PLOS ONE: [sortOrder=DATE_NEWEST_FIRST, sort=Date, newest first, q=subject:"Nuclear engineering"]PLOShttps://journals.plos.org/plosone/webmaster@plos.orgaccelerating the publication of peer-reviewed sciencehttps://journals.plos.org/plosone/search/feed/atom?sortOrder=DATE_NEWEST_FIRST&unformattedQuery=subject:%22Nuclear+engineering%22&sort=Date,+newest+firstAll PLOS articles are Open Access.https://journals.plos.org/plosone/resource/img/favicon.icohttps://journals.plos.org/plosone/resource/img/favicon.ico2024-03-28T11:25:13ZUSA vs Russia in the scientific arenaGiovanni AbramoCiriaco Andrea D’AngeloFlavia Di Costa10.1371/journal.pone.02881522023-07-06T14:00:00Z2023-07-06T14:00:00Z<p>by Giovanni Abramo, Ciriaco Andrea D’Angelo, Flavia Di Costa</p>
This work contrasts the scientific standing of the USA and Russia in 146 scientific disciplines. We consider four dimensions of competitive positioning: the contribution to global scientific advancement, the researchers’ productivity, the scientific specialization indexes, and the efficiency in resource allocation across disciplines. Differently from previous literature, we use discipline-normalized output to input indicators, thus avoiding distortions due to different intensities of publication across disciplines. Results show that the USA outperforms Russia in contribution to world scholarly impact in all but four disciplines, and is more productive in all but two disciplines. The USA is less efficient in allocating resources to the disciplines where it performs better, probably due to its higher research diversification.Objective stress values during radiation emergency medicine for future human resources: Findings from a survey of nursesKeita IyamaYoshinobu SatoTakashi OhbaArifumi Hasegawa10.1371/journal.pone.02744822022-09-14T14:00:00Z2022-09-14T14:00:00Z<p>by Keita Iyama, Yoshinobu Sato, Takashi Ohba, Arifumi Hasegawa</p>
Introduction <p>Shortages of human resources in radiation emergency medicine (REM) caused by the anxiety and stress of due to working in REM, are a major concern. The present study aimed to quantify stress and identify which tasks involved in REM response are most stressful to help educate (human resource development) and effectively reduce stress in workers. Furthermore, the final goal was to reduce the anxiety and stress of medical personnel in the future, which will lead to sufficient human resources in the field of REM.</p> Methods <p>In total, 74 nurses who attended an REM seminar were asked to answer a questionnaire (subjective) survey and wear a shirt-type electrocardiogram (objective survey). Then, informed consent was obtained from 39 patients included in the analysis. In the objective survey, average stress values of participants for each activity during the seminar were calculated based on heart rate variability (HRV). The average stress value was output as stress on a relative scale of 0–100, based on the model which is the percentile of the low-frequency/high-frequency ratio derived from HRV at any point in time obtained over time.</p> Results <p>A total of 35 (89.7%) participants answered that they had little or no knowledge of nuclear disaster and 33 (84.6%) had more than moderate anxiety. Stress values observed during the decontamination process were significantly higher than those observed when wearing and removing protective gear and during the general medical treatment process (<i>P</i> = 0.001, 0.004, and 0.023, respectively). Stress values did not increase during general medical treatment performed in protective clothing, but increased during the decontamination process, which is the task characteristic of REM.</p> Discussion <p>Stress felt by medical personnel throughout the entire REM response may be effectively reduced by providing careful education/training to reduce stress during the decontamination process. Reducing stress during REM response effectively could contribute to resolving the shortage of human resources in this field.</p>Concerns related to returning home to a “difficult-to-return zone” after a long-term evacuation due to Fukushima Nuclear Power Plant Accident: A qualitative studyTomoo HidakaHideaki KasugaTakeyasu KakamuShota EndoYusuke MasuishiTetsuhito Fukushima10.1371/journal.pone.02736842022-08-29T14:00:00Z2022-08-29T14:00:00Z<p>by Tomoo Hidaka, Hideaki Kasuga, Takeyasu Kakamu, Shota Endo, Yusuke Masuishi, Tetsuhito Fukushima</p>
