Daiichi Nuclear Power Plant Accident Research Articles

Thirty-year simulation of environmental fate of 137Cs in the Abukuma River basin considering the characteristics of 137Cs behavior in land uses

The Fukushima Daiichi Nuclear Power Plant accident caused a radioactive contamination of deposited radionuclides, including 137Cs, on the land surface. Cesium-137 deposited on the land surface was strongly adsorbed on soil particles and was then washed off through soil erosion. Trends of temporal variation of 137Cs wash-off varied greatly depending on land use. Therefore, it is important to reflect the characteristics of 137Cs migration processes in each land use to clarify the long-term fate of 137Cs. In this study, a 30-year simulation of environmental fate of 137Cs was conducted using a distributed radiocesium prediction model, taking into account the characteristics of the 137Cs behavior in each land use. Overall, in the Abukuma River basin, the 137Cs transported into the ocean for 30 years was estimated to correspond to 4.6 % of the initial deposition in the basin, and the effective half-life of 137Cs deposited in the basin was estimated to be 3.7 years shorter (by 11.6 %) than its physical half-life. These results suggested that 137Cs deposited from the accident could still remain for decades. Based on the analysis of the 137Cs behavior in land use, in 2011, the contribution of 137Cs export to the ocean from urban lands was estimated to correspond to 70 % of the total 137Cs export. Meanwhile, from 2012 to 2040, the contribution of 137Cs export from agricultural lands was estimated to correspond to 75 % of the total 137Cs export. The reduction ratios excluding radioactive decay of 137Cs remained in areas with and without human activities for 30 years after the accident, defined as the ratios of the total outflow to the initial deposition, were estimated to be 11.5 %–17.7 % and 0.4 %–1.4 %, respectively. These results suggested that human activities enhance the reduction of 137Cs remaining in land in the past and future.

Relationship between radiation knowledge and radiation effect anxiety on the next generation: An analysis of a questionnaire survey disseminated to residents in Fukushima Prefecture

Objectives Since the Fukushima Daiichi Nuclear Power Plant accident caused by the Great East Japan Earthquake, many people in Fukushima Prefecture have been concerned about the effects of radiation on their offspring. Although this fear should be relieved since no epidemiological study has shown evidential cases, situations wherein some people misunderstood the existence of evidence have been independently reported. Therefore, in this study, we examined the relationship between radiation knowledge and anxiety about radiation-based genetic effects using a survey mailed to residents in Fukushima Prefecture.Methods In August 2016, we attempted to contact 2,000 people aged 20 to 79 years in Fukushima Prefecture through a survey distributed by mail inquiring about residents' health. We received 861 responses. Respondents selected their level of concern about radiation effects on the next generation on a four-point scale and answered five knowledge questions about radiation effects and protection. Responses were "correct," "incorrect," or "not sure." After adjusting according to residential area, family configuration, age, sex, academic background, media used, and trusted information source, we conducted multiple regression analyses to investigate the relationship between the level of concern and answers to the knowledge questions.Results People who answered the knowledge questions more correctly had lower levels of anxiety. The number of "not sure" responses was unrelated to anxiety level. The results indicated that correct answers to questions related to radiation residuals in the body and genetic effects were negatively associated with anxiety. Incorrect answers to the question about genetic effects and another related to cell repair systems were positively associated with anxiety. Moreover, while a correct answer to another question related to the linear threshold model had a positive association, the association was insignificant. Further, any response related to radiation reference values in foods showed no association.Conclusion Based on these results, we observed an association between the number of respondents with a correct knowledge of radiation and the degree of anxiety about radiation effects on the next generation. However, this relationship and its strength varied depending on the specific knowledge content. As a limitation of this study, the study could not establish any causality. Further studies, such as prospective interventional studies, should be conducted.

Impact of the Fukushima Accident on 3H and 14C Environmental Levels: A Review of Ten Years of Investigation

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

Comparison of quality of life between elderly and non-elderly adult residents in Okuma town, Japan, in a post-disaster setting.

