Nuclear Accident Research Articles

Assessment of radiation environmental risks for fish fauna of the cooling pools of a number of operating nuclear power plants

Relevance. The need to assess radiation risks for the main types of fish in pools that are under the constant influence of the nuclear power plants. Aim. To assess the radiation environmental risks for the ichthyofauna of cooling pools of the operating nuclear power plants, to analyze the sources and features of formation of the radiation risks at different stages of their operation. Objects: monitoring studies of radiation environmental risks for reference fish species in cooling reservoirs of the Leningrad, Beloyarsk and Novovoronezh NPP. Methods. Calculation of the exposure dose rate and quantitative assessment of the risk of exposure to technogenic radionuclides of the ichthyofauna of the cooling pools of the Beloyarskaya, Leningradskaya and Novovoronezhskaya NPPs were carried out using the international computer complex of the updated version of ERICA Tool 2.0. Results. The paper demonstrates that the radiation ecological risks for the ichthyofauna in the cooling pools of the operating nuclear power plants are caused by the combined effect of radioisotopes of the different origin. The features of the formation of the radiation risks for each pool are specific and depend on the current radiation situation. The cooling pool of the Beloyarskaya NPP is characterized by a pronounced dependence of the radiation load on the types of operating power units. The ichthyofauna experienced the greatest radiation risks during the operation of the first two power units with thermal reactors AMB-100 and AMB-200. The decommissioning of the first power units and the construction of the units with the fast neutron reactors (BN-600 and BN-800) led to a significant reduction in the radiation load on the ichthyofauna of the cooling pool. At present, the radiation risks are caused mainly by the influence of 90Sr, which is almost not discharged from the Beloyarskaya NPP into the cooling pools, but has a predominantly global origin. Therefore, the formation of the risks is more associated with atmospheric fallout of 90Sr, and not with the operation of the nuclear power plant. The radiation risks for the ichthyofauna of the Leningradskaya NPP cooling pool are caused by the combined effect of 137Cs as a result of the radiation accident at the Chernobylskaya NPP and radionuclides with induced activity (14C; 60Co; 3H 54Mn and 65Zn), the origin of which may be associated with the operation of the nuclear reactors of the NPP. The level of radiation risk for the fish fauna of the Novovoronezhskaya NPP cooling pool for 2009–2019 increased 2.2 times due to an increase in the content of 60Co in many components of the pool. As a result, 81.7% of the radiation risks in demersal fish species were formed by the influence of 60Co. It cannot be ruled out that the increase in the 60Co content in the cooling pool of the Novovoronezhskaya NPP is a consequence of radioactive contamination of the groundwater as a result of the 1985 accident. The ecological risks for the fish fauna in all cooling pools are two to three orders of magnitude lower than the maximum allowable hazard coefficient. Thus, the normal operation of the nuclear power plants does not create unacceptable radiation risks that pose a real environmental threat to the fish fauna of the cooling pools.

Selected Legal and Safety Aspects of the “Coal-To-Nuclear” Strategy in Poland

Poland is actively exploring the application of nuclear power as a substitute for its present reliance on fossil fuels for the generation of heat and electricity. This change reflects a calculated attempt to reduce carbon emissions, diversify the nation’s energy sources, and enhance the sustainability of its energy infrastructure. However, the implementation of nuclear technology faces many challenges, such as radiation exposure, the production of radioactive waste, the off-site effects of nuclear accidents, and high capital costs. Addressing such nuclear-safety-related issues is crucial for nuclear technology’s successful deployment. An extended analysis of the “coal-to-nuclear” process in terms of its safety has to be performed. Therefore, this review paper covers multidisciplinary studies related to the rollout of nuclear energy in Poland. The first stage of this study was the identification of the key areas of analysis, which included (i) formal requirements and recommendations imposed by international and national organizations on the process of designing and operating nuclear power systems; (ii) potential nuclear hazards for the personnel working at a nuclear reactor unit and the local population; (iii) the applied solutions of the security systems of a reactor itself, the steam turbine cycle, and the auxiliary infrastructure; and (iv) the management of spent nuclear fuel and radioactive waste. This methodology, developed based on a review of the literature and international standards, was tested for the selected country—Poland.

Longitudinal effects of disaster-related experiences on problem drinking among Fukushima nuclear plant workers.