This study aimed to identify concerns related to returning to the Nagadoro district of Iitate Village, Fukushima Prefecture, Japan, in 2023 among its residents as it is designated as a difficult-to-return zone after the Fukushima Daiichi nuclear power plant accident. The following four concerns were extracted from the interviews and qualitative analysis: “Difficulties in restarting/continuing farming,” which represent the difficulties in making a living from agriculture due to the absence of family members and neighbors, and the insufficient radiation decontamination; “Discriminatory treatment of products and residents from villagers,” which suggests the presence of discriminations that residents of Nagadoro district are eccentrics and its agricultural products should not be treated together with those of other districts in the Village due to the recognition that the district is severely polluted by radiation; “Shift of the responsibility of returning home from the country to residents by scapegoating,” which is characterized by the shift of responsibility from the government to the residents, including harsh social criticism of the residents of Nagadoro district for not returning even though the evacuation order has been lifted, when it should have been the government’s responsibility to recover the district to a habitable state; “Loss of options for continued evacuation,” which is the loss or weakening of the position of residents of the Nagadoro district who continue to evacuate, and of administrative compensation, resulting from the legal change that they are no longer “evacuees” after the evacuation order is lifted. The findings of this study will provide a foundation for the support of residents of the Nagadoro district after lifting the evacuation order scheduled for the spring of 2023. The findings may be transferable to the residents of other difficult-to-return zones expected to be lifted after the Nagadoro district and to also a radiation disaster-affected place in the future.Important factors for public acceptance of the final disposal of contaminated soil and wastes resulting from the Fukushima Daiichi nuclear power station accidentMomo TakadaKosuke ShiraiMichio MurakamiSusumu OhnumaJun NakataniKazuo YamadaMasahiro OsakoTetsuo Yasutaka10.1371/journal.pone.02697022022-06-22T14:00:00Z2022-06-22T14:00:00Z<p>by Momo Takada, Kosuke Shirai, Michio Murakami, Susumu Ohnuma, Jun Nakatani, Kazuo Yamada, Masahiro Osako, Tetsuo Yasutaka</p>
Large-scale decontamination work has been carried out in the aftermath of the Fukushima Daiichi nuclear power station accident in Japan in 2011. The soil that was removed and the wastes that were generated during the decontamination will be finally disposed of outside Fukushima Prefecture by 2045. To ensure successful and socially acceptable implementation of this final disposal process, it is essential to have a good understanding of what is considered important by the public. We used a choice-based conjoint analysis in the form of a web-based questionnaire to examine the relative importance of several factors in the choice of the final disposal sites of the removed soil and incinerated ash of the wastes. The questionnaires covered four attributes and 12 levels, namely the distance between the disposal site and a person’s residential area, procedural fairness (decision process), distributive fairness (direct mitigation of inequity through multiple siting locations), and the volume and radioactivity of the substances to be disposed. Responses were received from 4000 people nationwide, excluding Fukushima residents. The results showed that the respondents gave high importance to choosing sites that were far from residential areas and to the two types of fairness, especially distributive fairness. The respondents showed no preference for the volume and radioactivity. This indicates that the public cares about the fairness of the siting for the final disposal sites and feels uncomfortable with plans for a final disposal site located close to them. Distributive fairness is necessary to pursue consensus in addition to procedural fairness.Individual external doses below the lowest reference level of 1 mSv per year five years after the 2011 Fukushima nuclear accident among all children in Soma City, Fukushima: A retrospective observational studyMasaharu TsubokuraMichio MurakamiShuhei NomuraTomohiro MoritaYoshitaka NishikawaClaire LeppoldShigeaki KatoMasahiro Kami10.1371/journal.pone.01723052017-02-24T14:00:00Z2017-02-24T14:00:00Z<p>by Masaharu Tsubokura, Michio Murakami, Shuhei Nomura, Tomohiro Morita, Yoshitaka Nishikawa, Claire Leppold, Shigeaki Kato, Masahiro Kami</p>
