Search Results (81)

To reduce environmental contamination following the release of various radionuclides during the Fukushima Daiichi Nuclear Power Plant accident, the Japanese government has continued decontamination work and decided to use interim storage facilities (ISFs) in the towns of Okuma and Futaba to house large quantities of contaminated soil and waste until their final disposal. This study aims to clarify whether there are differences in the acceptance of removed soil for recycling between people who provided land for ISFs and those who do not. Furthermore, we analyzed the risk perception of the radiation effects on offspring, trust in information from public authorities, and intention to return to their hometown. A questionnaire survey was conducted at Okuma and Futaba town homes in the ISF area. Compared with those who did not provide land to the ISFs (n = 538, 68.0%), people who provided land (n = 141, 77.9%) responded that they were accepting the building of the ISFs (p = 0.018). Meanwhile, approximately half of the respondents were “unable to decide” concerning the recycling of removed soil in their current region of residence regardless of whether the land provided or not. Similarly, there were no significant differences between the groups regarding radiation risk perceptions of the offspring effects on residents and intention to return, or whether to provide land to the ISFs. The study suggests that it is important to continue radiation risk communication to determine whether people have provided land to the ISFs. Full article

This study focused on the measurement of anthropogenic radionuclides such as americium (Am) and plutonium (Pu) in environmental samples. Plutonium isotopes, particularly ${}^{239}\mathrm{Pu}$, ${}^{240}\mathrm{Pu}$, and ${}^{241}\mathrm{Pu}$, originated from nuclear weapons testing, nuclear power plants, and accidents like Chernobyl and Fukushima Daiichi. Accurate measurement of these isotopes, considering their half-lives and trace concentrations, provides critical information about their persistence and environmental transport. Using the 1 MV Tandetron accelerator, we expanded the measurement capabilities to include ${}^{241}\mathrm{Pu}$, ${}^{241}\mathrm{Am}$. Chemical separation of these isotopes was achieved through ion chromatography, employing reference isotopes ${}^{242}\mathrm{Pu}$ and ${}^{243}\mathrm{Am}$ for method validation. Certified reference materials, including IAEA-410 (Bikini Atoll sediment) and Sample 05, were analyzed to ensure accuracy. We validated the ${}^{241}\mathrm{Am}$/${}^{243}\mathrm{Am}$ ratio in an Am standard (IFIN-STD-Am, our laboratory produced standard for Am), achieving a measured value of 0.158 at·at⁻¹ (3%), in good agreement with the nominal value of 0.154 at·at⁻¹. Additionally, we determined the ${(}^{241}\mathrm{Pu}$ + ${}^{241}\mathrm{Am}){/}^{242}\mathrm{Pu}$ ratio in the ColPuS standard to be equal to 0.029 at ·at⁻¹ (7%). These results demonstrate the potential of AMS for improved detection of actinides at low concentrations and contribute to understanding the behavior of Pu and Am isotopes. Full article

Even before the Fukushima Daiichi Nuclear Power Plant accident, people were continuously exposed to various naturally occurring radioactive materials, including radon. However, public awareness and understanding of this exposure remain limited. When communicating the risks of radiation exposure from the Fukushima accident, explanatory materials have not typically incorporated data from coastal areas of Fukushima Prefecture collected after the incident to clarify the actual levels of artificial and natural radiation exposure. This study aimed to assess whether presenting radiation dose data from coastal areas of Fukushima Prefecture—using natural radiation as a reference point—could influence risk perception regarding the health effects of radiation exposure and its potential impact on future generations. The study focused on students enrolled in health science-related departments at Hirosaki University. Before being presented with the data, the students had limited understanding of radiation. However, after reviewing the explanatory materials, 89 students (48.4%) demonstrated an improved understanding of its potential impact on future generations, while 87 students (47.3%) showed increased awareness of the effects on their own health. Regarding the reduction in risk perception, many students attributed it to the fact that radiation levels 10 years after the Fukushima nuclear accident were not significantly different from natural background radiation in most areas. These findings suggest that providing actual radiation measurement data from affected areas can significantly influence risk perception and decision-making processes. The results indicate that participants became more aware of the presence of natural background radiation, and the comparison with current radiation levels in Fukushima played a key role in shaping their risk perception. Full article

