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Journal Articles

Deposition and dispersion of radio-cesium released due to the Fukushima Nuclear accident, 2; Sensitivity to aerosol microphysical properties of Cs-bearing microparticles (CsMPs)

Kajino, Mizuo*; Adachi, Koji*; Igarashi, Yasuhito*; Satou, Yukihiko; Sawada, Morihiro*; Sekiyama, Tsuyoshi*; Zaizen, Yuji*; Saya, Akane*; Tsuruta, Haruo*; Moriguchi, Yuichi*

Journal of Geophysical Research; Atmospheres, 126(1), 23 Pages, 2021/01

 Times Cited Count:0

Journal Articles

Model intercomparison of atmospheric $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Plant accident; Simulations based on identical input data

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

Journal of Geophysical Research; Atmospheres, 123(20), p.11748 - 11765, 2018/10

 Times Cited Count:11 Percentile:29.77(Meteorology & Atmospheric Sciences)

A model intercomparison of the atmospheric dispersion of $$^{137}$$Cs emitted following the Fukushima Daiichi Nuclear Power Plant accident was conducted by 12 models to understand the behavior of $$^{137}$$Cs in the atmosphere. The same meteorological data, horizontal grid resolution, and an emission inventory were applied to all the models to focus on the model variability originating from the processes included in each model. The multi-model ensemble captured 40% of the observed $$^{137}$$Cs events, and the figure-of-merit in space for the total deposition of $$^{137}$$Cs exceeded 80. Our analyses indicated that the meteorological data were most critical for reproducing the $$^{137}$$Cs events. The results also revealed that the differences among the models were originated from the deposition and diffusion processes when the meteorological field was simulated well. However, the models with strong diffusion tended to overestimate the $$^{137}$$Cs concentrations.

Journal Articles

Atmospheric modeling of $$^{137}$$Cs plumes from the Fukushima Daiichi Nuclear Power Plant; Evaluation of the model intercomparison data of the Science Council of Japan

Kitayama, Kyo*; Morino, Yu*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.

Journal of Geophysical Research; Atmospheres, 123(14), p.7754 - 7770, 2018/07

 Times Cited Count:12 Percentile:26.05(Meteorology & Atmospheric Sciences)

We compared seven atmospheric transport model results for $$^{137}$$Cs released during the Fukushima Daiichi Nuclear Power Plant accident. All the results had been submitted for a model intercomparison project of the Science Council of Japan in 2014. We assessed model performance by comparing model results with observed hourly atmospheric concentrations of $$^{137}$$Cs, focusing on nine plumes over the Tohoku and Kanto regions. The results showed that model performance for $$^{137}$$Cs concentrations was highly variable among models and plumes. We also assessed model performance for accumulated $$^{137}$$Cs deposition. Simulated areas of high deposition were consistent with the plume pathways, though the models that best simulated $$^{137}$$Cs concentrations were different from those that best simulated deposition. The ensemble mean of all models consistently reproduced $$^{137}$$Cs concentrations and deposition well, suggesting that use of a multimodel ensemble results in more effective and consistent model performance.

Journal Articles

Estimation of desorption ratios of radio/stable caesium from environmental samples (aerosols and soils) leached with seawater, diluted seawater and ultrapure water

Sakaguchi, Aya*; Chiga, Haruka*; Tanaka, Kazuya; Tsuruta, Haruo*; Takahashi, Yoshio*

Geochemical Journal, 52(2), p.187 - 199, 2018/00

 Times Cited Count:6 Percentile:40.34(Geochemistry & Geophysics)

An aerosol sample collected on the 15th of March 2011 at Kawasaki City (Kanagawa) was sequentially leached with seawater for 30 days. As a result, about 60% of the total $$^{137}$$Cs was extracted. In addition, a surface soil sample collected from Kawamata Town (Fukushima) two months after the Fukushima accident, was leached for 223 days with a natural seawater, a 1:1 mixture of ultrapure water and seawater, and ultrapure water. Eventually, more than 15% of the total $$^{137}$$Cs in the surface soil sample was efficiently desorbed by seawater leaching. In comparison, about 9% of the total $$^{137}$$Cs was leached with 1:1 diluted seawater and less than 1% of the total $$^{137}$$Cs was leached with ultrapure water over the 223 days. Overall, $$^{133}$$Cs and $$^{137}$$Cs showed similar leaching behaviour.

