Radioactivity of the atmospheric aerosols detected by CTBTO stations in Africa following the accident at the Fukushima Daiichi nuclear power plant.

Radionuclides from the reactor accident Fukushima Daiichi nuclear power plant were observed in the airborne aerosols at CTBT International Monitoring System (IMS) stations (MRP43, CMP13) in Africa. The maximum activity concentrations in the air measured in Mauritania were 186.44 10-6 Bq.m-3, 264.16 10-6 Bq.m-3 and 1269.94 10-6 Bq.m-3 for 134Cs, 137Cs and 131I respectively, and in Cameroon 16.42 10-6 Bq.m-3, 25.53 10-6 and 37.58 10-6 Bq.m-3 respectively for 134Cs, 137Cs and 131I. The activity ratio of 134Cs/137Cs is almost constant throughout the period of time relevant to this study due to their long half-lives of 30.2 years for 137Cs and 2.06 years for 134Cs. Whereas the 131I/137Cs activity ratio varies in time according to the radioactive decay with a half-live of 8.06 days for 131I and different removal rates of both radionuclides from the atmosphere during transport. The EMAC atmospheric chemistry-general circulation was used to simulate the emission and transport of the isotope 137Cs and map the deposition of the 137Cs deposition over Africa.

Measuring team situation awareness through team communication: A study on nuclear main control room crews.

Situation awareness (SA) in complex socio-technical systems is considered a key cognitive activity, as control crews are often engaged in simultaneous task processes and are required to monitor and evaluate system parameters, making decisions and projections for the future accordingly. However, measuring SA at the team level is still a challenging area of research within the topic. In our research, we applied verbal protocol analysis as an alternative method to assess nuclear power plant control room crews' team SA. We conducted a study of 10 control room crews, examining their intrateam communication and its relatedness to team performance. We have found that communication categories related to the second and third levels of team SA increased significantly after the onset of an emergency event. Furthermore, while none of the team communication categories was related to team performance before the emergency event, all of them showed a strong positive correlation with team performance after the emergency situation occurred. Our results underline the importance of adequate verbalization of key information within the team, so as to support the rapid and accurate development of team SA during emergency situations.

Long-term radiological assessment of a Mediterranean freshwater ecosystem surrounding a nuclear power plant.

The radionuclide concentration of man-made radionuclides on non-human biota in freshwater ecosystems has been extensively studied in environments affected by the Chernobyl and Fukushima accidents, in both humid continental and subtropical climates, respectively. However, there are very few studies that assess the long-term effects of operating nuclear facilities in Mediterranean environments. In the present study, a temporal analysis of the impact on carp, cattail, and bulrushes in the cooling pond of the currently operating Almaraz nuclear power plant was investigated for the period 2000-2020. The results do not show a general trend in man-made radionuclide concentrations. Instead, depending on their availability and the type of organism, trends decrease over time. This is also reflected in the effective half-lives obtained, which are lower than the physical half-life for some radionuclides. Transfer coefficients for the main man-made radionuclides detected were obtained, and it was found that these were significantly lower than the typical ranges found for benthic fish and vascular plants in freshwater ecosystems. Finally, the internal and external doses received by the carp have been evaluated using ERICA tool, and it has been observed that the main contribution to the total dose is due to the internal dose (0.65-7.04) × 10-4 µGy/h.

Public knowledge, perception of and willingness-to-accept nuclear energy in China: Evidence from a representative national survey.

