Fukushima Nuclear Accident In March Research Articles

Seismic mitigation analysis of three-dimensional base-isolated nuclear structures with soil-dependent isolation system under extreme earthquakes

The Fukushima nuclear accident in March 2011 has raised more stringent requirements for the ability of nuclear power plants (NPPs) to withstand extreme disasters such as extreme earthquakes. To address this challenge, this study proposed a new hybrid multi-dimensional passive control system that combines three-dimensional base isolation and geotechnical seismic isolation. In this system, high-damper rubber bearings were employed to isolate horizontal seismic motions, whereas disc springs, accounting for frictional forces, were used to mitigate vertical seismic motions. Additionally, a geotechnical seismic isolation system arranged under the base mat was leveraged to further reduce the seismic response of the superstructure. Taking a large-scale reactor building in complex layered sites as an example, the effectiveness of the hybrid multi-dimensional isolation system was studied using a wave motion method. The research results indicate that when subjected to extreme earthquakes, hybrid multi-dimensional isolation exhibits superior isolation performance compared with three-dimensional base isolation, which can significantly reduce the three-dimensional dynamic response of nuclear structures without increasing the displacement of the isolation bearings. The proposed hybrid multi-dimensional isolation system offers an effective solution to the challenges faced by three-dimensional isolation systems, thereby enhancing the seismic resistance of nuclear structures against extreme earthquakes.

Visualization of the initial radiocesium dynamics after penetration in living apple trees with bark removal using a positron-emitting 127Cs tracer

Following the Fukushima nuclear accident in March 2011, radiocesium (rCs) contamination in deciduous trees remains over 10 years later even though the trees were leafless at the time of the accident. This phenomenon is considered to be the result of repeated retranslocation of rCs that initially penetrated the bark into the internal tissues. To implement effective measures after a possible accident in the future, it is necessary to clarify how rCs is translocated in the tree after penetration. In this study, rCs translocation was dynamically visualized using a positron-emitting tracer imaging system (PETIS) and autoradiography after the bark of apple branches was removed. The PETIS results showed the translocation of 127Cs from the branch to young shoots and the main stem in apple trees under controlled spring growing conditions. The transport velocity of rCs in the branch was faster than that in the main stem. The transport of rCs, which was either acropetal or basipetal, in the main stem through the branch junction favored basipetal movement. Autoradiography of transverse sections of the main stem indicated that basipetal translocation was due to transport in the phloem. This study demonstrated the initial translocation responses of rCs similar to previous field research, which indicates that rCs transport to the young shoots tends to be higher under controlled conditions. Our laboratory-based experimental system may be useful to gain an improved understanding of rCs dynamics in deciduous trees.

Imaging Plate Autoradiography for Ingested Anthropogenic Cesium-137 in Butterfly Bodies: Implications for the Biological Impacts of the Fukushima Nuclear Accident.

The Fukushima nuclear accident in March 2011 caused biological impacts on the pale grass blue butterfly Zizeeria maha. At least some of the impacts are likely mediated by the host plant, resulting in "field effects". However, to obtain the whole picture of the impacts, direct exposure effects should also be evaluated. Here, we examined the distribution of experimentally ingested anthropogenic cesium-137 (137Cs) in adult butterfly bodies using imaging plate autoradiography. We showed that 137Cs ingested by larvae was incorporated into adult bodies and was biased to females, although the majority of ingested 137Cs was excreted in the pupal cuticle and excretory material during eclosion. 137Cs accumulation in adult bodies was the highest in the abdomen, followed by the thorax and other organs. These results suggest that 137Cs accumulation in reproductive organs may cause adverse transgenerational or maternal effects mediated by reactive oxygen species (ROS) on germ cells. 137Cs accumulation was detected in field individuals collected in September 2011 and September 2016 but not in May 2011, which is consistent with the abnormality dynamics known from previous studies. Taken together, these results contribute to an integrative understanding of the multifaceted biological effects of the Fukushima nuclear accident in the field.

