Assessment of radiation in fishes derived from radiocesium in the port of Fukushima Daiichi nuclear power plant.

This study established specialized radiation dose models to evaluate the internal radiation doses derived from 137Cs and 134Cs in fishes in the port of the Fukushima Daiichi Nuclear Power Plant from 2012 to 2023. By August 2018, the activities of 134Cs and 137Cs in fishes decreased at the T1/2 of 176 d and 191 d, respectively. The corresponding mass concentrations were far lower than 1 mg/kg and the chemical toxicity can be negligible. Regarding radiotoxicity, 18,000 Bq/kgfresh weight of 134Cs and 137Cs in grouper Sebastes schlegelii produced 276 µGy/h of radiation dose, which was below the no-effect-dose-rate benchmarks (400 µGy/h). 740,000 Bq/kgfresh weight of 134Cs and 137Cs in greenling Hexagrammos otakii produced 12,600 µGy/h of radiation dose, which was much higher than 400 µGy/h, indicating the possibility of radiation effects. If a person eats these two reported fishes, the resulting committed effective doses for humans are 7.7 µSv and 6.31 mSv, respectively.

Radiological safety assessment for transportation of reactor pressure vessel during decommissioning of a nuclear power plant in Korea.

In Korea, decommissioning of nuclear power plants and transportation of the decommissioning waste are expected to expand in the near future. It is necessary to confirm that radiological risks to the public and workers are not significant through radiological safety assessment. The objective of this study is to assess the radiological safety for transportation of RPV waste, which is a major decommissioning waste with relatively high level of radioactivity. It was assumed that the waste would be transported to the Gyeongju disposal facility by land transportation. First, the source term and transportation method of the RPV waste were determined, and the external dose rates from the waste were calculated using MCNP. Then, transportation scenarios were assumed under both normal and accident conditions. Under the scenarios, radiation doses were calculated using the RADTRAN. Under normal operation scenarios without a transportation accident, assuming 40 shipments per year, the average individual doses for the public ranged from 6.56×10-6to 2.18×10-2mSv yr-1. The maximum individual doses for only a single shipment ranged from 2.43×10-6to 3.14×10-1mSv. For cargo handlers and vehicle crew members, the average doses were 2.26×101mSv yr-1and 2.95 mSv yr-1, respectively. Under transportation accident scenarios, average individual radiological risks which are product of the radiation doses and the annual accident rates ranged from 1.14×10-11to 1.61×10-10mSv yr-1by transportation route segment when considering the transportation accident rate. Average individual doses assuming transportation accident occurrence ranged from 2.62×10-4to 1.42×10-3mSv. The maximum individual dose under accident conditions was 7.99×10-2mSv. The calculated doses were below the regulatory limits in Korea. However, relatively high doses were observed for cargo handlers and vehicle crew members because of conservative assumptions. This study results can be used as basic data for the radiological safety assessment for the decommissioning waste transportation in the future.

Low-Cost Sensor Deployment on a Public Minibus in Fukushima Prefecture.

This study analyzed radiation dose data to observe the annual decline in ambient radiation doses and assess the factors contributing to fluctuations in reconstructed areas of the Fukushima prefecture. Utilizing a novel mobile monitoring system installed on a community minibus, the study employed a cost-effective sensor, namely, Pocket Geiger which was integrated with a microcontroller and telecommunication system for data transfer, access, visualization, and accumulation. The study area included the region between Okuma and Tomioka towns. The ambient dose rate recorded along the minibus route was depicted on a map, averaged within a 1 × 1 km mesh created with the Quantum Geographic Information System. To ensure accuracy, the shielding factor of the minibus material is determined to adjust the dose readings. A significant decrease (p < 0.001) in the radiation dose ranges from 2022 to 2023 was observed. The land use classification by the Advanced Land Observation Satellite revealed an ecological half-life ranging from 2.41 years to 1 year, suggesting a rapid radiation decay across all land types. This underscores the close connection between radiation attenuation and environmental factors, as well as decontamination efforts across diverse land categories.