In the Fukushima nuclear power plant disaster of March 11, 2011, plant workers were exposed to various traumatic events and reported a subsequent increase in alcohol use. To determine the relationship between disaster-related experiences and problem drinking, we conducted a three-year follow-up study. Problem drinking among the nuclear plant workers was assessed annually from 2012-2014 using a modified version of the CAGE questionnaire that asked about current, rather than lifetime, drinking. A total of 1378 workers provided at least one CAGE response, and 2875 observations were used in the present analysis. Mixed-effects logistic regression models were used to analyze the relationship between disaster-related experiences and problem drinking over time. The prevalence of problem drinking (CAGE score ≥2) increased over time. At the baseline assessment in 2012, a year after the disaster, plant workers who had experienced life-threatening danger and discrimination had significantly more symptoms of problem drinking, which persisted over the following 2 years. Although at baseline, plant workers who had experienced major property loss or the death of a colleague showed no significant differences in problem drinking symptoms from those without such experiences, over the next 2 years their problem drinking increased significantly. Individuals who experienced life-threatening danger and discrimination during the Fukushima nuclear power plant disaster reported an increase in problem drinking. Although major property loss and the death of a colleague did not elevate problem drinking prevalence at baseline, it did so over the next 2 years. Different adverse effects of a natural disaster appear to differentially increase drinking behavior over time.

Constructing a map of potassium inputs to paddy fields from irrigation

Geographical and geological parameters, including land use, lithology, and water quality, and volume of irrigation were investigated to map K inputs into paddy fields from irrigation in the eastern part of Fukushima, Japan. This area has had one of the greatest needs for K maintenance worldwide due to the control of radiocesium uptake by plants after the Fukushima nuclear accident in 2011. The K+ concentration in irrigation water and its sources was in the range of 0.2–5.2 mg L−1, which was probably affected by both the natural conditions (e.g., amount of silicate mineral dissolution and presence of hot springs and coal seams) and human activities (e.g., agriculture and urbanization). Irrigation volume was estimated to range from 306 to 2300 mm in response to daily water requirement rates. K inputs were computed by multiplying the concentrations and volumes, giving estimated inputs of 2.5–133 kg K2O ha−1 crop−1. The inputs proved spatially variable and were high in the western and southeastern parts of the study area. Irrigation was estimated to supply more than half of the K application rate in the rice cultivation guidelines to 12% of the paddy field area. This map should provide useful information for devising K maintenance plans.

The Legal Basis for Civil Liability in the Nuclear Field

This study examined the legal basis of civil liability in the nuclear field by assessing the feasibility of fault-based liability, whether it is based on proven fault or presumed fault, to establish civil liability for nuclear damages. Furthermore, the study addressed strict liability as the most suitable solution for establishing liability in the nuclear field, given the inadequacy of fault-based liability in addressing the issues of nuclear incidents and compensation for them. The study recommended the necessity of implementing strict and absolute liability in the nuclear field to protect individuals, society, and the environment from the catastrophic severity of nuclear incidents. It emphasized the importance of focusing on all means of nuclear safety and security to avoid any nuclear incident, and the significance of solidarity among nuclear operators and insurance pools and funds when facing nuclear incidents and addressing the severe damages they cause.

Level, distribution and sources of Np, Pu and Am isotopes in Peter the Great Bay of Japan sea

Transuranium elements such as Np, Pu and Am, are considered to be the most important radioactive elements in view of their biological toxicity and environmental impact. Concentrations of 237Np, Pu isotopes and 241Am in two sediment cores collected from Peter the Great Bay of Japan Sea were determined using radiochemical separation combined with inductively coupled plasma mass spectrometry (ICP-MS) measurement. The 239,240Pu and 241Am concentrations in all sediment samples range from 0.01 Bq/kg to 2.02 Bq/kg and from 0.01 Bq/kg to 1.11 Bq/kg, respectively, which are comparable to reported values in the investigated area. The average atomic ratios of 240Pu/239Pu (0.20 ± 0.02 and 0.21 ± 0.01) and 241Am/239+240Pu activity ratios (3.32 ± 2.76 and 0.45 ± 0.17) in the two sediment cores indicated that the sources of Pu and Am in this area are global fallout and the Pacific Proving Grounds through the movement of prevailing ocean currents, and no measurable release of Np, Pu and Am from the local K-431 nuclear submarine incident was observed. The extremely low 237Np/239Pu atomic ratios ((2.0–2.5) × 10−4) in this area are mainly attributed to the discrepancy of their different chemical behaviors in the ocean due to the relatively higher solubility of 237Np compared to particle active plutonium isotopes. It was estimated using two end members model that 23% ± 6% of transuranium radionuclides originated from the Pacific Proving Grounds tests, and the rest (ca. 77%) from global fallout.