Slow activism in third places: de-normalizing radiation and rebuilding ethical relations after Fukushima

ABSTRACT What are the possibilities for action and agency in a world of chronic, invisible environmental harm? How can environmental social movements address crises wherein affected communities have ambivalent or conflicting perceptions of the environmental harm in question? Through extensive participant observation and in-depth interviews, this study explores these questions in the aftermath of the Fukushima nuclear accident of March 2011. One way in which concerned citizens and advocates across the country responded to this accident was to organize recuperation retreats, meant to provide temporary relief from the physical threat of radiation exposure for children and families still living in Fukushima prefecture. Such retreats are primarily sites of relaxation, play, and immersion in nature. In providing ‘third places’ for conversation about shared experiences, ongoing concerns, and practical information about radiation risk, retreats also function to de-normalize radiation contamination and cultivate ethical relations based on transparency, trust, and mutual support. I argue that recuperation retreat organizing, as well as the act of participation, represents a form of slow activism that falls outside of the binary of resistance and quiescence. Recuperation retreats present a potential model for a public health response to environmental health crises, particularly in cases of environmental uncertainty and contestation.

A brief overview of the registration system of radiation exposure doses for decontamination workers and their occupational health management.

Following the Fukushima nuclear accident in March 2011, decontamination and related works have been carried out over a wide area, mainly in Fukushima Prefecture. In November 2013, the Radiation Dose Registration and Management System for Decontamination Workers was established to manage the occupational exposure doses of workers engaged in such work. The Radiation Effects Association mainly operates the registration system. This paper summarizes existing reports on this system and occupational health issues among decontamination workers. We collected previous reports and related regulatory laws on occupational health management for decontamination workers working in Fukushima Prefecture, summarized the outline of the radiation dose registration and management system for these decontamination workers, and discussed future issues related to their health management. Approximately 100 000 decontamination workers were registered in the system as of 2020, but none showed radiation doses that exceeded the dose limit. To our knowledge, there have been no reports of decontamination workers presenting physical symptoms suspected to be related to radiation exposure. On the other hand, heatstroke countermeasures and anxiety about radiation exposure have been reported as possible issues in the occupational health management of decontamination workers. Although decontamination workers are unlikely to experience biological effects from radiation exposure, epidemiological studies are needed to examine this evidence. Further analysis is also needed on non‐radiation effects, which pose occupational health concerns for decontamination workers. The registration system would allow for tracking decontamination workers, providing data for analyzing radiological and non‐radiological effects.

Overwintering States of the Pale Grass Blue Butterfly Zizeeria maha (Lepidoptera: Lycaenidae) at the Time of the Fukushima Nuclear Accident in March 2011.

The Fukushima nuclear accident in March 2011 caused the massive release of anthropogenic radioactive materials from the Fukushima Dai-ichi Nuclear Power Plant to its surrounding environment. Its biological effects have been studied using the pale grass blue butterfly, Zizeeria maha (Lepidoptera: Lycaenidae), but the overwintering states of this butterfly remain elusive. Here, we conducted a series of field surveys in March 2018, March 2019, and April 2019 in Fukushima and its vicinity to clarify the overwintering states of this butterfly at the time of the Fukushima nuclear accident. We discovered overwintering individuals in situ associated with the host plant Oxalis corniculata under natural straw mulch as first-instar to fourth-instar larvae in March 2018 and 2019. No other developmental stages were found. The body length and width were reasonably correlated with the accumulated temperature. On the basis of a linear regression equation between body size and accumulated temperature, together with other data, we deduced that the pale grass blue butterfly occurred as fourth-instar larvae in Fukushima and its vicinity at the time of the accident. This study paves the way for subsequent dosimetric analyses that determine the radiation doses absorbed by the butterfly after the accident.