Conceptualization of the comprehensive phyto-radiotoxicity incurred by radiocesium and strategies to expunge the metal using biotechnological and phytoremediative approaches.

Agricultural pollution with 137Cs is an ecological threat due to its sustained half-life and radioactivity. Release of radiocesium isotopes after major nuclear power plant accidents like the Fukushima Dai-ichi and the Chernobyl nuclear power plant disasters have severely affected the surrounding growth of agricultural crops and vegetables cultivated across extensive areas. Even years after the nuclear accidents, biosafety in these agricultural fields is still questionable. Due to similarity in charge and ionic radius between radiocesium and K+, the radionuclides are promiscuously uptaken via K+ channels expressed in plants. Bioaccumulation of radiocesium reportedly promotes physiological and anatomical anomalies in crops due to radiation and also affects the rhizospheric architecture. Due to radiation hazard, the ecological balance and quality are compromised and ingestion of such contaminated food results in irreversible health hazards. Recently, strategies like exogenous supplementation of K+ or genetic engineering of K+ channels were able to reduce radiocesium bioaccumulation in plants taking the advantage of competition between radiocesium and K+ translocation. Furthermore, bioremediation strategies like phycoremediation, mycoremediation, phytoremediation and rhizofiltration have also showed promising results for removing radiocesium from polluted sites. It has been proposed that these eco-friendly ways can be adopted to de-pollute the contaminated sites prior to subsequent cultivation of crops and vegetables. Hence it is essential to: 1) understand the basic radiotoxic effects of radiocesium on agricultural crops and surrounding vegetation and, 2) design sustainable ameliorative strategies to promote radiocesium tolerance for ensuring food and social security of the affected population.

Development of a dose estimation system for external exposure assessment at the late phase for individuals living in areas affected by the Fukushima nuclear accident.

Although the elevated ambient dose equivalent (ADE) rates in areas radiologically affected by the 2011 Fukushima nuclear plant accident decreased as time passed, the assessment of Fukushima residents' external dose is still important. A dose estimation system for external exposure assessment at the late phase for individuals living in Fukushima Prefecture was developed for this purpose. The developed system enables the estimations of external doses over the future based on an individual behavioral pattern and ADE-rate distributions from aerial monitoring data and its predicted ADE rate. To validate the system, the estimated results were compared with the measured readings of personal dosemeters. The results indicate that the developed system properly reproduced the individual external doses of subjects living in areas where the outdoor ADE rates exceeded 0.2 µSv h-1.

Radiation risk assessment of coastal biota from a quasi-Fukushima hypothetical accident in the Mediterranean Sea.

The occurrence of the February 6, 2023, earthquake in Turkey was the idea of this research to define a Fukushima-like accident scenario in the Akkuyu nuclear reactor and investigate its radiation effects on the coastal organisms of the Mediterranean Sea. The concentration rate (CR), activity concentration in organisms, internal dose, external dose, and total dose rate were estimated using the ERICA Tool from 137Cs, 134Cs and 131I radionuclides. The minimum and maximum radiocesium CR were calculated at 0.063 Bq kg-1 fresh weight (f.w)/Bq kg-1 soil and 4.042 Bq kg-1 (f.w)/Bq kg-1 soil dry weight (d.w). Where this value for 131I ranged from 0.005 to 0.295 Bq kg-1 (f.w)/Bq kg-1 soil. For mammals-large and arthropods, we calculated the significant internal and external dose rates. All of the estimated dose rates were higher than the ICRP's derived consideration reference levels (10 µGy h-1).

Impact of Lifestyle and Psychosocial Factors on the Incidence of Hepatobiliary Enzyme Abnormalities After the Great East Japan Earthquake: Seven-Year Follow-up of the Fukushima Health Management Survey.

