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The article presents a summary of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) White paper which shows developments on the radiation levels and exposure due to the nuclear accident at Fukushima Daiichi Nuclear Power Station (FDNPS) in Japan since 2013. Topics discussed include the radionuclide releases to atmosphere and water, assessment of radiation doses to the public from external exposure, and radiation doses to FDNPS workers.

Radiocesium released by the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident still exists in the environment in two forms: adsorbed species on mineral particles in the soil and microparticles containing radiocesium mainly composed of silicate glass (CsMPs). CsMPs are dispersed not only around the FDNPP but also over a wide area of the Kanto region. The behavior and characteristics of CsMPs must be investigated to evaluate the impact of the FDNPP accident. Deposited particles including radiocesium were wiped from metal handrails on balconies and car hoods using tissue papers at six locations in the Kanto region (Tokai village, Ushiku City, Abiko City, Chiba City, Kawaguchi City, and Arakawa Ward) between March 15 and 21, 2011. CsMPs were isolated from the samples, and their characteristics were investigated. In total, 106 CsMPs derived from Unit 2 were successfully separated from 13 tissue paper samples. The radiation images of the two types of CsMPs discovered in Ushiku City demonstrate that CsMPs can easily become susceptible to fragmentation over time, even in the absence of weathering effects. [ABSTRACT FROM AUTHOR]

Background: The need to call out and expose authors for their persistence in improperly using epidemiology has been previously noted. Tsuda et al. have done well to expose Schüz et al.'s arguments/assertions in their recent publication in Environmental Heath. In this Comment, I point out that, also warranting being called out, are the arguments/assertions of Cléro et al. who, in their recent response to an article by Tsuda et al., reiterated the conclusions and recommendations derived from their European project, which were published in Environment International in 2021. Tsuda et al. had critiqued the Cléro et al. 2021 publication in their 2022 review article. However, in their response to it, Cléro et al. deflected by not addressing any of the key points that Tsuda et al. had made in their review regarding the aftermath of the Chernobyl and Fukushima nuclear accidents. In this Comment, I critique Cléro et al.'s inadequate response. Publication of this Comment will help in routing out the improper use of epidemiology in the formulation of public health policy and thereby reduce the influence of misinformation on both science and public policy. My critique of Cléro et al. is not dissimilar from Tsuda et al.'s critique of Schüz et al.: in as much as Schüz et al. should withdraw their work, so should Cléro et al.'s article be retracted. Main body: The response by Cléro et al. consists of four paragraphs. First was their assertion that the purpose of the SHAMISEN project was to make recommendations based on scientific evidence and that it was not a systematic review of all related articles. I point out that the Cléro et al. recommendations were not based on objective scientific evidence, but on biased studies. In the second paragraph, Cléro et al. reaffirmed the SHAMISEN Consortium report, which claimed that the overdiagnosis observed in non-exposed adults was applicable to children because children are mirrors of adults. However, the authors of that report withheld statements about secondary examinations in Fukushima that provided evidence against overdiagnosis. In the third paragraph, Cléro et al. provided an explanation regarding their disclosure of conflicting interests, which was contrary to professional norms for transparency and thus was unacceptable. Finally, their insistence that the Tsuda et al. study was an ecological study susceptible to "the ecological fallacy" indicated their lack of epidemiological knowledge about ecological studies. Ironically, many of the papers cited by Cléro et al. regarding overdiagnosis were, in fact, ecological studies. Conclusion: Cléro et al. and the SHAMISEN Consortium should withdraw their recommendation "not to launch a mass thyroid cancer screening after a nuclear accident, but rather to make it available (with appropriate information counselling) to those who request it." Their recommendation is based on biased evidence and would cause confusion regarding public health measures following a nuclear accident. Those authors should, in my assessment, acquaint themselves with modern epidemiology and evidence-based public health. Like Tsuda et al. recommended of Schüz et al., Cléro et al. ought also to retract their article. [ABSTRACT FROM AUTHOR]

The United States Nuclear Regulatory Commission issued requests for licensees to re-evaluate the seismic hazards at their sites after the accident at the Fukushima Daiichi Nuclear Power Plant in Japan on March 11 in 2011 and to identify and address any site-specific vulnerabilities associated with seismic hazards. The primary guidance for performing those evaluations is provided in the Electric Power Research Institute EPRI-1025287 report, which also provides guidance for evaluating spent fuel pool (SFP) integrity. In addition, the EPRI-3002009564 report also provides evaluation approaches regarding the effects of seismic ground motions on SFPs that supplement the guidance provided in EPRI-1025287. SFP integrity has become increasingly important for active and decommissioned nuclear power plants. According to EPRI-1025287, the SFP integrity evaluation emphasizes failure modes of the SFP that could result in "rapid drain-down." The definition of "rapid drain-down" is a failure that could lead to the uncovering of irradiated fuel stored in the SFP within 72 h of an earthquake. Possible failures can be classified into two categories: failures relevant to the SFP structure and failures relevant to non-structural elements. This paper aims to study the approaches of implementing seismic evaluation of an SFP structure. EPRI-3002009564 provides separate seismic evaluation approaches for plants with a ground motion response spectrum (GMRS) peak Sa ≤ 0. 8 g and for plants with a GMRS peak Sa > 0. 8 g. Structural dynamic analysis is also a common approach for implementing seismic evaluation if a detailed finite element model is available. In this paper, a sample SFP structure was evaluated using the two approaches, structural dynamic analysis and structural analysis criteria. The results indicate that shear failure controlled the failure mode of the SFP structure for both approaches. This shows that the two approaches drew the same conclusion regarding the failure mode. Furthermore, a smaller seismic margin was obtained using the structural analysis criteria, which means this evaluative approach is more conservative. [ABSTRACT FROM AUTHOR]

With combined use of the ocean-atmosphere simulation models and field observation data, we evaluate the parameters associated with the total caesium-137 amounts of the direct release into the ocean and atmospheric deposition over the Western North Pacific caused by the accident of Fukushima Daiichi nuclear power plant (FNPP) that occurred in March 2011. The Green's function approach is adopted for the estimation of two parameters determining the total emission amounts for the period from 12 March to 6 May 2011. It is confirmed that the validity of the estimation depends on the simulation skill near FNPP. The total amount of the direct release is estimated as 5.5-5.9x1015 Bq, while that of the atmospheric deposition is estimated as 5.5-9.7x1015 Bq, which indicates broader range of the estimate than that of the direct release owing to uncertainty of the dispersion widely spread over the Western North Pacific. [ABSTRACT FROM AUTHOR]