Journal Articles

Report of the Special Symposium on the Transport and Diffusion of Contaminants from the Fukushima Dai-ichi Nuclear Power Plant; Present status and future directions

Kondo, Hiroaki*; Yamada, Tetsuji*; Chino, Masamichi; Iwasaki, Toshiki*; Katata, Genki; Maki, Takashi*; Saito, Kazuo*; Terada, Hiroaki; Tsuruta, Haruo*

Tenki, 60(9), p.723 - 729, 2013/09

AA2013-0745.pdf:0.51MB

no abstracts in English

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2006

Nishio, Kazuhisa; Matsuoka, Toshiyuki; Mikake, Shinichiro; Tsuruta, Tadahiko; Amano, Kenji; Oyama, Takuya; Takeuchi, Ryuji; Saegusa, Hiromitsu; Hama, Katsuhiro; Yoshida, Haruo*; et al.

JAEA-Review 2009-001, 110 Pages, 2009/03

JAEA-Review-2009-001.pdf:49.84MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is developing a geoscientific research project named Mizunami Underground Research Laboratory (MIU) project in crystalline rock environment in order to establish scientific and technological basis for geological disposal of HLW. Geoscientific research at MIU is planned to be carried out in three phases over a period of 20 years; Surface-based Investigation Phase (Phase 1), Construction Phase (Phase 2) and Operation Phase (Phase 3). Currently, the project is under the Construction Phase. This document presents the following results of the research and development performed in 2006 fiscal year, as a part of the Construction Phase based on the MIU Master Plan updated in 2002, (1) Investigation at the MIU Construction Site, (2) Construction at the MIU Construction Site, (3) Research Collaboration.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2005

Nishio, Kazuhisa; Matsuoka, Toshiyuki; Mikake, Shinichiro; Tsuruta, Tadahiko; Amano, Kenji; Oyama, Takuya; Takeuchi, Ryuji; Saegusa, Hiromitsu; Hama, Katsuhiro; Yoshida, Haruo*; et al.

JAEA-Review 2008-073, 99 Pages, 2009/03

JAEA-Review-2008-073-1.pdf:37.33MB
JAEA-Review-2008-073-2.pdf:37.16MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is developing a geoscientific research project named Mizunami Underground Research Laboratory (MIU) project in crystalline rock environment in order to establish scientific and technological basis for geological disposal of HLW. Geoscientific research at MIU is planned to be carried out in three phases over a period of 20 years; Surface-based Investigation Phase (Phase 1), Construction Phase (Phase 2) and Operation Phase (Phase 3). Currently, the project is under the Construction Phase. This document presents the following results of the research and development performed in 2005 fiscal year, as a part of the Construction Phase based on the MIU Master Plan updated in 2002, (1) Investigation at the MIU Construction Site, (2) Construction at the MIU Construction Site, (3) Research Collaboration.

JAEA Reports

Development and management of the knowledge base for the geological disposal technology; Annual report 2006

Umeda, Koji; Oi, Takao; Osawa, Hideaki; Oyama, Takuya; Oda, Chie; Kamei, Gento; Kuji, Masayoshi*; Kurosawa, Hideki; Kobayashi, Yasushi; Sasaki, Yasuo; et al.

JAEA-Review 2007-050, 82 Pages, 2007/12

JAEA-Review-2007-050.pdf:28.56MB

This report shows the annual report which shows the summarized results and topic outline of each project on geological disposal technology in the fiscal year of 2006.