OBJECTIVE: Residents who lived near the Fukushima Power Plant accident were forced to change their lifestyle after the 2011 accident. This study aimed to elucidate the association of resident lifestyle and psychological factors with onset of hepatobiliary enzyme abnormalities (HEA) after the accident. METHODS: This longitudinal study included 15705 residents who underwent a comprehensive health check, as well as a mental health and lifestyle survey between June 2011 and March 2012. Follow-up surveys were conducted between June, 2012 and March 2018. Risk factors for new HEA onset were evaluated using the Cox proportional hazards model, moreover, population attributable risks for new HEA onset were calculated. RESULTS: HEA developed in 29.7% of subjects. In addition to metabolic factors such as overweight, hyperglycemia, and hyperlipidemia; there were differences in alcohol intake, evacuation, unemployment, educational background, and psychological distress between subjects with and without HEA onset. After we adjusted for potential confounding factors, an association of being overweight, hypertension, and dyslipidemia, as well as alcohol consumption, evacuation, and psychological distress with increased risk of HEA onset was realized. Among these identified risk factors, evacuation accounted for the greatest share. CONCLUSIONS: Metabolic characteristics and disaster-related lifestyle aspects, including mental status, were risk factors for HAE onset after the Fukushima Power Plant accident.

Bioaccumulation and risk assessment of radiocesium in the Northwest Pacific Ocean from Fukushima Dai-ichi Nuclear Power Plant accident.

To understand which biota are more exposed to radionuclides, the bioaccumulation and risk assessment of radiocesium (137Cs and 134Cs) release from FDNPP in the Northwest Pacific Ocean were analyzed using ERICA tools. The activity level was determined by the Japanese Nuclear Regulatory Authority (RNA) in 2013. The data were used as input to the ERICA Tool modeling software to evaluate the accumulation and dose of marine organisms. The highest and lowest accumulate concentration rate were observed in birds (4.78E+02 Bq kg-1/Bq L-1) and the Vascular plant (1.04E+01 Bq kg-1/Bq L-1), respectively. The total dose rate range for the 137Cs and 134Cs ranged between 7.39E-04 and 2.65E+00 µGy h-1 and 4.24E-05 and 2.91E-01 µGy h-1, respectively. There is no considerable risk to the marine biota in the research region since the cumulative dose rates of radiocesium to the chosen species were all less than 10 µGy h-1.

The Predicament and Outlet of Environmental Impact Assessment Mechanism from the Perspective of Risk Society: Taking Japan's Accident-Type Nuclear Sewage Disposal as a Cut-In.

As an important yardstick of social modernization, nuclear technology not only promotes the in-depth development of the national economy but also hangs a sword of Damocles in the field of the risk society. Against the background of the unrest of the nuclear leakage disaster at the Fukushima nuclear power plant, the Japanese government has announced its unilateral decision to discharge nuclear sewage into the sea, undoubtedly putting at least the Pacific Rim countries at huge potential risks. In order to maximize risk reduction and focus on preventive construction in advance, Japan's measures to discharge accident nuclear sewage into the sea have a legitimate basis for the application of an environmental impact assessment system. At the same time, in the process of operation, there are numerous risk dilemmas, such as lack of safety treatment standards, long follow-up disposal cycle and negative domestic supervision system, which need to be broken through one by one. The effective application of the environmental impact assessment system in the Japanese nuclear accident not only helps to reduce the environmental crisis caused by accidental nuclear effluent discharge to the sea but also has a positive and far-reaching international demonstration significance, which helps to better build a foundation of international trust and preventive guarantee system in advance for the possible accidental nuclear effluent treatment in the future.

Assessment of Radiation Risk Perception and Interest in Tritiated Water among Returnees to and Evacuees from Tomioka Town within 20 km of the Fukushima Daiichi Nuclear Power Plant.

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.

External exposure assessment in the Fukushima accident area for governmental policy planning in Japan; Part 2. Matters to be attended for assessments of external exposure.

After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, individual exposure doses to residents have been assessed by many municipalities, governments and research institutes. Various methods including measurements with personal dosimeters and simulations have been used for this evaluation depending on purposes, but the information of assessments and methods has not been systematically organized. A comprehensive review of the knowledge and experiences of individual exposure doses assessments accumulated so far and understanding the characteristics of the assessment methods will be very useful for radiation protection and risk communication, following to governmental policy planning. We reviewed the efforts made by the Japanese government and research institutes to assess radiation doses to residents after the FDNPS accident in Part 1. On the other hand, each method of assessing individual exposure doses includes uncertainties and points to be considered for the appropriate assessment. These knowledge and experiences are important for the assessment implementation and applying the assessment results to the governmental policy planning, and are summarized in Part 2 of this article.

