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高井 静霞; 木村 英雄*; 打越 絵美子*; 宗像 雅広; 武田 聖司

JAEA-Data/Code 2020-007, 174 Pages, 2020/09





木村 仁宣; 宗像 雅広; 波戸 真治*; 菅野 光大*

JAEA-Data/Code 2020-002, 38 Pages, 2020/03




Development of an external radiation dose estimation model for children returning to their homes in areas affected by the Fukushima Nuclear Accident

森 愛理; 高原 省五; 吉田 浩子*; 眞田 幸尚; 宗像 雅広

Health Physics, 117(6), p.606 - 617, 2019/12

 被引用回数:0 パーセンタイル:100(Environmental Sciences)

On 1 April 2017, evacuation orders in large areas were lifted. To estimate external radiation doses to children after returning to these areas, a dose estimation model based on a probabilistic approach has been developed. Validation of the model in an area for which individual personal dosimetry measurements were available show that it is valid for infants, kindergarteners, 3rd to 6th grade elementary school students, and junior high school students. As a result of our estimations, 95th percentile doses to all age groups were less than 20 mSv y$$^{-1}$$ in period from 2017 to 2020 and in all areas. Doses in some areas were less than 1 mSv y$$^{-1}$$, which is the long-term dosimetric target set by Japanese government. It is noted that our results are preliminary. To estimate doses to the children precisely, further considerations for assumptions and limitations on the environmental contamination conditions and behavioral patterns of children will be needed.


Investigation on the influence of additional protective measures on sheltering effectiveness for internal exposure

廣内 淳; 高原 省五; 駒ヶ峯 弘志*; 宗像 雅広

Proceedings of Asian Symposium on Risk Assessment and Management 2019 (ASRAM 2019) (USB Flash Drive), 7 Pages, 2019/09



Influence of artificial radionuclide deposited on a monitoring post on measured value of ambient dose rate

平岡 大和; 外間 智規; 宗像 雅広

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 5 Pages, 2019/05



Evaluation of the radiation protection capability in shelter facilities with positive pressure ventilation

石崎 梓; 中西 千佳*; 田窪 一也*; 宗像 雅広

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05

In case of a nuclear facility accident, inhabitants living around the nuclear facility generally evacuate further area to prevent radiation exposure. However, people who are unable to move immediately from inhabited areas are supposed to evacuate in local sheltering facilities. Therefore, such facilities have to have enough radiation protection capability for inhabitant's evacuation by equipping a strong construction to shield radiation and a positive pressure ventilation equipment with radioactive materials removal filters to decrease internal exposure. In Japan, such facilities are selected among local public facilities and also these facilities are almost built with wood construction, steel construction and reinforced concrete structure. In addition, facility characteristic, such as floor area, window area, airtightness, positive ventilation performance and so on, are different. To select appropriate facilities to use as sheltering facilities, an evaluation method of radiation protection capability of each facility is necessary. In our study, we focused on air-ventilation and developed an evaluation method of radiation protection capability of internal exposure by inhalation in facilities with positive pressure ventilation equipment. Then, we evaluate radiation protection capabilities of some facilities with various characteristics under various climate conditions. To simulate inflow of radioactive materials, we constructed a compartment model and use computational fluid dynamics analysis. From our evaluation results, it was cleared the relationship between an outdoor wind velocity and a necessary differential pressure to keep positive pressure, and the relationship between internal exposure dose and airtightness.


Development of integrated system for accident consequence evaluation using Level 2 and Level 3 PRA codes

木村 仁宣; 石川 淳; 小栗 朋美*; 宗像 雅広

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 5 Pages, 2019/05




森 愛理; 石崎 梓; 普天間 章; 田辺 務; 和田 孝雄; 加藤 貢; 宗像 雅広

保健物理(インターネット), 54(1), p.45 - 54, 2019/04

Large quantities of radionuclides were released as a result of Fukushima Daiichi Nuclear Power Station accident. It is known that these radionuclides contaminated inside houses as well as outdoor environment. Considering the radiation protection of residents after a nuclear power station accident, it is important to know the influence of radionuclides inside houses to radiation dose to residents. In this study, we investigated removal factors and fractions of fixed contamination of various materials inside houses in Okuma Town, Futaba Town, and Namie Town to assess the contamination level inside house appropriately. Nine kinds of materials, fibers, woods (smooth), woods rough), glasses, concretes (smooth), concretes (rough), plastics, PVCs and metals, were used in examinations. The lowest and the highest removal factors were 23% - 16% of woods (rough) and 79% - 7.7% of glasses, respectively. Removal factors of all materials were higher than 10% which is recommended by Japanese Industrial Standard. The negative correlation was found between removal factors and fractions of fixed contamination. Using this correlation, the decontamination factor, which means the ratio of the activity removed from the surface by one smear sample to the activity of the total surface activity, was proposed. The air dose rate from the contamination inside house was calculated using obtained decontamination factors and removal factor of 10%. In the case using the removal factor of 10%, the air dose rate derived by indoor contamination was approximately 2 times higher than the case using obtained decontamination factors. We found that the air dose rate derived by indoor contamination was much lower than the air dose rate outside house, and the influence of indoor contamination on the external exposure was small.



