TEPCO Fukushima Daiichi Nuclear Power Research Articles

Rapid Environmental Mapping with Instrumented Unmanned Aerial Vehicle: Experience and Lessons Learned from the Commissioning and Trial Measurements in the Areas Affected by TEPCO Fukushima Daiichi Nuclear Power Plant Accident

Rapid Environmental Mapping with Instrumented Unmanned Aerial Vehicle: Experience and Lessons Learned from the Commissioning and Trial Measurements in the Areas Affected by TEPCO Fukushima Daiichi Nuclear Power Plant Accident

CHARACTERISATION OF RADIOACTIVE CAESIUM IN SEDIMENTS AT THE NOGAWA RIVER, JAPAN.

The TEPCO Fukushima Daiichi Nuclear Power Plant accident that occurred in March 2011 resulted in the release of radioactive caesium into the environment. The radioactive caesium has been detected in the Tama River watershed. Previous investigations have shown that the concentration of radioactive caesium in sediment was relatively high in the Nogawa River. In this study, the relationship between the concentration of radioactive caesium in the sediment and the sediment characteristics was investigated. We found that 137Cs concentration in the tributary sediment has difficulty migrating downstream, while exhibiting a strong correlation with the amount of organic matter and a correlation with the clay, silt layer. Based on the results, we inferred that 137Cs is deposited together with the organic matter and clay, silt layer in the sediment and migrates at a slower pace than that in the mainstem.

The reducing rate of radiocesium 137Cs in the North Pacific surface water after the TEPCO fukushima Dai-ichi nuclear power plant accident

The reducing rate of radiocesium 137Cs in the North Pacific surface water after the TEPCO fukushima Dai-ichi nuclear power plant accident

Revenue Management and Characteristics of Forest Owners’Cooperatives within TEPCO Fukushima Daiichi Nuclear Power Station Accident Evacuation Areas

Revenue Management and Characteristics of Forest Owners’Cooperatives within TEPCO Fukushima Daiichi Nuclear Power Station Accident Evacuation Areas

1. Current Status and Issues of Forestry Damage Caused by the TEPCO Fukushima Daiichi Nuclear Power Station Accident in Tamura City, Fukushima Prefecture (“Impact of Radioactive Contamination on Diverse Forest Uses and Local Communities”: Joint Symposium held by The Japanese Forest Economic Society, Japanese Association for Environmental Sociology, and The Society of Fukushima Forestry Research)

1. Current Status and Issues of Forestry Damage Caused by the TEPCO Fukushima Daiichi Nuclear Power Station Accident in Tamura City, Fukushima Prefecture (“Impact of Radioactive Contamination on Diverse Forest Uses and Local Communities”: Joint Symposium held by The Japanese Forest Economic Society, Japanese Association for Environmental Sociology, and The Society of Fukushima Forestry Research)

The relationship between information sources, media, and "anxiety about the effects of radiation on future generations" in Hamadori and Fukushima Prefecture's evacuation areas after the nuclear accident

Objectives Nine years after the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in March 2011, anxiety about the effects of radiation on future generations persists. We considered the possibility that information from mass media sources and the Internet might influence this anxiety. Thus, this study examined the relationship between information sources and anxiety; based on the results, we consider the necessary measures to reduce this anxiety.Methods We conducted a mail-based survey by distributing an anonymous self-administered questionnaire to 2,000 Fukushima Prefecture residents aged 20 to 79. We randomly selected 500 residents from Aizu, Nakadori, Hamadori, and the evacuation areas, and compared the data obtained from Hamadori and the evacuation areas. The objective variable was anxiety about the effects (of radiation) on future generations, while the explanatory variables were trusted sources and media the respondents used to get information on radiation. Other variables assessed included health status and knowledge of radiation. We conducted univariate analysis of combined data to assess the relationship between anxiety and the questionnaire items. This was followed by multiple regression analysis with anxiety as the objective variable and those showing significant differences in the univariate analysis as the explanatory ones. We then conducted multiple regression analysis, that included the interaction means between explanatory variables and evacuation areas.Results Of the 500, 201 respondents were from Hamadori (40.2%) and 192 from the evacuation areas (38.4%). Multiple regression analysis revealed that anxiety was significantly lower among those who trusted government ministries and those who were healthy. Anxiety was also significantly lower among those who correctly answered the question on the genetic influence of radiation, while it was significantly higher among those who correctly answered the question on the dose-response model of radiation-induced cancer. In Hamadori, anxiety was significantly higher among those who watched private national television. In the evacuation areas, the result was the same as that of the combined data.Conclusion Different information sources and media were significantly associated with anxiety about the effects of radiation on future generations. Therefore, media sensationalism should be reduced to prevent anxiety among citizens. Our findings highlight the importance of selecting information sources and media that disseminate accurate information, as well as the need to improve media literacy among citizens. Furthermore, a dose-response model of radiation-induced cancer must be communicated in a way that is not misleading. Receiving accurate information on the genetic effects of radiation can reduce anxiety among citizens.