After the 2011 Fukushima Daiichi nuclear power plant accident, little information has been available on individual doses from external exposure among residents living in radioactively contaminated areas near the nuclear plant; in the present study we evaluated yearly changes in the doses from external exposure after the accident and the effects of decontamination on external exposure. This study considered all children less than 16 years of age in Soma City, Fukushima who participated in annual voluntary external exposure screening programs during the five years after the accident (n = 5,363). In total, 14,405 screening results were collected. The median participant age was eight years. The geometric mean levels of annual additional doses from external exposure attributable to the Fukushima accident, decreased each year: 0.60 mSv (range: not detectable (ND)–4.29 mSv), 0.37 mSv (range: ND–3.61 mSv), 0.22 mSv (range: ND–1.44 mSv), 0.20 mSv (range: ND–1.87 mSv), and 0.17 mSv (range: ND–0.85 mSv) in 2011, 2012, 2013, 2014, and 2015, respectively. The proportion of residents with annual additional doses from external exposure of more than 1 mSv dropped from 15.6% in 2011 to zero in 2015. Doses from external exposure decreased more rapidly than those estimated from only physical decay, even in areas without decontamination (which were halved in 395 days from November 15, 2011), presumably due to the weathering effects. While the ratios of geometric mean doses immediately after decontamination to before were slightly lower than those during the same time in areas without decontamination, annual additional doses reduced by decontamination were small (0.04–0.24 mSv in the year of immediately after decontamination was completed). The results of this study showed that the levels of external exposure among Soma residents less than 16 years of age decreased during the five years after the Fukushima Daiichi nuclear power plant accident. Decontamination had only limited and temporal effects on reducing individual external doses.Relationship between Individual External Doses, Ambient Dose Rates and Individuals’ Activity-Patterns in Affected Areas in Fukushima following the Fukushima Daiichi Nuclear Power Plant AccidentWataru NaitoMotoki UesakaChie YamadaTadahiro KurosawaTetsuo YasutakaHideki Ishii10.1371/journal.pone.01588792016-08-05T14:00:00Z2016-08-05T14:00:00Z<p>by Wataru Naito, Motoki Uesaka, Chie Yamada, Tadahiro Kurosawa, Tetsuo Yasutaka, Hideki Ishii</p>
The accident at Fukushima Daiichi Nuclear Power Plant on March 11, 2011, released radioactive material into the atmosphere and contaminated the land in Fukushima and several neighboring prefectures. Five years after the nuclear disaster, the radiation levels have greatly decreased due to physical decay, weathering, and decontamination operations in Fukushima. The populations of 12 communities were forced to evacuate after the accident; as of March 2016, the evacuation order has been lifted in only a limited area, and permanent habitation is still prohibited in most of the areas. In order for the government to lift the evacuation order and for individuals to return to their original residential areas, it is important to assess current and future realistic individual external doses. Here, we used personal dosimeters along with the Global Positioning System and Geographic Information System to understand realistic individual external doses and to relate individual external doses, ambient doses, and activity-patterns of individuals in the affected areas in Fukushima. The results showed that the additional individual external doses were well correlated to the additional ambient doses based on the airborne monitoring survey. The results of linear regression analysis suggested that the additional individual external doses were on average about one-fifth that of the additional ambient doses. The reduction factors, which are defined as the ratios of the additional individual external doses to the additional ambient doses, were calculated to be on average 0.14 and 0.32 for time spent at home and outdoors, respectively. Analysis of the contribution of various activity patterns to the total individual external dose demonstrated good agreement with the average fraction of time spent daily in each activity, but the contribution due to being outdoors varied widely. These results are a valuable contribution to understanding realistic individual external doses and the corresponding airborne monitoring-based ambient doses and time-activity patterns of individuals. Moreover, the results provide important information for predicting future cumulative doses after the return of residents to evacuation order areas in Fukushima.Measurement of Individual Doses of Radiation by Personal Dosimeter Is Important for the Return of Residents from Evacuation Order Areas after Nuclear DisasterMakiko OritaNaomi HayashidaYasuyuki TairaYoshiko FukushimaJuichi IdeYuuko EndoTakashi KudoShunichi YamashitaNoboru Takamura10.1371/journal.pone.01219902015-03-25T14:00:00Z2015-03-25T14:00:00Z<p>by Makiko Orita, Naomi Hayashida, Yasuyuki Taira, Yoshiko Fukushima, Juichi Ide, Yuuko Endo, Takashi Kudo, Shunichi Yamashita, Noboru Takamura</p>
