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JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2020 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Ishizaki, Azusa; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Sato, Kazuhiko*; Haginoya, Masashi*; Matsunaga, Yuki*; Kikuchi, Hikaru*; et al.

JAEA-Technology 2021-029, 132 Pages, 2022/02

JAEA-Technology-2021-029.pdf:24.58MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter has been conducted around FDNPS. The results of the airborne radiation monitoring and the evaluation for temporal change of dose rate in the fiscal 2020 were summarized in this report. Analysis considering topographical effects was applied to the result of the airborne monitoring to improve the accuracy of conventional method. In addition, technique for discriminating gamma rays from the ground and those from the airborne Rn-progenies was also utilized to evaluate their effect on airborne radiation monitoring.

Journal Articles

Assessment of radiation doses to off-site responders in TEPCO Fukushima Daiichi Nuclear Power Station Accident

Shimada, Kazumasa; Iijima, Masashi*; Watanabe, Masatoshi*; Takahara, Shogo

Proceedings of Asian Symposium on Risk Assessment and Management 2021 (ASRAM 2021) (Internet), 17 Pages, 2021/10

The radiation doses received by the off-site responders in the Fukushima Daiichi Nuclear Power Station accident were assessed. Atmospheric dispersion simulation was conducted with the source term of the previous research to calculate the atmospheric concentration and ground surface deposition in the municipalities where off-site responders actives. The external exposure dose from cloudshine and groundshine, the internal exposure dose due to inhalation of radioactive plume and resuspended radio nuclei, and the temporal and spatial distribution within each municipality were assessed. As a result of comparing the assessed values of the external exposure dose with the measured values of the personal dosimeter, the measured values were within the assessed range. As a result of our assessment with internal dose exposure, if the exposures occurred without protective measures, the potential daily effective dose in the period between 12 and 31 March 2011 were several tens mSv per day or more in the relatively high dose area. Therefore, to keep the doses received by the responders below the reference level of 20 mSv recommended by the ICRP, it is necessary to ensure that the protective measures for internal exposures such as masks are taken, and to manage the time spent for their activity at least daily.

JAEA Reports

Comparison analysis between U.S. and Japan on Evacuation Time Estimation for nuclear emergency planning zones

Shimada, Kazumasa; Takahara, Shogo

JAEA-Review 2021-013, 142 Pages, 2021/09

JAEA-Review-2021-013.pdf:4.74MB

In this report, the authors reviewed the published reports of Evacuation Time Estimation (ETE) conducted in Japan and United States and examined the issues of ETE in Japan. The authors obtained public ETE reports in Japan from 16 prefectures up to February 2020. In addition, the authors obtained 58 ETE reports in United States from 2011 to 2018. Next, the overview of ETE for the Emergency Planning Zone (EPZ) around the nuclear power plant in United States was described based on the NUREG/CR-7002 of the U.S Nuclear Regulatory Commission (NRC). Then, based on the guidance of the ETE of the Cabinet Office of Japan, the overview of ETE in Japan for the Precautionary Action Zone (PAZ) and the Urgent Protective Action Planning Zone (UPZ) was described and compared with the ETE in United States. It was found that ETE in Japan often outputs only the time of 90% or 100% that population complete evacuation. Therefore, in order to use ETE in Japan for emergency decision-making, it is necessary to unify the inputs and outputs of ETE as in the United States' ETE reports.

Journal Articles

Lifetime risk assessment of lung cancer incidence for nonsmokers in Japan considering the joint effect of radiation and smoking based on the life span study of atomic bomb survivors

Shimada, Kazumasa; Kai, Michiaki*

Journal of Radiation Protection and Research, 46(3), p.83 - 97, 2021/09

[Background] The lifetime risk of lung cancer incidence owing to radiation for non-smokers is overestimated because the average cancer baseline among a population including smokers is used. In recent years, the generalized multiplicative (GM) excess relative risk (ERR) model has been developed in the life span study of atomic bomb survivors to consider the joint effect of radiation and smoking. Based on this background, the issues of radiation risk assessment considering smoking will be discussed in this paper in 2 parts. [Materials and Methods] Part 1: We proposed a simple method of estimating the baseline risk for non-smokers using current smoking data. We performed sensitivity analysis on baseline risk estimation to discuss the birth cohort effects of birth year effect and smoking history. Part 2: We applied the GM ERR model for Japanese smokers to calculate lifetime attributable risk (LAR). We also performed a sensitivity analysis with other ERR models (e.g., simple additive (SA) ERR model). [Results] Part 1: The lifetime baseline risk (LBR) for non-smokers were 54% (44% - 60%) or males and 24% (18% - 29%) for females, which were lower than the LBRs for all adults including smokers. Part 2: When comparing the LAR between the SA ERR model and the GM ERR model, if the radiation dose was $$leq$$ 200 mGy or less, the difference between these ERR models was within the standard deviation of the LAR owing to the uncertainty of the smoking information.