Spatiotemporal distributions of anthropogenic radionuclides in surface sediments off Miyagi, Fukushima, and Ibaraki Prefectures were analyzed on the basis of data collected during the monitoring program launched by the Japanese Ministry of Education, Sports, Science and Technology in 2011 right after the Fukushima Nuclear Power Plant accident. Concentrations of 137Cs in the surface sediments varied spatially by two orders of magnitude from 1.7 to 580 Bq kg-dry-1, and there was no obvious correlation between 137Cs concentration and the proximity of the sampling location to the site of the accident. The total inventory of 137Cs accumulated in the upper 3 cm of surface sediment in the monitoring area was estimated to be 3.78x1013 Bq, that is 0.1-2% of the total 137Cs flux from the plant to the ocean as a result of the accident (the percentage depends on the model used to estimate the total flux). The spatial variations of 137Cs concentration and inventory depended on two main factors: the 137Cs concentration in the overlying water during the first several months after the accident and the physical characteristics of the sediment (water content and bulk density). The tem-poral variations of the concentrations of other anthropogenic radionuclides (90Sr, 95Nb, 110mAg, 125Sb, 129Te, and 129mTe) in the sediments were also investigated. The temporal variations of the activity ratios of these nuclides to 137Cs suggest that before the Fukushima-derived nuclides became homogeneous in seawater, they were removed from the water to the sediment. [ABSTRACT FROM AUTHOR]

Effects of a heavy rain event on radiocesium export were studied at stations on the Natsui River and the Same River in Fukushima Prefecture, Japan after Typhoon Roke during 21-22 September 2011, six months after the Fukushima Daiichi Nuclear Power Plant accident. Radioactivity of 134Cs and 137Cs in river waters was 0.011- 0.098 Bq L-1 at normal flow conditions during July-September in 2011, but it increased to 0.85 Bq L-1 in high flow conditions by heavy rains occurring with the typhoon. The particulate fractions of 134Cs and 137Cs were 21-56% in the normal flow condition, but were close to 100% after the typhoon. These results indicate that the pulse input of radiocesium associated with suspended particles from land to coastal ocean occurred by the heavy rain event. Export flux of 134Cs and 137Cs by the heavy rain accounts for 30-50% of annual radiocesium flux in 2011. Results show that rain events are one factor controlling the transport and dispersion of radiocesium in river watersheds and coastal marine environments. [ABSTRACT FROM AUTHOR]

Following the failure of the nuclear power plant in Fukushima Prefecture in March 2011, peer-reviewed publications describing radioactivity levels in organisms inhabiting coastal environments are scarce. This paper reports on elevated levels of 134Cs and 137Cs in macroalgae and mussels (up to ~800 Bq kg-1 drywt.) in June 2011. Cs concentrations in biota sampled in early June 2011 were higher in areas south of Fukushima than sampled in the last third of the month north of Fukushima. Radioactivity from 134+137Cs in organisms south of Fukushima were comparable to or lower than that from the naturally occuring 40K in the same samples. While 210Pb and Po concentrations were generally lower than these other radionuclides, 210Po as an α-emitter is more significant from a radiological viewpoint than γ-emitters as it can inflict greater biological damage. By applying known bioconcentration factors of Cs in biota, measured biota concentrations of Cs were also used to estimate Cs concentraitons in coastal seawater to be in the range of 10²-10³ Bqm-3. These estimates show that 3 months after the accident and maximal release of radioactive Cs, levels of Cs persisted in coastal waters, although at levels that were two orders of magnitude lower than at the time of release. These June coastal seawater Cs levels were four orders of magnitude above Cs concentrations off Japan prior to the Fukushima disaster. [ABSTRACT FROM AUTHOR]

The impact of the earthquake and tsunami in the east coast of Japan in 11 March 2011 caused a loss of power at the Fukushima Dai-ichi Nuclear Power Plant (NPP) that resulted in one of the most important releases of artificial radioactivity to the environment. Although several works were devoted to evaluate the atmospheric dispersion of radionuclides, the impact of the discharges to the ocean has been less investigated. Here we evaluate the distribution of Fukushima-derived 90Sr and 89Sr throughout waters 30-600 km offshore in June 2011. Concentrations of 90Sr and 89Sr in both surface waters and shallow profiles ranged from 0.8 ± 0.2 to 85 ± 3 Bq m-3 and from 19 ± 6 to 265 ± 74 Bq m-3, respectively. Because of its short half-life, all measured 89Sr was due to the accident, while the 90Sr concentrations can be compared to the background levels in the Pacific Ocean of about 1.2 Bq m-3. Fukushima-derived radiostrontium was mainly detected north of Kuroshio Current, as this was acting as a southern boundary for transport. The highest activities were associated with near-shore eddies, and larger inventories were found in the closest stations to Fukushima NPP. The data evidences a major influence of direct liquid discharges of radiostrontium compared to the atmospheric deposition. Existing 137Cs data reported from the same samples allowed us establishing a 90Sr/137Cs ratio of 0.0256 ± 0.0006 in seawater off Fukushima, being significantly different than that of the global atmospheric fallout (i.e. 0.63) and may be used in future studies to track waters coming from the east coast of Japan. Liquid discharges of 90Sr to the ocean were estimated, resulting in an inventory of 53 ± 1 TBq of 90Sr in the inshore study area in June 2011 and total releases of 90Sr ranging from 90 to 900 TBq, depending upon the reported estimates of 137Cs releases that are considered. [ABSTRACT FROM AUTHOR]

After the Fukushima nuclear accident, the development of new accident-tolerant fuel cladding materials has become a research hotspot around the world. Due to its outstanding corrosion resistance, radiation resistance, and creep properties at elevated temperatures, the oxide dispersion strengthened (ODS) FeCrAl alloy, as one of the most promising candidate materials for accident-tolerant fuel cladding, has been extensively studied during the past decade. Recent research on chemical composition design as well as its effects on the microstructure and mechanical properties has been reviewed in this paper. In particular, the reasonable/optimized content of Cr is explained from the aspects of oxidation resistance, radiation resistance, and thermal stability. The essential role of the Al element in oxidation resistance, high-temperature stability, and workability was reviewed in detail. The roles of oxide-forming elements, i.e., Y (Y2O3), Ti, and Zr, and the solid solution strengthening element, i.e., W, were discussed. Additionally, their reasonable contents were summarized. Typical types of oxide, i.e., Y–Ti–O, Y–Al–O, and Y–Zr–O, and their formation mechanisms were also discussed in this paper. All aspects mentioned above provide an important reference for understanding the effects of composition design parameters on the properties of nuclear-level ODS FeCrAl alloy. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of the suitability of nuclear power as an option to combat the escalating climate emergency. Summarizing and evaluating key arguments, we elucidate why nuclear power is unsuitable for addressing climate change. The primary argument centers around the unresolved technical and human risks of accidents and proliferation, which are unlikely to be effectively mitigated in the future. Furthermore, we highlight the significant cost disparities between nuclear power and other non-fossil energy sources, such as solar photovoltaics and wind power, considering levelized costs of electricity. We also address the incompatibility of nuclear power with renewable energy systems, emphasizing the need for flexibility in the face of variable solar and wind resources. Alternative reactor technologies will not be available in time to make a major contribution. Nuclear power also poses challenges in power plant operation amid climate change and war. Ultimately, we argue that other motivations should be explored to explain the continued interest in nuclear power in some countries, as energy supply arguments alone are insufficient to justify new investments. [ABSTRACT FROM AUTHOR]