東京電力福島第一原子力発電所事故以降に福島県及び周辺地域で採取された土壌試料の整備及びデータベースシステムの構築

東京電力福島第一原子力発電所事故以降に福島県及び周辺地域で採取された土壌試料の整備及びデータベースシステムの構築

Impact on Fisheries in Contaminated Water Discharged from Nuclear Power and Reprocessing Plants: The Cases of La Hague Reprocessing Plant, Sellafield Nuclear Fuel Reprocessing Plant, and TEPCO Fukushima Daiichi Nuclear Power Plant

This paper statistically analyzes residents’ understanding of problems related to radioactively contaminated water discharged from nuclear power and nuclear reprocessing plants. Moreover, this paper examines their impact on the surrounding fisheries by using the cases of La Hague, Sellafield, and Fukushima Daiichi Nuclear Power Plant. Survey data shows that more than 60% respondents disagree with the release of contaminated water, and this sentiment is particularly strong among both British and French respondents. Regarding seafood caught in the vicinity of the nuclear power and nuclear reprocessing plants, although British respondents noted that they hold it in high regard, many people do not purchase this seafood. In contrast, many Japanese respondents reported that they were less concerned, and thus, willingly purchase seafood caught off the coast of Fukushima Prefecture. In all three countries, many people did not trust government information on the release of contaminated water. Compensation to the affected people was provided by the central government, companies involved, and local governments, in that order. Japanese and British respondents reported higher expectation for compensation as compared to French respondents. Japanese and French respondents noted that they have knowledge of radioactive materials and contaminated water, and many of them purchased seafood caught in the vicinity of the nuclear power and reprocessing plants. British respondents were the most opposed to the release of contaminated water, whereas Japanese respondents were the least reliant on government information about the release of contaminated water. Finally, among those who trusted information from the government and retailers, French respondents were the least concerned about contamination. French respondents were also the least likely to expect any compensation for the fishermen affected by contamination. Both British and French residents around the affected plants expected the central government to compensate the affected fishermen, whereas those who did not reside around the affected plants did not expect the fishermen to be compensated. French respondents were more likely to expect compensation from the local governments; affluent respondents were more likely to expect the compensation to be funded by taxation, whereas less affluent respondents expected them to be funded by donations. Respondents who were more skeptical of government information wanted the companies involved to compensate the fishermen. British respondents reported a tendency for wanting the companies involved to provide this compensation, and did not support the concept of compensation provided through donations.

Effects of 137Cs contamination after the TEPCO Fukushima Dai-ichi Nuclear Power Station accident on food and habitat of wild boar in Fukushima Prefecture

After the Tokyo Electric Power Company Fukushima Dai-ichi Nuclear Power Station accident, wild boar was found to have greater radiocesium (137Cs) activity concentrations in their bodies than other wild animals in Japan; however, the reason for this remains unknown. To understand the mechanism of 137Cs transfer from the environment to wild boar, and the factors that affect variation in 137Cs contamination in wild boar, we sampled muscle and stomach contents from wild boar captured in Fukushima Prefecture and analyzed the relationships among 137Cs concentrations in muscle tissue and in the stomach contents, 137Cs ground deposition at capture sites, and wild boar food habits. Significant positive relationships were observed among 137Cs activity concentrations in muscle and stomach contents, as well as 137Cs deposition density at capture sites. These results suggest that 137Cs is transferred from the environment to plant and animal materials consumed by wild boar, and then from these foods to the bodies of wild boar through digestion. However, no correlation was observed between 137Cs concentrations in stomach contents and the presence of any particular food item in stomachs of wild boar, including mushrooms. These findings suggest mushrooms and underground food items, which were found to affect 137Cs concentrations in wild animals in Europe, were not important contributors to high levels of 137Cs contamination in Japanese wild animals.