To confirm the availability of individual dose evaluation for the return of residents after the accident at the Fukushima Dai-ichi Nuclear Power Plant (FNPP), we evaluated individual doses of radiation as measured by personal dosimeters in residents who temporarily stayed in Evacuation Order Areas in Kawauchi village, which is partially located within a 20 km radius of the FNPP. We also compared individual doses with the external radiation doses estimated from the ambient dose rates and with doses estimated from the concentrations of radionuclides in the soil around each individual’s house. Individual doses were significantly correlated with the ambient doses in front of the entrances to the houses (r = 0.90, p<0.01), in the backyards (r = 0.41, p<0.01) and in the nearby fields (r = 0.80, p<0.01). The maximum cumulative ambient doses in the backyards and fields around the houses were 6.38 and 9.27 mSv/y, respectively. The maximum cumulative individual dose was 3.28 mSv/y, and the median and minimum doses were 1.35 and 0.71 mSv/y. The estimated external effective doses from concentrations of artificial radionuclides in soil samples ranged from 0.03 to 23.42 mSv/y. The individual doses were moderately correlated with external effective doses in the backyards (r = 0.38, p<0.01) and in the fields (r = 0.36, p<0.01); however, the individual doses were not significantly correlated with the external effective doses in front of the entrances (r = 0.01, p = 0.92). Our study confirmed that individual doses are low levels even in the evacuation order area in Kawauchi village, and external effective dose levels are certainly decreasing due to the decay of artificial radionuclides and the decontamination of contaminated soil. Long-term follow-up of individual doses as well as internal-exposure doses, environmental monitoring and reconstruction of infrastructure are needed so that residents may return to their hometowns after a nuclear disaster.Cost and Effectiveness of Decontamination Strategies in Radiation Contaminated Areas in Fukushima in Regard to External Radiation DoseTetsuo YasutakaWataru NaitoJunko Nakanishi10.1371/journal.pone.00753082013-09-17T14:00:00Z2013-09-17T14:00:00Z<p>by Tetsuo Yasutaka, Wataru Naito, Junko Nakanishi</p>
The objective of the present study is to evaluate the cost and effectiveness of decontamination strategies in the special decontamination areas in Fukushima in regard to external radiation dose. A geographical information system (GIS) was used to relate the predicted external dose in the affected areas to the number of potential inhabitants and the land use in the areas. A comprehensive review of the costs of various decontamination methods was conducted as part of the analysis. The results indicate that aerial decontamination in the special decontamination areas in Fukushima would be effective for reducing the air dose rate to the target level in a short period of time in some but not all of the areas. In a standard scenario, analysis of cost and effectiveness suggests that decontamination costs for agricultural areas account for approximately 80% of the total decontamination cost, of which approximately 60% is associated with storage. In addition, the costs of decontamination per person per unit area are estimated to vary greatly. Appropriate selection of decontamination methods may significantly decrease decontamination costs, allowing more meaningful decontamination in terms of the limited budget. Our analysis can help in examining the prioritization of decontamination areas from the viewpoints of cost and effectiveness in reducing the external dose. Decontamination strategies should be determined according to air dose rates and future land-use plans.Vertical Distribution and Estimated Doses from Artificial Radionuclides in Soil Samples around the Chernobyl Nuclear Power Plant and the Semipalatinsk Nuclear Testing SiteYasuyuki TairaNaomi HayashidaRimi TsuchiyaHitoshi YamaguchiJumpei TakahashiAlexander KazlovskyMarat UrazalinTolebay RakhypbekovShunichi YamashitaNoboru Takamura10.1371/journal.pone.00575242013-02-28T14:00:00Z2013-02-28T14:00:00Z<p>by Yasuyuki Taira, Naomi Hayashida, Rimi Tsuchiya, Hitoshi Yamaguchi, Jumpei Takahashi, Alexander Kazlovsky, Marat Urazalin, Tolebay Rakhypbekov, Shunichi Yamashita, Noboru Takamura</p>
