Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hirouchi, Jun; Takahara, Shogo; Watanabe, Masatoshi*
Journal of Radiological Protection, 45(2), p.021506_1 - 021506_13, 2025/05
Times Cited Count:0 Percentile:0.00(Environmental Sciences)Sheltering is a key countermeasure for mitigating radiation exposures during nuclear power plant accidents. The effectiveness of sheltering in minimizing inhalation exposure is commonly expressed using the reduction factor, which is the ratio of indoor to outdoor cumulative doses. The indoor dose is primarily influenced by the air exchange rate, penetration factor, and indoor deposition rate. Additionally, the air exchange rate is dependent on wind speed. In previous studies, the reduction factor was often treated as a constant value or calculated under constant wind speed conditions. However, wind speed varies in reality. This study investigated the effect of temporal variations in wind speed on the reduction factor and developed a simplified correction method to account for these variations. The results revealed that temporal variations in wind speed caused the reduction factor to differ by a factor of approximately two. Using the simplified correction method, the corrected reduction factors agreed, on average, within 10% of those calculated using a method that explicitly considers temporal variations in actual wind speed. Additionally, the computational cost was reduced by more than 20 times.
Hirouchi, Jun; Watanabe, Masatoshi*; Hayashi, Naho; Nagakubo, Azusa; Takahara, Shogo
Journal of Radiological Protection, 45(1), p.011506_1 - 011506_11, 2025/03
Times Cited Count:0 Percentile:0.00(Environmental Sciences)Public living in areas contaminated by nuclear accidents is exposed to radiation in the early phase and over the long term. Even under similar accident scenarios, radiation doses and sheltering effectiveness, which is one of the protective measures, depend on meteorological conditions and the surrounding environment. Radiation doses and sheltering effectiveness in the early phase of nuclear accidents are crucial information for the public as well as national and local governments planning a nuclear emergency preparedness. In this study, we assessed radiation doses and sheltering effectiveness at sites with nuclear facilities in Japan using the Off-Site Consequence Analysis code for Atmospheric Release accidents, which is one of the level-3 probabilistic risk assessment codes, for five accident scenarios: three scenarios from past severe accident studies, a scenario defined by the Nuclear Regulation Authority in Japan, and a scenario corresponding to the Fukushima-Daiichi Nuclear Power Station accident. The sheltering effectiveness differed by up to approximately 50% among the accident scenarios at the same sites and by approximately 20%50% among sites under the same accident scenario. Differences in the radionuclide composition among the accident scenarios and the differences in wind speeds among the sites primarily caused these differences in sheltering effectiveness.
Hirouchi, Jun; Kujiraoka, Ikuo; Takahara, Shogo; Takada, Momo*; Schneider, T.*; Kai, Michiaki*
Journal of Radiological Protection, 45(1), p.011508_1 - 011508_14, 2025/03
Times Cited Count:0 Percentile:0.00(Environmental Sciences)no abstracts in English
Masuda, Tsuyoshi*; Manabe, Kentaro
Journal of Radiological Protection, 44(3), p.031517_1 - 031517_8, 2024/09
Times Cited Count:0 Percentile:0.00(Environmental Sciences)If organic compound containing tritium or C-14 is taken into the body, it is metabolised into inorganic matter at a certain rate and excreted quickly. On the other hand, tritium and C-14 that remain in the organic form have a longer biological half-life than inorganic forms, and therefore contribute more to the radiation dose. For this reason, the metabolic ratio of organic matter is important for dose assessment. However, the International Commission on Radiological Protection (ICRP) sets the metabolic ratio based on animal experiments or carbon mass balance. Therefore, we conducted a dose assessment by referring to the results of measuring the metabolic ratio by orally administering organic matter labelled with deuterium or C-13 to humans. As a result, it was found that the ICRP dose coefficient was appropriate for organic matter containing tritium, but that it was about twice as conservative for organic matter containing C-14.
