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.

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.

Rain-induced bioecological resuspension of radiocaesium in a polluted forest in Japan

It is the conventional understanding that rain removes aerosols from the atmosphere. However, the question of whether rain plays a role in releasing aerosols to the atmosphere has recently been posed by several researchers. In the present study, we show additional evidence for rain-induced aerosol emissions in a forest environment: the occurrence of radiocaesium-bearing aerosols in a Japanese forest due to rain. We carried out general radioactive aerosol observations in a typical mountainous village area within the exclusion zone in Fukushima Prefecture to determine the impacts and major drivers of the resuspension of radiocaesium originating from the nuclear accident in March 2011. We also conducted sampling according to the weather (with and without rain conditions) in a forest to clarify the sources of atmospheric radiocaesium in the polluted forest. We found that rain induces an increase in radiocaesium in the air in forests. With further investigations, we confirmed that the fungal spore sources of resuspended radiocaesium seemed to differ between rainy weather and nonrainy weather. Larger fungal particles (possibly macroconidia) are emitted during rainy conditions than during nonrainy weather, suggesting that splash generation by rain droplets is the major mechanism of the suspension of radiocaesium-bearing mould-like fungi. The present findings indicate that radiocaesium could be used as a tracer in such research fields as forest ecology, meteorology, climatology, public health and agriculture, in which fungal spores have significance.

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.

Long-term decay heat removal in a submerged SMR

Following the Fukushima-Daiichi nuclear accident in March 2011, innovations are needed to improve the reliability of new generation nuclear power plants toward scenarios where electrical power and ultimate heat sink are lost. This paper describes an integral design and basic passive safety strategy of a Small Modular Reactor (SMR) submerged in the sea or in an artificial lake, then performing a preliminary analysis of the long-term decay heat removal. The analysis considers a pressurized reactor placed in a horizontal cylindrical hull, which is surrounded by the external water. The simulated system is based on the Flexblue concept, developed by French company DCNS (now Naval Group). The object of the investigation is the natural circulation in the submerged containment, which is the key component for the long-term cooling. Following a rupture in the primary circuit, decay heat must be removed according to a fully passive safety strategy for an indefinitely long period. The purpose of this work is to study the effectiveness of a sump natural circulation flow to cool the fuel rods, up to several days after the scram. Decay heat generates steam in the core, which is released in the containment and condensed on the metal surface, transferring the heat to the exterior. Relap5-Mod3.3 has been employed to simulate the accident scenario. Results show the consistency of the safety principles and stimulate experimental investigations. However, the sensitivity analysis identifies the nodalization of the reactor containment as a modeling and numerical issue, deserving further analyses.

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.

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.

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.

CO<sub>2</sub>ハイドレート発電システムの試作試験機の開発

The development of distributed generation systems using renewable energy has advanced in Japan due to the influence of the Fukushima Daiichi nuclear accident in March 2011. In this work, the power generation system using the unique change of state of CO2 hydrate is developed. Because the proposed system is not accompanied by combustion of a fossil fuel, it is a clean energy device. Furthermore, renewable energy, the open air, etc, can be used as the source of high temperature heat, and a low temperature heat source. In this study, we investigated the characteristics of the output of the proposed generation system by experimental model. As a result, maximum power output of 30W and total energy conversion efficiency of 2.68% were obtained.

Changes in the Factors Influencing Public Acceptance of Nuclear Power Generation in Japan Since the 2011 Fukushima Daiichi Nuclear Disaster

Public support for nuclear power generation has decreased in Japan since the Fukushima Daiichi nuclear accident in March 2011. This study examines how the factors influencing public acceptance of nuclear power changed after this event. The influence factors examined are perceived benefit, perceived risk, trust in the managing bodies, and pro-environmental orientation (i.e., new ecological paradigm). This study is based on cross-sectional data collected from two online nationwide surveys: one conducted in November 2009, before the nuclear accident, and the other in October 2011, after the accident. This study's target respondents were residents of Aomori, Miyagi, and Fukushima prefectures in the Tohoku region of Japan, as these areas were the epicenters of the Great East Japan Earthquake and the locations of nuclear power stations. After the accident, trust in the managing bodies was found to have a stronger influence on perceived risk, and pro-environmental orientation was found to have a stronger influence on trust in the managing bodies; however, perceived benefit had a weaker positive influence on public acceptance. We also discuss the theoretical and practical implications of these findings.