Radionuclide impact of the Fukushima Dai-ichi nuclear power plant accident on the distribution of radionuclides in seawater of the NW Pacific Ocean is compared with global fallout from atmospheric tests of nuclear weapons. Surface and water column seawater samples collected during the international expedition in June 2011 were analyzed for 134Cs, 137Cs, 129I and ³H. The 137Cs, 129I and 3H levels in surface seawater offshore Fukushima varied between 0.002--3.5 Bq L-1, 0.01--0.8 µ Bq L-1, and 0.05--0.15 Bq L-1, respectively. At the sampling site about 40 km from the coast, where all three radionuclides were analyzed, the Fukushima impact on the levels of these three radionuclides represent an increase above the global fallout background by factors of about 1000, 30 and 3, respectively. The water column data indicate that the transport of Fukushimaderived radionuclides downward to the depth of 300 m has already occurred. The observed 137Cs levels in surface waters and in the water column are in reasonable agreement with predictions obtained from the Ocean General Circulation Model, which indicates that the radionuclides have been transported from the Fukushima coast eastward. The 137Cs inventory in the water column (the area from 34 to 37° N, and from 142 to 147° E) due to the Fukushima accident is estimated to be about 2.2 PBq. The amount of 129I and ³H released and deposited on the NW Pacific Ocean after the Fukushima accident was estimated to be about 7 GBq and 0.1 PBq, respectively. Due to a suitable residence time in the ocean, Fukushima-derived radionuclides will provide useful tracers for isotope oceanography studies on the transport of water masses in the NW Pacific Ocean. [ABSTRACT FROM AUTHOR]

Rate of cesium-137 (137Cs) release to the sea from the Fukushima Dai-ichi Nuclear Power Plant was estimated until September 2012. Based on publicly released data of 137Cs in seawater near the power plant by Tokyo Electric Power Company, a continuing release of radionuclides to the sea is strongly suggested. The plant has an artificial harbour facility, and the exchange rate of harbour water with surrounding seawater was estimated by decrease of radioactivity immediately after an intense event of radioactive water release. The estimated exchange rate of water in the harbour is 0.44 day-1 during the period from 6 to 19 April 2011. 137Cs radioactivity of the harbour water is substantially higher than seawater outside and remained relatively stable after June 2011. A quasi-steady state was assumed with continuous water exchange, and an average release rate of 137Cs was estimated to be 93 GBq day-1 in summer 2011 and 8.1 GBq day-1 in summer 2012. [ABSTRACT FROM AUTHOR]

At two stations in the western North Pacific, K2 in the subarctic gyre and S1 in the subtropical gyre, time-series sediment traps were collecting sinking particles when the Fukushima Daiichi Nuclear Power Plant (FNPP1) accident occurred on 11 March 2011. Radiocesium (134Cs and 137Cs) derived from FNPP1 accident was detected in sinking particles collected at 500m by late March 2011 and at 4810m by early April 2011 at both stations. The sinking velocity of 134Cs and 137Cs was estimated to be 8 to 36m day-1 between the surface and 500m and > 180m day-1 between 500m and 4810m. 137Cs specific activity varied from 0.14 to 0.25 Bq g-1 dry weight. These values are higher than those of surface seawater, suspended particles, and zooplankton collected in April 2011. Although the radiocesium may have been adsorbed onto or in- corporated into clay minerals, correlations between 134Cs and lithogenic material were not always significant; therefore, the form of the cesium associated with the sinking particles is still an open question. The total 137Cs flux by late June at K2 and by late July at S1 was 0.5 to 1.7 Bq m-2 at both depths. Compared with 137Cs input to both stations by April 2011, estimated from the surface 137Cs activity and mixed layer depth and by assuming that the observed 137Cs flux was constant throughout the year, the estimated removal rate of 137Cs from the upper layer (residence time in the upper layer) was 0.3 to 1.5% (68 to 312 yr). The estimated removal rates and residence times are comparable to previously reported values. [ABSTRACT FROM AUTHOR]

Radium has four naturally occurring isotopes that have proven useful in constraining water mass source, age, and mixing rates in the coastal and open ocean. In this study, we used radium isotopes to determine the fate and flux of runoff-derived cesium from the Fukushima Nuclear Power Plant (NPP). During a June 2011 cruise, the highest Cs concentrations were found along the eastern shelf of northern Japan, from Fukushima south, to the edge of the Kuroshio current, and in an eddy ~130 km from the NPP site. Locations with the highest cesium also had some of the highest radium activities, suggesting much of the direct ocean discharges of Cs remained in the coastal zone 2-3 months after the accident. We used a short-lived Ra isotope ( 223Ra, t1/2 = 11.4 d) to derive an average water mass age (Tr) in the coastal zone of 32 days. To ground-truth the Ra age model, we conducted a direct, station-by-station comparison of water mass ages with a numerical oceanographic model and found them to be in excellent agreement (model avg. Tr = 27days). From these independent Tr values and the inventory of Cs within the water column at the time of our cruise, we were able to calculate an offshore 134 Cs flux of 3.9-4.6x1013 Bq d-1. Radium-228 (t1/2 = 5.75 yr) was used to derive a vertical eddy diffusivity (Kz) of 0.7m² d-1 (0.1 cm² s-1); from this Kz and 134Cs inventory, we estimated a 134 Cs flux across the pycnocline of 1.8x104 Bq d-1 for the same time period. On average, our results show that horizontal mixing loss of Cs from the coastal zone was ~109 greater than vertical exchange below the surface mixed layer. Finally, a mixing/dilution model that utilized our Ra-based and oceanographic model water mass ages produced a direct ocean discharge of 134Cs from the FNPP of 11-16 PBq at the time of the peak release in early April 2011. Our results can be used to calculate discharge of other water-soluble radionuclides that were released to the ocean directly from the Fukushima NPP. [ABSTRACT FROM AUTHOR]

Huge amounts of radionuclides, especially 137Cs, were released into the western North Pacific Ocean after the Fukushima nuclear power plant (FNPP) accident that occurred on 11 March 2011, resulting in contamination of the marine biota. In this study we developed a radioecological model to estimate 137Cs concentrations in phytoplankton and zooplankton populations representing the lower levels of the pelagic trophic chain. We coupled this model to a lower trophic level ecosystem model and an ocean circulation model to take into account the site-specific environmental conditions in the area. The different radioecological parameters of the model were estimated by calibration, and a sensitivity analysis to parameter uncertainties was carried out, showing a high sensitivity of the model results, especially to the 137Cs concentration in seawater, to the rates of uptake from water and to the radionuclide assimilation efficiency for zooplankton. The results of the 137Cs concentrations in planktonic populations simulated in this study were then validated through comparison with the some data available in the region after the accident. The model results have shown that the maximum concentrations in plankton after the accident were about two to four orders of magnitude higher than those observed before the accident depending on the distance from FNPP. Finally, the maximum 137Cs absorbed dose rate for phyto- and zooplankton populations was estimated to be about 10−2 μGy h−1, and was, therefore, lower than the 10 μGy h−1 benchmark value defined in the ERICA assessment approach from which a measurable effect on the marine biota can be observed. [ABSTRACT FROM AUTHOR]