Ishii, Junya*; Shimizu, Morihito*; Kato, Masahiro*; Kurosawa, Tadahiro*; Tsuji, Tomoya; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Watabe, Hiroshi*
Journal of Radiological Protection, 44(3), p.031516_1 - 031516_8, 2024/09
Times Cited Count:0 Percentile:0.00(Environmental Sciences)Saisu, Motofumi*; Ando, Tadahiko*; Uchiyama, Keizo*; Ueno, Toshihiro*; Takizawa, Koichi*; Endo, Yuji*; Yoshimura, Kazuya; Sanada, Yukihisa
Journal of Radiological Protection, 44(2), p.021518_1 - 021518_16, 2024/06
Times Cited Count:0 Percentile:0.00(Environmental Sciences)Hirouchi, Jun; Kujiraoka, Ikuo; Takahara, Shogo; Takada, Momo*; Schneider, T.*; Kai, Michiaki*
Journal of Radiological Protection, 44(2), p.021510_1 - 021510_10, 2024/06
Times Cited Count:2 Percentile:75.80(Environmental Sciences)no abstracts in English
Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*
Journal of Radiological Protection, 42(4), p.041503_1 - 041503_12, 2022/12
Times Cited Count:3 Percentile:41.50(Environmental Sciences)Sheltering is one of the countermeasures against radiation exposure during nuclear accidents. The effectiveness of sheltering for inhalation exposure is often expressed by the reduction factor, which is defined as the ratio of the indoor to the outdoor cumulative radioactivity concentrations or doses. The indoor concentration is mainly controlled by the air exchange rate, penetration factor, and indoor deposition rate. Meanwhile, the air exchange rate depends on surrounding environmental conditions: the wind speed, leakage area normalized by the floor area of the house, and gross building coverage ratio. In this study, the ranges of the uncertainty of the reduction factors for particles and I were investigated under various environmental conditions, and sensitivity analyses were conducted to understand the parameter with the most influence on the uncertainty of the reduction factor. From the results of the uncertainty analyses, the calculated reduction factor was highly variable depending on the environmental condition and the airtightness of the houses. The uncertainty ranges of the reduction factor for particles and I
were up to 0.9 and 0.3, respectively, and were smaller for newer houses. From the results of the sensitivity analyses, the wind speed was the most influential parameter on the reduction factor. Additionally, the wind speed was less influential for the reduction factor in newer houses.
Andresz, S.*; Papp, C.*; Clarijs, T.*; Sakoda, Akihiro; Sez-Mu
oz, M.*; Qiu, R.*
Journal of Radiological Protection, 42(3), p.031516_1 - 031516_10, 2022/09
Times Cited Count:0 Percentile:0.00(Environmental Sciences)While online working seems to become more common since the start of the Covid-19 pandemic, social media has the potential to offer greater interactivity and networking capacities. It seems therefore relevant for the IRPA Young Generation Network to investigate the usage of social media by the young generation in radiation protection trough a survey disseminated online. It was also the opportunity to investigate the early feedbacks about on-line learning. The survey collected 89 answers from 15 countries. The most commonly used social media platforms are first Facebook, then LinkedIn and Twitter, but other social media where reported too. The respondents have a multi-objectives approach on social media, using it for different purposes (chiefly for sharing of news and RP related information/education material) and different audiences (ex. public, professional audience), and are not frenetic users based on the frequencies of publication and consultation and the challenges they see within social media. The survey collected the view of the young generation about their practical experience about learning in virtual setting and its advantages and disadvantages vs. in-person. Most participants expressed mixed-feeling about on-line learning. These results show that the young generation can play a role in supporting the extra and intra-communication of the RP community.
Yokoyama, Sumi*; Tatsuzaki, Hideo*; Tanimura, Yoshihiko; Yoshitomi, Hiroshi; Hirao, Shigekazu*; Aoki, Katsunori; Tachiki, Shuichi*; Ezaki, Iwao*; Hoshi, Katsuya; Tsujimura, Norio
Journal of Radiological Protection, 42(3), p.031504_1 - 031504_17, 2022/09
Times Cited Count:3 Percentile:28.39(Environmental Sciences)In Japan, the radiation-dose limit for the lens of the eye was revised in April 2021. Consequently, for workers, the numerical values of the equivalent dose to the lens of the eye are equal to those of the effective dose. Radiation workers, radiation safety officers and licensees must comply with regulations related to radiation protection and optimize protection. The new guidelines on dose monitoring of the lens of the eye developed by the Japan Health Physics Society recommend for the dose to be estimated near the eye for accurate estimation, when the dose to the lens approaches or exceeds the management criteria. However, there is limited information regarding the non-uniform exposure of nuclear power plant workers. In this study, the dose equivalents of high-dose-rate workplaces and the personal doses of 88 workers were estimated at four Japanese commercial nuclear power plant sites (RWR: 3 units and BWR: 3 units) and the dose to the lens of the eye and the exposure situations of the workers were analyzed.
