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Cs from the Fukushima Daiichi Nuclear Power Plant accident; Simulations based on identical input dataSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu
lo, D.*; et al.
Journal of Geophysical Research; Atmospheres, 123(20), p.11748 - 11765, 2018/10
Times Cited Count：40 Percentile：84.89(Meteorology & Atmospheric Sciences)A model intercomparison of the atmospheric dispersion of Cs emitted following the Fukushima Daiichi Nuclear Power Plant accident was conducted by 12 models to understand the behavior of 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 Cs events, and the figure-of-merit in space for the total deposition of Cs exceeded 80. Our analyses indicated that the meteorological data were most critical for reproducing the 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 Cs concentrations.
Ota, Masakazu; Kwamena, N.-O. A.*; Mihok, S.*; Korolevych, V.*
Journal of Environmental Radioactivity, 178-179, p.212 - 231, 2017/11
Times Cited Count：14 Percentile：43.09(Environmental Sciences)Environmental transfer models assume that organically-bound tritium (OBT) is formed directly from tissue-free water tritium (TFWT) in environmental compartments. Nevertheless, studies in the literature have shown that measured OBT/TFWT ratios are variable. The importance of soil-to-leaf HTO transfer pathway in controlling the leaf tritium dynamics is not well understood. A model inter-comparison of two tritium transfer models (CTEM-CLASS-TT and SOLVEG-II) was carried out with measured environmental samples from an experimental garden plot set up next to a tritium-processing facility. The garden plot received one of three different irrigation treatments - no external irrigation, irrigation with low tritium water and irrigation with high tritium water. The contrast between the results obtained with the different irrigation treatments provided insights into the impact of soil-to-leaf HTO transfer on the leaf tritium dynamics. Concentrations of TFWT and OBT in the garden plots that were not irrigated or irrigated with low tritium water were variable, responding to the arrival of the HTO-plume from the tritium-processing facility. In contrast, for the plants irrigated with high tritium water, the TFWT concentration remained elevated due to a continuous source of high HTO in the soil. Calculated concentrations of OBT in the leaves showed an initial increase followed by quasi-equilibration with the TFWT concentration. In this quasi-equilibrium state, concentrations of OBT remained elevated and unchanged despite the arrivals of the plume. These results from the model inter-comparison demonstrate that soil-to-leaf HTO transfer significantly affects OBT/TFWT ratio in the leaf regardless of the atmospheric HTO concentration, only if there is elevated HTO concentrations in the soil. The results of this work indicate that assessment models should be refined to consider the importance of soil-to-leaf HTO transfer to ensure that dose estimates are accurate and conservative.
Saito, Kimiaki; Nagai, Haruyasu; Kinase, Sakae; Takemiya, Hiroshi
Nihon Genshiryoku Gakkai-Shi ATOMO
, 59(6), p.40 - 44, 2017/06
no abstracts in English
Mikami, Satoshi; Matsuda, Norihiro; Ando, Masaki; Kinase, Sakae; Kitano, Mitsuaki; Kawase, Keiichi; Matsumoto, Shinichiro; Yamamoto, Hideaki; Saito, Kimiaki
Radioisotopes, 64(9), p.589 - 607, 2015/09
This article presents the features of regional distributions and temporal changes in air dose rate and radionuclide deposition densities in Fukushima on the basis of analyses on large-scale environmental monitoring results using diverse methods. The continuity of decontamination effects is discussed according to repeated monitoring data after the decontamination model project. Further, some examples are shown on the projection of air dose rates together with the ecological half lives for different land uses.
Terada, Hiroaki; Chino, Masamichi
Proceedings of 2nd International Conference on Radioactivity in the Environment, p.15 - 18, 2005/10
The previous version of Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI) has been composed of mass-consistent wind field model WSYNOP and particle dispersion model GEARN. Because WSYNOP has no capability to predict meteorological fields, its accuracy and resolution depends on meteorological input data, and it is impossible to treat physical processes realistically. To improve these problems, an atmospheric dynamic model MM5 is introduced and applied to the Chernobyl accident for the verification. Two calculation cases are conducted, CASE-1 a calculation for European region Domain-1, and CASE-2 a domain nesting calculation for Domain-1 and the region around Chernobyl Domain-2. The air concentration and surface deposition of Cs calculated by CASE-1 agree well with the measurements by statistical analysis and comparison for the horizontal distribution. In the result of CASE-2, the detailed distribution of surface Cs deposition around Chernobyl which was impossible to calculate in CASE-1 is predicted with high accuracy.
Cs deposition due to the Chernobyl nuclear accidentTerada, Hiroaki; Chino, Masamichi
Journal of Nuclear Science and Technology, 42(7), p.651 - 660, 2005/07
Times Cited Count：18 Percentile：74.82(Nuclear Science & Technology)The prediction performance of WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information), which consists of the atmospheric dynamic model MM5 and the Lagrangian particle dispersion model GEARN-new, is evaluated by measurements of precipitation and surface deposition of Cs over Europe during the Chernobyl accident. It is concluded that MM5/GEARN-new can predict Cs deposition distribution with good accuracy when accurate precipitation is predicted by using a explicit scheme on cloud microphysics with ice phase processes. High-resolutional calculation is also conducted for the area surrounding Chernobyl by a nesting method. MM5/GEARN-new can predict quite a realistic distribution of Cs deposition around Chernobyl which was not calculated by the previous version.
Terada, Hiroaki; Furuno, Akiko; Chino, Masamichi
Journal of Nuclear Science and Technology, 41(5), p.632 - 640, 2004/05
Times Cited Count：22 Percentile：79.05(Nuclear Science & Technology)The new version of WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information) is developed by introducing the combination of models, the atmospheric dynamic model MM5 and the Lagrangian particle dispersion model GEARN-new to improve the prediction capability. One of the improvements by the new system is that Environmental contaminations in multi domains are predicted simultaneously, and the other is that more precise physical processes are considered by using predicted meteorological conditions with high resolution in time and space. The performance of the system is evaluated for the test calculations of hypothetical nuclear accident in the East Asia region and the Chernobyl accident. The results of test calculation in East Asia seem to be reasonable and the calculated surface air concentrations of Cs from Chernobyl show good agreement with measurements.
Kataoka, Isao*; Matsuura, Keizo*; Yoshida, Kenji*
JAERI-Tech 2002-015, 83 Pages, 2002/03
JAERI-Tech-2002-015.pdf:3.62MB
no abstracts in English
Noguchi, Hiroshi
Purazuma, Kaku Yugo Gakkai-Shi, 73(12), P. 1360, 1997/12
no abstracts in English
Ishikawa, Hirohiko
Journal of Nuclear Science and Technology, 31(9), p.969 - 978, 1994/09
Times Cited Count：7 Percentile：56.56(Nuclear Science & Technology)no abstracts in English
Ezzidi, A.*; Okubo, Tsutomu; Murao, Yoshio
JAERI-M 93-133, 39 Pages, 1993/07
no abstracts in English
Okubo, Tsutomu; Ezzidi, A.*; Murao, Yoshio
JAERI-M 93-069, 115 Pages, 1993/03
no abstracts in English
Murata, Mikio; Noguchi, Hiroshi
Nihon Genshiryoku Gakkai-Shi, 34(2), p.149 - 152, 1992/02
Times Cited Count：2 Percentile：43.73(Nuclear Science & Technology)no abstracts in English
Matsui, Hiroshi; Noguchi, Hiroshi
Earozoru Kenkyu, 7(4), p.346 - 355, 1992/00
no abstracts in English