Spatiotemporal abnormality dynamics of the pale grass blue butterfly: three years of monitoring (2011-2013) after the Fukushima nuclear accident.

BackgroundLong-term monitoring of the biological impacts of the radioactive pollution caused by the Fukushima nuclear accident in March 2011 is required to understand what has occurred in organisms living in the polluted areas. Here, we investigated spatial and temporal changes of the abnormality rate (AR) in both field-caught adult populations and laboratory-reared offspring populations of the pale grass blue butterfly, Zizeeria maha, which has generation time of approximately one month. We monitored 7 localities (Fukushima, Motomiya, Hirono, Iwaki, Takahagi, Mito, and Tsukuba) every spring and fall over 3 years (2011–2013).ResultsThe adult ARs of these localities quickly increased and peaked in the fall of 2011, which was not observed in non-contaminated localities. In the offspring generation, the total ARs, which include deaths at the larval, prepupal, and pupal stages and morphological abnormalities at the adult stage, peaked either in the fall of 2011 or in the spring of 2012, with much higher levels than those of the parent field populations, suggesting that high incidence of deaths and abnormalities might have occurred in the field populations. Importantly, the elevated ARs of the field and offspring populations settled back to a normal level by the fall of 2012 and by the spring of 2013, respectively. Similar results were obtained not only in the spatiotemporal dynamics of the number of individuals caught per minute but also in the temporal dynamics of the correlation coefficient between the adult abnormality rate and the ground radiation dose or the distance from the Power Plant.ConclusionsThese results demonstrated an occurrence and an accumulation of adverse physiological and genetic effects in early generations, followed by their decrease and leveling off at a normal level, providing the most comprehensive record of biological dynamics after a nuclear accident available today. This study also indicates the importance of considering generation time and adaptive evolution in evaluating the biological impacts of artificial pollution in wild organisms.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0297-1) contains supplementary material, which is available to authorized users.

Uptake and translocation of radiocesium in cedar leaves following the Fukushima nuclear accident

Cryptomeria japonica trees in the area surrounding Fukushima, Japan, intercepted 137Cs present in atmospheric deposits soon after the Fukushima nuclear accident in March 2011. To study the uptake and translocation of 137Cs in C. japonica leaves, we analyzed activity concentrations of 137Cs and the concentration ratios of 137Cs to 133Cs (137Cs/133Cs) in old and new leaves of C. japonica collected from a forest on Mount Tsukuba between 9 and 15months after the accident. Both isotopes were also analyzed in throughfall, bulk precipitation and soil extracts. Water of atmospheric and soil origin were used as proxies for deciphering the absorption from leaf surfaces and root systems, respectively. Results indicate that 20–40% of foliar 137Cs existed inside the leaf, while 60–80% adhered to the leaf surface. The 137Cs/133Cs ratios inside leaves that had sprouted before the accident were considerably higher than that of the soil extract and lower than that of throughfall and bulk precipitation. Additionally, more than 80% of 137Cs in throughfall and bulk precipitation was present in the dissolved form, which is available for foliar uptake, indicating that a portion of the 137Cs inside old leaves was presumably absorbed from the leaf surface. New leaves that sprouted after the accident had similar 137Cs/133Cs ratios to that of the old leaves, suggesting that internal 137Cs was translocated from old to new leaves. For 17 species of woody plants other than C. japonica, new leaves that sprouted after the accident also contained 137Cs, and their 137Cs/133Cs ratios were equal to or higher than that of the soil extract. These results suggested that foliar uptake and further translocation of 137Cs is an important vector of contamination in various tree species during or just after radioactive fallout.