石崎 梓; 普天間 章; 田窪 一也*; 中西 千佳*; 宗像 雅広

JAEA-Data/Code 2018-022, 20 Pages, 2019/03





嶋田 和真; 佐々木 利久*; 飯島 正史*; 宗像 雅広

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




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

廣内 淳; 西澤 幸康*; 卜部 嘉*; 嶋田 和真; 眞田 幸尚; 宗像 雅広

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

 被引用回数:0 パーセンタイル:100(Chemistry, Inorganic & Nuclear)

The influence of $$gamma$$-rays from natural nuclides (particularly the radon progenies, $$^{214}$$Pb and $$^{214}$$Bi) must be excluded from aerial radiation monitoring (ARM) data to accurately estimate the deposition amount of artificial radionuclides. A method for discriminating the influence of $$^{214}$$Pb and $$^{214}$$Bi in air from the ARM data was developed. The influence of the radon progenies in air was excluded using the relation between the count rates of six NaI (Tl) detectors and a LaBr$$_{3}$$ detector. The discrimination method was applied to the ARM data obtained from around the Sendai Nuclear Power Station. To verify the validity of the discrimination method, the dose rate estimated from the ARM data was compared with the dose rate measured using a NaI survey meter at a height of 1 m above the ground. The application of the discrimination method improved the dose rate estimation, showing the validity of the discrimination method.


Investigation of reduction factor of internal exposure for sheltering in Japan

廣内 淳; 高原 省五; 駒ヶ峯 弘志*; 宗像 雅広

Proceedings of Asian Symposium on Risk Assessment and Management 2018 (ASRAM 2018) (USB Flash Drive), 8 Pages, 2018/10



Estimation of radiocesium dietary intake from time series data of radiocesium concentrations in sewer sludge

Pratama, M. A.; 高原 省五; 宗像 雅広; 米田 稔*

Environment International, 115, p.196 - 204, 2018/06

 被引用回数:1 パーセンタイル:88.59(Environmental Sciences)

After the Fukushima accident, it became important to determine the quantity of radionuclide ingested by inhabitants. The most common methods currently used to obtain such data are the market basket (MB) and duplicate (DP) methods. The newly proposed method, which we designate as SL, consists of three steps: (1) the separation of wet weather and dry weather data, (2) determining the mass balance of the wastewater treatment plant (WWTP), and (3) developing a reverse biokinetic model to relate the amount of radionuclides ingested to the amounts contained in the sewer sludge. We tested the new method using the time-dependent radiocesium concentrations in sewer sludge from the WWTP in Fukushima City. The results from the SL method agreed to those from the MB while overestimated those from DP method. The trend lines for all three methods, however, are in good agreement. Sensitivity analyses of SL method indicate further studies on uncertainties of sensitive parameters are deemed necessary to improve the accuracy of the method.



石崎 梓; 眞田 幸尚; 西澤 幸康*; 普天間 章; 宗像 雅広

JAEA-Research 2017-012, 58 Pages, 2018/03




Dose-reduction effects of vehicles against gamma radiation in the case of a nuclear accident

高原 省五; 渡邊 正敏*; 廣内 淳; 飯島 正史*; 宗像 雅広

Health Physics, 114(1), p.64 - 72, 2018/01


 被引用回数:1 パーセンタイル:75.54(Environmental Sciences)

The aim of this paper is to evaluate the dose-reduction effects of vehicles. To achieve this aim, a model for calculating the dose reduction factor (DRF) was developed based on the actual shape and weight of Japanese vehicles. This factor is defined as the ratio of dose rate inside a vehicle to that outside. In addition to model calculation, we evaluated the DRFs by actual measurements in the areas contaminated by the Fukushima accident. A comparison between the simulated and the measured results revealed that the DRFs obtained using the developed models were in good agreement with the results of actual measurements. Using this model, we also evaluated the DRFs for cloudshine and groundshine in the case of a nuclear accident. The evaluations were performed for four vehicle models whose weights were 800-1930 kg. The DRF for cloudshine with photon energy of 0.4-1.5 MeV was 0.66-0.88, and that for groundshine from $$^{137}$$Cs was 0.64-0.73.


Application of topographical source model for air dose rates conversions in aerial radiation monitoring

石崎 梓; 眞田 幸尚; 石田 睦司; 宗像 雅広

Journal of Environmental Radioactivity, 180, p.82 - 89, 2017/12

 被引用回数:5 パーセンタイル:64.11(Environmental Sciences)



Factors affecting the effectiveness of sheltering in reducing internal exposure

廣内 淳; 高原 省五; 駒ヶ峯 弘志*; 渡邊 正敏*; 宗像 雅広

Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 11 Pages, 2017/11



Improvement of a metabolic model for iodine and consideration of a equivalent dose to the thyroid reduction factor for application to the OSCAAR code

木村 仁宣; 波戸 真治*; 松原 武史*; 菅野 光大*; 宗像 雅広

Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 9 Pages, 2017/11



Identification of penetration path and deposition distribution of radionuclides in houses by experiments and numerical model

廣内 淳; 高原 省五; 飯島 正史; 渡邊 正敏; 宗像 雅広

Radiation Physics and Chemistry, 140, p.127 - 131, 2017/11


 被引用回数:0 パーセンタイル:100(Chemistry, Physical)

The dose assessment for people living in preparation zones for the lifting of the evacuation order is needed with the return of the residents. However, it is difficult to assess exactly indoor external dose rate because the indoor distribution and infiltration pathways of radionuclides are unclear. This paper describes indoor and outdoor dose rates measured in eight houses in the difficult-to-return zone in Fukushima prefecture to examine the distribution of radionuclides in a house and the main infiltration pathway of radionuclides. In addition, it describes also dose rates calculated with a Monte Carlo photon transport code to understand thoroughly the measurements. These measurements and calculations provide that radionuclides can infiltrate mainly through ventilations, windows, and doors, and then deposit near the gaps, while those infiltrate hardly through sockets and air conditioning outlets.



高井 静霞; 武田 聖司; 酒井 隆太郎*; 島田 太郎; 宗像 雅広; 田中 忠夫

日本原子力学会和文論文誌, 16(1), p.34 - 48, 2017/03


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