With the growing elderly population who are susceptible to poor health, improvement of their quality of life is essential. In the post-disaster setting of the 2011 Fukushima Dai-ichi nuclear power plant (FDNPP) accident, affected municipalities such as Okuma town commenced their recovery processes and lifted evacuation orders in 2019. This study examines the differences in self-reported mental and physical health status, social functioning, risk perception, and intention to return between elderly (age ≥65 years) and non-elderly (age 20-64 years) residents. Questionnaires were distributed to current residents and evacuees of Okuma. Results revealed that the elderly had a 1.4 times higher odds ratio (95%CI 1.0-1.8, p = 0.034) for having anxiety regarding radiation-related health effects on future generations and a 1.3 times higher odds ratio (95%CI 1.1-1.5, p = 0.001) for wanting to know about the release of FDNPP-treated water into the environment than the younger group. Elderly residents also demonstrated a 2.2 times higher odds ratio for reporting poor physical health than younger residents. Clearing misconceptions and disseminating coherent information will reduce risk perception among this group. Further in-depth research regarding the disposal of FDNPP-treated water and its perceived risks is required. Health promotion through the encouragement of social participation, improvement of surroundings to facilitate healthy behaviors, and enhanced access to health services will improve the quality of life of elderly Okuma residents.

Model behavior regarding in- and below-cloud 137Cs wet scavenging following the Fukushima accident using 1-km-resolution meteorological field data

Wet deposition remains an important source of uncertainty in modeling of the atmospheric transport of 137Cs following the Fukushima Daiichi Nuclear Power Plant accident. Its behavior is often difficult to investigate owing to the limited resolution of meteorological field data and inconsistent model implementations. This study investigated the detailed behavior of 25 combinations of in- and below-cloud wet scavenging models using high-resolution (1 km × 1 km) meteorological input. These combinations were all implemented in the Weather Research and Forecasting-Chemistry model, thereby enabling consistent evaluation. The 1-km-resolution simulations were compared with simulations obtained previously using 3-km-resolution meteorological field data. Results revealed that rainfall of <1 mm/h is critical for simulation accuracy. The 1-km results revealed better representation of rainfall than that revealed by the 3-km results, but with spatiotemporal variability in accuracy. Owing to their sensitivity to rainfall, single-parameter wet deposition models showed improvements in performance in the 1-km simulations relative to that in the 3-km simulations. The multiparameter models showed more robust performance in terms of both simulations, and the Roselle–Mircea model presented the best performance among the 25 models considered. Wind transport showed substantial influence on the removal of atmospheric 137Cs, and it was nonnegligible even during periods in which wet deposition was dominant. The 1-km-resolution simulations effectively reproduced local-scale 137Cs concentrations but with deviations in timing, mainly because of biased wind direction. These findings indicate the necessity for a refined wind and dispersion model for local-scale simulation of 137Cs concentration.

Potassium buffering characteristics and detection of soils with challenges in evaluating radiocesium uptake risk of crops by exchangeable potassium

ABSTRACT In surrounding areas influenced by the Fukushima Dai-ichi Nuclear Power Plant accident, the radiocesium uptake by crops was evaluated based on soil exchangeable K. As risk evaluation does not function effectively in several fields, K buffering was characterized using quantity/intensity (Q/I) relationship analysis to evaluate the availability of exchangeable K. The results of the analysis clearly explain the difficulty in the risk evaluation: i) difficulty in increasing exchangeable K, owing to retention as non-exchangeable K by vermiculite; ii) difficulty in retaining exchangeable K due to low K buffering capacity, reflecting the lack of K-selective clay minerals; and iii) difficulty in increasing soil solution K intensity due to high K buffering capacity, reflecting the abundance of K-selective clay minerals. Among the parameters calculated from the Q/I relationship analysis, β values, corresponding to the retention rate of loaded K to the soil, for total K (βt), exchangeable K (βe), and non-exchangeable K (βn) would be useful as simple indicators of soils with a predicament in the risk evaluation of radiocesium uptake by crops through exchangeable K. These soils showed distinctively low βt values (0.18 or lower), high βe value (0.37 or higher), or high βn/βt ratio (0.53 or higher).