The Chinese government promotes nuclear energy development in the context of mitigating climate change. However, the large-scale development is still facing challenges related to the knowledge gap among the general public and the potential "not-in-my-back-yard" objection. Based on a representative national survey, we analyze Chinese people's knowledge and perceptions of nuclear energy and estimate their willingness-to-accept the potential risks of new nuclear programs in neighborhoods via the Contingent Valuation Method. Generally, more than half of people do not know anything about nuclear energy. The main factors influencing public knowledge are identified, such as the residential distance to existing nuclear power stations and the frequency of internet use. Moreover, approximately 12% of individuals with some knowledge seem to be willing to accept new nuclear power plants in their neighborhoods with no compensation needed. Specifically, the perceptions of nuclear risks and pollution from fossil fuels are significant factors influencing people's acceptance of nuclear energy. Although public knowledge does not directly influence acceptance, more knowledge seems to reduce risk perception and increase benefit perception. The residential distance to exiting nuclear stations has limited effects on people's acceptance of newly planned nuclear programs for those living in the same county with some knowledge. In general, a typical Chinese household is willing to accept USD $5.66 every month or USD $67.97 every year to bear the potential risks of the new nuclear program in neighborhoods. Significant practical implications that can be transferable to other new energy technologies and countries or regions are provided.

Assessment of the impact of Tianwan Nuclear Power Plant on the adjacent marine ecosystem.

Based on the monitoring data of 137Cs and 90Sr in Tian Bay in 2005-2023, the impacts of the operation of Tianwan Nuclear Power Plant on the marine ecosystem were assessed. The 137Cs and 90Sr activity concentrations in the seawater and sediment varied within the background ranges. The radiation dose rates derived from 137Cs and 90Sr for the marine organisms ranged from 2.4 × 10-5 to 2.2 × 10-4 nGy/h, it was far below the most conservative screening dose rate (10 µGy/h). The committed effective dose for humans was 0.070-0.094 µSv, 1/1500th of the world's mean annual effective dose (0.12 mSv) from ingesting food containing uranium and thorium series nuclides. Radiation risk assessment showed no radiation risk for the long-term discharge of nuclear wastes in the future. Overall, the long-term normal operation of TNPPs has almost no radiation impact on the adjacent marine ecosystem.

Assessment of radiation in fishes derived from radiocesium in the port of Fukushima Daiichi nuclear power plant.

This study established specialized radiation dose models to evaluate the internal radiation doses derived from 137Cs and 134Cs in fishes in the port of the Fukushima Daiichi Nuclear Power Plant from 2012 to 2023. By August 2018, the activities of 134Cs and 137Cs in fishes decreased at the T1/2 of 176 d and 191 d, respectively. The corresponding mass concentrations were far lower than 1 mg/kg and the chemical toxicity can be negligible. Regarding radiotoxicity, 18,000 Bq/kgfresh weight of 134Cs and 137Cs in grouper Sebastes schlegelii produced 276 µGy/h of radiation dose, which was below the no-effect-dose-rate benchmarks (400 µGy/h). 740,000 Bq/kgfresh weight of 134Cs and 137Cs in greenling Hexagrammos otakii produced 12,600 µGy/h of radiation dose, which was much higher than 400 µGy/h, indicating the possibility of radiation effects. If a person eats these two reported fishes, the resulting committed effective doses for humans are 7.7 µSv and 6.31 mSv, respectively.

Radiological complexity of nuclear facilities: an information complexity approach to workplace monitoring.

Nuclear energy is crucial for achieving net-zero carbon emissions. A big challenge in the nuclear sector is ensuring the safety of radiation workers and the environment, while being cost-effective. Workplace monitoring is key to protecting workers from risks of ionising radiation. Traditional monitoring involves radiological surveillance via installed radiation monitors, continuously recording measurements like radiation fields and airborne particulate radioactivity concentrations, especially where sudden radiation changes could significantly impact workers. However, this approach struggles to detect incremental changes over a long period of time in the radiological measurements of the facility. To address this limitation, we propose abstracting a nuclear facility as a complex system. We then quantify the information complexity of the facility's radiological measurements using an entropic metric. Our findings indicate that the inferences and interpretations from our abstraction have a firm basis for interpretation and can enhance current workplace monitoring systems. We suggest the implementation of a radiological complexity-based alarm system to complement existing radiation level-based systems. The abstraction synthesized here is independent of the type of nuclear facility, and hence is a general approach to workplace monitoring at a nuclear facility.

Analysis of population distribution for anticipating radiological consequences of nuclear power plant program in West Kalimantan.