External exposure assessment in the Fukushima accident area for governmental policy planning in Japan: part 1. Methodologies for personal dosimetry applied after the accident.

The evacuation order areas established due to the accident at the Tokyo Electric Power Company Holdings' (TEPCO) Fukushima Daiichi Nuclear Power Plant (FDNPP) have been reorganized according to the decrease in ambient dose rates and the decontamination progress. The Japanese government decided to decontaminate the difficult-to-return areas and lift the evacuation order by 2030. This radiation protection strategy can be optimized by examining emergency exposure situations to date and the existing exposure after the accident. This article reviews the methods that can determine the individual radiation doses of residents who should return to their homes when the evacuation order is lifted in the specific reconstruction reproduction base area and the difficult-to-return areas outside this base area and summarizes the points to be considered when implementing these methods. In Part 1 of this article, we review the efforts made by the Japanese government and research institutes to assess radiation doses to residents after the FDNPP accident.

External Doses Available for Epidemiological Studies Related to the Fukushima Health Management Survey: First 4-month Individual Doses and Municipality-average Doses for the First Year.

BACKGROUND: One of the components of the Fukushima Health Management Survey (FHMS) is the Basic Survey, which estimates individual external doses for the first 4 months after the 2011 nuclear power plant accident. However, external exposure continues long-term. According to estimations by international organizations, the external dose during the first year accounts for a significant part of the long-term dose. Thus, the present study was intended to estimate the first-year doses by extrapolating the Basic Survey results. METHODS: For most municipalities of non-evacuated areas, ambient dose rate had been continuously measured for at least one designated point in each municipality after the accident. In the present study, a municipality-average dose received by residents for a period was assumed to be proportional to the ambient dose measured at the designated point of that municipality during the same period. Based on this assumption, 4-month municipality-average doses calculated from the Basic Survey results were extrapolated to obtain first-year doses. RESULTS: The extrapolated first-year doses for 49 municipalities in the non-evacuated areas had a good correlation with those estimated by UNSCEAR, although the extrapolated doses were generally higher (slope of the regression line: 1.23). The extrapolated municipality-average doses were in reasonable agreement (within 30%) with personal dosimeter measurements, suggesting that the extrapolation was reasonable. CONCLUSION: The present paper reports the first 4-month average doses for all 59 municipalities of Fukushima Prefecture and the extrapolated first-year doses for 49 municipalities. The extrapolated doses will be the basis for future epidemiological studies related to the FHMS.

InterDosi Monte Carlo study of radiation exposure of a reference crab phantom due to radioactive wastewater deposited in marine environment following the Fukushima nuclear accident.

S-values are typically used to quantify internal doses of biota internally due to the incorporation of radionuclides. In this study, the InterDosi 1.0 Monte Carlo code was used to estimate S-values in five main organs of a crab phantom as well as in surrounding seawater for eleven radionuclides, namely 3H, 14C, 134Cs, 137Cs, 60Co, 125Sb, 90Sr, 129I, 99Tc, 106Ru, and 238Pu. After the Fukushima accident, these radionuclides have been detected in wastewater by the Japan Nuclear Regulatory Authority. In this work, S-values were calculated for all crab organs and the surrounding seawater. These values can be used in conjunction with any measured activities in water, to determine internal doses absorbed by crab organs. Furthermore, it is shown that for a self-absorption condition the studied radionuclides can be classified into five main categories, with 238Pu showing the highest S-values for any organ. Moreover, the results demonstrate that the obtained S-values decrease with increasing organ mass. In contrast, for a cross-absorption condition, the studied organs can be classified into seven main categories. In addition, by taking seawater as a source of irradiation, 238Pu had the highest cross-absorption S-values in two organs of particular biological relevance, the heart and gonads, when compared to the remaining radionuclides. It is concluded that due to the pre-calculated S-value database of a reference crab, it will become easier to use this organism as a bio indicator to study any radiation-induced effects on the marine environment.