Subsurface dispersion path and travel time of radiocesium from Fukushima by Mode Water

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March 11, 2011 resulted in the release of immense amounts of radioactive materials into the ocean. However, the dispersion of radioactive materials in the subsurface has not yet been clarified due to the spatiotemporal limitation of observations. Thus, herein, a tracer experiment was implemented using a three-dimensional numerical model to estimate the dispersion path of 137Cs released directly from the FDNPP and its travel time in the subsurface of the North Pacific Ocean from 2011 to 2020. The results show that the subsurface 137Cs spreads by two mode waters, namely, Sub-Tropical Mode Water (STMW) and Central Mode Water (CMW). Subsurface 137Cs primarily spreads clockwise in the sub-tropical region, while a portion driven by STMW is dispersed southward. The clockwise dispersion path of 137Cs released into the ocean by STMW is relatively shallower and inward than that by CMW. The 137Cs that was spread clockwise reached the east of Taiwan and the Philippines via STMW and CMW nine years after the accident, respectively. The model described in this study is applicable for estimating the water path and travel time of tritium water planned to be discharged from Fukushima.

Importance of continuing health care before emergency hospital evacuation: a fatal case of a hospitalized patient in a hospital within 5 km radius of Fukushima Daiichi Nuclear Power Plant: a case report

BackgroundAfter a disaster, it is essential to maintain the health care supply levels to minimize the health impact on vulnerable populations. During the 2011 Fukushima Daiichi Nuclear Power Plant accident, hospitals within a 20 km radius were forced to make an immediate evacuation, causing a wide range of short- and long-term health problems. However, there is limited information on how the disaster disrupted the continuity of health care for hospitalized patients in the acute phase of the disaster.Case presentationAn 86-year-old Japanese man who needed central venous nutrition, oxygen administration, care to prevent pressure ulcers, skin and suctioning care of the trachea, and full assistance in the basic activities of daily living had been admitted to a hospital within 5 km radius of Fukushima Daiichi Nuclear Power Plant and experienced Fukushima Daiichi Nuclear Power Plant accident. After the accident, the hospital faced a manpower shortage associated with hospital evacuation, environmental changes caused by infrastructure and medical supply disruptions, and the difficulty of evacuating seriously ill patients. As a result, antibiotics and suction care for aspiration pneumonia could not be appropriately provided to the patient due to lack of caregivers and infrastructure shortages. The patient died before his evacuation was initiated, in the process of hospital evacuation.ConclusionsThis case illustrates that decline in health care supply levels to hospitalized patients before evacuation during the acute phase of a radiation-released disaster may lead to patient fatalities. It is important to maintain the health care supply level even in such situations as the radiation-released disaster; otherwise, patients may experience negative health effects.

Flexible Ion Adsorption Electrodes Using Natural Zeolite and Rice Husk Charcoal for FEM-EK Treatment

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

The development of a long-term predictive model of the changes in debris properties during interaction with aqueous solutions. Thermodynamic–kinetic modeling

This article presents a long-term predictive model of the properties’ changes of the molten core–concrete interaction (MCCI) debris material formed during the Fukushima Daiichi nuclear power plant (NPP) accident based on the available experimental data. For the development of the model, samples of MCCI debris were synthesized to represent the composition of the actual Fukushima debris. The samples' composition simulated different stages of ablation of the concrete basement beneath the NPP unit, i.e., various “concrete–corium” ratios. MCCI simulated debris samples (monoliths and powders) were exposed to aqueous solutions under the following conditions:1) continuous contact with water, i.e., no renewal of aqueous solutions (batch leaching experiments);2) periodic renewal of aqueous solutions by fresh ones (conditions simulating an open system with a constant inflow of fresh portions of aqueous solution).Experiments were performed under various conditions (temperature, pH) in two types of aqueous solutions: deaerated deionized and aerated deionized water. During the experiments, aliquots were taken to measure the concentrations of dissolved components (Ca, Si, Al, U, Zr, Fe, Ni, and Cr) in the aqueous solution.MCCI debris “aging” experiments were interpreted using kinetic curves and their relationship with physicochemical conditions (temperature, pH, type of aqueous solution). In this interpretation, the chemical processes of the MCCI debris components in water phase (dissolution and precipitation) were considered.The model was extended to 50 years and used to interpret debris aging experiments: (1) prediction of components’ releases into the aqueous phase caused by dissolution of solid phases, and (2) prediction of dusty secondary phase formation at the “debris–aqueous solution” interface.

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.