Oral presentation

Environmental dynamics analysis of $$^{137}$$Cs due to the Fukushima Daiichi Nuclear Power Station accident based on the intercomparison of atmospheric dispersion models

Morino, Yu*; Kitayama, Kyo*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.

no journal, , 

For the evaluation of the validity and variability of atmospheric transport model results, we compared results of seven models submitted for the model inter-comparison project of Science Council of Japan to simulate $$^{137}$$Cs released from the Fukushima Daiichi Nuclear Power Plant. Model reproducibility was assessed with the observed hourly atmospheric concentrations of $$^{137}$$Cs in Tohoku and Kanto regions. Among nine plumes from 12 to 21 in March 2011, performance of the models was the best for the plume which dispersed over the Kanto region in 15 March. The models generally reproduced the observed $$^{137}$$Cs concentrations in plumes which widely spread inland of Tohoku or Kanto regions. By contrast, the models largely underestimated the observed $$^{137}$$Cs concentrations for the case which passed coastal areas of Japan. Ensemble average of seven models showed reasonable performance for most of plumes, and no individual models reproduced better than the ensemble average.

Oral presentation

Model inter-comparison of atmospheric Cs-137 from the Fukushima Daiichi Nuclear Power Plant accident

Kitayama, Kyo*; Morino, Yu*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.

no journal, , 

For the evaluation of the validity and variability of atmospheric transport model results, we compared results of seven models submitted for the model inter-comparison project of Science Council of Japan to simulate $$^{137}$$Cs released from the Fukushima Daiichi Nuclear Power Plant. Model reproducibility was assessed with the observed hourly atmospheric concentrations of $$^{137}$$Cs in Tohoku and Kanto regions. Among nine plumes from 12 to 21 in March 2011, performance of the models was the best for the plume which dispersed over the Kanto region in 15 March. The models generally reproduced the observed $$^{137}$$Cs concentrations in plumes which widely spread inland of Tohoku or Kanto regions. By contrast, the models largely underestimated the observed $$^{137}$$Cs concentrations for the case which passed coastal areas of Japan. Ensemble average of seven models showed reasonable performance for most of plumes, and no individual models reproduced better than the ensemble average.

Oral presentation

2nd atmospheric model intercomparison project for Fukushima Daiichi Nuclear Power Plant Accident on March 2011; 2nd FDNPP-MIP

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Grahn, H.*; Br$"a$nnstr$"o$m, N.*; von Schoenberg, P.*; Kondo, Hiroaki*; Terada, Hiroaki; Nagai, Haruyasu; et al.

no journal, , 

The second intercomparison of atmospheric model targeting on the radionuclide (i.e. $$^{137}$$Cs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) on March 2011 is conducted. Thirteen atmospheric models, which include both the Lagrangian- and Eulerian-based dispersion models, participate in this model intercomparison project (MIP). The purposes of this MIP are to (1) understand the transport process of the radionuclide in atmosphere, (2) estimate the uncertainties in wet and dry deposition process among the models, (3) reveal the essential key processes to reproduce the plume of $$^{137}$$Cs, (4) assess the multi-model ensemble mean, and (5) obtain the knowledge for improving the physical processes of the models. To exclude the uncertainties of the model results originated from the emission inventory, all models used the same emission inventory. The meteorological data with fine spatiotemporal resolution, which was calculated by the Japanese operational weather forecast model coupled with the local ensemble transform Kalman Filter data assimilation system, was applied for all models to reduce the uncertainties originated from the difference in the meteorological field. As well as the comparison among the models, the comparison between the models and in-situ measurement from the national suspended particle matter (SPM) sampling network are conducted. The comparisons between the model results and the SPM data indicate that the $$^{137}$$Cs concentration near the FDNPP transported without precipitation process was relatively well reproduced by using the meteorological data with fine spatiotemporal resolution. On the contrary, $$^{137}$$Cs concentration accompanied with precipitation has large inter-model spread. In the presentation, we will discuss the more detailed analyses about the physical process to determine the $$^{137}$$Cs concentration.

Oral presentation

Model intercomparison study for atmospheric $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Plant Accident using identical input data

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

no journal, , 

An intercomparison of atmospheric dispersion model targeting on the physical process of $$^{137}$$Cs released from the Fukushima Daiichi Nuclear Power Plant was conducted. Twelve atmospheric models participated in this project. To exclude the uncertainties of the model result due to the emission inventory and meteorological data, all models used the same emission and meteorological data. Concentration of $$^{137}$$Cs from the national suspended particle matter monitoring network and the deposition density by the aircraft were used for the comparison between results of the model and observation. Our analyses elucidated the figure of merit in space (FMS) of the model ensemble mean was improved from a previous model intercomparson about the accumulated deposition. The model ensemble mean captured approximately 36% of the observed high concentration. The inter-model spread of the capture rate was from 8% to 38%. It was originated from the difference in deposition and diffusion processes among the models.

