the 1960s in Southern Algeria, is located in one of the most active dust source regions responsible for recurrent massive Saharan dust events reaching Western Europe and affecting air quality. After a major outbreak in March 2022, a citizen participative science campaign was launched to study the radioactivity born by the dust. One hundred ten deposit samples were collected from six countries in Western Europe with 53 demonstrated as scientifically representative. Geochemical and mineralogical sample analyses combined with satellite observations and back trajectory calculations confirmed an origin from South Algeria, including the Reggane site. Plutonium isotopic signatures, a unique nuclear bomb fingerprint, remained in the range of the global fallout signatures largely dominated by US and former USSR nuclear tests, significantly different from French fallout signatures. Radioactive contamination detected in all samples did not, however, present a risk to public health in terms of radioactivity exposure.
Project description:Although radioactivity is released routinely at every stage of nuclear power generation, the regulation of these releases has never taken into account those potentially most sensitive—women, especially when pregnant, and children. From uranium mining and milling, to fuel manufacture, electricity generation and radioactive waste management, children in frontline and Indigenous communities can be disproportionately harmed due to often increased sensitivity of developing systems to toxic exposures, the lack of resources and racial and class discrimination. The reasons for the greater susceptibility of women and children to harm from radiation exposure is not fully understood. Regulatory practices, particularly in the establishment of protective exposure standards, have failed to take this difference into account. Anecdotal evidence within communities around nuclear facilities suggests an association between radiation exposure and increases in birth defects, miscarriages and childhood cancers. A significant number of academic studies tend to ascribe causality to other factors related to diet and lifestyle and dismiss these health indicators as statistically insignificant. In the case of a major release of radiation due to a serious nuclear accident, children are again on the frontlines, with a noted susceptibility to thyroid cancer, which has been found in significant numbers among children exposed both by the 1986 Chornobyl nuclear accident in Ukraine and the 2011 Fukushima-Daiichi nuclear disaster in Japan. The response among authorities in Japan is to blame increased testing or to reduce testing. More independent studies are needed focused on children, especially those in vulnerable frontline and Indigenous communities. In conducting such studies, greater consideration must be applied to culturally significant traditions and habits in these communities.