Message from the Winner

I would like to express my sincere gratitude for the MURAKAMI Suminao Award for Disaster Research 2022 and the JDR Award for the Most Contributory Reviewer 2022. It has been a great pleasure to serve on the editorial board for many years, and I have had the opportunity to talk with distinguished members of the editorial board who specialize in natural disasters such as earthquakes, volcanoes, and floods, which are completely outside my field of expertise, biology and medicine, and who have greatly broadened my perspective. The saying goes that disasters come just when you forget about them, but we have been in a situation recently where disasters come before we forget about them. There have been so many disasters: the panic that began with the discovery of cattle infected with bovine spongiform encephalopathy in Japan in 2001, the simultaneous terrorist attacks in the U.S. and the U.S. military invasion of Afghanistan around the same time, the poisoning of frozen dumplings made in China in 2007, the Tohoku Earthquake and Fukushima Daiichi Nuclear Power Plant accident in 2011, the COVID-19 problem that has continued from 2019 to the present, the invasion of Ukraine by Russia in 2022 and the resulting energy crisis and food shortages, as well as earthquakes, torrential rains, landslides, and typhoons that have occurred every year. The purpose of JDR, I believe, would be to stimulate research on these disasters, thereby providing a basis for the development of technologies for disaster prevention and control. In this regard, I have been concerned about the distance between science and technology: in the case of COVID-19, research on the causative virus, combined with messenger RNA vaccine technology, led to the fastest vaccine ever developed. On the other hand, the development of a cure has been slow, and the only treatment for pneumonia has been the old-fashioned one. Recently, antiviral drugs have been developed, but their efficacy has yet to be determined. There are many reasons for the distance between science and technology, and I hope that the research results published in JDR will play a role in reducing that distance.

Impact evaluation of typhoons and remediation works on spatiotemporal evolution of air dose rate in two riverside parks in Fukushima, Japan after the Dai-ichi nuclear power plant accident

This study elucidated the impacts of typhoon events and remediation works on the spatiotemporal evolution of the air dose rate in riverside areas frequented by residents. Spatial distribution of the air dose rate and radiocesium concentration in the sediments were measured in two riverside parks located near each other in Fukushima Prefecture, Japan, for 2015–2020. The air dose rates measured by walk surveys were interpolated using ordinary kriging to generate air dose rate maps, to facilitate a comparison between the results at different points in time during the measurement campaigns. After the typhoons that occurred during 2015–2018, the air dose rate near the riverside in one park decreased, but not in the other, because the erosion and sediment deposition patterns differed between them. This could be due to the presence of a dam upstream, which serves a flood mitigation function. However, the extreme event of typhoon Hagibis in 2019 dropped the air dose rates near the riversides in both parks. In contrast to the typhoon events which affected the riverside areas, remediation works such as decontamination undertaken during 2015–2019 reduced the air dose rates around the garden and lawn areas which are frequently used as recreational sites. Modeling the temporal evolutions in the air dose rates for the entire area of the riverside parks revealed that 35% of the reduction was caused by physical decay of radiocesium on average, 14% by vertical migration of radiocesium in the soil through precipitation, and 51% by the three typhoons and remediation works during 2015–2019. The contribution of 20% from the strongest typhoon Hagibis highlights the fact that floods resulting from large typhoons are effective in causing natural attenuation of air dose rates in riverside parks.

Comparison between external and internal doses to the thyroid after the Fukushima Daiichi Nuclear Power Plant accident.

To analyze the association between radiation dose and thyroid cancer after the 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, external doses have often been used because of the difficulty to estimate internal thyroid doses individually due to the lack of human data. However, no evaluation has been made as to whether external dose is a good surrogate marker for internal thyroid dose individually. This study aimed at analyzing the relationship between external doses and internal thyroid doses estimated by recently developed methodology. For four municipalities affected by the accident, 200 individuals aged under 20 at the time of the accident per municipality were randomly selected, and their external and internal thyroid doses and their ratios were estimated individually. In a separate analysis, median and arithmetic mean values for external thyroid doses estimated for persons of 16 municipalities that included the above four were compared with those for previously estimated internal thyroid doses. The ratios of the median of internal thyroid dose to that of external thyroid dose in these 16 municipalities ranged from 0.56 to 13.8 for 15-year-old children and 0.91 to 21.1 for 1-year-old children. No consistent relationship between external and internal thyroid doses was found in all 16 municipalities. Thus, thyroid doses from both external and internal exposures should be used to analyze the association between radiation dose and thyroid cancer detection rates for persons who lived in Fukushima Prefecture at the time of the FDNPP accident. (240).