This paper's theme "Creative Robot Contest for Decommissioning (hereinafter, this Creative Robot Contest)" may be called a contest that would never have been planned in the absence of the Great East Japan Earthquake on March 11, 2011 and the core meltdown accident at Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company. When it was decided to decommission the nuclear reactors, their decommissioning was immediately put in hand, which, however, met with a high barrier of high radiation doses unconquerable even by the modern science and technologies. In order to advance the stagnating decommissioning work and in hopes of some creative breakthrough ideas from KOSEN students, this Robot Contest, first held in 2016, has been held by KOSEN teams who have shown their willingness to participate in it as a venue useful to address any difficulties they will face in the real world or as teaching material for them to consider social problems. This Robot Contest, sponsored by the Japan Atomic Energy Agency and the Council of Technical Colleges for Human Resource Development for Decommissioning, is planned and managed by the Executive Committee of Creative Robot Contest for Decommissioning (hereinafter, the Executive Committee) with its secretariat at National Institute of Technology, Fukushima College (hereinafter, Fukushima KOSEN) in Fukushima Prefecture where Fukushima Daiichi Nuclear Power Plant is located. In this paper, teachers at Osaka Metropolitan University College of Technology (hereinafter, Osaka Metropolitan University KOSEN) and at Nara National College of Technology, Nara College (hereinafter, Nara KOSEN), whose respective teams have participated in this Robot Contest every year from the first one, and teachers at Fukushima KOSEN who organize and manage the executive committee describe their own views on this Robot Contest based on their viewpoints as KOSEN educators. In the first half, this paper reviews this Robot Contest and outlines the robots of Osaka Metropolitan University KOSEN which participated in it in FY2016 and FY2017 and of Nara KOSEN which did in FY2016. In the latter half, this paper describes the views of the KOSEN teachers who educate engineers in the framework of robot contests from the viewpoints of the teachers who have instructed the teams of Osaka Metropolitan University KOSEN and Nara KOSEN who have participated in this Robot Contest up to the sixth one and who have held this Robot Contest. [ABSTRACT FROM AUTHOR]

Anthropogenic radionuclides were released into the environment in large quantities by the Fukushima Daiichi Nuclear Power Plant (1FNPP) accident. To evaluate accident- derived 129I, the 129I concentrations in seawater before and after the accident were compared.-2010), the 129I concentrations in the western margin of the North Pacific between 36° N and 44° N showed a latitudinal gradient that was expressed as a linear function of latitude. The highest and average 129I concentrations after the accident were 73 times and approximately 8 times, respectively, higher than those before the accident in this study area. Considering the distribution of 129I in surface seawater, the accident-derived 129I in the southern and northern stations of the 1FNPP was predominantly supplied by seawater advection and atmospheric deposition, respectively. As of October 2011, depth profiles of 129I revealed that 129I originating from the 1FNPP existed mainly in the upper 100m depth. From the depth profiles, the cumulative inventories of accident-derived 129I were estimated to be (1.8-9.9) x 1012 atoms m-2 in this study area. On the basis of the 129I data in the seawater near Fukushima, the effective dose of 129I from seafood ingestion was much smaller than the annual dose limit. [ABSTRACT FROM AUTHOR]

Fillet samples of marine fish collected from the East/West Greenland current (GC) and from the Baltic Sea (BS), have been investigated by gamma-ray spectrometry within the regular German monitoring program. In samples of the second half of 2011 134Cs traces have been detected, suggested to originate from the Fukushima fallout being deposited in March/April 2011 over the northern North Atlantic and accumulated by fish. The radionuclide 134Cs (half-live 2 yr) was indeed detected with quite small activities at about 0.0036 Bqkg-1 w.w. Existing box-models describing the transport of Cs within seawater boxes of the NE Atlantic allowed estimating that 134Cs contributions from other sources, i.e. from the Chernobyl fallout and from discharges by the two major European nuclear reprocessing plants, both were negligible around Greenland, while for the Chernobyl fallout a small 134Cs background contribution to BS fish was estimated. Model results confirmed the level of 134Cs measured in BS fish and showed its maximum to have occurred in winter 2011/2012 followed by a continuous decrease. It was also determined that 134Cs activity, but not that of 137Cs, showed a significant negative correlation with sampling depth (150-400 m) of GC fish; this strengthens our Fukushima fallout assumption. As a result, the Fukushima fallout in these sea areas only marginally enhanced (GC: 4 %; BS: 0.1 %) pre-Fukushima levels of individual dose rates received by human fish consumers; the addition was around 0.001 µSv following the consumption of 10 kg fish per year, which is not expected to cause concern according to present guidelines for radiation protection. [ABSTRACT FROM AUTHOR]

The horizontal distribution of radioactive cesium (Cs) derived from the Fukushima Dai-ichi Nuclear Power Plant (FNPP) in the North Pacific is still unclear due to the limitation of direct measurement of the seawater in the open ocean. We present the result of direct observation of radioactive Cs in surface seawater collected from broad area in the western and central North Pacific in July, October 2011 and July 2012. We also conducted a simple particle tracking experiment to estimate the qualitative spatial distribution of radioactive Cs in the North Pacific. 134Cs were detected at 94 stations out of 123 stations and 137Cs was detected at all stations. The high 134Cs and 137Cs concentrations more than 10mBq kg-1 were observed in the area where the northern part of Kuroshio extension at 144° E and 155° E in July 2011, in the area 147° E-175° E around 40° N in October 2011, and the northern part of Kuroshio extension at 155° E and 175° 30' E in July 2012. Combining the result of direct observations and particle tracking experiment, the radioactive Cs derived from FNPP had been dispersed eastward to the central North Pacific during 2011. It was considered from the horizontal distribution that radioactive Cs was dispersed not only eastward but also north- and southward in the central North Pacific. Pronounced dilution process of radioactive Cs from FNPP during study period is suggested from temporal change in the activity ratio of 134Cs/137Cs which was decay corrected at 6 April 2011, and relationships between radioactive Cs and temperature. [ABSTRACT FROM AUTHOR]

The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident led to the release of large amounts of radionuclides into the atmosphere as well as direct discharges into the sea. In contrast to the intensive studies on the distribution of the released high volatility fission products, such as 131I, 134Cs and 137Cs, similar studies of the actinides, especially the Pu isotopes, are limited. To obtain the vertical distribution of Pu isotopes in marine sediments and to better assess the possible contamination of Pu from the FDNPP accident in the marine environment, we determined the activities of 239+240Pu and 241Pu as well as the atom ratios of 240Pu/239Pu and 241Pu/239Pu in sediment core samples collected in the western North Pacific off Fukushima from July 2011 to July 2012. We also measured surface sediment samples collected from seven Japanese estuaries before the FNDPP accident to establish the comprehensive background baseline data. The observed results of both the Pu activities and the Pu atom ratios for the sediments in the western North Pacific were comparable to the baseline data, suggesting that the FDNPP accident did not cause detectable Pu contamination to the studied regions prior to the sampling time. The Pu isotopes in the western North Pacific 30 km off Fukushima coast originated from global fallout and Pacific Proving Ground close-in fallout. [ABSTRACT FROM AUTHOR]

