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Shimada, Taro; Namekawa, Masakazu*; Miwa, Kazuji; Takeda, Seiji
Proceedings of Waste Management Symposia 2023 (WM2023) (Internet), 8 Pages, 2023/02
It is supposed that radioactive dust deposited at the land surface will be moved downstream and concentrated at the depression by overland flow at heavy rain after the accidental release of radioactive dusts accumulated at the filters in the decommissioning stage of nuclear facilities. The authors are developing a calculation code to evaluate distribution changes of radioactivity on the surface and public dose considering the conditions such as rainfall, topography and types of cover surface. It is necessary to construct methods for setting parameter values used for the calculations based on the actual situation. Therefore, the parameter values were obtained by the experiments where FeO powder spread on the cover surface such as smooth and aged-asphalt, concrete and bare soil, was eroded by overland flow and raindrops and they were collected at the lower end of the slope at a minute interval. The collected weights of overland flow and FeO powder were measured. Based on the Manning's roughness coefficient for smooth asphalt already known as a fixed value, the erosion velocity coefficient was evaluated. Then Manning's roughness coefficients for other cover surfaces were obtained using the erosion velocity coefficient. Manning's roughness coefficients were slightly smaller than the range of literature values. In addition, elevations for the cover surface were measured by 3D scanner as point cloud data, and the surface roughness were evaluated. The values of surface roughness and Manning's roughness coefficients had a correlation. It indicated a possibility to utilize the surface roughness to set the Manning's roughness coefficient for the evaluation of radioactivity distribution change by heavy rainfall.
Onodera, Naoyuki; Idomura, Yasuhiro; Hasegawa, Yuta; Nakayama, Hiromasa
Dai-36-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Rombunshu (Internet), 3 Pages, 2022/12
We have developed a wind simulation code named CityLBM to realize wind digital twins. Mesoscale wind conditions are given as boundary conditions in CityLBM by using a nudging data assimilation method. It is found that conventional approaches with constant nudging coefficients fail to reproduce turbulent intensity in long time simulations, where atmospheric stability conditions change significantly. We propose a dynamic parameter optimization method for the nudging coefficient based on an ensemble Kalman filter. CityLBM was validated against plume dispersion experiments in the complex urban environment of Oklahoma City. The nudging coefficient was updated to reduce the error of the turbulent intensity between the simulation and the observation. The mean error of velocity variance is reduced by 10% compared to the conventional nudging method with a constant nudging coefficient.
Onodera, Naoyuki; Idomura, Yasuhiro; Hasegawa, Yuta; Nakayama, Hiromasa
Dai-35-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Rombunshu (Internet), 3 Pages, 2021/12
A detailed wind simulation is very important for designing smart cities. Since a lot of tall buildings and complex structures make the air flow turbulent in urban cities, large-scale CFD simulations are needed. We develop a GPU-based CFD code based on a Lattice Boltzmann Method (LBM) with a block-based Adaptive Mesh Refinement (AMR) method. In order to reproduce real wind conditions, the wind condition and ground temperature of the mesoscale weather forecasting model are given as boundary conditions. In this research, a surface heat flux model based on the Monin-Obukhov similarity theory was introduced to improve the calculation accuracy. We conducted a detailed wind simulation in Oklahoma City. By executing this computation, wind conditions in the urban area were reproduced with good accuracy.
Moriguchi, Yuichi*; Sato, Yosuke*; Morino, Yu*; Goto, Daisuke*; Sekiyama, Tsuyoshi*; Terada, Hiroaki; Takigawa, Masayuki*; Tsuruta, Haruo*; Yamazawa, Hiromi*
KEK Proceedings 2021-2, p.21 - 27, 2021/12
no abstracts in English
Saito, Kimiaki
Tokyo Denryoku Fukushima Daiichi Genshiryoku Hatsudensho Jiko Ni Yoru Kankyo Osen No Kenkyu Chosa No Shinten To Kadai (Internet), p.8 - 10, 2020/07
no abstracts in English
Sakai, Toshihiro; Matsuoka, Toshiyuki
JAEA-Research 2015-004, 109 Pages, 2015/06
We update the geologic map and the database of the geological mapping published by Funaki et al. (2005a) and Ota et al. (2007) based on geological survey and topographical analysis data in and around the Horonobe area. There are many geological survey data which are derived from natural resources (petroleum, natural gas and coal, etc.) exploration in and around Horonobe-cho. We also use these data in addition to data in Funaki et al. (2005a) and Ota et al. (2007)'s data. As results of this report, we also construct a digital geologic map and a digital database of geological survey using GIS. These results can be expected to improve the precision of modeling and analyzing of geological environment, and its long-term evaluation.
Komatsu, Teruhisa; Adachi, Takeo
Journal of Applied Meteorology, 42(9), p.1330 - 1334, 2003/09
no abstracts in English
Amano, Hikaru
Fusion Science and Technology, 41(3), p.488 - 492, 2002/05
no abstracts in English
Komatsu, Teruhisa
Journal of the Physical Society of Japan, 70(12), p.3755 - 3756, 2001/12
Times Cited Count:4 Percentile:33.14(Physics, Multidisciplinary)no abstracts in English
Koarashi, Jun; Amano, Hikaru; Atarashi-Andoh, Mariko; Iida, Takao*; Koma, T.*
Radiation Protection Dosimetry, 93(3), p.237 - 243, 2001/00
Times Cited Count:8 Percentile:52.3(Environmental Sciences)no abstracts in English
Koarashi, Jun*; Amano, Hikaru; Atarashi-Andoh, Mariko; Iida, Takao*
Radiation Protection Dosimetry, 87(2), p.121 - 131, 2000/01
Times Cited Count:24 Percentile:80.77(Environmental Sciences)no abstracts in English
Yamazawa, Hiromi; Nagai, Haruyasu
JAERI-Conf 99-001, p.151 - 160, 1999/03
no abstracts in English