Fukushima Nuclear Power Plant Accident Research Articles

Non-returning factors from an interview survey of 16 residents of Katsurao village 12years after the Fukushima nuclear power plant accident.

People generally wish to return home after being evacuated due to disaster situations. Evacuation orders have now been lifted in the Fukushima region following the nuclear accident in 2011, and the Japanese government is promoting a return policy. However, many residents who wish to return home remain unable to and continue living in evacuation sites or other areas. Sixteen residents of Katsurao village were interviewed after evacuation orders were lifted in 2016 who have not yet returned. Concerns were cited regarding radiation, prolonged evacuation, health problems, buying a house in the evacuation area and schooling. The problems identified were primarily due to the rapid ageing and decline of the regional population, reflecting similar issues throughout Japan. In particular, health problems and intention to return were thought to be closely related. Over 10 y have passed since the evacuation, and many residents have experienced familial separation and divided living situations.

Prevalence, incidence, and recovery of metabolic syndrome after the fukushima nuclear power plant disaster: A 10-year longitudinal study

After the 2011 Fukushima nuclear power plant accident, the prevalence of metabolic syndrome sharply increased in municipalities near the nuclear power plant, where a massive evacuation of community residents occurred (the evacuation area). However, after the initial increase, the rate of increase in metabolic syndrome in the evacuation area was slower than that in the surrounding area (non-evacuation area). In this study, we compared the incidence of and recovery from metabolic syndrome as well as its prevalence between evacuation and non-evacuation areas during the 10 years after the accident to explore whether the slower increase in metabolic syndrome after the initial increase in the evacuation area stemmed from suppressed incidence or from fast recovery. We analyzed specific health check-up data of community residents aged 40–74 in Fukushima Prefecture from fiscal year (FY) 2012 to FY 2021 (N = 710,201). To explore the prevalence of metabolic syndrome, we examined the associations of time, residential area, and their interaction with metabolic syndrome using mixed-model repeated measures. We used data from those without metabolic syndrome in FY 2012 to investigate the incidence. We similarly examined the associations of time, residential area, and their interaction with metabolic syndrome using FY 2013 to FY 2021 data. To explore recovery, we used the data of those with metabolic syndrome in FY 2012 and repeated the same procedure. The rate of increase in the prevalence and incidence of metabolic syndrome was slower in the evacuation area than in the non-evacuation area. On the other hand, as for the recovery, the time trend of metabolic syndrome did not differ between the two areas. The slower increase in metabolic syndrome in the evacuation area was partly explained by the slower incidence in the evacuation area but not by recovery.

Radiation-Induced Childhood Thyroid Cancer after the Fukushima Daiichi Nuclear Power Plant Accident.

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

Impact of the Great East Japan Earthquake followed by the nuclear power plant accident on the nursing students’ academic progress in Soma, Fukushima, Japan: a retrospective cohort study with questionnaire survey

BackgroundThe Great East Japan Earthquake and the subsequent Fukushima nuclear power plant accident in 2011 posed significant challenges to the educational sector, particularly affecting nursing students in the disaster area. However, to the best of our knowledge, there are no reports on the effects of the natural disaster coupled with the nuclear accident on the nursing students. Therefore, this study aimed to determine the impact of the Fukushima disasters on rate of academic failure events in nursing education.MethodsA retrospective cohort approach was conducted, focusing on 677 students from Soma Nursing School admitted between 2001 and 2017. Four failure events—failure to pass the national examination, student retention, suspension, and withdrawal from school—were compared between three time periods: pre-disaster, early peri-disaster, and later peri-disaster. This analysis was followed by a questionnaire survey among the students and an interview with faculty members to gain further insights.ResultsOf the student cohort, 17% had at least one failure event. Students in the later peri-disaster phase faced an elevated failure rate at 29%. Variables such as being male, admission during later peri-disaster period, and local pre-admission residence played a significant role in these failure events in multivariate logistic regression analysis (adjusted odds ratio [95% confidence interval, p value]; 2.63 [1.49–4.64, < 0.001], 3.207 [2.00–5.15, < 0.001], and 1.84 [1.12–3.02, 0.02], respectively).ConclusionsThis study highlights the impact of the Great East Japan Earthquake and the following nuclear accident on nursing education. The elevated failure rates in the later peri-disaster period emphasize the challenges posed by continuing disaster phases. Thus, there is a need for intensified and tailored strategies in nursing education in disaster-affected regions.