Special Issue on Robotic, Mechatronic and Information Systems for Decommissioning

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.

Development of a Radiation-induced Pulmonary Fibrosis Partial Body Irradiation Model in C57BL/6 Mice.

With the current volatile geopolitical climate, the threat of nuclear assault is high. Exposure to ionizing radiation from either nuclear incidents or radiological accidents often lead to major harmful consequences to human health. Depending on the absorbed dose, the symptoms of the acute radiation syndrome and delayed effects of acute radiation exposure (DEARE) can appear within hours, weeks to months. The lung is a relatively radiosensitive organ with manifestation of radiation pneumonitis as an acute effect, followed by apparent fibrosis in weeks or even months. A recently developed, first-of-its-kind murine model for partial-body irradiation (PBI) injury, which can be used to test potential countermeasures against multi-organ damage such as gastrointestinal (GI) tract and lungs was used for irradiation, with 2.5% bone marrow spared (BM2.5-PBI) from radiation exposure. Long-term damage to lungs from radiation was evaluated using µ-CT scans, pulmonary function testing, histopathological parameters and molecular biomarkers. Pulmonary fibrosis was detected by ground glass opacity observed in µ-CT scans of male and female C57BL/6J mice 6-7 months after BM2.5-PBI. Lung mechanics assessments pertaining to peripheral airways suggested fibrotic lungs with stiffer parenchymal lung tissue and reduced inspiratory capacity in irradiated animals 6-7 months after BM2.5-PBI. Histopathological evaluation of the irradiated lungs revealed presence of focal and diffuse pleural, and parenchymal inflammatory and fibrotic lesions. Fibrosis was confirmed by elevated levels of collagen when compared to lungs of age-matched naïve mice. These findings were validated by findings of elevated levels of pro-fibrotic biomarkers and reduction in anti-inflammatory proteins. In conclusion, a long-term model for radiation-induced pulmonary fibrosis was established, and countermeasures could be screened in this model for survival and protection/mitigation or recovery from radiation-induced pulmonary damage.

Determination of 90Sr in highly radioactive aqueous samples via conversion to a kinetically stable 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complex followed by concentration–separation–fractionation based on capillary electrophoresis–liquid scintillation

BackgroundThe Fukushima Daiichi Nuclear Power Plant accident (2011) released large amounts of radioactive substances into the environment and generated highly radioactive debris. Post-accident countermeasures are currently in the phase of fuel debris removal, which requires the analysis of radioactive contaminants in the environment and fuel. The spectra of solely β-emitting nuclides, such as 90Sr, overlap; thus, an effective method for nuclide separation is desired. Since conventional methods for high-dose sample analysis pose substantial exposure risks and generate large amounts of secondary radioactive waste, faster procedures allowing for decreased radiation emission are highly desirable. ResultsIn this study, we developed a 90Sr2+ quantitation technique based on liquid scintillation counting (LSC)–coupled capillary transient isotachophoresis (ctITP), along with two-point detection and relying on the rapid concentration, separation, and fractionation of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-complexed 90Sr2+ in a single run. The applicability of our method for the analysis of real-world samples was verified by conducting addition-recovery experiments using a seawater reference material and radioactive liquid waste obtained from the radioactive waste treatment facility at the Japan Atomic Energy Agency. The recovery determined by LSC was 95–113%, indicating successful quantitative analysis. 90Sr recovery was determined to be 90.1% from a contaminated water sample obtained from the Fukushima Daiichi Nuclear Power Plant, which was analyzed using the standard addition of 90Sr. The sensitivity (detection limit = 0.016 Bq) of the proposed method on a radioactivity basis was equal to or higher than that of the conventional method using ion exchange-LSC (0.012–0.07 Bq). Significance and noveltyOur method allows for the handling of high-dose radioactive samples at the microliter level and is substantially faster than conventional ion exchange protocols, whereas ctITP has not been used for practical applications due to inaccurate collection and lack of a suitable chemical system. The concentration–separation–fractionation protocol in ctITP is successful due to the existence of a rare inert Sr2+ complex and precise fractionation. This study establishes a pathway toward safer and more practical analysis of radionuclides.