Dose dependence of pediatric thyroid cancer prevalence in the 6 years after the Fukushima nuclear power plant accident

Background: After the Fukushima nuclear accident in March 2011, Fukushima Prefecture initiated thyroid ultrasound screening as part of the Fukushima Health Management Survey (FHMS). Regional differences in external radiation dose were often reported not associated with thyroid cancer prevalence in the firstround screening E-I (2011-2013). The association between childhood thyroid cancer and radiation exposure in the 6 years after the accident is studied by analyzing the results of the first and second-round examinations E-I+II (2011-2015). Methods: Dose dependence of thyroid cancer proportion in E-I and E-II for all residents aged ≤18 years at the accident was analyzed for FHMS external dose and UNSCEAR effective dose by regression analysis using Microsoft Excel. Two divisions of Fukushima prefecture, O-model in the order of decreasing external dose and S-model according to the initial screening schedule, were adopted. Results: In O-model, thyroid cancer proportion per 100,000 in E-II and in E-I+II were found to increase linearly to FHMS external dose in 0.2–1.4 mSv range and UNSCEAR effective dose in 1.6–5 mSv range. Thyroid cancer proportion in E-II and E-I+II was observed to increase linearly to effective dose in Smodel. Conclusion: The observed linear prevalence–dose relation after 6 years from the accident and incidencedose relation during 4-6 years after exposure suggest a possible association between pediatric thyroid cancer and radiation exposure. Regional differences were not obvious in E-I presumably because of the short interval from exposure to screening in high-dose areas. High prevalence of thyroid cancer cannot be attributed only to mass screening effect that does not depend on radiation dose and elapsed time from exposure.

Assessment of multiple anthropogenic contaminants and their potential genotoxicity in the aquatic environment of Plitvice Lakes National Park, Croatia.

In this study, the influence of anthropogenic pollution on the aquatic environment of Plitvice Lakes National Park (PLNP) was investigated during 2011-2012 using a combination of chemical and cytogenetic analyses. Four groups of major contaminants [(volatile organic compounds: benzene, toluene, ethylbenzene, and xylenes (BTEX); persistent organochlorine pollutants: organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs); major and trace elements; anthropogenic radionuclides (90Sr, 134Cs, and 137Cs)] were determined in three aquatic compartments (water, sediment, fish). Mass fractions of inorganic constituents in different compartments reflected the geological background of the area, indicating their origin from predominantly natural sources. Levels of volatile and persistent organic compounds in water and fish, respectively, were very low, at levels typical for remote pristine areas. Analysis of anthropogenic radionuclides in water and sediment revealed elevated activity concentrations of 137Cs in water, and measurable 134Cs in the upper sediment layers from April 2011, possibly as a consequence of the Fukushima nuclear accident in March 2011. The potential genotoxicity of river and lake water and lake sediment was assessed under laboratory conditions using the alkaline comet assay on human peripheral blood lymphocytes, and measured levels of primary DNA damage were within acceptable boundaries. The results showed that despite the protected status of the park, anthropogenic impact exists in both its terrestrial and aquatic components. Although contaminant levels were low, further monitoring is recommended to make sure that they will not rise and cause potentially hazardous anthropogenic impacts.

REMOVAL OF RADIOACTIVE CESIUM FROM OCEAN SLUDGE BY THE BACTERIUM USING PURIFICATION SYSTEM OF CIRCULATION TYPE

The Fukushima nuclear accident of March 11, 2011, resulted in soil and water contamination by radioactive cesium. Radioactive cesium transported by rivers was also found in the ocean sludge of Tokyo Bay. Cesium adsorbed on the sludge is not easily removed. One of the authors has developed an ocean sludgedecomposition system that employs micro-bubble circulation. The circulation of micro-bubbles creates anaerobic state that activates aerobic bacteria, facilitating decomposition and purification of the sludge. The objective of this study was to investigate the effect of the addition of bacteria to the micro-bubble circulation system on the efficient removal of radioactive cesium from ocean sludge. We tested the water purification effect of the system by adding bacteria directly. Results confirmed that the decomposition of the deposited sludge using our system facilitates the elution of the radioactive cesium. Any cesium eluted in the water can be remedied using existing technology such as zeolites. Purification efficiency seems to be greatest when additional bacteria are added directly to the process. With time, bacterial concentration doubles, and 76% of cesium in the liquid phase (dried sludge) and 51% of cesium in the solid phase (water) is removed.