Potassium applications reduced cesium uptake and altered strontium translocation in soybean plants

ABSTRACT After the Tokyo Electric Power Company’s Fukushima Dai-ichi Nuclear Power Plant accident in 2011, radioactive cesium (RCs) was released in greater concentrations than radioactive strontium (RSr) in the surrounding environment. Most of the countermeasures were developed to mitigate the RCs transfer from the soil to plants. However, to avoid what has happened after the Chernobyl and Mayak accidents, preventing the transfer of RSr from soil to plants should be a priority. Although the application of potassium (K) fertilizers is the most effective method for preventing agricultural crops from absorbing RCs in contaminated fields, this implementation increases the cost and labor requirements. Considering the preparedness for nuclear accidents, it remains unclear how this countermeasure will be affected if RCs and RSr are released simultaneously. We aimed to explore the effect of K applications on cesium (Cs) and strontium (Sr) uptake and their interaction with and correlation to other elements in the soybean plants and soil. The field experiments were conducted in Fukushima Prefecture, Japan, using different K applications (i.e., no, normal, and high K applications). The dry weight and mineral concentrations of K, Cs, Sr, calcium (Ca), magnesium (Mg), and nitrogen (N) concentration in plants and exchangeable K (ExK), exchangeable Cs (ExCs), exchangeable Sr (ExSr), exchangeable Ca (ExCa), exchangeable Mg (ExMg), NH4+ (ammonium), and NO3- (nitrate) concentrations in the soils were evaluated. This study revealed that K application reduced Cs, Ca, and Mg uptake but did not affect the ExSr, ExCa, and ExMg concentrations in the soil and did not change the uptake of Sr. On the other hand, K concentration of the plant especially at later growth stage, which indicates re-translocation of Sr was negatively regulated by K concentration.

No evidence of thyroid consequences in seven nuclear workers at the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Plant accident: 10-year follow-up results of thyroid status.

Seven emergency nuclear workers, who had internal exposure due to an intake of radionuclides, mainly I-131, during the emergency response operation in March 2011, after the accident at the Tokyo Electric Power Company (TEPCO) Fukushima Daiichi Nuclear Power Plant (FDNPP), visited the National Institute of Radiological Sciences (NIRS) outpatient clinic for medical evaluation. They were followed up after their first visit for 10 years. The estimated committed equivalent doses to the thyroid were distributed between 3.2 to 1.2 × 10Sv. This group thought to be received highest exposure at the accident. None of the workers had symptoms related to abnormal thyroid function. The examinations, including thyroid function tests and ultrasound, detected no abnormalities related to radiation exposure. However, there is a need for continuous monitoring of their thyroid status for longer periods in the future.

Relationship between haematological data and radiation doses of TEPCO workers before and after the FDNNP accident.

We evaluated the correlation between radiation dose and the medical examination data of Tokyo Electric Power Company Holdings, Inc (TEPCO) employees working during the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011. This study included 2164 male TEPCO workers who received periodic medical examinations from March 2006 to January 2013. First, we conducted log-linear regression analyses using the haematological data of 585 emergency workers and confounding factors to examine the effect of internal radiation exposure in March 2011. Since external radiation exposure was a major influence, we then evaluated the correlation between both internal and external radiation dose and the haematological data of 1801 emergency workers and confounding factors before and after the accident. Among 585 workers, internal radiation exposure in March 2011 alone was mainly due to thyroid doses (0.1-10Gy) but not to bone marrow (BM) doses (0.01-1mGy). Compared to before and after the accident, we found that the levels of monocytes, eosinophils (Eos) and basophils increased slightly, whereas the frequency of smoking and alcohol consumption decreased substantially. External dose exposure was positively correlated with haemoglobin (Hb), red blood cell and Eos but negatively correlated with age, haematocrit and frequency of alcohol consumption. Among these variables, Hb exhibited the strongest correlation with external dose. Regarding the correlation with Hb, although there is a possibility that confounding factors other than exposure were not evaluated, our findings on emergency workers can serve as a reference for the evaluation of health conditions during the emergency period of future nuclear-related accidents.