In the frame of the France-Japan agreement on nuclear collaboration, a bilateral collaboration agreement on nuclear energy was signed on March 21st, 2017, including a topic dedicated to Sodium-cooled Fast Reactor (SFR). This agreement has set the framework to start a bilateral discussion on a joint view of an SFR concept. France (CEA and FRAMATOME) and Japan (JAEA, MHI and MFBR) have carried out these studies from 2017 to 2019. Based on the beginning of the basic design phase of ASTRID project − ASTRID − 600 MWe (ASTRID for Advanced Sodium Technological Reactor for Industrial Demonstration), the two countries performed a common work to examine ways to develop a feasible common design concept, which could be realized both in France and in Japan. The subject was then extended and extrapolated with the ASTRID − 150 MWe data (reduced power reactor and enhanced experimental capabilities) in a second phase of this study. France and Japan first focused on design requirements. Common requirements were identified, as well as differences in the safety approach and the structural design requirements, according to national standards and respective site conditions, in particular considering seismic hazards. The teams developed common Top-Level design Requirements (TLRs) to allow common specification data, then joint design. This collaborative work was carried out through the implementation of twelve France-Japan Working Groups, working jointly. This paper is providing a review of this joint synthesis on Sodium Fast Reactor design concept. It is summarizing the context and objectives, then the definition and approaches of the Top Level Requirements. This paper is then dealing with the major design features: the core design and their related safety aspects, and the nuclear island design. Thus, this paper is providing a comprehensive review of this joint work gathering French and Japan nuclear design teams during two full years. [ABSTRACT FROM AUTHOR]

Robots usually carry out rescue tasks after nuclear accidents due to harsh environmental conditions such as radiation, high temperatures, and pressure. The assignment of rescue robots is a crucial aspect of this study, serving as a preliminary step in multi-robot task allocation. Its primary objective is to allocate robots to different groups based on the distribution of tasks. This paper models robot assignment as a multi-objective optimization problem by considering total execution time, regional load balance degree, and total transfer time. An improved hypervolume estimated multi-objective evolutionary algorithm (IHypE) is proposed. An encoding method is devised to represent the assignment of the robots. A corner-point-based hypervolume approximation method is proposed to efficiently measure the quality of each solution. An environmental selection that is more applicable to this problem is developed. In the experimental section, we conduct a comparative analysis between the proposed method and four state-of-the-art algorithms, namely MMODE-ICD, MOEA/D-2TH, NSGA-II, and SPEA2SDE. This comparison is performed on nine instances with varying scales. By evaluating the algorithm's performance using five evaluation indicators, including hypervolume, inverse generational distance, C-Metric, Spacing, and Spread, we demonstrate the competitiveness of the proposed algorithm in terms of convergence and diversity. [ABSTRACT FROM AUTHOR]

Following Russia's invasion of Ukraine in February 2022 there has been renewed attention on the security and protection of civilian nuclear infrastructure. This has been a longstanding issue in Pakistan, where the security of the country's nuclear estate has attracted considerable international attention for decades. However, rather than looking at Pakistan's civilian estate, assessments have instead prioritised the security of the country's nuclear arsenal. They have also been widely divergent: Western analysts have raised serious concerns over Pakistan's ability to secure sensitive nuclear materials, the country's domestic instability and its poor non-proliferation history. In contrast Pakistani officials downplay these risks, and point to various programmes of reform. Against this backdrop, this article reviews the available literature on Pakistan's civilian nuclear security regime and provides new insights by benchmarking developments against key elements of IAEA guidance. It concludes that Pakistan's civilian nuclear security regime is largely consistent with accepted international principles and approaches, although there are still areas where improvements in transparency would help the completeness of available information and the external evaluation of the country's regime. The paper also identifies several areas where improvements could be made, most notably in the promotion of cyber security and nuclear security culture. [ABSTRACT FROM AUTHOR]

Surface seawater 134Cs and 137Cs samples were collected in the central and western North Pacific Ocean during the 1.5 yr after the Fukushima Dai-ichi nuclear power plant accident to monitor dispersion patterns of these radioisotopes towards the Hawaiian Islands. In the absence of other recent sources and due to its short half-life only those parts of the Pacific Ocean would have detectable 134Cs that were impacted by Fukushima releases. Between March and May 2011, 134Cs was not detected around the Hawaiian Islands and Guam. Here, most 137Cs activities (1.2-1.5 Bqm-3) were in the range of expected preexisting levels. Some samples north of the Hawaiian Islands (1.6-1.8 Bqm-3) were elevated above the 18-month baseline established in surface seawater in Hawaii indicating that those might carry atmospheric fallout. The 18-month time-series analysis of surface seawater from Hawaii did not reveal any seasonal variability or trends, with an average activity of 1.46±0.06 Bqm-3 (Station Aloha, 17 values). In contrast, samples collected between Japan and Hawaii contained 134Cs activities in the range of 1-4 Bqm-3 and 137Cs levels were about 2-3 times above the pre-existing activities. We found that the southern boundary of the Kuroshio and Kuroshio extension currents represented a boundary for radiation dispersion with higher activities detected within and north of the major currents. The radiation plume has not been detected over the past 1.5 yr at the main Hawaiian Islands due to the transport patterns across the Kuroshio and Kuroshio extension currents. [ABSTRACT FROM AUTHOR]

Carbon footprint reduction issues have been drawing more and more attention these days. Reducing the energy consumption is among the basic directions along this line. In the paper, a low-energy approach to tsunami danger evaluation is concerned. After several disaster tsunamis of the XXIst century, the question arises whether is it possible to evaluate in a couple of minutes the tsunami wave parameters, expected at the particular geo location. The point is that it takes around 20 min for the wave to approach the nearest coast after a seismic event offshore of Japan. Currently, the main tool for studying tsunamis is computer modeling. In particular, the expected tsunami height near the coastline, when a major underwater earthquake is detected, can be estimated by a series of numerical experiments of various scenarios of generation and the following wave propagation. Reducing the calculation time of such scenarios and the necessary energy consumption for this is the scope of this study. Moreover, in case of the major earthquake, the electric power shutdown is possible (e.g., the accident at the Fukushima nuclear power station in Japan on 11 May 2011), so the solution should be of low energy-consuming, preferably based at regular personal computers (PCs) or laptops. The way to achieve the requested performance of numerical modeling at the PC platform is a combination of efficient algorithms and their hardware acceleration. Following this strategy, a solution for the fast numerical simulation of tsunami wave propagation has been proposed. Most of tsunami researchers use the shallow-water approximation to simulate tsunami wave propagation at deep water areas. For software implementation, the MacCormack finite-difference scheme has been chosen, as it is suitable for pipelining. For hardware code acceleration, a special processor, that is, the calculator, has been designed at a field-programmable gate array (FPGA) platform. This combination was tested in terms of precision by comparison with the reference code and with the exact solutions (known for some special cases of the bottom profile). The achieved performance made it possible to calculate the wave propagation over a 1000 × 500 km water area in 1 min (the mesh size was compared to 250 m). It was nearly 300 times faster compared to that of a regular PC and 10 times faster compared to the use of a central processing unit (CPU). This result, being implemented into tsunami warning systems, will make it possible to reduce human casualties and economy losses for the so-called near-field tsunamis. The presented paper discussed the new aspect of such implementation, namely low energy consumption. The corresponding measurements for three platforms (PC and two types of FPGA) have been performed, and a comparison of the obtained results of energy consumption was given. As the numerical simulation of numerous tsunami propagation scenarios from different sources are needed for the purpose of coastal tsunami zoning, the integrated amount of the saving energy is expected to be really valuable. For the time being, tsunami researchers have not used the FPGA-based acceleration of computer code execution. Perhaps, the energy-saving aspect is able to promote the use of FPGAs in tsunami researches. The approach to designing special FPGA-based processors for the fast solution of various engineering problems using a PC could be extended to other areas, such as bioinformatics (motif search in DNA sequences and other algorithms of genome analysis and molecular dynamics) and seismic data processing (three-dimensional (3D) wave package decomposition, data compression, noise suppression, etc.). [ABSTRACT FROM AUTHOR]