Global and Regional Emissions of Radiocarbon from Nuclear Power Plants from 1972 to 2016

ABSTRACTCH4 and CO2 emissions from geologic sources, which are devoid of radiocarbon (14C), dilute the atmospheric 14C/C ratio. Observations of 14C/C can be used to estimate fossil fuel-derived CH4 and CO2. However, the atmospheric 14C/C ratio is perturbed by emissions of 14C from nuclear power plants (NPPs) and fuel reprocessing sites, which may affect such 14C/C-based estimation if they are not correctly quantified. We calculate NPP 14C emissions for CO2 and CH4 from 1972–2016 using standard emission factors (14C emitted per unit of power produced) and analyze trends in global and regional emissions. We use available observations of 14C emissions and power generation in Europe to assess emission factors for different reactor types, as well as potential differences related to the age or manufacturer of the NPPs. Globally, nuclear 14C emissions increase until 2005 and then decrease, mostly because of the closure of gas-cooled reactors in the United Kindom and the shutdown of light water reactors after the Fukushima nuclear accident in March 2011. Observed emission factors in Europe show strong variability, spanning values from 0.003 to 2.521 TBq/GWa for PWR and from 0.007 to 1.732 TBq/GWa for BWR reactors, suggesting more information and more sophisticated models are needed to improve estimates of 14C emissions.

Effect of mass of organic layers on variation in 137Cs distribution in soil in different forest types after the Fukushima nuclear accident

ABSTRACT Forests over a wide area were contaminated with radiocesium following the Fukushima nuclear accident in March 2011. Most radiocesium in the forests migrated into the soil a year after the accident and it is therefore necessary to clarify the distribution pattern of radiocesium in soil to evaluate the actual state and possible future changes of the radiocesium cycle in forest ecosystems. We investigated the stock and vertical distribution patterns of 137Cs in soil under evergreen and deciduous tree species from 2012 to 2014 in a mountainous area in Fukushima Prefecture. The 137Cs stock in soil was higher in evergreen forests than in deciduous forests. This was likely caused by the difference in tree leaf biomass at the time of the initial deposition, when deciduous trees were defoliated. The organic layer (particularly the humified layer) retained 137Cs in high concentration and stock, indicating limited migration of 137Cs into the mineral layer during the study period. This may reflect the incorporation of 137Cs into organic matter and the retention of fungi in the organic layer. Analyses of these data and those from other studies conducted in regions contaminated by the accident showed that the ratio of radiocesium stock in the organic layer to the total amount in soil was positively correlated with the mass of the organic layer (organic layers with a mass of >2.0 kg/m2 retained more than 50% of total radiocesium). Thus, the status of the organic layer is an important factor regulating the downward migration of radiocesium.

CHARACTERISTICS OF THE SLUDGE PARTICLES IN REMOVAL PROCESS OF RADIOACTIVE CESIUM FROM OCEAN SLUDGE BY DECOMPOSITION SYSTEM WITH CIRCULATION TYPE USING MICRO BUBBLES AND ACTIVATING MICROORGANISMS

The Fukushima nuclear accident of March 11, 2011, soil and water had been contaminated by radioactive cesium. Moreover, radioactive cesium was found in the ocean sludge in Tokyo Bay flowing from rivers. Cesium which is adsorbed to the sludge cannot be easily removed. One of the authors developed decomposition and purification system, a circulation-type system by micro bubbles, that is, by creating aerobic state, aerobic bacteria are activated resulting to decomposition and purification of ocean sludge. Based on the hypothesis that radioactive cesium is adsorbed on the surface of the sludge deposition. It is considered cesium can be eluted after decomposing the deposited sludge. Once the cesium is eluted in the water, it can fix to a mineral such as zeolite. Now we need the properties of sludge in removal process by decomposition system with circulation type. In this study, our objects is to check the characteristics of the sludge particle in removal process of radioactive cesium from ocean sludge by decomposition system with circulation type using micro bubbles and activating microorganisms. As the results of this experiments, we had very good purification ratio on total nitrogen and had made 40 times of smaller size on diameter of the particle of sludge.