For the current on-site evaluation of the environmental contamination and contributory external exposure after the accident at the Chernobyl Nuclear Power Plant (CNPP) and the nuclear tests at the Semipalatinsk Nuclear Testing Site (SNTS), the concentrations of artificial radionuclides in soil samples from each area were analyzed by gamma spectrometry. Four artificial radionuclides (<sup>241</sup>Am,<sup> 134</sup>Cs, <sup>137</sup>Cs, and <sup>60</sup>Co) were detected in surface soil around CNPP, whereas seven artificial radionuclides (<sup>241</sup>Am, <sup>57</sup>Co,<sup> 137</sup>Cs, <sup>95</sup>Zr, <sup>95</sup>Nb, <sup>58</sup>Co, and <sup>60</sup>Co) were detected in surface soil around SNTS. Effective doses around CNPP were over the public dose limit of 1 mSv/y (International Commission on Radiological Protection, 1991). These levels in a contaminated area 12 km from Unit 4 were high, whereas levels in a decontaminated area 12 km from Unit 4 and another contaminated area 15 km from Unit 4 were comparatively low. On the other hand, the effective doses around SNTS were below the public dose limit. These findings suggest that the environmental contamination and effective doses on the ground definitely decrease with decontamination such as removing surface soil, although the effective doses of the sampling points around CNPP in the present study were all over the public dose limit. Thus, the remediation of soil as a countermeasure could be an extremely effective method not only for areas around CNPP and SNTS but also for areas around the Fukushima Dai-ichi Nuclear Power Plant (FNPP), and external exposure levels will be certainly reduced. Long-term follow-up of environmental monitoring around CNPP, SNTS, and FNPP, as well as evaluation of the health effects in the population residing around these areas, could contribute to radiation safety and reduce unnecessary exposure to the public.Evaluation of Environmental Contamination and Estimated Radiation Doses for the Return to Residents’ Homes in Kawauchi Village, Fukushima PrefectureYasuyuki TairaNaomi HayashidaHitoshi YamaguchiShunichi YamashitaYuukou EndoNoboru Takamura10.1371/journal.pone.00458162012-09-26T14:00:00Z2012-09-26T14:00:00Z<p>by Yasuyuki Taira, Naomi Hayashida, Hitoshi Yamaguchi, Shunichi Yamashita, Yuukou Endo, Noboru Takamura</p>
To evaluate the environmental contamination and radiation exposure dose rates due to artificial radionuclides in Kawauchi Village, Fukushima Prefecture, the restricted area within a 30-km radius from the Fukushima Dai-ichi Nuclear Power Plant (FNPP), the concentrations of artificial radionuclides in soil samples, tree needles, and mushrooms were analyzed by gamma spectrometry. Nine months have passed since samples were collected on December 19 and 20, 2011, 9 months after the FNPP accident, and the prevalent dose-forming artificial radionuclides from all samples were <sup>134</sup>Cs and <sup>137</sup>Cs. The estimated external effective doses from soil samples were 0.42–7.2 µSv/h (3.7–63.0 mSv/y) within the 20-km radius from FNPP and 0.0011–0.38 µSv/h (0.010–3.3 mSv/y) within the 20–30 km radius from FNPP. The present study revealed that current levels are sufficiently decreasing in Kawauchi Village, especially in areas within the 20- to 30-km radius from FNPP. Thus, residents may return their homes with long-term follow-up of the environmental monitoring and countermeasures such as decontamination and restrictions of the intake of foods for reducing unnecessary exposure. The case of Kawauchi Village will be the first model for the return to residents’ homes after the FNPP accident.Absorption of Radionuclides from the Fukushima Nuclear Accident by a Novel Algal StrainHiroki ShimuraKatsuhiko ItohAtsushi SugiyamaSayaka IchijoMasashi IchijoFumihiko FuruyaYuji NakamuraKen KitaharaKazuhiko KobayashiYasuhiro YukawaTetsuro Kobayashi10.1371/journal.pone.00442002012-09-12T14:00:00Z2012-09-12T14:00:00Z<p>by Hiroki Shimura, Katsuhiko Itoh, Atsushi Sugiyama, Sayaka Ichijo, Masashi Ichijo, Fumihiko Furuya, Yuji Nakamura, Ken Kitahara, Kazuhiko Kobayashi, Yasuhiro Yukawa, Tetsuro Kobayashi</p>