The potential establishment of a nuclear power plant (NPP) in the West Kalimantan is under consideration to address low electrification rates. This research assesses the demographic characteristics and population growth in the vicinity of the proposed NPP site in West Kalimantan. The investigation focuses on demographic aspects, population density, and anticipated growth during the operational phase of the reactor. The study area encompasses districts within a 25 km radius of the site. Employing a descriptive quantitative approach, this research integrates verified population data and utilizes spatial and temporal analysis. The exponential method is employed to forecast population growth throughout the operational lifespan of the reactor, to anticipate population increases in around NPP site. Reactor operation has potential radiological consequences. Results reveal that the suggested NPP site adheres to regulations concerning population density away from densely populated areas. Projected population growth is notable in specific regions, necessitating monitoring and policy attention. A gender-specific analysis highlights the higher female populations, with sensitivity to radiation exposure. These findings offer essential information for evaluating the radiological impact of the NPP on the population, so meeting NPP siting requirements. The study contributes valuable insights for decision-making regarding NPP development and safety considerations in West Kalimantan.

Health risk assessment for soil radioactivity around Shidaowan nuclear power plant in Shandong, China.

Monitoring radioactivity levels in the environment around nuclear power plants is of great significance to assessing environmental safety and impact. Shidaowan nuclear power plant is currently undergoing commissioning; however, the baseline soil radioactivity is unknown. The naturally occurring radionuclides 238U, 232Th, 226Ra and 40K, and artificial radionuclide (AR) 137Cs in soil samples around the Shidaowan nuclear power plant were measured to establish the baseline levels. Human health hazard indices such as external hazard indices (Hex), Radium equivalent (Raeq), outdoor absorbed dose rate (Dout), annual effective dose (AED) and excess lifetime cancer risk (ELCR) were estimated. The average concentration of 232Th, 40K, 137Cs, 238U and 226Ra were 42.6 ± 15, 581 ± 131, 0.68 ± 0.38, 40.13 ± 9.07 and 40.8 ± 12.8 Bq per kg, respectively. The average Hex, Raeq, Dout, AED and ELCR were 0.40, 146 Bq per kg, 68.8 nGy per h, 0.09 mSv per y and 3.29E-04, respectively. These data showed an acceptable level of risk to residents near the nuclear power plant and that the current radioactivity in the soil may not pose immediate harm to residents living close to the nuclear power plant. The observed lower AED and 40 K and 137Cs concentrations were comparable to other studies, whilst ELCR was higher than the world average of 2.9E-04. The commissioning of the Shidaowan nuclear power plant is potentially safe for the surrounding residents; further continuous monitoring is recommended.

Radiological safety assessment for transportation of reactor pressure vessel during decommissioning of a nuclear power plant in Korea.

In Korea, decommissioning of nuclear power plants and transportation of the decommissioning waste are expected to expand in the near future. It is necessary to confirm that radiological risks to the public and workers are not significant through radiological safety assessment. The objective of this study is to assess the radiological safety for transportation of RPV waste, which is a major decommissioning waste with relatively high level of radioactivity. It was assumed that the waste would be transported to the Gyeongju disposal facility by land transportation. First, the source term and transportation method of the RPV waste were determined, and the external dose rates from the waste were calculated using MCNP. Then, transportation scenarios were assumed under both normal and accident conditions. Under the scenarios, radiation doses were calculated using the RADTRAN. Under normal operation scenarios without a transportation accident, assuming 40 shipments per year, the average individual doses for the public ranged from 6.56×10-6to 2.18×10-2mSv yr-1. The maximum individual doses for only a single shipment ranged from 2.43×10-6to 3.14×10-1mSv. For cargo handlers and vehicle crew members, the average doses were 2.26×101mSv yr-1and 2.95 mSv yr-1, respectively. Under transportation accident scenarios, average individual radiological risks which are product of the radiation doses and the annual accident rates ranged from 1.14×10-11to 1.61×10-10mSv yr-1by transportation route segment when considering the transportation accident rate. Average individual doses assuming transportation accident occurrence ranged from 2.62×10-4to 1.42×10-3mSv. The maximum individual dose under accident conditions was 7.99×10-2mSv. The calculated doses were below the regulatory limits in Korea. However, relatively high doses were observed for cargo handlers and vehicle crew members because of conservative assumptions. This study results can be used as basic data for the radiological safety assessment for the decommissioning waste transportation in the future.