Demonstrating the undermining of science and health policy after the Fukushima nuclear accident by applying the Toolkit for detecting misused epidemiological methods.

It is well known that science can be misused to hinder the resolution (i.e., the elimination and/or control) of a health problem. To recognize distorted and misapplied epidemiological science, a 33-item "Toolkit for detecting misused epidemiological methods" (hereinafter, the Toolkit) was published in 2021. Applying the Toolkit, we critically evaluated a review paper entitled, "Lessons learned from Chernobyl and Fukushima on thyroid cancer screening and recommendations in the case of a future nuclear accident" in Environment International in 2021, published by the SHAMISEN (Nuclear Emergency Situations - Improvement of Medical and Health Surveillance) international expert consortium. The article highlighted the claim that overdiagnosis of childhood thyroid cancers greatly increased the number of cases detected in ultrasound thyroid screening following the 2011 Fukushima nuclear accident. However, the reasons cited in the SHAMISEN review paper for overdiagnosis in mass screening lacked important information about the high incidence of thyroid cancers after the accident. The SHAMISEN review paper ignored published studies of screening results in unexposed areas, and included an invalid comparison of screenings among children with screenings among adults. The review omitted the actual state of screening in Fukushima after the nuclear accident, in which only nodules > 5 mm in diameter were examined. The growth rate of thyroid cancers was not slow, as emphasized in the SHAMISEN review paper; evidence shows that cancers detected in second-round screening grew to more than 5 mm in diameter over a 2-year period. The SHAMISEN consortium used an unfounded overdiagnosis hypothesis and misguided evidence to refute that the excess incidence of thyroid cancer was attributable to the nuclear accident, despite the findings of ongoing ultrasound screening for thyroid cancer in Fukushima and around Chernobyl. By our evaluation, the SHAMISEN review paper includes 20 of the 33 items in the Toolkit that demonstrate the misuse of epidemiology. The International Agency for Research on Cancer meeting in 2017 and its publication cited in the SHAMISEN review paper includes 12 of the 33 items in the Toolkit. Finally, we recommend a few enhancements to the Toolkit to increase its utility.

Returning Home after Decontamination? Applying the Protective Action Decision Model to a Nuclear Accident Scenario.

Studies of the aftermath of nuclear power plant accidents show that affected citizens assess higher risks and adopt more risk-avoidant behaviors than authorities expect. This results in differences between the planned recovery and actual outcomes. Based on this knowledge, this study examined the factors that affect citizens' preference to continue living in a decontaminated area. Testing the key aspects of the protective action decision model (PADM), this study analyzed Swedish survey data (N = 2291) regarding such an accident scenario. Several aspects of the PADM, from the layperson's view of threats and protective actions, to stakeholders and situational factors, were strongly supported. The most influential variables affecting settlement choices are perceptions of radiation risk, perceptions of decontamination effectiveness, government information, living with certain restrictions, and attachment to an area because of one's work. A novel contribution of this study is that it ranked the significance of such effects on behavioral intentions in an emergency scenario. Regarding the policy recommendations, this study concluded that a recovery program must facilitate most aspects of people's lives and provide trustworthy information on decontamination efficiency. As some people will avoid potential health risks and leave a decontaminated area, planning to implement one solution for everyone would likely not be optimal.

Assessment of doses in contaminated urban areas: modelling exercise based on Fukushima data.

State-of-the-art dose assessment models were applied to estimate doses to the population in urban areas contaminated by the Fukushima Daiichi Nuclear Power Plant accident. Assessment results were compared among five models, and comparisons of model predictions with actual measurements were also made. Assessments were performed using both probabilistic and deterministic approaches. Predicted dose distributions for indoor and outdoor workers from a probabilistic approach were in good agreement with the actual measurements. In addition, when the models were applied to assess the doses to the representative person, based on a concept recommended by the International Commission on Radiological Protection and in the International Atomic Energy Agency Safety Standards, it was evident that doses to the representative person obtained with a deterministic approach were always higher than those obtained with a probabilistic approach using the same model.