Social networks and posttraumatic stress symptoms five to ten years after the Fukushima nuclear power plant disaster

Since the 2011 Fukushima nuclear power plant accident, multiple social network disruptions have been reported among the community in Fukushima, while posttraumatic stress symptoms among the residents have persisted. In this study, we aimed to explore the influence of time and social networks on the recovery of posttraumatic stress symptoms based on longitudinal data from community residents in Fukushima, following up five to ten years after the nuclear power plant accident. We conducted five questionnaire surveys quasi-annually, the targets of which were randomly sampled 4900 non-evacuee community residents. In this study, the data of 1809 respondents who participated in at least one survey were used (36.9% of the initial target). Setting posttraumatic stress symptoms as the outcome, we examined the interaction between time and social network size using a mixed model, adjusting for sociodemographic characteristics and disaster-related events. Their interaction was statistically significant, and the posttraumatic stress symptoms of those with small social networks persisted, while those with larger social networks recovered. Maintaining and promoting social networks may contribute to mental health recovery after a nuclear disaster.

Basic Performance Evaluation of a Radiation Survey Meter That Uses a Plastic-Scintillation Sensor.

After the Fukushima nuclear power plant accident in 2011, many types of survey meters were used, including Geiger-Müller (GM) survey meters, which have long been used to measure β-rays. Recently, however, a novel radiation survey meter that uses a plastic-scintillation sensor has been developed. Although manufacturers' catalog data are available for these survey meters, there have been no user reports on performance. In addition, the performance of commercial plastic-scintillation survey meters has not been evaluated. In this study, we experimentally compared the performance of a plastic-scintillation survey meter with that of a GM survey meter. The results show that the two instruments performed very similarly in most respects. The GM survey meter exhibited count losses when the radiation count rate was high, whereas the plastic-scintillation survey meter remained accurate under such circumstances, with almost no count loss at high radiation rates. For measurements at background rates (i.e., low counting rates), the counting rates of the plastic-scintillation and GM survey meters were similar. Therefore, an advantage of plastic-scintillation survey meters is that they are less affected by count loss than GM survey meters. We conclude that the plastic-scintillation survey meter is a useful β-ray measuring/monitoring instrument.

Ultrastructural Analysis of Large Japanese Field Mouse (Apodemus speciosus) Testes Exposed to Low-Dose-Rate (LDR) Radiation after the Fukushima Nuclear Power Plant Accident.

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

지리 교과에서 안전교육 내용 구성을 위한 방사능에 대한 위험 인식 분석

Objectives This study aims to provide basic data for the construction of safety education contents in geography subject by examining university students' risk perception of radioactivity with an optimism bias through a real case of the Fukushima nuclear power plant accident in Japan.&#x0D; Methods To this end, a questionnaire composed of questions asking about risk perception of radioactivity and optimism bias in risk perception of radioactivity was distributed and collected to 134 university students in Seoul, South Korea. A one-way ANOVA was conducted to see the difference in risk perception of radioactivity according to the type of visit to Japan (visit to Tokyo, non-visit to Japan, visit to Japan). In addition, factor analysis and multiple regression analysis were performed to identify the optimism bias in the risk perception of radioactivity, and then the difference in optimism bias according to the type of visit to Japan was analyzed through MANOVA (Multivariate Analysis of Variance).&#x0D; Results The terms of risk perception of radioactivity, the degree of perception that Tokyo is safe from radiation was significantly higher in the Tokyo visiting group than in the other two groups. As a result of factor analysis to identify optimism bias, three factors (optimistic perception, avoidance perception, and wait-and-see perception) were derived, and as a result of multiple regression analysis, it was found that optimistic perception and avoidance perception had a positive effect on optimism bias in order. As a result of MANOVA, the Tokyo visiting group showed significantly higher perceptions of both optimistic and avoidance compared to the other two groups.&#x0D; Conclusions Optimism bias and its sub-factors, optimistic perception and avoidance perception, were identified in the risk perception of radioactivity. Because optimism bias makes it difficult to make logical judgments and rational decision-making in risk situations, meta-cognition for optimism bias in relation to risk perception should be considered when constructing safety education contents in geography subject.&#x0D;

Prolonged impact of the Fukushima Nuclear Power Plant Accident on health and society