Long-term radiocarbon variation studies in the air and tree rings of Slovakia.

Fifty-five years of radiocarbon variation studies are reviewed with an emphasis on a better understanding of the impacts of the Bohunice nuclear power plant and fossil fuel CO2 on the atmosphere and biosphere of Slovakia. The maximum Δ14C levels in the air up to about 1200‰ were observed during the 1970s at the Zlkovce monitoring station, which after 2005 decreased to <30‰. A relative decrease in the atmospheric Δ14C levels due to increasing levels of fossil CO2 in the atmosphere has also been significant, for example, in Bratislava down to about -330‰, but after 2005 they were only <50‰ below the Jungfraujoch European clean-air level. The tree-ring data, averaging the annual Δ14C levels for several stations in Slovakia, have been in agreement with the atmospheric data, as well as with the newly established clean-air station at Jasná in central Slovakia. Future 14C levels will depend strongly on fossil CO2 levels in the atmosphere, which will change the bomb 14C era to the fossil CO2 era. New investigations of 14C variations in the atmosphere-biosphere-hydrosphere compartments represent a great challenge for radiocarbon science, important for better understanding of environmental processes, climate change, and impacts of human activities on the total environment. This new era of radiocarbon research will also need new developments in radiocarbon analytical technologies, as further progress in accuracy and precision of results (<1‰) will be needed to meet the new radiocarbon challenges.

Study on the relationship between the dispersal of wild boar (Sus scrofa) and the associated variability of Cesium-137 concentrations in its muscle Post-Fukushima Daiichi Nuclear Power Plant accident.

After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011, the wild boar (Sus scrofa) population within the Fukushima Evacuation Zone (FEZ) increased substantially in size and distribution. This growing population and their potential dispersal from the FEZ, where they are exposed to high levels of radionuclides, into the surrounding landscape underscores the need to better understand boar movement patterns in order to establish policies for managing shipping restrictions for boar meat and develop management strategies. In this study, we quantified the genetic population structure of boar in and around Fukushima prefecture using sequence data of the mitochondrial DNA control region and MIG-seq analysis using 348 boar samples to clarify boar dispersal patterns. Among boar samples, seven Asian haplotypes and one European haplotype were detected. The European haplotype originated from hybridization between domestic pigs and native boar in the evacuation zone after the accident and was detected in 15 samples across a broad geographic area. Our MIG-seq analysis revealed genetic structure of boar was significantly different between boar inhabiting the eastern (including FEZ. i.e., East clade) and western (i.e., West clade) regions in Fukushima prefecture. In addition, we investigated the relationships between boar dispersal and Cesium (Cs)-137 activity concentrations in boar muscle using MIG-seq genetic data in Nihonmatsu city, located in the central-northern region of Fukushima. High Cs-137 activity concentrations, exceeding 1000 Bq/kg, in boar muscle had a significantly high probability of belonging to the East clade within localized regions. Thus, our results provide evidence of the spatial scale of dispersal of individuals or offspring of boar from the FEZ. Results of this research also indicate that dispersal of individuals between areas with different Cs-137 contamination levels is one of the biggest factors contributing to variation in Cs-137 activity concentration in boar muscle within localized regions.

Categorization of disaster-related deaths in Minamisoma city after the Fukushima nuclear disaster using clustering analysis.