Evaluation of indoor air dose rate based on Cs‐137 depth distribution in surrounding artificially paved surfaces surveyed 10 years after the Fukushima Daiichi nuclear power plant accident

AbstractUnderstanding residual radioactive contamination state and the resulting radiation environment is vital before reconstructing the lives of residents in areas affected by nuclear power plant accidents. In this study, we surveyed the depth profiles of Cs‐137 in three artificially paved ground surfaces: impermeable asphalt, permeable asphalt, and concrete, in areas affected by the Fukushima Daiichi Nuclear Power Plant accident after a period of 10 years and analyzed the gamma‐ray air dose rate distribution in a two‐story wooden house model surrounded by different ground surfaces using the Particle and Heavy Ion Transport code System of the Japan Atomic Energy Agency. The air dose rate distribution tendencies within the building for different surrounding ground surfaces were clarified by analyzing the transport of gamma rays emitted from the Cs‐137 in the ground. Moreover, the shielding effect of an ordinal concrete fence on the indoor air dose rate was analyzed. The analysis showed that the indoor air dose rate was higher in an environment with artificial pavement than in that with a soil surface, and even a simple measure, such as installing an ordinal concrete fence, could significantly reduce indoor radiation dose rates.

Influence of post-disaster evacuation on childhood obesity and liver dysfunction: The Fukushima Health Management Survey.

After the Great East Japan Earthquake and subsequent Fukushima Daiichi Nuclear Power Plant accident in 2011, the Fukushima Prefectural Government launched a long-term health management survey for the population of Fukushima. Results of the Comprehensive Health Check (CHC) showed that some children aged 6-15 years, who resided in the evacuation area at the time of the disaster, had obesity, hyperlipidemia, liver dysfunction, and/or renal dysfunction from as early as 2011. The aim of the present study was to determine the long-term trend of obesity and hepatic enzyme abnormalities in Fukushima children. We evaluated the changes in body mass index standard deviation score (BMI-SDS), aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transpeptidase from 2011 to 2018. Obesity (BMI-SDS ≥ 2) was significantly associated with hepatobiliary enzyme abnormalities. The mean BMI-SDS was significantly higher in 2011 after the disaster, but then soon showed a gradual decrease. The frequency of obesity did not increase significantly after the disaster. There were no significant differences in the prevalence of hepatobiliary enzyme abnormalities in the children aged 6-15 years of either sex from 2011 to 2018. In the present study, we found that the increase in the mean BMI-SDS after the disaster was temporary, suggesting that the frequency of obesity and liver dysfunction might not have been significantly influenced by the disaster.

Nurse Administrators’ Roles for Nurse Retention when Radioactive Disaster occurs: Findings from Nurses’ Evacuation Consideration and Evacuation after the Fukushima Daiichi Nuclear Power Plant accident

Background: In 2011, a nuclear accident severely affected many hospitals in Fukushima. Many nurses faced adilemma of whether to evacuate voluntarily or keep working. This study examined the voluntary evacuation andreturning of nurses and then suggested how nurse administrators can prepare for such situations.Methods: The study was conducted from July through September 2018. Eight hundred nurses who had beenworking prior to the incident in three hospitals in Koriyama and Aizuwakamatsu participated. Although bothcities had higher-than-normal terrestrial radiation levels, Koriyama’s level was three times higher. An anonymousquestionnaire was administered, and individual interviews were conducted with participants. For statisticalanalyses, SPSS Statistics for Windows, version 25.0, was used.Results: Ultimately, 723 questionnaires were collected. The proportions of those who considered evacuating (33.1%)and who evacuated (8.1%) were significantly higher in Koriyama. The characteristics of the group who consideredevacuation were being pregnant, living with an adult cohabitant, and/or living with small child (ren). The evacuatednurses were all female and had similar characteristics as the group that considered evacuating; however, the age oftheir children was not related. Four out of six interviewees contacted nurse administrators and/or colleagues andovercame their feelings of guilt when their superiors and colleagues welcomed them back to work.Conclusion: Nurse administrators should understand that, when a radioactive disaster occurs, individuals whoare more likely to consider evacuation have conflicts between their personal life and professional responsibilities.Nursing departments should inform nurses of their policies in advance and respect individuals’ decision to leave,supporting them when they return to work. Departments should also have a plan in place for managing with atemporarily reduced workforce.