Prolonged impact of the Fukushima Nuclear Power Plant Accident on health and society Naomi Ito, Research Assistant at the Fukushima Medical University, tells us how the 2011 Fukushima Daiichi Nuclear Power Plant Accident impacted and continues to impact local residents. The health effects on local residents following a nuclear power plant accident are diverse, not only because of radiation exposure but also because of changes in lifestyle and social environment. It has also been indicated that various environmental changes that could emerge during the restoration process may affect residents in various ways over a long time. On March 11, 2011, the Great East Japan Earthquake struck Japan with a magnitude of 9.0. Within an hour, a tsunami hit the shore. Three reactors at the Fukushima Daiichi Nuclear Power Plant (FDNPP, operated by Tokyo Electric Power Company) lost power. The reactors could not be cooled, and core meltdowns occurred, which resulted in an explosion due to hydrogen being generated at high temperatures. As a result, radioactive materials were released and scattered northwest from the power plant.

Five years after the Earthquake and nuclear accident: Loss and its psychological effect

Abstract Background On March 11, 2011, the Great East Japan Earthquake hit Tohoku. The Fukushima nuclear power plant accident forced many people to relocate, leaving their hometowns. This study focused on the sense of loss and its psychological effect on the people of Fukushima five years after the earthquake and nuclear accident. Methods Quantitative and qualitative analysis from a questionnaire survey including the IES-R scale and open-ended questions. Results 1021 people participated in this study. At the time of the survey, 490 people relocated within Fukushima prefecture and 531 people left. During the nuclear accident, 632 participants were close to the nuclear power plant; 407 participants reported actual nuclear accident experiences such as exposure to blast ashes, seeing the explosion, hearing explosive sounds and escaping. People lost family members (n = 112) and homes (n = 338) due to the tsunami and earthquake; 439 lost jobs after the earthquake and 410 had economic difficulties; 736 reported their sadness over losing hometowns; 391 people showed IES-R scores over 25, suggesting potential PTSD (Post Traumatic Syndrome). From a multivariate analysis, psychological distress was significantly affected by nuclear accident experience (OR = 1.43, p = 0.04), lost jobs (n = 1.57, p = 0.01), economic difficulty (OR = 1.68, p &amp;lt; 0.01), hometown loss (OR = 1.58, p &amp;lt; 0.05), feeling difficulty living (OR = 3.84, p &amp;lt; 0.01) and social isolation (OR = 1.74, p &amp;lt; 0.01). For hometown loss, significant factors were lost houses (n = 596, p &amp;lt; 0.01), friends (n = 590, p &amp;lt; 0.05), life (n = 421, p &amp;lt; 0.01), family relationships (n = 377, p &amp;lt; 0.01), community (n = 403, p &amp;lt; 0.01) and futures (n = 310, p &amp;lt; 0.01). From qualitative analysis,”I relocated with the children, leaving behind my husband which I regret (a mother with children)” and others. Discussion and conclusions After natural disasters, nuclear accidents and wars, people suddenly lose their special monitoring and support are necessary for affected people. Key messages • Many people still suffer from PTSD after the Nuclear Power Plant accident after 5 years. • Many people suffer from a variety of loss such as loss of hometown, friends, family and others due to migration from Fukushima.

No increase in translocated chromosomal aberrations, an indicator of ionizing radiation exposure, in childhood thyroid cancer in Fukushima Prefecture

To investigate the effects of radiation exposure due to the Fukushima nuclear power plant accident, following the disaster Fukushima Prefecture launched thyroid ultrasound examinations of residents who were generally younger than 18 years at the time of the earthquake. As the rate of pediatric thyroid cancer was higher than expected, we conducted biological dose assessment based on the frequency of translocated chromosome (Tr) aberrations using peripheral blood lymphocytes. Tr formation frequency was compared among the thyroid cancer (n = 38, median age 18 years, age range 12–26 years), thyroid-related disease (n = 30, median age 21 years, age range 15–28 years), and healthy controls (n = 31, median age 22 years, age range 20–23 years) groups. Tr aberration frequency was initially significantly higher in the thyroid cancer than in the other two groups; however, differences among the groups disappeared after adjusting for history of CT scan, as 92%, 67%, and 28% of those in the thyroid cancer, thyroid-related disease, and control groups, respectively, had undergone CT previously. Therefore, the significant difference in the initial number of Tr formations is presumably due to radiation exposure from CT. Accordingly, the effects of medical exposure on the chromosomes of children and adolescents should be noted.