Journal Articles

Integration of transportation simulation with a level 3 PRA code for nuclear power plants

Shimada, Kazumasa; Sakurahara, Tatsuya*; Reihani, S.*; Mohagehgh, Z.*

Proceedings of Asian Symposium on Risk Assessment and Management 2020 (ASRAM 2020) (Internet), 12 Pages, 2020/11

Level 3 Probabilistic Risk Assessment (Level 3 PRA) and Traffic simulation were integrated to evaluate the effects of evacuation more realistically on radiation exposure to residents in the offsite consequence analysis. In this study, WinMACCS was used as the Level 3 PRA code. As a test case, the Sequoyah Nuclear Power Plant(NPP) site, which was targeted by the State-of-the-Art Reactor Consequence Analyzes (SOARCA) issued by U.S. Nuclear Regulatory Commission in 2017, was adopted. The MultiAgent Transport Simulation (MATSim) was used to simulate the evacuation of a Sequoyah NPP's 10-mile Emergency Planning Zone. For the transportation route choice, the route where each vehicle chooses the shortest distance and the route where the total evacuation time is shortened by iterative calculation were chosen. In the calculation of MACCS, the source term with the shortest release start time in the SOARCA report was adopted. As an example of the results, the radiation dose of the residents when the evacuation time was optimized was reduced by about 30% from the dose when the shortest distance was selected. Furthermore, a sensitivity analysis was conducted, and it was shown that the evacuation preparation time was the largest factor that contributed to the radiation dose to residents.

JAEA Reports

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2018 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Komiya, Tomokazu; Iwai, Takeyuki*; Seguchi, Eisaku*; Matsunaga, Yuki*; Kawabata, Tomoki*; Haginoya, Masashi*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2019-017, 95 Pages, 2019/11

JAEA-Technology-2019-017.pdf:12.09MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background radiation monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in the aerial monitoring around FDNPS against nuclear emergency response. The results of monitoring around Shimane and Hamaoka Nuclear Power Stations in the fiscal 2018 were summarized in this report. In addition, technical issues were described.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2018 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Ishizaki, Azusa; Komiya, Tomokazu; Iwai, Takeyuki*; Seguchi, Eisaku*; Matsunaga, Yuki*; Kawabata, Tomoki*; Haginoya, Masashi*; Hiraga, Shogo*; et al.

JAEA-Technology 2019-016, 116 Pages, 2019/11

JAEA-Technology-2019-016.pdf:14.09MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter has been conducted around FDNPS. The results in the fiscal 2018 were summarized in this report. Discrimination method of gamma rays from Rn-progenies was also utilized to evaluate their effect on aerial radiation monitoring. In addition, analysis taken topographical effects into consideration was applied to previous results of airborne monitoring to improve the precision of conventional method.

JAEA Reports

Background radiation monitoring using manned helicopter for establishment of technique of nuclear emergency response in the fiscal year 2017 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Iwai, Takeyuki*; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2018-016, 98 Pages, 2019/02

JAEA-Technology-2018-016.pdf:18.64MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in Fukushima against nuclear emergency response. The results of monitoring around Tomari, Kashiwazaki-Kariwa and Genkai Nuclear Power Station in the fiscal 2017 were summarized in this report. In addition, technical issues were described.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2017 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Ishizaki, Azusa; Iwai, Takeyuki*; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo*; et al.

JAEA-Technology 2018-015, 120 Pages, 2019/02

JAEA-Technology-2018-015.pdf:15.01MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. The results in the fiscal 2017 were summarized in this report. In addition, we developed and systemized the discrimination technique of the Rn-progenies. The accuracy of aerial radiation monitoring was evaluated by taking into consideration GPS data error.