KHG: The German Emergency Response Organization for Nuclear Accidents

This article describes the German emergency response organization for nuclear accidents “Kerntechnische Hilfsdienst GmbH (KHG)” and informs about its tasks, structures, and working methods. At the end the current status of radiation campaigns, a component of a remote controlled systems is reported.

Determinants of Performance for Robotics Teleoperated Activities: From Emergency Response to Decommissioning

After the nuclear accidents of Chernobyl and Fukushima, several countries concerned with nuclear energy production set up robotic accident intervention groups with the aim to intervene in place of humans in hostile environments with high levels of contamination or irradiation. It is the case of France. The operational feedback of such robotic groups may be of interest for teams performing decommissioning on nuclear facilities. In this aim, a comparative analysis of robotic intervention contexts was undertaken between training contexts and a real operating situation. This allowed us to confirm determinants of performance already identified in the literature and highlighted new determinants of performance for intervention in nuclear environments.

Framing Differences in Reports on Japan’s Discharge of Nuclear Wastewater: A Comparative Analysis of The New York Times and China Daily

Since Chornobyl, nuclear disasters have long overshadowed global environmental concerns. Recently, the discharge of nuclear wastewater from the Fukushima Daiichi Nuclear Power Plant in Japan has reignited discussions on such incidents’ environmental and geopolitical implications. In the aftermath of the earthquake and tsunami 2011, the Fukushima Daiichi Nuclear Power Station was severely damaged, accumulating radioactive-contaminated water used to cool the reactors. In August 2023, Japan began discharging nuclear wastewater into the Pacific Ocean, overseen by the International Atomic Energy Agency (IAEA). This paper aims to analyze and compare the reports of China Daily and The New York Times on this issue. China Daily is China’s state-owned mainstream media dedicated to reporting news to English-speaking countries, while The New York Times is one of the most influential media in the United States. Through framing theory, this paper will use different frameworks to showcase how these two media outlets try to influence people’s perception of Japan’s discharge of nuclear wastewater and the geopolitical landscape.

3D analysis of spray effect on long-term depressurization of VVER-1000 containment during LB-LOCA

Containment as the last barrier of defence in depth strategy plays the most important role in protecting the environment and public from the release of radioactive material. As a result, analysing its performance in nuclear accidents and the reliability and effectiveness of its engineering safety features (ESFs) in the depressurization of containment is a key step in safety assessment. This study demonstrates the effect of the spray system as one of the ESFs in long-term depressurization of VVER-1000 containment during an LB-LOCA accident by using GOTHIC code. In the first step toward this goal, the as-built 3D structure of VVER-1000/V446 containment has been prepared in AutoCAD and used as GOTHIC geometry input by applying the input preparation process. Long-term 3D profiles of temperature and pressure were simulated in GOTHIC without spray actuation. The next step deals with considering the effects of spray and sensitivity analysis of spray temperature and droplet diameter on long-term depressurization. 3D profiles of thermal-hydraulic parameters during long-term depressurization of containment have been presented as research outcomes and validated against FSAR data and finally, the effects of spray on profiles were concluded. Results can obviously prove the effect of spray on the long-term depressurization of containment. The required time to achieve half of the peak pressure of the containment was calculated as 1380 s which is completely in agreement with NRC safety criteria. Research outcomes confirm the success of the spray system to support the integrity of containment which could be jeopardized without spray system intervention.