The Fukushima-Daiichi accidents in 2011 underlined the importance of severe accident management (SAM), including external events, in nuclear power plants (NPP) and the need of implementing efficient mitigation strategies. To this end, the Euratom work programmes for 2012 and 2013 was focused on nuclear safety, in particular on the management of a possible severe accident at the European level. Relying upon the outcomes of the successful Euratom SARNET and SARNET2 projects, new projects were launched addressing the highest priority issues, aimed at reducing the uncertainties still affecting the main phenomena. Among them, PASSAM and IVMR project led by IRSN, ALISA and SAFEST projects led by KIT, CESAM led by GRS and sCO2-HeRO lead by the University of Duisburg-Essen. The aim of the present paper is to give an overview on the main outcomes of these projects. [ABSTRACT FROM AUTHOR]

This paper overviews the achievements and challenges of radioactive contamination countermeasures, food inspection systems, and reputational damage to agricultural products in Fukushima Prefecture during the early stages of the Great East Japan Earthquake and nuclear disaster. It outlines the effectiveness of early countermeasures such as absorption control measures and soil decontamination, and observes how efforts aimed at revitalizing afflicted areas were initiated and advanced primarily through the leadership of residents and agricultural producers. Furthermore, it examines food inspection systems such as the "all-bag-all-volume" testing system for rice that was implemented in Fukushima, and suggests that a failure to extend such countermeasures to outside of Fukushima Prefecture was a contributing factor to the ongoing issue of reputational damage and consumer reluctance to purchase products from the area. Lastly, the paper categorizes early consumer trends in four groups based on differing perceptions of risk and safety, and concludes that dealing with reputational damage should entail creating maps of radioactive material distribution, and also building a rational inspection system that allows consumers to objectively identify the safety of agricultural products. [ABSTRACT FROM AUTHOR]

On 26 April 1986, the accident at the Chernobyl nuclear power plant in Soviet Ukraine led to a massive disaster, the consequences of which affected millions of people in northern and eastern Europe. Today, 35 years later, we recall it not only as one of the greatest catastrophes in the history of nuclear power but also as one of the main political preconditions or factors that led to the end of the USSR. This paper presents the initial stage of a comparative study on the memories of this disastrous event among Ukrainians, Belarusians, Russians, and Bulgarians living on the periphery of the affected zone. The aim is to trace diverse aspects of public reflection in connection with people's awareness and the degree to which they were affected, the reactions to the disaster, its effects and consequences, the preparedness of the population, and the latter's assessment of post-disaster management. [ABSTRACT FROM AUTHOR]

After the Fukushima nuclear accident in Japan, whether the structural safety of the nuclear power plant (NPP) can be guaranteed under an earthquake has been of wide concern. Automatic seismic trip systems (ASTS) have been deployed in NPPs. There are generally two units or more double units on the one NPP site, and the vibration energy of the structure can certainly affect its adjacent structures through the soil, and there is energy transfer and conversion between adjacent structures. At present, the distance between two reactors of NPPs of different reactor types is generally 100–200 m (this distance is referring to the distance between the centers of two reactors, which is slightly different for different reactor types). In the past, seismic instruments were used in the ASTS and the setting of shutdown threshold, so the impact of only one unit was considered in the structural analysis of NPPs, and the interaction of two reactors through site conditions was not considered. In addition, as the site conditions of NPPs become more and more complex, it is necessary to consider the impact of one reactor structure on another reactor structure through the soil on the same site under an earthquake. In order to analyze the influence of structure–soil–structure interaction (SSSI), a three-dimensional refined finite element model of NPPs is established in this paper. The soil–structure interaction (SSI) is considered by using viscoelastic boundary. The seismic responses of different positions of the raft foundation and NPP structure, under the conditions of considering SSI effect (one reactor) and SSSI effect (two reactors), are compared. The influence of SSSI effect on the seismic responses of the raft foundation and NPP structure is revealed. It is proposed that SSSI effect should be reasonably considered according to the site conditions for the structural analysis of NPPs for the NPP ASTS. [ABSTRACT FROM AUTHOR]

Nuclear energy was one among business opportunities brought by the take off in science and technology after the Second World War. The narratives of the milestones of atomic history neglect the commercial, industrial and organizational aspects that made it possible. This paper concentrates on what makes the nuclear business exceptional (or not). We undertake an analysis of the nuclear supply business (designing, manufacturing and installing nuclear facilities) distinct from the analysis of the demand side (business operating nuclear power plants). We identify a continuing role of the state in civil nuclear businesses and a symbiotic relationship with private atomic business. And yet, for the most part the nuclear business applies the usual criteria of cost minimization and profit maximization within the boundaries of a non-perfectly competitive market. We argue that the development of civil nuclear projects is core not just to business history as a discipline but to post-war history. [ABSTRACT FROM AUTHOR]

The majority of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident is covered with forests. We developed a dataset for radiocaesium (137Cs) in trees, soil, and mushrooms measured at numerous forest sites. The 137Cs activity concentration and inventory data reported in scientific journal papers written in English and Japanese, governmental reports, and governmental monitoring data on the web were collated. The ancillary information describing the forest stands were also collated, and further environmental information (e.g. climate) was derived from the other databases using longitude and latitude coordinates of the sampling locations. The database contains 8593, 4105, and 3189 entries of activity concentration data for trees, soil, and mushrooms, and 471 and 3521 entries of inventory data for trees and soil, respectively, which were collected from 2011 to 2017, and covers the entire Fukushima prefecture. The data can be used to document and understand the spatio-temporal dynamics of radiocaesium in the affected region and to aid the development and validation of models of radiocaesium dynamics in contaminated forests. Measurement(s) activity (of a radionuclide) • Cesium Cs 137 Technology Type(s) digital curation Factor Type(s) geographic location Sample Characteristic - Organism Cryptomeria japonica • Chamaecyparis obtusa • Pinus densiflora • Quercus serrata Sample Characteristic - Environment temperate evergreen needleleaf forest • temperate deciduous broadleaf forest • leaf • wood • litter layer • forest soil • mushroom (food source) • bark • pollen Sample Characteristic - Location Japan • Fukushima Prefecture Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.13166462 [ABSTRACT FROM AUTHOR]