Assessment of localized and resuspended 137 Cs due to decontamination and demolition in the difficult-to-return zone of Tomioka town, Fukushima Prefecture.

As the next step that occurred more than one decade after the accident at the Fukushima Dai-ichi Nuclear Power Station (FDNPS), decontamination and demolition have been carried out in the Specified Reconstruction and Revitalization Base (SRRB) of the difficult-to-return zone around the FDNPS. However, the risk of internal exposure among workers due to airborne dust inhalation after building demolition operations has not been sufficiently evaluated. To evaluate the working environment and internal exposure risk due to inhalation in the SRRB of Tomioka town, Fukushima Prefecture, the cesium-137 (137 Cs) radioactivity levels in the airborne dust at building demolition sites were analyzed using gamma spectrometry. The 137 Cs radioactivity levels and resuspension factors of the airborne dust at the subject building sites in the difficult-to-return zone remained at high levels compared with those of the control, which was located in the evacuation order-lifted area in Tomioka town. However, the 137 Cs radioactivity levels did not increase significantly, despite demolition operations that used heavy machinery. In this case, no substantial increases in accident-derived 137 Cs levels due to decontamination and demolition in the SRRB of Tomioka town, Fukushima Prefecture, were observed in the airborne dust samples, which suggests that the 137 Cs radioactivity in the airborne dust is primarily associated with particles that are resuspended by localized winds accompanied by the transfer of construction vehicles as opposed to the decontamination and demolition operations. However, the internal exposure doses due to aspirating airborne dust containing 137 Cs were extremely low compared with the estimated annual effective doses of decontamination workers or the limits recommended by the Japanese government. Additionally, countermeasures such as wearing protective masks could help reduce the on-site inhalation of soil-derived radionuclides. Integr Environ Assess Manag 2022;18:1555-1563. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Long-term Follow-up of Affected Residents After Lifting Evacuation Orders in Fukushima Prefecture, Japan: Findings from an Interview-Based Psychological Survey.

We examined the relationship between social support and psychological variables, and investigated the status of social support among villagers whose evacuation order had been lifted. The survey used for the analysis is the data of FY 2018 and 2019. In fiscal year 2018, a written questionnaire was posted to 4828 registered residents of Iitate Village and 1405 valid responses were received. The main finding (in joint assessment by local and external experts) was the 'need for professional support' (191 respondents, 13.6%). Multivariate analysis found that among those living in permanent housing outside the village, the need for support was significantly more likely for those without emotional support, or instrumental support, and those not providing support. The 2019 follow-up showed a slight improvement in perceived social support (PSS). The associations between perceived social support and living environment suggest the need to strengthen social support measures in areas where evacuation orders are yet to be lifted, which will provide useful information with which to examine the effects of future support efforts.

A Global Collaboration for Community-Based Disaster Preparation and Health Promotion: Fukushima to Zuunbayan in Mongolia.

Excessive radiation exposure has adverse effects on health. In Fukushima, psychological issues such as anxiety are still affecting people nine years after the Fukushima nuclear power plant accident in 2011. In light of the lessons learned from Fukushima communities, a joint Japanese and Mongolian research team introduced a community program to the Zuunbayan district in Mongolia, which is located near a uranium deposit, to promote good health by strengthening radiation emergency preparedness. The program, which commenced in 2017, aimed to increase community participation, education, information dissemination, and capacity of community preparedness. After two years a monitoring study showed that, out of 227 respondents, the proportions who thought that any level of radiation was dangerous decreased from 53.3% in 2017 to 33.9% in 2019. Moreover, half of the respondents knew that there were safe and unsafe radiation levels and that their community was safe. This global collaboration demonstrated that a lesson learned from a disaster can be applied to other countries and changed people's recognition and behavior toward good health and disaster/emergency preparedness.