Prevalence of cardiovascular diseases following man-made disasters; a systematic review

Objective: Disasters increase the incidence of infectious and contagious diseases, non-communicable diseases, and trauma. This systematic review aims to investigate the impact of man-made disasters on cardiovascular diseases (CVDs).
 Methods: This is a systematic review conducted following the PRISMA protocol. The population, intervention, control, outcome (PICO) framework utilized for this research is as follows: P: people with CVDs; I: various man-made disasters; C: no intervention is being compared; O: prevalence, treatment, and management of the disease. In the present study, English-language articles published until November 9, 2022 that investigated CVDs in human-made disasters were included. We conducted an extensive search in Medline, Web of Science, Embase, and SCOPUS.
 Results: The primary search of the databases resulted in 1878 articles, from which 1219 non-duplicate records. Finally, 18 articles were included; 13 studies were in the area of nuclear and atomic accidents, four studies were related to the sulfur mustard gas, and one was related to methyl chloride.
 Conclusion: CVDs increased in prevalence after man-made disasters, particularly among high-risk individuals. The likelihood of developing CVDs is higher with increasing dose, intensity, and duration of exposure.

Regenerating murine CD8+ lung tissue resident memory T cells after targeted radiation exposure.

Radiation exposure occurs during medical procedures, nuclear accidents, or spaceflight, making effective medical countermeasures a public health priority. Naïve T cells are highly sensitive to radiation-induced depletion, although their numbers recover with time. Circulating memory CD8+ T cells are also depleted by radiation; however, their numbers do not recover. Critically, the impact of radiation exposure on tissue-resident memory T cells (TRM) remains unknown. Here, we found that sublethal thorax-targeted radiation resulted in the rapid and prolonged numerical decline of influenza A virus (IAV)-specific lung TRM in mice, but no decline in antigen-matched circulating memory T cells. Prolonged loss of lung TRM was associated with decreased heterosubtypic immunity. Importantly, boosting with IAV-epitope expressing pathogens that replicate in the lungs or peripheral tissues or with a peripherally administered mRNA vaccine regenerated lung TRM that was derived largely from circulating memory CD8+ T cells. Designing effective vaccination strategies to regenerate TRM will be important in combating the immunological effects of radiation exposure.

Design, synthesis, biological evaluation and in silico studies of novel quinoline derivatives as potential radioprotective molecules targeting the TLR2 and p53 pathways

Ionizing radiation in space, radiation devices or nuclear disasters are major threats to human health and public security. In this paper, in order to find the potential novel compounds decreasing the radiation-induced damage by targeting p53 apoptosis pathway and TLR2 passway, a series of novel quinoline derivatives were designed, synthesized, and evaluated their biological activities. Most of the synthesized compounds showed significant radioprotective effects in vitro, and the compound 5 has the best performance. Therefore, we verified its radioprotective activity in vivo and investigated the mechanism of its excellent activity. The results in vivo indicated that compound 5 not only markedly enhanced the survival rate (80 %) of mice 30 days after lethal exposure to irradiation, but also significantly reduced the radiation-induced damage to haematopoietic system and intestinal tissue of mice. The mechanistic studies indicated that compound 5 acted on the p53 pathway to reduce radiation-induced cell apoptosis and at the same time stimulated TLR2 to up-regulate the expressions of radiation protection factors. Molecular dynamics study shows that compound 5 would effectively bind to the TLR2 protein and further revealed the binding mechanism. Taken together, all the findings of our study demonstrate the quinoline derivative 5 is a potent radioprotective compound, which holds a great therapeutic potential for further development.

Transport of radioactive materials from terrestrial to marine environments in Fukushima over the past decade

Abstract While 20 % of radionuclides released from the Fukushima Daiichi Nuclear Power Plant accident had been deposited in the terrestrial environment, rivers remain the long-term source for 137Cs, primarily through particulate transfer, from terrestrial to marine ecosystems. In this study, we estimated the suspended 137Cs flux to the ocean at 11 sites in the coastal area between October 2012 and December 2020 to be 17 TBq, based on our long-term monitoring data of concentrations of suspended 137Cs and suspended solids. The cumulative loss of suspended 137Cs from each site to the ocean ranged from 0.1 % to 1.7 % of initial deposition throughout the observation period, depending on the effect of dam lakes and normalized river discharge. The higher loss is also thought to be the large outflow of runoff during the typhoon. The current level of the suspended 137Cs concentrations was lowered to 1/10–1/100 of those immediately after the accident. The average value of the decreasing trend for each site was approximated using the equation: y = a1 e −k 1 t + a2 e −k 2t. The rate constant k 1 is higher in areas with intensive land use, such as pastures, bare land, and water surfaces, and k 2 is lower in urban areas.