The medical situation during disasters often differs from that at usual times. Disasters can lead to significant mortality that can be difficult to monitor. The types of disaster-related deaths are largely unknown. In this study, we conducted a survey to categorize the disaster-related deaths caused by a radiation disaster. A total of 520 people living in Minamisoma City, Fukushima Prefecture, at the time of the Fukushima Daiichi Nuclear Power Plant accident, who were certified to have died due to disaster-related causes were surveyed. We divided the participants into those who were at home at the time of the earthquake and those who were in hospitals or facilities when the disaster struck and conducted a hierarchical cluster analysis of the two groups. Disaster-related deaths could be divided into seven groups for those who were at home at the time of the disaster and five groups for those who were in hospitals or facilities at the time of the disaster. Each group showed different characteristics, such as "the group with disabilities," "the group receiving care," and "the group with depression," and it became evident that not only uniform post-disaster support, but support tailored to the characteristics of each group is necessary.

Measuring cognitive workload in the nuclear control room: a review.

Despite the substantial literature and human factors guidance, evaluators report challenges in selecting cognitive workload measures for the evaluation of complex human-technology systems. A review of 32 articles found that self-report measures and secondary tasks were systematically sensitive to human-system interface conditions and correlated with physiological measures. Therefore, including a self-report measure of cognitive workload is recommended when evaluating human-system interfaces. Physiological measures were mainly used in method studies, and future research must demonstrate the utility of these measures for human-system evaluation in complex work settings. However, indexes of physiological measures showed promise for cognitive workload assessment. The review revealed a limited focus on the measurement of excessive cognitive workload, although this is a key topic in nuclear process control. To support human-system evaluation of adequate cognitive workload, future research on behavioural measures may be useful in the identification and analysis of underload and overload.

This review provides background for the selection of cognitive workload measures for the evaluation of complex human­technology systems and identifies future research needs for applied cognitive workload assessment.

Assessment of Radiation Doses to the General Public around Nuclear Power Plants Based on Representative Person Concept.

ABSTRACT: The International Commission on Radiological Protection recommended that the representative person concept should be used in radiation dose assessment of the general public to specify exposed individuals. The objective of this study is to assess radiation doses of the residents around nuclear power plants (NPPs) in relation to the introduction of the representative person concept. Critical group candidates and representative agro-livestock product producing areas were selected around a NPP site by considering radioactive effluents and regional meteorological data, geographical information, etc. A total of five exposure scenarios, including adult (non-fishery, fishery, and commuter), 10-y-old, and 1-y-old groups, were selected for the dose assessment. Generally, radiation doses were higher for 1-y-old, 10-y-old, and adult groups, in that sequence. There was no significant difference among the radiation doses by occupation in adult groups. Radiation dose results calculated by applying the representative person concept and dose assessment method currently used in Korea were compared. Application of the representative person concept results in lower radiation dose by 68.2% due to consideration of actual residential and agro-livestock product producing areas for the radiation dose assessment, by 13.3% due to the application method of habit data for dose calculation, and by 33.3% due to representative value of the dose results. Finally, considering all the factors above, radiation dose calculated by the current dose assessment method was 8.16 × 10 -2 mSv y -1 , while that calculated using the representative person concept was 1.40 × 10 -2 mSv y - 1 (82.8% lower). The results of this study can be used as reference data when introducing the representative person concept to the regulatory systems in Korea.

Continuing Steady Challenges Involved in the Lifting of Evacuation Orders after the Fukushima Daiichi Nuclear Power Plant Accident.

ABSTRACT: Steady efforts for recovery and reconstruction after the accident at the Fukushima Daiichi Nuclear Power Plant have been underway for 12.5 y. The present study reports on the world's first-ever efforts for a gradual and safe return to areas contaminated with radiation fallout and reconstruction support by providing an overview of the actual situation regarding the strategy for return, especially with the transition after the lifting of the evacuation order by the Japanese government. A stage-by-stage progression of the evacuation order and lifting strategy is summarized chronologically in the following three phases: the Emergency Phase in 2011, the Reconstruction Phase from 2013 to 2020, and the Challenging Phase for Lifting All the Evacuation Zones from 2023. Through the lifting strategy of the government, the number of evacuees decreased significantly, especially during the Reconstruction Phase, from 152,113 in May 2013 to 37,826 in May 2020. It is crucial to strengthen support for reconstruction and convey an unbiased and accurate understanding of Fukushima Prefecture by developing a concrete strategy for community development and increasing the size of the exchange population.