Development of reference material for quality control of uranium analysis in marine sediments

Environmental radioactivity monitoring is strengthening due to public concerns over radioactive contamination since the Fukushima nuclear power plant accident. Therefore, various research laboratories, institutes, and universities have been conducting environmental radioactivity surveys around nuclear power plants (NPPs). However, the reliability of the results continues to trigger controversy in society. This study was conducted to develop reference material (RM) for the quality control of 238U and 234U analyses in marine sediments. The RM was prepared according to ISO Guides 31, 34, and 35. A homogeneity test of the marine sediment RM was implemented by analyzing two batch samples from ten bottles using multiple acid digestion and alkali fusion, respectively. We found that the 238U and 234U reference values of the RM were 43.0 ± 1.7 Bq kg−1(k=1) and 41.5 ± 1.9 Bq kg−1(k=1), respectively. This marine sediment RM will be useful for the quality control of analytical methods for similar samples and proficiency tests.

Internal organ dose rate conversion coefficients of Japanese macaques to 134Cs,137Cs and 131I†.

The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two species. For γ-radiation, there was excellent agreement in the self-absorption rate with the approximate curve of the Japanese macaque, with an average deviation of 2%. The maximum deviation of 12% was for the kidney, which has two organs, so the error with the approximate curve is slightly larger due to the energy loss created between organs.

Analysis of purification in radioactively contaminated ocean water near the Fukushima nuclear accident site

AbstractThe nuclear‐contaminated water in the seawater near the site of the Fukushima nuclear power plant (NPP) accident is being investigated for treating the radioactive material. One of the most important considerations in the treatment is the management of the vast aquatic area of the oceanic scale. There are two methods in the application of osmosis and filtration for the modeling. There is the molecule quantity by the water volume where the list of transition of quantities is shown, where it decreases to 10% from the reversed osmosis method and to 0.01% from the filtration method in 9 days. In the filtrations, the discharge variations in the sea are described as the maximum and minimum values within 100 square velocities. A design for the general radioactive contaminated seawater treatment facility is introduced.

Radiation doses to non-human species after the Fukushima accident and comparison with ICRP’s DCRLs: A systematic qualitative review

This study reviewed publications on radiation dose estimations for non-human species after the 2011 Fukushima nuclear power plant accident and discussed the accident’s potential effects on the environment. Articles published from 2011 to December 2022 in online database were manually searched, and 27 eligible articles were identified. The estimated doses were summarized according to reference animals and plants and derived consideration reference levels (DCRLs) from ICRP Publication 108. Most estimated dose rates were on or below DCRL bands, but several greatly exceeded the DCRLs, mainly immediately after the accident. Half of the articles focused on dose estimation, but 13 also contained assessments of radiation effects. Effects such as chromosomal aberrations, morphological abnormalities, and population decline, were observed and the observed effects corresponding to estimated dose rates were implied in agreement with DCRL. Although a broader integration of knowledge is needed to obtain more robust data on environmental effects and improve environmental protection systems, our review contributes to refining the objectives of the environmental radiological protection approach.

Effects of disaster-related traumatic events on worry about radiation and COVID-19: A decade after the Fukushima nuclear power plant accident

Community residents exposed to nuclear power plant (NPP) accidents have long-term worry about the effects of radiation. After the 2011 Fukushima NPP accident, those who experienced traumatic events during the Great East Japan Earthquake (GEJE) tended to have greater worry about radiation. Along with the prolonged worry about radiation, there may also be cognitive changes caused by the traumatic events. We hypothesized that if there were cognitive changes underlying the prolonged worry about radiation, those who experienced the traumatic events would tend to have greater worry about other issues unrelated to radiation. We examined the effects of the traumatic events during the GEJE on community residents’ worry about radiation and COVID-19 a decade after the Fukushima NPP accident. Using the data of a longitudinal questionnaire survey following a random sample of 4900 community residents outside the evacuation zone in Fukushima, this study analyzed 774 responses (15.8%). The traumatic events consisted of (1) injury, (2) injury or death of a family member, and (3) the loss of a house or other property. We developed a mediation model drawing paths from the traumatic events to worry about radiation and COVID-19, including posttraumatic stress symptoms (PTSS) as a mediator, using structural equation modeling. The traumatic events directly affected worry about radiation. Although it did not directly affect worry about COVID-19, it did so indirectly through worry about radiation and PTSS. Traumatic events can increase trauma-related worry independently of PTSS and increase trauma-unrelated worry indirectly through trauma-related worry and PTSS.