OCEAN DECONTAMINATION: HIGH ABILITY REMOVAL METHOD TO RADIOACTIVE CESIUM FROM OCEAN SLUDGE BY USING MICRO BUBBLES AND ACTIVATING MICROORGANISMS

The Fukushima nuclear accident of March 11, 2011, soil and water had been contaminated by radioactive cesium. Moreover, radioactive cesium was found in the ocean sludge in Tokyo Bay flowing from rivers. Cesium which is adsorbed to the sludge cannot be easily removed. One of the authors developed decomposition and purification system, a circulation-type system by micro bubbles, that is, by creating aerobic state, aerobic bacteria are activated resulting to decomposition and purification of ocean sludge. Based on the hypothesis that radioactive cesium is adsorbed on the surface of the sludge deposition. It is considered that cesium can be eluted after decomposing the deposited sludge. Once the cesium is eluted in the water, it can fix to a mineral such as zeolite. Eluting and fixing cesium adsorbed on sludge takes so much time. In this case, the concept of removing the left sludge by flocculation method and then followed by coagulating sedimentation method is studied. In this study, our objects is to show the effectivity and efficiency of using flocculation and coagulating sedimentation in removing radioactive cesium. As the results, we pointed out this method is very good.

EFFECT OF ADDITION OF BACTERIA ON THE REMOVAL OF RADIOACTIVE CESIUM FROM OCEAN SLUDGE IN A CIRCULATION TYPE PURIFICATION SYSTEM

Following the Fukushima nuclear accident of March 11, 2011, soil and water were contaminated by radioactive cesium. Moreover, radioactive cesium was found in the ocean sludge in Tokyo Bay, carried by rivers flowing into the bay. The cesium adsorbed in the sludge cannot easily be removed. The objective of this study was to investigate the effect of the addition of bacteria to the micro-bubble circulation system on the efficient removal of radioactive cesium from ocean sludge. One of the authors has developed an ocean sludge decomposition system employing circulation of micro-bubbles. Model sludge was prepared using seawater, sea sludge, and cesium chloride. Bacteria were added to the system after 24 h. Dried tangle extract was added as a nutrient at 24 h and 36 h. The decomposition experiment was carried out for 120 h.The circulation of micro-bubbles created an aerobic state that activated aerobic bacteria, facilitating decomposition and purification of the sludge. Thus, decomposition of the deposited sludge using our system renders the elution of the radioactive cesium possible. If the cesium is eluted in the water, we can fix it usingexisting technology such as zeolites. We identified and isolated the most useful bacteria for sludge decomposition. Effects on purification seem to be greatest when additional bacteria are added directly to the process. The methodology proposed is expected to facilitate decomposition of sludge and removal of radioactive cesium from the environment.

Impacts of nuclear plant shutdown on coal-fired power generation and infant health in the Tennessee Valley in the 1980s

The Fukushima nuclear accident in March 2011 generated deep public anxiety and uncertainty about the future of nuclear energy. However, differently to fossil fuel plants, nuclear plants produce virtually no greenhouse gas emissions or air pollutants during power generation. Here we show the effect on air pollution and infant health in the context of the temporary closure of nuclear plants by the Tennessee Valley Authority (TVA) in the 1980s. After the Three Mile Island accident in 1979, the US Nuclear Regulatory Commission intensified inspections throughout the nation, leading to the shutdown of two large nuclear power plants in the TVA area. In response to that shutdown, electricity generation shifted one to one to coal-fired power plants within TVA, increasing particle pollution in counties where they were located. Consequently, infant health may have deteriorated in the most affected places, indicating deleterious effects to public health. Nuclear accidents generate vast echoes in public opinion, and often determine policy decisions to suspend nuclear programs. This study shows the unintended implications of nuclear plant shutdown in Tennessee Valley between 1983 and 1986, demonstrating deleterious consequences for public health.

Communicating With Residents About Risks Following the Fukushima Nuclear Accident.

The Fukushima nuclear accident in March 2011 posed major threats to public health. In response, medical professionals have tried to communicate the risks to residents. To investigate forms of risk communication and to share lessons learned, we reviewed medical professionals' activities in Fukushima Prefecture from the prefectural level to the individual level: public communication through Fukushima Health Management Surveys, a Yorozu ("general") health consultation project, communications of radiological conditions and health promotion in Iitate and Kawauchi villages, dialogues based on whole-body counter, and science communications through online media. The activities generally started with radiation risks, mainly through group-based discussions, but gradually shifted to face-to-face communications to address comprehensive health risks to individuals and well-being. The activities were intended to support residents' decisions and to promote public health in a participatory manner. This article highlights the need for a systematic evaluation of ongoing risk communication practices, and a wider application of successful approaches for Fukushima recovery and for better preparedness for future disasters.