Copyright of International Studies: Interdisciplinary Political & Cultural Journal is the property of Wydawnictwo Uniwersytetu Lodzkiego and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose -- Japan's 2011 natural disasters were accompanied by a devastating nuclear disaster in Fukushima. This paper used cross-country data obtained immediately after the Japanese disaster to explore how, and the extent to which, corruption affects the perception of citizens regarding the risk of nuclear accidents. The paper aims to discuss these issues. Design/methodology/approach -- Endogeneity bias was controlled for using instrumental variables when the author conducted regression estimation. Findings -- The cross-country analysis showed that citizens in less corrupt countries tend to perceive there to be a lower possibility of nuclear accident. Originality/value -- The finding made it evident that transparency of government enables citizens to access accurate information, reducing information asymmetry between citizens and government. Keywords Governance, Corruption [ABSTRACT FROM AUTHOR]

Mindful of the challenges to long-term operation, especially the severe safety and environmental consequences shown through historical nuclear power plant accidents (e.g. Fukoshima, Chernobyl, etc), it is imperative that European research and innovation focuses on demonstrating reliable long-term operation. Five examples of European Commission supported projects meeting such objectives are INCEFA+, SOTERIA, ATLAS+, MEACTOS and NUGENIA+. There are economies of scale within, and synergies across these projects which enable further advantage to be gained. Additionally, since researchers are well engaged internationally, this brings into European Organisations latest developments in understanding from further afield (e.g. USA, Japan), further enabling safety assurance advances, and enabling work overseas to be influenced consistent with European requirements. Through examples, this paper provides evidence of the advances claimed, whilst being careful to also declare areas of interest for which further work is still a priority. [ABSTRACT FROM AUTHOR]

The Fukushima Daiichi Nuclear Power Plant accident, triggered by the Great East Japan Earthquake and the tsunami, has had a major impact on societies across the world. The subsequent focus on decommissioning efforts has attracted worldwide attention. It has been consistently asserted since the aftermath of the accident that the decommissioning of the Fukushima Daiichi Nuclear Power Plant will take approximately 30 to 40 years. The promotion of decommissioning work means that we will continue to face the problems with uncertainties in the work, as sometimes referred to as Unknown Unknowns. Typical elemental technologies required in remotely operated robotic systems for decommissioning include mobile mechanisms and their control, handling mechanisms and their control, information communication, operation interface (information presentation and command input), shielding (radiation resistance) and so on. Although many tasks using remotely operated robotic systems have been carried out with noteworthy results, there are lingering issues yet to be clarified. To ensure the safe and effective execution of various types of decommissioning tasks over a period of several decades, continuous research and development of each elemental technology are imperative, and these technologies must be integrated into a system appropriately to the assumed tasks. In addition, human resource development and the transfer of knowledge and experience are also important issues. From such viewpoint, this special issue is titled "Robotic, Mechatronic and Information Systems for Decommissioning." It contains papers and development reports on robotics, mechatronics, information processing, and information systems technologies relevant to decommissioning work. It also features recent activities of nuclear emergency response organizations. We hope this special issue will acquaint readers with the latest research and development results and organizational activities related to decommissioning. At the same time, we hope that we were able to provide readers interested in robots, mechatronics, and information technology with an opportunity to become aware of the issues and necessary perspectives related to decommissioning and nuclear disasters. Lastly, we would like to thank the editorial board of the Journal of Robotics and Mechatronics, the editorial team of Fuji Technology Press, and the reviewers for their support in the planning and publication of this special issue. Their dedicated efforts are deeply appreciated. [ABSTRACT FROM AUTHOR]

Radionuclide dispersion model, which is of critical importance to the emergency response of severe nuclear accident, is used to estimate the consequences arising from accidental or routine releases and to predict areas of high contamination. It is difficult to evaluate the radioactive consequence accurately and rapidly for the accidental release of radionuclides from marine reactor because of the complex mobility feature in the sea. Based on CFD method, a finite-volume, three-dimensional regional oceanic dispersion model was developed in this paper to simulate the dispersion of radionuclides originating from marine reactor. The simulated dose variation of 137Cs presented good agreement with the monitoring data of marine radioactive pollution caused by Fukushima Dai-ichi nuclear accident, which demonstrated the validity of the method. A severe accident scenario of marine reactor was simulated and analyzed, which indicates that the regional oceanic dispersion model can provide dose assessment for nuclear emergency response. [ABSTRACT FROM AUTHOR]

In Europe, the two main nuclear accident response decision support systems in use are ARGOS and JRODOS, both of which make use of the FDMT (Food Chain and Dose Module for Terrestrial pathways) model to simulate the transfer of radioactivity along terrestrial food chains and to predict radionuclide activity concentrations in human foodstuffs. FDMT was originally developed in the early 1990s for Southern German agricultural conditions. Its application to other geographical settings has raised concerns regarding its fitness for purpose. Furthermore, the FDMT model in its original format lacks transparency, flexibility, and the possibility to be run probabilistically. In order to improve FDMT's fitness for purpose and overcome its main shortcomings, it has been implemented in a new modelling platform which incorporates powerful numerical solvers and renders uncertainty and sensitivity analysis possible. The modelling structure of FDMT has been re-configured, and a library configuration has been introduced which offers flexibility in working such that model components can be tested, modified, or replaced easily. The new FDMT allows for the consideration of case/region-specific issues and to make predictions which are of more relevance and of better use with regard to decision making and management of risk. Furthermore, the default databases of FDMT have been updated and wherever possible PDFs have been assigned. In this paper, the transition of FDMT from an old to a new modelling structure is presented along with a demonstration of developments achieved. [ABSTRACT FROM AUTHOR]

The overall goal of nuclear power plant safety is to protect individuals, society and the environment from undue radiological hazard so that nuclear power production does not significantly add to the health risks to which individuals and society are already exposed. This paper addresses the safety principles followed during the design phase of life cycle of a nuclear power plant. The principles followed such as safety classification, design rules based on failure modes, detailed stress analysis, stress categorization, consideration of design basis events, failure probability, flaw tolerance, leak-before-break are described. Engineering structures always contain flaws, albeit of very small size. Fatigue and fracture are the two important failure modes affected by flaws. Thus flaw tolerance becomes very important. This is assessed by applying fracture mechanics principles. The R6 procedure, which is used for evaluation of structures containing flaws, has been incorporated in the software BARC-R6. Improvements by way of shell-nozzle junction pull-out, adoption of hot wire GTAW with narrow gap technique have been brought out. Post Fukushima incidence, resistance to seismic loading and containment design have assumed great importance. The paper describes these aspects in detail. Regulatory aspects of seismic design regarding siting, Seismic margin assessment, base isolation, retrofitting are the aspects covered under seismic design. Under the action of seismic loading, the piping in a nuclear power plant piping is vulnerable to a phenomenon called ratcheting. The process of seismic margin assessment and consideration of ratchetting has been backed up by a large experimental data. The experiments carried out on structures and piping components form a part of the paper. [ABSTRACT FROM AUTHOR]