After the Fukushima Nuclear Power Plant accident in March 2011, a large-scale ultrasound examination of childhood thyroid cancer for all Fukushima residents aged 18 years old or younger was initiated. Fukushima was divided into four areas according to the external radioactivity released by the accident: the highest (A), high-intermediate (B), low-intermediate (C), and the lowest (D). Five rounds of surveys were carried out from October 2011 to March 2023. The annual incidence rates of the “Common Case” not affected by the accident were able to be estimated. The difference between the incidence rate of whole patients and the “Common Case” is that of the “Radiation-induced Case”. The annual incidence rate of the “Radiation-induced Case” began to increase immediately after the accident, where the highest level was seen in A area, and the order was A > B > C > D. It showed that the development of childhood thyroid cancer was affected by the radiation released by the accident. The effect of the radiation consisted of two phases: the first phase may have been due to the damage to the immune system, and the second phase may have been due to the genetic mutation in the children who were youngest at the time of the accident. Full article

The year 2023 marks the 12th anniversary of the Great East Japan Earthquake (GEJE). Immediately after the disaster, the number of evacuees reached approximately 470,000, but by November 2022, the number had decreased to approximately 31,000. The reconstruction of housing, disposal of debris, public infrastructure development, and overall restoration and reconstruction has progressed steadily. However, a re-examination of the status of industrial restoration and reconstruction reveals that restoration and reconstruction have not progressed in some areas. This research statistically analyzes how the Japanese public perceives the issues around the recovery process and what memories and records they would like to learn from regarding the GEJE. The purpose of this study is to ask about reconstruction issues and lessons learned from the GEJE by conducting a web-based survey with 2000 respondents in Japan. The method of estimation is the use of ordinal logistic regression analysis to statistically estimate whether there are differences in recovery issues and lessons learned depending on individual attributes. The results suggest that those who are interested in, remember, and express anxiety about the recovery issues and lessons learned tend to be men, do not have children, are highly educated, and have a higher income. In sum, many of Japan’s citizens are highly interested in the reconstruction of agriculture, forestry, fisheries, housing, urban development, living environment, industry, and livelihood in the affected areas. In the future, they will play a central role in modernizing, scaling up, and integrating the agriculture, forestry, and fisheries industries, as well as in rebuilding towns and livelihoods. In the affected areas, it will be necessary to draw on the lessons learned from the GEJE and create reconstruction plans for the future, and then, policymakers will need to formulate reconstruction policies that reflect the concerns of the Japanese people. Full article

Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, great attention has been paid to the impact of chronic low-dose-rate (LDR) radiation exposure on biological systems. The reproductive system is sensitive to radiation, with implications connected to infertility. We investigated the testis ultrastructure of the wild large Japanese field mouse (Apodemus speciosus) from three areas contaminated after the FDNPP accident, with different levels of LDR radiation (0.29 µSv/h, 5.11 µSv/h, and 11.80 µSv/h). Results showed good preservation of the seminiferous tubules, comparable to the unexposed animals (controls), except for some ultrastructural modifications. Increases in the numerical density of lipid droplet clusters in spermatogenic cells were found at high levels of LDR radiation, indicating an antioxidant activity rising due to radiation recovery. In all groups, wide intercellular spaces were found between spermatogenic cells, and cytoplasmic vacuolization increased at intermediate and high levels and vacuolated mitochondria at the high-level. However, these findings were also related to the physiological dynamics of spermatogenesis. In conclusion, the testes of A. speciosus exposed to LDR radiation associated with the FDNPP accident showed a normal spermatogenesis, with some ultrastructural changes. These outcomes may add information on the reproductive potential of mammals chronically exposed to LDR radiation. Full article