Robustness and Radiation Resistance of the Pale Grass Blue Butterfly from Radioactively Contaminated Areas: A Possible Case of Adaptive Evolution.

The pale grass blue butterfly, Zizeeria maha, has been used to evaluate biological impacts of the Fukushima nuclear accident in March 2011. Here, we examined the possibility that butterflies have adapted to be robust in the contaminated environment. Larvae (n = 2432) were obtained from adult butterflies (n = 20) collected from 7 localities with various contamination levels in May 2012, corresponding to the 7th generation after the accident. When the larvae were reared on non-contaminated host plant leaves from Okinawa, the normality rates of natural exposure without artificial irradiation (as an indication of robustness) were high not only in the least contaminated locality but also in the most contaminated localities. The normality rates were similarly obtained when the larvae were reared on non-contaminated leaves with external irradiation or on contaminated leaves from Fukushima to deliver internal irradiation. The normality rate of natural exposure and that of external or internal exposure were correlated, suggesting that radiation resistance (or susceptibility) likely reflects general state of health. The normality rate of external or internal exposure was divided by the relative normality rate of natural exposure, being defined as the resistance value. The resistance value was the highest in the populations of heavily contaminated localities and was inversely correlated with the distance from the Fukushima Dai-ichi nuclear power plant. These results suggest that the butterfly population might have adapted to the contaminated environment within approximately 1 year after the accident. The present study may partly explain the decrease in mortality and abnormality rates later observed in the contaminated areas.

The Emerging U.S.-Japan Energy Alliance and Its Implications for China

Since the Tohoku earthquake and Fukushima nuclear accident in March 2011, Japan’s energy policy has undergone great changes, resulting in closer energy cooperation with the United States. To serve its own national interests, the United States also began to emphasize the significance of energy cooperation under the U.S.-Japan alliance. Consequently, both countries have made strategic breakthroughs in terms of energy politics, energy economics and energy security, and a U.S.-Japan energy alliance is now taking shape. The progress of U.S.-Japan energy cooperation, on one hand, will help reduce the cost of China’s natural gas import and create favorable conditions for China to promote domestic reforms in the energy sector. On the other hand, it will also present new challenges to China’s geopolitical environment and its global role. While the United States continues to increase its export of liquefied natural gas (LNG) to Asian markets, China should make full use of the opportunity to speed up the development of its own shale gas resources, optimize its energy consumption structure, promote domestic energy reforms, and diversify its energy import sources. In the meantime, it should try to work with the United States and Japan to foster an all-inclusive, long-term mechanism for energy cooperation among all countries in the Asia-Pacific.

Robust Energy Mix Options in Japan under Uncertainty

AbstractIt is crucial for the Japanese government to establish a new energy mix plan since the previous plan was subject to review after the Fukushima nuclear accident in March 2011. The Japanese government proposed a new energy mix option in June 2015. However, the high degree of uncertainty will impair the robustness of energy mix options decided based on predictions. This paper uses robust decision making (RDM) to take uncertainty into account and determine robust energy mix options. An hourly electricity dispatch and power plant renewal simulation covering 2016–2035 in Japan is conducted to analyze the economic and environmental impacts of several energy mix options. The results show that the options with greater use of coal-fired and wind power plants have robustness against future uncertainties and that the current government plan is inefficient.

Rare Events and Risk Perception: Evidence from Fukushima Accident

We study changes in nuclear-risk perception following the Fukushima nuclear accident of March 2011. Using an exhaustive registry of individual housing transactions in England and Wales between 2007 and 2014, we implement a difference-in-difference strategy and compare housing prices in at-risk areas to areas further away from nuclear sites before and after Fukushima incident. We find a persistent price malus of about 3.5% in response to the Fukushima accident for properties close to nuclear plants. We show evidence that this price malus can be interpreted as a change in nuclear-risk perception. In addition, the price decrease is much larger for high-value properties within neighborhoods, and deprived zones in at-risk areas are more responsive to the accident. We discuss various theoretical channels that could explain these results.