Large quantities of radionuclides have leaked from the Fukushima Daiichi Nuclear Power Plant into the surrounding environment. Effective prevention of health hazards resulting from radiation exposure will require the development of efficient and economical methods for decontaminating radioactive wastewater and aquatic ecosystems. Here we describe the accumulation of water-soluble radionuclides released by nuclear reactors by a novel strain of alga. The newly discovered green microalgae, <i>Parachlorella</i> sp. <i>binos</i> (Binos) has a thick alginate-containing extracellular matrix and abundant chloroplasts. When this strain was cultured with radioiodine, a light-dependent uptake of radioiodine was observed. In dark conditions, radioiodine uptake was induced by addition of hydrogen superoxide. High-resolution secondary ion mass spectrometry (SIMS) showed a localization of accumulated iodine in the cytosol. This alga also exhibited highly efficient incorporation of the radioactive isotopes strontium and cesium in a light-independent manner. SIMS analysis showed that strontium was distributed in the extracellular matrix of Binos. Finally we also showed the ability of this strain to accumulate radioactive nuclides from water and soil samples collected from a heavily contaminated area in Fukushima. Our results demonstrate that Binos could be applied to the decontamination of iodine, strontium and cesium radioisotopes, which are most commonly encountered after nuclear reactor accidents.Decontamination Efficiencies of Pot-Type Water Purifiers for <sup>131</sup>I, <sup>134</sup>Cs and <sup>137</sup>Cs in Rainwater Contaminated during Fukushima Daiichi Nuclear DisasterShogo HigakiMasahiro Hirota10.1371/journal.pone.00371842012-05-16T14:00:00Z2012-05-16T14:00:00Z<p>by Shogo Higaki, Masahiro Hirota</p>
Rainwater was contaminated by a large release of radionuclides into the environment during the Fukushima Daiichi nuclear disaster. It became a matter of concern for Japan when several water purification plants detected <sup>131</sup>I contamination in the drinking water. In the present study, the decontamination efficiency of two easily obtainable commercial water purifiers were examined for rainwater contaminated with <sup>131</sup>I, <sup>134</sup>Cs and <sup>137</sup>Cs. The water purifiers removed 94.2–97.8% of the<sup> 131</sup>I and 84.2–91.5% of the <sup>134</sup>Cs and <sup>137</sup>Cs after one filtration. Seven filtrations removed 98.2–99.6% of the <sup>131</sup>I and over 98.0% of the <sup>134</sup>Cs and <sup>137</sup>Cs. From a practical perspective, over the fourth filtrations were not needed because of no significant improvements after the third filtration.Individual Radiation Exposure Dose Due to Support Activities at Safe Shelters in Fukushima PrefectureSatoru MonzenMasahiro HosodaShinji TokonamiMinoru OsanaiHironori YoshinoYoichiro HosokawaMitsuaki A. YoshidaMasatoshi YamadaYasushi AsariKei SatohIkuo Kashiwakura10.1371/journal.pone.00277612011-11-16T14:00:00Z2011-11-16T14:00:00Z<p>by Satoru Monzen, Masahiro Hosoda, Shinji Tokonami, Minoru Osanai, Hironori Yoshino, Yoichiro Hosokawa, Mitsuaki A. Yoshida, Masatoshi Yamada, Yasushi Asari, Kei Satoh, Ikuo Kashiwakura</p>
Immediately after the accidents in the nuclear power stations in Fukushima on March 11, the Japanese Government ordered the evacuation of the residents within a 20-km radius from the station on March 12, and asked various institutions to monitor the contamination levels of the residents. Hirosaki University, which is located 355 km north of Fukushima City, decided to send support staff to Fukushima. This report summarizes the results of the exposure of 13 individual teams from March 15 to June 20. The support teams surveyed more than 5,000 people during this period. Almost all subjects had external contamination levels of less than 13 kcpm on Geiger-Müller (GM) survey meter, which is categorized as “no contamination level.” The 1<sup>st</sup> team showed the highest external exposure dose, but the 4<sup>th</sup> team onward showed no significant change. Subsequently, the internal radiation exposure was measured using a whole body counter that indicated undetectable levels in all staff members. Although the measured external radiation exposure dose cannot have serious biological effects on the health of an individual, a follow-up study of the residents in Fukushima and other regions where the radioactive material has spread will be required for a long time.