Relationship between radiocaesium in muscle and physicochemical fractions of radiocaesium in the stomach of wild boar

After the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 2011, it became important to study radiation dynamics, assess internal radiation exposure and specify factors affecting radionuclide variation in wildlife. Therefore, it is necessary to investigate which physicochemical fractions of radiocaesium (137Cs) are absorbed from ingested material in species with high activity concentrations of 137Cs, such as wild boar. This study analysed the physicochemical fractions of 137Cs in the stomach contents of wild boar to evaluate the transfer from ingested food to muscle. The 137Cs activity concentration in muscle showed a significantly positive relationship with the 137Cs activity concentration in the exchangeable fraction, and the sum of the 137Cs activity concentrations in the exchangeable and bound to organic matter fractions. Seasonal variations were also found in the 137Cs activity concentration in the exchangeable fraction, and the sum of the 137Cs activity concentrations in the exchangeable and bound to organic matter fractions. These findings suggest that the proportions of the physicochemical fractions of 137Cs in the exchangeable and bound to organic matter fractions in the stomach contents are important factors affecting the increases and seasonal dynamics of the activity concentrations of 137Cs in wild boar muscle.

東京電力福島第一原子力発電所事故急性期：何が問題だったのか――看護師の立場から――

東京電力福島第一原子力発電所事故急性期：何が問題だったのか――看護師の立場から――

A 30-year record reveals re-equilibration rates of 137Cs in marine biota after the Fukushima Dai-ichi nuclear power plant accident: Concentration ratios in pre- and post-event conditions

Concentration ratios (CRs), expressed by dividing 137Cs activity in seawater by that in marine biota (mainly fish), were obtained from the monitoring of 137Cs in coastal areas around Japan between 1984 and 2016. Before the TEPCO Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident (1984–2010), mean CRs of 137Cs, mainly from global fallout (i.e. CRGF), were almost constant for each species throughout the monitoring period, but were different among species, while the values for several species were dependent on their length (i.e. CRGF-SIZE). Thus, CRGF and CRGF-SIZE values for 29 of marketable species are given here as references for conditions where marine biota are in approximate equilibrium (or steady state) with their host water with respect to 137Cs activities in the marine environment. After the FDNPP accident (2011–2016), the impact of the accident has been sustained in eastern Japan waters as indicated by apparent CRs (CRas) which are being used here as indicators of disequilibrium between organisms and their host water. The recession rates of this disequilibrium (the effective CRa half-lives) ranged from 100 to 1100 days. The identified distinct variation was due to the sample locations, even for the same species, because of the change in 137Cs activity concentrations in their host water and diet preference differences. Variation among species, even those captured from the same area, was mainly due to diet differences as well as metabolic-physiological differences in 137Cs retention. Thus, our results from >30 years of systematically monitoring have helped quantify the recession rates of post-FDNPP disequilibrium of 137Cs in biota for assessment of how long term is required from contaminated condition by underlying spatial, inter- and intra-species factors.

Radiocesium in the swash zones off the coast of the Japan Sea

Radiocesium concentrations were measured in seawater and sediment samples collected in the swash zones in Ishikawa and Niigata prefectures, off the coast of Japan Sea opposite to the side where TEPCO Fukushima dai-ichi Nuclear Power Plant (FDNPP) is located in September 2016 and August 2017, five to six years after the accident. Cs-134 in the seawater samples was detected, suggesting the intrusion of FDNPP-derived radiocesium in both swash zones. FDNPP-derived radiocesium was appeared to be transported by the Tsushima Warm Current. In the surface sediments only 137Cs was detected during the sampling period. We could not find out the presence of the FDNPP-derived radiocesium in the corresponding sediment on the swash zones; however, detected radiocesium in those sediments was assumed to be influenced by 137Cs of FDNPP-derived radiocesium little for Ishikawa area and some for Niigata area.

Reduction of water content in calcium aluminate cement with/out phosphate modification for alternative cementation technique

Cementation of the secondary aqueous wastes from TEPCO Fukushima Daiichi Nuclear Power Plant is challenging due to the significant strontium content and radioactivity, leading to a potential risk of hydrogen gas generation via radiolysis of water content. The present study investigates the reduction of water content in calcium aluminate cement (CAC) with/out phosphate modification by a heat-treatment during the solidification. The reduction of water in the CAC was found restricted by the rapid formation of crystalline hydration phases, whereas the phosphate-modified system allowed the gradual reduction of water, achieving the reduction of 60% water content at 95 °C. Curing at 60–95 °C also eliminated the significant cracks found at 35 °C in the phosphate system. The possible difference in the amorphous products, NaCaPO4∙nH2O type at 35 °C and Ca(HPO4)∙xH2O type at 60–95 °C, may have contributed to the improvement in the microstructure together with the change in the pore size distribution.