JAEA Reports

External dose evaluation of emergency responder in off-site at the time of Fukushima-Dai-ichi Nuclear Power Station Accident (Contract research)

Shimada, Kazumasa; Sasaki, Toshihisa*; Iijima, Masashi*; Munakata, Masahiro

JAEA-Research 2018-012, 68 Pages, 2019/02

JAEA-Research-2018-012.pdf:4.15MB

The external exposure dose of off-site emergency responders at Fukushima Dai-ichi Nuclear Power Station accident were evaluated in order to consider a radiation protection of emergency responders. The maximum value of individual daily dose of emergency responders whose activities details were recorded from 12th to 31th March 2011 was 650 $$mu$$Sv engaged in evacuation support in Futaba Town on 12th. Next, atmospheric concentrations and deposition of radionuclides were calculated from the source terms estimated by previous studies using atmospheric diffusion and deposit calculation codes, and air dose rates at off-site were estimated. Then, the external exposure dose was calculated for 6 emergency responders whose daily activities and personal doses were continuously recorded. Furthermore, the maximum value and the average value of the calculation external dose of emergency responders in the activity area were compared with the measurement value of the personal dosimeter of them. These results showed that the calculated value of the external exposure dose of emergency responders calculated from the maximum value of the dose rate in the active area roughly includes the measured value.

Journal Articles

Development and application of a method for discriminating the influence of radon progenies in air from aerial radiation monitoring data

Hirouchi, Jun; Nishizawa, Yukiyasu*; Urabe, Yoshimi*; Shimada, Kazumasa; Sanada, Yukihisa; Munakata, Masahiro

Applied Radiation and Isotopes, 141, p.122 - 129, 2018/11

 Times Cited Count:1 Percentile:15.51(Chemistry, Inorganic & Nuclear)

JAEA Reports

Background radiation monitoring using manned helicopter for establishment of technique of nuclear emergency response in the fiscal year 2016 (Contract research)

Sanada, Yukihisa; Mori, Airi; Iwai, Takeyuki; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo; Sato, Yoshiharu; et al.

JAEA-Technology 2017-035, 69 Pages, 2018/02

JAEA-Technology-2017-035.pdf:32.92MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We carried out the background monitoring around the nuclear power stations of the whole country to apply a technique of the airborne radiation monitoring that is cultivated in Fukushima as a technology of nuclear emergency response. This result of the aerial radiation monitoring using the manned helicopter around Ooi, Takahama and Ikata Nuclear Power Station and in the fiscal 2016 were summarized in the report. In addition, technical issues were described.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2016 (Contract research)

Sanada, Yukihisa; Mori, Airi; Iwai, Takeyuki; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo; Sato, Yoshiharu; et al.

JAEA-Technology 2017-034, 117 Pages, 2018/02

JAEA-Technology-2017-034.pdf:25.18MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. This result of the aerial radiation monitoring using the manned helicopter in the fiscal 2016 were summarized in the report. In addition, we developed the discrimination technique of the Rn-progenies. The accuracy of aerial radiation monitoring was evaluated by taking into consideration GPS position error.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2015 (Contract research)

Sanada, Yukihisa; Munakata, Masahiro; Mori, Airi; Ishizaki, Azusa; Shimada, Kazumasa; Hirouchi, Jun; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika*; Yamada, Tsutomu*; et al.

JAEA-Research 2016-016, 131 Pages, 2016/10

JAEA-Research-2016-016.pdf:20.59MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. In addition, background dose rate monitoring was conducted around Sendai Nuclear Power Station. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2015 were summarized in the report.

JAEA Reports

Actions to protect the public in an emergency due to severe conditions at a light water reactor (Translated document)

Homma, Toshimitsu; Takahara, Shogo; Iijima, Masashi; Sato, Sohei; Kimura, Masanori; Shimada, Kazumasa

JAEA-Review 2016-013, 162 Pages, 2016/07

JAEA-Review-2016-013.pdf:16.95MB

This is a Japanese translation of "Actions to Protect the Public in an Emergency due to Severe Conditions at a Light Water Reactor", which is published by the International Atomic Energy Agency in May 2013. The original IAEA Publication is available on the IAEA Website (https://www-pub.iaea.org/MTCD/Publications/PDF/EPR-NPP_PPA_web.pdf).