Takahara, Shogo; Charnock, T. W.*; Silva, K.*; Hwang, W. T.*; Lee, J.*; Yu, C.*; Kamboj, S.*; Yankovich, T.*; Thiessen, K. M.*
Journal of Radiological Protection, 42(2), p.020517_1 - 020517_13, 2022/06
Times Cited Count:0 Percentile:0.00(Environmental Sciences)State-of-the-art dose assessment models were applied to estimate doses to the population in urban areas contaminated by the Fukushima Daiichi Nuclear Power Plant accident. Assessment results were compared among five models, and comparisons of model predictions with actual measurements were also made. Assessments were performed using both probabilistic and deterministic approaches. Predicted dose distributions in indoor and outdoor workers from a probabilistic approach were in good agreement with the actual measurements. In addition, when the models were applied to assess the doses to a representative person, based on a concept suggested by the International Commission on Radiological Protection (ICRP), it was evident that doses to the representative person obtained with a deterministic approach were always higher than those obtained with a probabilistic approach.
Strand, P.*; Jefferies, N.*; Koma, Yoshikazu; Plyer, J.*
Journal of Radiological Protection, 42(2), p.020501_1 - 020501_16, 2022/06
Times Cited Count:2 Percentile:28.39(Environmental Sciences)Thiessen, K. M.*; Boznar, M. Z.*; Charnock, T. W.*; Chouhan, S. L.*; Federspiel, L.; Grai
, B.*; Grsic, Z.*; Helebrant, J.*; Hettrich, S.*; Hulka, J.*; et al.
Journal of Radiological Protection, 42(2), p.020502_1 - 020502_8, 2022/06
Times Cited Count:5 Percentile:60.29(Environmental Sciences)Sakoda, Akihiro; Nomura, Naoki*; Kuroda, Yujiro*; Kono, Takahiko; Naito, Wataru*; Yoshida, Hiroko*
Journal of Radiological Protection, 41(4), p.1258 - 1287, 2021/12
Times Cited Count:1 Percentile:6.95(Environmental Sciences)Following the Fukushima Daiichi Nuclear Power Plant accident, many radiation experts directly experienced a vast gap between ideal and real public understanding (PU) of radiation in risk communication. Therefore, this study collated and reviewed information about PU activities for radiation and its risk that six Japanese academic societies - which seemed to be socially neutral expert communities - related to radiation and radiation risk conducted before and after the accident. Activities these radiation-related societies provided to general public were discussed from the following perspectives: (1) difficulties in two-way communication due to resources, motivation, public interest and concerns; (2) balance between academic research and PU activities; (3) academic societies' building trust with the public whilst ensuring member experts' neutrality and independence; (4) discussions among academic societies to prepare for public engagement. We hope that this paper encourages experts and academic societies in radiation protection to hold more national and international discussions about their roles in public communication and outreach.
Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*; Kato, Nobuyuki*; Matsui, Yasuto*; Yoneda, Minoru*
Journal of Radiological Protection, 41(3), p.S139 - S149, 2021/09
Times Cited Count:4 Percentile:39.96(Environmental Sciences)Sheltering is one of the countermeasures for protection against radiation exposures in nuclear accidents. The effectiveness of sheltering is often expressed by the reduction factor, that is the ratio of the indoor to the outdoor cumulative radioactivity concentrations or doses. The indoor concentration is mainly controlled by the air exchange rate, penetration factor, and indoor deposition rate. The penetration factor and indoor deposition rate depend on the surface and opening materials. We investigated experimentally these parameters of I and particles. The experiment was performed in two apartment houses, three single-family houses, and chambers. The obtained penetration factor ranged 0.3
1 for particles of 0.3
1
m and 0.15
0.7 for I
depending on the air exchange rate. The indoor deposition rate for a house room ranged 0.007
0.2 h
for particles of 0.3
1
m and 0.2
1.5 h
for I
depending on floor materials.