Spatial assessment of radiocaesium in the largest lagoon in Fukushima after the TEPCO Fukushima Dai-ichi Nuclear Power Station accident

Radionuclides deposited on land by global fallouts and nuclear power station accidents spread over coastal environments through estuarine areas connecting land to ocean. In this study, we monitored activity concentration of radiocaesium in surface sediment and re-suspended particles in Matsukawa-ura lagoon, the largest lagoon in Fukushima, after the TEPCO Fukushima Dai-ichi Nuclear Power Station accident. Radiocaesium distribution in surface sediment varied spatiotemporally and irregularly due to the effect of tidal waves. The effective half-life was significantly shorter than physical half-life, suggesting some system of radiocaesium discharge in the lagoon. Sediment trap observation revealed re-suspended particles from sediment were transported to the ocean. For these reasons, it is suggested that re-suspension of particles in the lagoon and their transportation to the ocean by the seawater exchange process are important processes of radiocaesium discharge. Moreover, our results show that seawater exchange process contributes to the dispersion of radiocaesium in the ocean.

Early Intake of Radiocesium by Residents Living Near the Tepco Fukushima Dai-ichi Nuclear Power Plant After the Accident. Part 2: Relationship Between Internal Dose and Evacuation Behavior in Individuals.

The Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident exposed members of the public to radiation. This study analyses the relation between personal behavior data obtained from 112 out of 174 subjects who underwent whole-body measurements by the National Institute of Radiological Sciences (NIRS) during the period from 27 June to 28 July 2011 and their committed effective doses (CEDs) from Cs and Cs. The whereabouts of the 112 persons living in municipalities near the FDNPP (mainly, Namie town) on several days in March 2011 are graphed on maps. It was confirmed that most subjects started evacuation promptly and had left the 20-km-radius of the FDNPP by the end of 12 March. The individual CEDs were poorly correlated with the person's distances from the FDNPP at any day in March. Meanwhile, the percentage of persons remaining within the 20-km radius of the FDNPP was 100% at 16:00 on 12 March and 42.9% at 0:00 on 15 March for those with CEDs > 0.1 mSv, whereas the corresponding values were much lower for those with CEDs ≤ 0.1 mSv. This suggests that the time of evacuation would be one of the crucial factors for the early intake; however, more personal behavior data are needed to be analyzed to clarify the relevance to the individual internal dose.

Using and Explaining Individual Dosimetry Data.

Measurement of individual radiation dose is crucial for planning protective measures after nuclear accidents. The purpose of this article is to explain the various initiatives taken after the TEPCO Fukushima Daiichi Nuclear Power Plant accident, including the D-shuttle project wherein residents from affected areas wore a personal dosimeter to measure their own external exposure. The experience in Fukushima revealed several issues such as gaining residents' trust and ensuring appropriate communication of the measured data. The D-shuttle project also revealed that obtaining individual dose measurement data had 2 purposes, as the information obtained was to be utilized by the residents for self-protection and by the authorities for deriving the dose distribution of the population to aid in designing large-scale protection measures. The lessons learned are that both the residents and the authorities need to understand and share the meaning of individual dose measurements and the measurement results must be used with due respect for the residents' privacy and other concerns.

Changes in the Biota of Paddy Fields before and after an Accident at the TEPCO Fukushima Daiichi Nuclear Power Plant

Changes in the Biota of Paddy Fields before and after an Accident at the TEPCO Fukushima Daiichi Nuclear Power Plant

Estimation of Available Nitrogen in Paddy Field after Fallow by TEPCO Fukushima Daiichi Nuclear Power Station Accident

Estimation of Available Nitrogen in Paddy Field after Fallow by TEPCO Fukushima Daiichi Nuclear Power Station Accident

Early Internal Exposure to the Public due to the Accident of TEPCO Fukushima Daiichi Nuclear Power Station

Early Internal Exposure to the Public due to the Accident of TEPCO Fukushima Daiichi Nuclear Power Station