The Fukushima Daiichi Nuclear Power Plant accident caused an accumulation of ¹³⁷Cs in coastal sediment. The ¹³⁷Cs supply from rivers to the ocean can affect the long-term fate of ¹³⁷Cs in coastal sediment. Since the Fukushima coastal river basins include large decontaminated and evacuation order areas, considering the decontamination work and resumption of agriculture is important for predicting the ¹³⁷Cs supply. We conducted a 30-year prediction of the ¹³⁷Cs supply from the Fukushima coastal rivers to the ocean using a distributed radiocesium prediction model, considering the effects of human activities. In river basins with decontaminated and evacuation order areas, human activities reduced the total ¹³⁷Cs outflow from agricultural lands, urban lands, and forest areas to the rivers and the ¹³⁷Cs supply to the ocean by 5.0% and 6.0%, respectively. These results indicated that human activities slightly impacted the ¹³⁷Cs outflow and supply. The ¹³⁷Cs supply from rivers impacted by the accident to the coastal sediment was estimated to correspond to 11–36% of the total ¹³⁷Cs in the coastal sediment in the early phase of the accident. Therefore, the ¹³⁷Cs supply from rivers to the ocean is important for the long-term behavior of ¹³⁷Cs in coastal sediment. Full article

Two crystalline phases, which are analogues of common secondary uranyl minerals, namely, becquerelite (Ca[(UO₂)₆O₄ (OH)₆]·8H₂O) and phurcalite (Ca₂[(UO₂)₃O₂ (PO₄)₂]·7H₂O) were identified on the surface of a Chernobyl corium-containing sample affected by hydrothermal alteration in distilled water at 150 °C for one year. Phases were characterized using Single-Crystal X-ray Diffraction Analysis (SCXRD) as well as optical and scanning electron microscopy. Features of the structural architecture of novel phases, which come from the specific chemical composition of the initial fragment of Chernobyl sample, are reported and discussed. Precise identification of these phases is important for modelling of severe nuclear accidents and their long-term consequences, including expected corium–water interaction processes at three damaged Units of the Nuclear Power Plant Fukushima Daiichi. Full article

Over 10 years have passed since the Fukushima Daiichi Nuclear Power Plant accident. This study verifies the efficacy of longitudinal regulation on internal exposure doses and analyzes food group contributions to radiation doses using accumulated monitoring test results. The committed effective doses in 10,000 virtual persons from fiscal year (FY) 2012 to 2021, with and without regulation, were estimated as products of radioactivity concentrations randomly sampled from the test results, food intake, and dose coefficient. The distributed values of food intake rather than a mean value in dose estimation were assumed to reflect food intake variations and avoid underestimation of internal exposure doses for high-intake consumers. Furthermore, the ingestion of radioactive cesium from the calculation was analyzed per food group. The 95th percentile of the internal exposure dose (the dose of a “representative person”) was less than 1 mSv/year in both FYs. The regulation effect was substantial in FY 2012, and no noticeable difference in radiation doses was found between the regulation and no regulation conditions after FY 2016. Internal exposure doses decreased until approximately FY 2016 and then remained constant. It was also shown that not only radioactivity concentration but also food intake is a major factor affecting cesium intake. In summary, it was confirmed that Japan had ensured food safety regarding radioactive materials. Full article

The investigation of the impact of the Fukushima accident is still going on although more than ten years have passed since the disaster. The main goal of this paper was to summarize the results of tritium and radiocarbon determinations in different environmental samples, possibly connected with the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. A document containing compiled data may serve as a solid basis for further research in the selected fields. To accomplish such effort, we went through dozens of relevant published papers, reporting ³H and ¹⁴C activity concentrations in precipitations, groundwater, seawater, river systems, tree rings, and, in some more extraordinary samples, such as herbaceous plants or debris from the damaged reactor buildings. As the referenced results would not be obtainable without adequate analytical techniques, the most common methods for routine measurement of tritium and radiocarbon concentrations are discussed as well. We believe that the correct identification of the affected environmental compartments could help quantify the released ³H and ¹⁴C activities and track their following fate, which could be especially important for plans to discharge contaminated water from the FDNPP in the upcoming years. Full article