Current status and issues of Local Vitalization Cooperators in 12 municipalities affected by Fukushima nuclear power plant accident

本研究の目的は、原子力被災12市町村における地域おこし協力隊の現状と課題を明らかにすることである。我々は、原子力被災12市町村とそこで活動する地域おこし協力隊を対象としたアンケート調査を行った。その結果を基に原子力被災12市町村は生活環境を改善すること、学びの機会を地域おこし協力隊へ提供すること、起業・継業と住宅に関する支援をすることが必要であることを指摘した。

A study on the actual situation and issues of agricultural corporations in 12 municipalities affected by Fukushima nuclear power plant accident

本研究は、原子力被災12市町村における農業法人の実態と今後の課題を明らかにすることを目的とするものである。原子力被災12市町村の農業法人と自治体を対象にして実施したアンケート調査の結果によると、原子力被災12市町村の多くの農業法人と自治体は、特に人材や人員の確保・育成を課題であると認識している。以上のことを踏まえ、農業法人は正社員・正職員を通年雇用することができる環境づくりを進める必要があること、経営状況の改善をする必要があること、自治体は地域おこし協力隊の制度の活用を検討する必要があることを指摘した。

Development of a Passive Reactor Shutdown Device to Prevent Core Disruptive Accidents in Fast Reactors: A Preliminary Study

AbstractFollowing the Fukushima Nuclear Power Plant accident in 2011, it has become increasingly important for reactor safety designs to consider measures that can prevent the occurrence of severe accidents. This report proposes a novel subassembly-type passive reactor shutdown device that expands the diversity and robustness of core disruptive accident (CDA) prevention strategies for sodium-cooled fast reactors. The developed device contains pins with a fuel material that is in the solid state during normal operation but melts into a liquid when the temperature exceeds a certain value (i.e., during a potential accident). When an unprotected loss of flow (ULOF) or unprotected transient overpower (UTOP) accident occurs, the device can passively provide significant negative reactivity by rapidly transferring liquefied device fuel into the lower plenum region of the pins via gravitation alone. The reactors containing some of the proposed devices in place of original fuel subassemblies become subcritical before the driver fuels are damaged, even if ULOF or UTOP transient events occur. The present study evaluates candidate materials for device fuels (e.g., metallic alloy, chloride), optimal device pin structures for liquefied fuel relocation, and nuclear and thermal-hydraulic characteristics of the device-loaded core under accident conditions to demonstrate the engineering applicability of the proposed device. This report discusses preliminary results regarding the nuclear requirements for inducing negative reactivity to achieve reactor shutdown under the expected device conditions during an accident.

Deprivation of Furusato: The damage faced by evacuees after the Fukushima nuclear power plant accident

AbstractThis paper considers the damage caused by the Great East Japan Earthquake and the meaning of the Fukushima Nuclear Power Plant accident, and reflects on the evacuees' experiences over past 12 years. During this time, several lawsuits demanding the clarification of responsibility for the accident and compensation for damages have been filed against TEPCO (Tokyo Electric Power Company) and the Japanese Government. The “loss and transformation of hometowns (furusato in Japanese)” has become one of the key issues in these lawsuits. While the casees were being litigated, the mandated “evacuation designated zones” were gradually lifted. Even in the “Difficult‐to‐Return Areas” where annual integrated doses of radioactive substances are over 50 mSv and evacuation orders are still in effect, efforts are being made to lift the evacuation orders. Because they were forced to leave their places of residence, evacuees have claimed, “we lost oue furusato [hometown].” However, because they are able to return after evacuation orders are lifted, both TEPCO and the Japanese Government have insisted that “their furusato has not been lost” and “they cannot claim compensation for furusato damages.” In this paper, I call the irreversible and absolute damage caused by the nuclear power plant accident “the deprivation of furusato.” I look at furusato from three aspects: the relationship between people and nature, the connection between people, and notions of persistence and sustainability. Then, I discuss what kind of reconstruction is being promoted to respond to the deprivation of furusato and for whom.