Oral presentation

Model intercomparison project for $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source term

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Improvement of assessment methods for atmospheric behavior of accidentally discharged hazardous materials by comprehensively analyzing nuclear accident data

Yamazawa, Hiromi*; Oura, Yasuji*; Moriguchi, Yuichi*; Terada, Hiroaki; Sekiyama, Tsuyoshi*; Goto, Daisuke*; Tsuruta, Haruo*

no journal, , 

no abstracts in English

Oral presentation

Model intercomparison project for cesium ($$^{137}$$Cs) from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source term

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Detailed intercomparison of atmospheric transport models using newly obtained concentration data of Cs-137 from the Fukushima Daiichi Nuclear Power Plant Accident

Yamazawa, Hiromi*; Sato, Yosuke*; Adachi, Shinichiro*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; et al.

no journal, , 

Cs-137 released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident was conducted by 12 models. The present study focuses on differences in the model results of atmospheric Cs-137 concentration of Plume 2, which traveled southward in the morning of 15 March, 2011, in the area 100 to 200 km downwind from FDNPP by using the concentration data recently evaluated from gamma radiation spectral data at monitoring stations (MS data) and those measured from the suspended particulate matter filters (SPM data). Comparison was made from the following aspects: (1) plume arrival time, (2) concentration level, (3) cross-wind surface concentration profile, (4) vertical concentration profile and (5) mass balance of Cs-137 activity including deposition processes. Additional analyses were made also for Plume 4, which traveled over the same area on 16 March under rainy condition.

Oral presentation

Sophistication of dynamics evaluation method for harmful substances in the atmosphere

Yamazawa, Hiromi*; Sato, Yosuke*; Oura, Yasuji*; Moriguchi, Yuichi*; Terada, Hiroaki; Furuno, Akiko; Tsuzuki, Katsunori; Kadowaki, Masanao; Sekiyama, Tsuyoshi*; Adachi, Koji*; et al.

no journal, , 

no abstracts in English

Oral presentation

Review of model intercomparison projects (MIPs) of atmospheric dispersion model for $$^{137}$$Cs emitted from Fukushima Daiichi Nuclear Power Plant; MIPs with identical source term and meteorological data

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kadowaki, Masanao; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; et al.

no journal, , 

Two Model Intercomparison of Projects (MIPs) of atmospheric dispersion model targeting on $$^{137}$$Cs released from Fukushima Daiichi Nuclear Power Plant (FDNPP) on March 2011 were conducted. Both MIPs were conducted using an identical source term of $$^{137}$$Cs, identical meteorological data, and the same horizontal grid resolution (3 km and 1 km) to exclude the uncertainties of the model originated from them. Our analyses indicated that most of the model well simulated the atmospheric $$^{137}$$Cs obtained from the operational aerosol sampling of the national suspended particle matter network. Our analyses also indicated that meteorological data were most critical for reproducing the atmospheric $$^{137}$$Cs events, and the extent of the horizontal diffusion and the deposition were critical if the meteorological field was reasonably simulated. The comparison of the results between the two MIPs elucidated that the fine grid resolution is required to simulate atmospheric $$^{137}$$Cs in the vicinity of FDNPP, but the use of the fine grid resolution does not always improve the performance of the models especially for areas distant from the FDNPP. The results of both MIPs elucidated that the good performance of some models improved the performance of the multimodel, highlighting the advantage of using a multimodel ensemble.

Oral presentation

Evaluation of reproducibility of the early phase of the accident by ATDM using the estimates of air dose rate based on air concentration and surface deposition

Moriguchi, Yuichi*; Sato, Yosuke*; Goto, Daisuke*; Morino, Yu*; Sekiyama, Tsuyoshi*; Takigawa, Masayuki*; Terada, Hiroaki; Tsuruta, Haruo*; Yamazawa, Hiromi*

no journal, , 

no abstracts in English

19 (Records 1-19 displayed on this page)
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