Seki, Akiyuki; Saito, Kimiaki; Takemiya, Hiroshi
Journal of Radiological Protection, 41(3), p.S89 - S98, 2021/09
Times Cited Count:6 Percentile:55.57(Environmental Sciences)An enormous amount of environmental monitoring data has been acquired by various organizations for evaluation and implementation of countermeasure to mitigate the effects of the accident at the Fukushima Daiichi Nuclear Power Plant. We established procedures to collect these data, convert them into a unified format, classify them according to categories, and make the data accessible on a web-based database system. The database system enabled us to spatially and temporally compare large volumes of monitoring data. By using the database functions, characteristics of some representative data in the database were clarified.
Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*
Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09
Times Cited Count:28 Percentile:71.82(Environmental Sciences)UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.
Furuta, Takuya; El Basha, D.*; Iyer, S. S. R.*; Correa Alfonso, C. M.*; Bolch, W. E.*
Journal of Radiological Protection, 39(3), p.825 - 837, 2019/09
Times Cited Count:3 Percentile:25.69(Environmental Sciences)Despite large variation of human eye, only one computational eye model has been adopted in almost all the radiation transport simulation studies. We thus adopted a new scalable and deformable eye model and studied the radiation exposure by electrons, photons, and neutrons in the standard radiation fields such as AP, PA, RLAT, ROT, by using Monte Carlo radiation transport code PHITS. We computed the radiation exposure for 5 eye models (standard, large, small, myopic, hyperopic) and analyzed influence of absorbed dose in ocular structures on eye size and shape. Dose distribution of electrons is conformal and therefore the absorbed doses in ocular structures depend on the depth location of each ocular structure. We thus found a significant variation of the absorbed doses for each ocular structure for electron exposure due to change of the depth location affected by eye size and shape. On the other hand only small variation was observed for photons and neutrons exposures because of less conformal dose distribution of those particles.
Ishikawa, Tetsuo*; Matsumoto, Masaki*; Sato, Tatsuhiko; Yamaguchi, Ichiro*; Kai, Michiaki*
Journal of Radiological Protection, 38(4), p.1253 - 1268, 2018/12
Times Cited Count:8 Percentile:56.25(Environmental Sciences)The current knowledge on internal dose estimation and its health effect were reviewed in this paper. The goals were to discuss the uncertainty of current dose coefficients, to compare the effects of external and internal exposures, and to review recent epidemiological studies. Radionuclides focused on in this study were caesium-137 (Cs), caesium-134 (
Cs), and iodine-131 (
I), which primarily contributed to internal effective thyroid doses after the Fukushima Dai-ichi Nuclear Power Station accident. Current knowledge suggests that the risk of internal exposure could be generally the same as or less than that of external exposure, when they are compared at the same effective dose.
Sugiyama, Daisuke*; Kimura, Hideo; Tachikawa, Hirokazu*; Iimoto, Takeshi*; Kawata, Yosuke*; Ogino, Haruyuki*; Okoshi, Minoru*
Journal of Radiological Protection, 38(1), p.456 - 462, 2018/03
Times Cited Count:0 Percentile:0.00(Environmental Sciences)Experience after the accident at the Fukushima Daiichi Nuclear Power Station has shown that there is a need to establish radiation protection criteria for radioactive waste management consistent with the criteria adopted for the remediation of existing exposure situations. A stepwise approach to setting such criteria is proposed. Initially, a reference level for annual effective dose from waste management activities in the range 1-10 mSv should be set, with the reference level being less than the reference level for ambient dose. Subsequently, the reference level for annual effective dose from waste management activities should be reduced in one or more steps to achieve a final target value of 1 mSv. The dose criteria at each stage should be determined with relevant stakeholder involvement. Illustrative case studies show how this stepwise approach might be applied in practice.