Many irrigation ponds in Fukushima Prefecture were decontaminated due to the contamination of radiocesium released from Fukushima Daiichi Nuclear Power Plant. To evaluate the impact of decontamination on ¹³⁷Cs dynamics in an urban pond in Koriyama City, Fukushima Prefecture, Japan, temporal changes in ¹³⁷Cs concentrations in bottom sediments and pond water were investigated before and after bottom-sediment removal. Post-decontamination, ¹³⁷Cs inventories in bottom sediments decreased by 46–89%. ¹³⁷Cs inventories in bottom sediments were relatively high in fine sediments before decontamination, and were also high at points near the water inlet after decontamination. Following decontamination, the mean ¹³⁷Cs concentration in suspended solids (SS) and the mean dissolved ¹³⁷Cs concentration in pond water decreased by 52% and 5%, respectively. Even after decontamination, the normalized ¹³⁷Cs concentrations in SS and in water, which were calculated by dividing the ¹³⁷Cs concentrations by the mean ¹³⁷Cs inventories in each area, were higher than those in rivers, dam reservoirs, and ponds elsewhere in Fukushima. The positive correlations between δ¹⁵N values, an indicator of the source contribution to bottom sediments, and ¹³⁷Cs concentrations in the upper 5 cm of bottom sediments after decontamination implied that SS from urban areas gradually increased the ¹³⁷Cs inventories in the pond. The results underline the importance of secondary inputs of ¹³⁷Cs from highly urbanized catchments. Full article

The Fukushima Daiichi nuclear power plant accident happened after the devastating earthquake in the Pacific coastal area of Japan on 11 March 2011. After the accident, radioactive materials spread out over a wide area in Japan. Radioactive materials were retained on soil surfaces, causing environmental problems. Among the radioactive materials, cesium (¹³⁷Cs) has a long half-life of 30.2 years, and it remains near the surface soil; therefore, it is necessary to remove soil contaminated by ¹³⁷Cs. The contaminated soil layer of inhabited areas in Fukushima was already removed before April 2020. However, the remediation method of Cs with other radioactive materials needs further study, as the large quantity of contaminated soil is not easy to preserve. Electrokinetic (EK) treatment is one of the soil remediation technologies that utilizes EK phenomena at the interface between contaminated soils by transferring ions from the soil. We have developed a new type of EK method in which a cathode is placed on the surface of the soil and an anode is place inside the soil. By applying DC voltage in between the electrodes, the Cs ions can be removed from the contaminated soil. The removed Cs ions are gathered near to the cathode, and if the cathode can adsorb the Cs ions, then only the cathode needs to be preserved, solving the problem of storing a large amount of soil. We have been working to prepare a new type of cathode that can be effective in adsorbing Cs ions and at the same time easier to store and handle. We used natural zeolite and rice husk charcoal (kuntan) to prepare this electrode, which showed good potential for adsorbing Cs ions. The electrode showed flexibility, which is helpful for storing it in the same way as pasture rolls. However, the experiments were conducted in the laboratory with non-radioactive Cs; field experiments and observations are needed for practical applications of this method, as well as the new electrodes. Full article

In this study, we aimed to investigate radiation risk perception, mental health, and interest in tritiated water among evacuees from and returnees to Tomioka town, Japan, as well as to evaluate the intention to return (ITR) among evacuees living inside and outside Fukushima Prefecture. Of the 1728 respondents, 318 (18.4%) and 1203 (69.6%) participants reported living outside and inside Fukushima Prefecture, and 207 (12.0%) reported living in Tomioka. The ITR was not significantly different between those who lived inside and outside the prefecture among the evacuees. Similarly, there were no significant differences in radiation risk perception, mental health, and interest in tritiated water. However, the evacuees were independently associated with a motivation to learn about tritiated water (OR = 1.242, 95%Cl: 1.041–1.438, p = 0.016), reluctance to consume food from Tomioka (OR = 1.635, 95%Cl: 1.372–1.948, p < 0.001), and concern that adverse health effects would occur because of the Fukushima Daiichi Nuclear Power Plant accident (OR = 1.279, 95%Cl: 1.055–1.550, p = 0.012) compared to returnees, according to logistic regression analysis. Interestingly, the returnees were found to have better mental health but lower life satisfaction than the evacuees. These findings suggest the importance of ongoing risk communication about radiation exposure and tritiated water among residents regardless of their place of residency. Full article