Fukushima Nuclear Power Plant Accident Research Articles

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.
 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).
 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.
 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.

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 < 0.01), hometown loss (OR = 1.58, p < 0.05), feeling difficulty living (OR = 3.84, p < 0.01) and social isolation (OR = 1.74, p < 0.01). For hometown loss, significant factors were lost houses (n = 596, p < 0.01), friends (n = 590, p < 0.05), life (n = 421, p < 0.01), family relationships (n = 377, p < 0.01), community (n = 403, p < 0.01) and futures (n = 310, p < 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.

Development of a Floating Radiation Measurement System for Underwater Readings in the East Sea of Korea

Joung, S.; Ji, Y.-y., and Choi, Y., 2023. Development of a floating radiation measurement system for underwater readings in the East Sea of Korea. Journal of Coastal Research, 39(2), 384–393. Charlotte (North Carolina), ISSN 0749-0208. Following the Fukushima nuclear power plant accident and subsequent discharge of contaminated water, the need for marine radioactivity monitoring has emerged. Currently, various underwater radiation monitoring systems are being developed and utilized for monitoring radioactive contamination of seawater. In this study, a floating on-site radiation monitoring system that can measure the radiation energy spectrum of a water environment in the field in real time was designed and fabricated with the aim to reduce the effect of background radiation on the system, which is a problem for land-based measurement technology. This study performed computational simulations to derive the ambient dose rate conversion factor and efficiency of the developed floating on-site radioactivity analysis system, named MARK-U3. The system was tested in the laboratory and in the field in both freshwater and saltwater environments. From the experimental results, the MARK-U3 can perform precise radioactivity analysis without the need for a thick shield, and by strengthening mobility, it can operate continuously.

To Deal with Fukushima Nuclear Power Plant Accident

Fukushima nuclear power plant once got impact from an earthquake, and it was disabled by a tsunami following. The chain reaction stopped but the remaining products of the chain reaction still release tremendous energy continuously, and the cooling system doesn’t work. Continuous seawater was injected into the reaction cores to cool down the cores, but radioactive seawater after being used to cool down the cores accumulated. At last, Japan made the decision to eject the nuclear wastewater into the sea, but this would threaten people’s health which is same important as life. The stability of a nucleus should be determined by the number of the neutrons and protons it contained, when the total number of nucleons inside the nucleus was under a limitation, the nucleus could be stable when the N/Z (ratio of the number of neutrons over the number of protons) approaches a value about 1, this value will be larger as the Z grows because the stronger electromagnetic forces will make more β+ decay of protons which produce neutron and is in a dynamic equilibrium with β- decay of neutrons which produce proton; therefore, to make up some α particles into the chain reaction products remained in the reaction cores may convert the remained radioactive nuclei therein to be stable ones, and the fusion of α particles with the radioactive nuclei in the reaction cores of which the elemental numbers are all heavier than iron can also absorb the energy that may be released in the processes, applying thin α particles beam could ensure the α particles only to merge with the radioactive nuclei in the reaction cores but never each other.

In Utero Exposure to Radiation Fear and Birth Outcomes: Evidence from the Fukushima Nuclear Power Plant Accident

In Utero Exposure to Radiation Fear and Birth Outcomes: Evidence from the Fukushima Nuclear Power Plant Accident

Worry about Radiation and Its Risk Factors Five to Ten Years after the Fukushima Nuclear Power Plant Disaster.

Worry about radiation persists long after nuclear power plant accidents. Young age, low socioeconomic status, being married, and disaster-related experiences are known to be associated with greater worry about radiation. This study explored the duration of the effects of these risk factors on worry about radiation after the 2011 Fukushima nuclear power plant accident, using the longitudinal data of randomly sampled non-evacuee community residents who were followed five to ten years after the accident. Questionnaire surveys were conducted five times with 1825 respondents (37.2% of the 4900 initial targets). We examined the interaction of time and risk factors of worry about radiation using a mixed model. Fear or anxiety immediately after the accident had effects on worry about radiation that continued even after 10 years, though it slightly attenuated with time. Family problems stemming from the disaster retained their effects. While direct damage and evacuation experience were significantly associated with worry about radiation in the early phase, their effects diminished and became non-significant during the study period. Being under the age of 65, having low educational attainment, and being married were significantly associated with worry about radiation, although the association with age weakened over time. Individuals who experience intense fear or anxiety post-nuclear power plant accidents or disaster-related family problems may need continuous monitoring for their worry about radiation even 10 years after such accidents.

Trends in Lifestyle-related Diseases and Their Risk Factors After the Fukushima Daiichi Nuclear Power Plant Accident: Results of the Comprehensive Health Check in the Fukushima Health Management Survey.

Residents were forced to evacuate owing to the radiation released after the Fukushima Nuclear Power Plant (NPP) accident following the Great East Japan Earthquake on 11/03/2021; thus, their lifestyles drastically changed. The Comprehensive Health Check (CHC) of the Fukushima Health Management Survey (FHMS) was performed to evaluate health statuses and prevent lifestyle-related diseases in evacuation area residents. The first part of the CHC survey is a retrospective analysis of pre- and post-disaster data on health check-ups of evacuation area residents. The second part is a cross-sectional, prospective analysis of post-disaster (fiscal year (FY) 2011-2017) data on health check-ups. Subjects were men and women living in 13 municipalities in areas surrounding the NPP in Fukushima Prefecture. Post-disaster (FY 2011-2012) overweight, hypertension, dyslipidemia, diabetes mellitus, metabolic syndrome, liver dysfunction, hyperuricemia, polycythemia and atrial fibrillation cases increased from the pre-disaster (FY 2008-2010) levels. This tendency was strongest among residents who were forced to evacuate. Proportion of overweight people remained unchanged, the prevalence of liver dysfunction decreased and the proportion of people with treated hypertension and dyslipidemia increased during FY 2011-2017. Meanwhile, the prevalence of diabetes mellitus and mean levels of HbA1c increased. Furthermore, Evacuees showed higher risks of diabetes mellitus, dyslipidemia, chronic kidney diseases and liver dysfunction than non-evacuees. Therefore, residents in the evacuation area, especially evacuees, are at high risk of developing lifestyle-related diseases, especially cardiovascular diseases; therefore, it is necessary to observe health statuses and implement measures to prevent lifestyle-related diseases.