Background: The SHAMISEN (Nuclear Emergency Situations - Improvement of Medical And Health Surveillance) European project was conducted in 2015-2017 to review the lessons learned from the experience of past nuclear accidents and develop recommendations for preparedness and health surveillance of populations affected by a nuclear accident. Using a toolkit approach, Tsuda et al. recently published a critical review of the article by Cléro et al. derived from the SHAMISEN project on thyroid cancer screening after nuclear accident. Main body: We address the main points of criticism of our publication on the SHAMISEN European project. Conclusion: We disagree with some of the arguments and criticisms mentioned by Tsuda et al. We continue to support the conclusions and recommendations of the SHAMISEN consortium, including the recommendation not to launch a mass thyroid cancer screening after a nuclear accident, but rather to make it available (with appropriate information counselling) to those who request it. [ABSTRACT FROM AUTHOR]

Since the Fukushima nuclear accident, dozens of citizen radiation measuring organizations (CRMOs) continue to observe the nuclear fallout in Japan. Their activities intersect on a regular basis with those of the Japanese government. Recognizing the different policy levels involved in radiation measuring, this paper studies the relations between local governments and CRMOs. We examine how civic and governmental infrastructures initiated in the wake of the Fukushima accident (dis)engage with each other. We link these infrastructures with pre- and post-Fukushima socio-technical imaginaries. By doing so, we explore whether and how CRMOs challenge and reconfigure political culture in post-Fukushima Japan. We conclude that CRMOs and local governments have established themselves as separate infrastructures, living and operating in the same environment, yet apart in the majority of cases. We identify obstacles and opportunities for citizen engagement in the emergency and recovery process after a nuclear accident, and contextualize CRMOs within citizen mobilization after Fukushima. Document analysis, fieldwork, and interviews with CRMOs, local governments, and the Fukushima prefectural government make up the basis of our study. [ABSTRACT FROM AUTHOR]

Using a hedonic regression approach, this research aims to identify what factors affected land price fluctuations in Fukushima Prefecture following the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Station accident in 2011. In this paper, taking a long-term perspective, the analysis focuses on Iwaki City in Fukushima, where the real estate market behaved unexpectedly following the two catastrophic events, and land price fluctuation rates were rising abnormally. Results based on analysis of data for eight-year indicate the following: The impact of radiation air dose rate and distance from the nuclear power plant on land price fluctuation rate changed significantly from the fourth year after the disaster. Being located in a reconstruction base area had a negative impact on land price fluctuation rate, while access to sewers and city gas had a positive impact. It appears that the stigma associated with the accident had a little disappeared after approximately four years. [ABSTRACT FROM AUTHOR]

Following the Fukushima nuclear accident in March 2011, decontamination and related works have been carried out over a wide area, mainly in Fukushima Prefecture. In November 2013, the Radiation Dose Registration and Management System for Decontamination Workers was established to manage the occupational exposure doses of workers engaged in such work. The Radiation Effects Association mainly operates the registration system. This paper summarizes existing reports on this system and occupational health issues among decontamination workers. We collected previous reports and related regulatory laws on occupational health management for decontamination workers working in Fukushima Prefecture, summarized the outline of the radiation dose registration and management system for these decontamination workers, and discussed future issues related to their health management. Approximately 100 000 decontamination workers were registered in the system as of 2020, but none showed radiation doses that exceeded the dose limit. To our knowledge, there have been no reports of decontamination workers presenting physical symptoms suspected to be related to radiation exposure. On the other hand, heatstroke countermeasures and anxiety about radiation exposure have been reported as possible issues in the occupational health management of decontamination workers. Although decontamination workers are unlikely to experience biological effects from radiation exposure, epidemiological studies are needed to examine this evidence. Further analysis is also needed on non‐radiation effects, which pose occupational health concerns for decontamination workers. The registration system would allow for tracking decontamination workers, providing data for analyzing radiological and non‐radiological effects. [ABSTRACT FROM AUTHOR]

Probabilistic Risk Assessment (PRA) is one of the technologies that is used to inform the design, licensing, operation, and maintenance activities of nuclear power plants (NPPs). A PRA can be performed by considering the single hazard (e.g., earthquake, flood, high wind, landslide) or by considering multi-hazards (e.g., earthquake and tsunami, high wind and internal fire). Single hazard PRA was thought sufficient to cover the analysis of a severe accident until the Fukushima Daiichi NPP accident in 2011. Since then, efforts were made to consider multi-hazards as well; thus, multi-hazard PRAs are starting to be seen as being indispensable for NPPs. In addition to the changing frequency of global and local natural hazards, other reasons to be highlighted are that the number and diversity of NPPs will probably increase. Moreover, advanced reactors are close to becoming a reality by designing them with passive safety systems, smaller, standardized, and even transportable to make them cheaper across the design, licensing construction, and operation stages. Thus, multi-hazards should be addressed in any future full-scope PRA. Although we found a few studies discussing multi-hazards, a general framework for multi-hazard PRA is still missing. In this paper, we argue that the starting point for any multi-hazard PRA general framework should be the Advanced Non-LWR Licensing Basis Event Selection (LBE) Approach and Probabilistic Risk Assessment Standard for Non-LightWater Reactor (non-LWR) Nuclear Power Plants. For Probabilistic Risk Assessment (PRA), history has shown us the path forward before, with Three Mile Accident being seen as one milestone to understand the necessity of PRA. The Fukushima Daiichi NPP Accident is another milestone in the development of PRA, showing the need for performing multi-hazard PRA for the current and future NPPs. [ABSTRACT FROM AUTHOR]

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This paper conducted a questionnaire survey of evacuees (residents of public-funded rented housing, home buyers, etc.) from Tomioka Town, who were displaced because of the nuclear accident in Fukushima in 2011. It aimed to understand the characteristics of the wide area residents' associations as the “Third Place" by examining the relationship among the neighborhood association before and after the disaster, the neighborhood association at the evacuation district, and wide area residents' associations. It was revealed that wide area residents' associations could function as a relative Third Place, because the evacuees had a weak connection with the places they live in after evacuation, although they continue to have strong links with the neighborhood associations in the places where they lived before the disaster. [ABSTRACT FROM AUTHOR]

The Fukushima Daiichi Nuclear Power Plant accident also contaminates lakes in Japan. Especially in closed lakes, there is a problem of prolonged low-level 137 Cs contamination because the activity concentration of 137 Cs declines sharply immediately after the accident, but then begins to decrease slowly. In this paper, we derived a long-term prediction formula based on the fractional diffusion model (FDM) for the temporal variation in 137 Cs activity concentrations of the water in Lake Onuma on Mt. Akagi, one of the closed lakes, and of pond smelt (Hypomesus nipponensis), a typical fish species inhabiting in the lake. The formula reproduced well the measured 137 Cs activity concentration of the lake water and pond smelt for 5.4 years after the accident. Next, we performed long-term prediction for 10,000 days using this formula and compared it with the prediction results of the two-component decay function model (TDM), which is the most common model. The results suggest that the FDM prediction will lead to a longer period of contamination with low-level 137 Cs than the TDM prediction. [ABSTRACT FROM AUTHOR]

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