Nuclear accident sites and tourism: a comparative analysis of the Chernobyl and Fukushima exclusion zones

ABSTRACT This article aims to explore similarities and differences in the relationship between nuclear accident sites and tourism through a comparative study of two culturally different exclusion zones, namely Chernobyl (Ukraine) and Fukushima (Japan). Although the causes of the nuclear catastrophe were different, today it is possible to confirm some similarities in the transition and recovery process between these contaminated and abandoned sites. A range of grassroots initiatives lead to movements that try to look at nuclear accident sites from a new perspective. These activities include the ones that are planned and conducted to develop the sites as tourist destinations. In addition, in the context of war in Ukraine, the article shows, through the Stone’s darkest-lightest indicator, how the narration of the places of cultural dissonances changes with the changing geopolitical reality. In order to achieve the aim of this paper, a comparative analysis was conducted referring to qualitative data collected in the Chernobyl Exclusion Zone and secondary data on both Chernobyl and Fukushima exclusion zones. The following interviews with tourists, participatory observation and collected online sources of these two post-catastrophe sites have first and foremost provided a better understanding of the cultural dissonances emerging in these spaces.

Dispersant-enhanced migration of radiocesium among soil size fractions: A novel strategy for volume reduction of radioactively contaminated soil

In the aftermath of the Fukushima Daiichi Nuclear Power Plant accident, a pioneering large-scale decontamination project was initiated, aiming to enable the return of evacuees. This project, the first of its kind in human history, involved the transportation of soils collected during decontamination to interim storage facilities. Before recycling or disposal, these soils undergo processes like volume reduction. However, there's a need for innovative methods to reduce volume effectively and treat secondary wastes more efficiently. The current study explores the impact of a dispersant, sodium hexametaphosphate (SHMP), on the behavior of radiocesium (r-Cs: 137Cs) dynamics in different size fractions of radioactively contaminated soils from Fukushima. The solid-phase speciation analysis of Fukushima soils validated that at least 50% of the 137Cs or other minerals are associated with difficult-to-extract soil phases. Nonetheless, the low 137Cs/133Cs ratio in corresponding soil phases implies a slower r-Cs fixation mechanism. The wet-sieving of r-Cs contaminated soil fraction, < 2 mm, with SHMP, resulted in different soil subfractions (2000–212, 212–53, and < 53 μm). Following SHMP treatment, dispersion of > 92% of 137Cs associated with < 212 μm soil size fractions was observed. The migration of 137Cs towards smaller soil size fractions can be attributed to either SHMP-induced cation exchange or the formation of polyvalent complexes involving SHMP and soil minerals. The condensation of 137Cs in < 212 μm, as induced by SHMP, enabled the subsequent reuse of the larger soil fraction (> 212 μm), which was less contaminated. This study provides a new perspective on the effects of dispersants and contributes to a better understanding of the complex interactions among organic carbon, 137Cs, monovalent and polyvalent cations, and soil functional groups concerning the volume reduction of soils contaminated with r-Cs.

Intra-mediary expertise: Trans-science and expert understanding of the public.

What is the role of experts and their expertise in the context of trans-science, in which issues that are raised in scientific terms cannot be answered by science alone? This article examines the discourses and practices around safety of low-dose exposure to radiation in the ongoing aftermath of the Fukushima Daiichi Nuclear Power Plant accident in Japan in 2011. Following the nuclear fallout, scientific experts and STS scholars in Japan debated what forms of science communication were adequate to address the situation. Ethnographic research and textual analysis of their debates show a shift in emphasis on the role of experts from cultivating 'public understanding of science' for the sake of science and policy to an 'expert understanding of the public' for the sake of the public and its diverse everyday concerns. Two forms of expertise are emerging: 'co-expertise' and 'intra-mediary expertise'. Both are parts of a transition from a paternalistic form of expertise to one that acknowledges the need to engage the public to address issues of scientific uncertainty. However, co-expertise ultimately upholds the existing political structures that shape risk governance, while intra-mediary expertise engages those often excluded from current structures of accountability. Discussion of the potentials and limitations of emerging forms of expertise in Japan show that epistemic justice is not enough. Civic justice that acknowledges diverse publics and their needs must be upheld in the uncertain sphere between science, politics, and everyday life.