Journal Articles

Calculating disability-adjusted life years (DALY) as a measure of excess cancer risk following radiation exposure

Shimada, Kazumasa; Kai, Michiaki*

Journal of Radiological Protection, 35(4), p.763 - 775, 2015/12

AA2014-0479.pdf:1.53MB

 Times Cited Count:9 Percentile:66.89(Environmental Sciences)

This paper has proposed that disability-adjusted life year (DALY) can be used as a measure of radiation health risk. DALY is calculated as the sum of years of life lost (YLL) and years lived with disability (YLD). This multidimensional concept can be expressed as a risk index without a probability measure to avoid the misuse of the current radiation detriment at low doses. In this study, we calculated YLL and YLD using Japanese population data by gender. DALY for all cancers in Japan per 1 Gy per person was 0.84 year in men and 1.34 year in women. When we calculated the ICRP detriment from the same data, DALYs for the cancer sites were similar to the radiation detriment in the cancer sites, excluding leukemia, breast and thyroid cancer. A big advantage over the ICRP detriment is that DALY can calculate the risk components for non-fatal diseases without the data of lethality. This study showed that DALY is a practical tool that can compare many types of diseases encountered in public health.

Journal Articles

Application of health effect model of NUREG/CR-4214 to the Japanese population and comparison with a latest model

Takahara, Shogo; Iijima, Masashi; Shimada, Kazumasa

Hoken Butsuri, 50(3), p.172 - 181, 2015/09

Journal Articles

Conference report; The Seventh Asian Regional Conference on the Evolution of the System of Radiological Protection

Shimada, Kazumasa

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 57(6), P. 422, 2015/06

The conference of "The Seventh Asian Regional Conference on the Evolution of the System of Radiological Protection" was open in June 8-9 2015 in Tokyo University. In this conference, the various stakeholders presented and discuss about the activity of radiation protection in Fukushima prefecture. I will report this conference.

JAEA Reports

Development of deterministic approach to assess doses to the public from external exposures in the areas contaminated by the Fukushima Daiichi Nuclear Power Station Accident

Takahara, Shogo; Iijima, Masashi; Shimada, Kazumasa; Kushida, Teruo; Shiratori, Yoshitake

JAEA-Research 2014-024, 57 Pages, 2015/01

JAEA-Research-2014-024.pdf:5.49MB

In order to assess the doses to representative person using deterministic approach, we measured radiation dose rates and surveyed on behavioral patterns in the areas contaminated by the Fukushima Daiichi Nuclear Power Station Accident. Statistical analyzes were also performed to identify the characteristics of individual doses from external exposures, as well as radiation dose rates and behavioral patterns. Radiation dose rates measured in living areas distribute with lognormal form. Behavioral patterns of the populations were different corresponding to their occupation. Time spent outdoors of indoor workers were distributed in lognormal form and those of outdoor workers had the normal distribution. Multi-regression analyses were made to explore a significant relationship between individual doses and relevant contributors. These results indicated that the significant differences were given in individual doses due to the spatial differences of radiation dose rates as well as the interindividual differences of behavioral patterns. Based on the results of analyses of relevant contributors to the external exposures, deterministic dose assessment model was developed. The validity of this model was confirmed because the assessed values were higher than those measured.

Journal Articles

Statistical characterization of radiation doses from external exposures and relevant contributors in Fukushima Prefecture

Takahara, Shogo; Abe, Tatsuya*; Iijima, Masashi; Shimada, Kazumasa; Shiratori, Yoshitake

Health Physics, 107(4), p.326 - 335, 2014/10

AA2013-0905.pdf:0.46MB

 Times Cited Count:7 Percentile:53.3(Environmental Sciences)

Probabilistic dose assessment is one of the useful methods to describe the information on the dose distributions in the population. To use this assessment, statistically characterized data on the pathway-relevant contributors are necessary. The objectives of the paper are to determine the statistical values and the distribution forms of the contributors to external exposures, as well as to identify the causes of the variabilities of them. To achieve the objectives, we have measured and surveyed ambient dose rate and time spent outdoors in Fukushima Prefecture. The measurements and surveys were performed with the cooperation of indoor workers, outdoor workers and pensioners. These results allowed us to determine the statistically characters of the individual doses and its contributors. In addition, these contributors had the variabilities attributed to the spatial distributions of deposited radionuclides, as well as the temporal and interpopulational differences of behavioral patterns.

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