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Hasegawa, Yuta; Onodera, Naoyuki; Idomura, Yasuhiro
Dai-34-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Rombunshu (Internet), 3 Pages, 2020/12
We developed a real-time ensemble simulation code for analyzing urban wind conditions and plume dispersion using a locally mesh-refined lattice Boltzmann method. We validated the developed code against the wind tunnel experiment by AIST, and against the field experiment JU2003 in Oklahoma City. In the case of the wind tunnel experiment, the wind condition showed a good agreement with the experiment, and 61.2% of the tracer gas concentration data observed on the ground satisfied the FACTOR2 condition, that is an accuracy criterion given by the environmental assessment guideline. In the case of the field experiment JU2003, the instantaneous wind speed showed a good agreement with the experiment, while the wind direction showed a difference up to 100
. The means of the tracer gas concentration satisfied the FACTOR2 condition at all observation interval. These results demonstrate that the developed code is accurate enough for the environmental assessment.
Sakamoto, Hiroyuki*; Akagi, Yosuke*; Yamada, Kazuo*; Tachi, Yukio; Fukuda, Daisuke*; Ishimatsu, Koichi*; Matsuda, Mikiya*; Saito, Nozomi*; Uemura, Jitsuya*; Namihira, Takao*; et al.
Nihon Genshiryoku Gakkai Wabun Rombunshi, 17(2), p.57 - 66, 2018/05
Concrete debris contaminated with radioactive cesium and other nuclides have been generated from the accident in the Fukushima Dai-ichi Nuclear Power Plant and there will be generated due to the decommissioning of nuclear power plants in the future. Although conventional decontamination techniques are effective for flat concrete surfaces such as floors and walls, it is not clear what techniques to apply for decontaminating radioactive concrete debris. In this study, focusing on a pulsed power discharge technique, fundamental experimental works were carried out. Decontamination of concrete by applying the aggregate recycling technique using the pulsed power discharge technique was evaluated by measuring radioactivity of aggregate and sludge separated from the contaminated concrete. The results suggest that the separation into aggregate and sludge of the contaminated concrete debris could achieve decontamination and volume reduction of the radioactive concrete debris.
Matsunaga, Takeshi; Yanase, Nobuyuki; Hanzawa, Yukiko; Tsuzuki, Katsunori; Naganawa, Hirochika
Journal of Water and Environment Technology (Internet), 3(2), p.243 - 252, 2005/00
In a tributary watershed of the Kuji River of Japan, the hydrological components of runoff associated with a rain storm event were investigated using isotope tracers of hydrogen (
H) and oxygen (
O) in precipitations and stream water. The runoff was separated into either "old water" (pre-existing in the ground before the storm) and "new water"(from the storm precipitation). It was found that the discharge of several hazardous trace elements (Sb, Cu, Cr) was largely (24-54%) attributable to that of the new water in spite of its small contribution to the total water discharge. These investigations suggest that the new water may play an important role in the migration of atmospherically derived, hazardous trace elements to streams during rain storms.
Ito, Yasuhisa; Noda, Kimio; ;
JNC TN8410 2001-018, 67 Pages, 2001/04
JNC-TN8410-2001-018.pdf:2.96MB
There are waste storage pits where non-radioactive wastes generated from plutonium fuel facilities were stored in JNC Tokai Works. But radioactive wastes were found in one of the pit during wastes arrangement works. Therefore we set the pit temporary controlled area and recovered wastes from it. This report describes the radiation control technique of recovery work in detail.
JAERI-Research 95-006, 65 Pages, 1995/02
JAERI-Research-95-006.pdf:2.58MB
no abstracts in English
Tokunaga, Okihiro
Hoshasen Riyo Kokusai Shimpojiumu Rombunshu, 0, p.E110_1_1 - E110_1_5, 1994/00
no abstracts in English
Onodera, Naoyuki
no journal, ,
The plume dispersion simulations is very important from the viewpoint of nuclear security, and it is also required to satisfy both calculation speed and accuracy. GPU accelerated CFD method enables both high-resolution and real-time wind simulations in urban areas. In this presentation, we applied a communication reduced multi-time-step algorithm to AMR based CityLBM, and we realized a real-time plume dispersion simulation on GPU supercomputers.
Hasegawa, Yuta; Onodera, Naoyuki; Idomura, Yasuhiro
no journal, ,
Towards the prediction of the plume dispersion in the urban area, we are developing the urban wind simulation code CityLBM which is based on the lattice Boltzmann method with GPU computing. In this presentation, we implemented the ensemble simulation with MPI parallelization, and estimated the uncertainty of the plume dispersion simulation. The ensemble simulation with 100 members was performed, and the dependency of the simulation against the number of ensemble members was tested. We confirmed that the ensemble simulation can be statistically assessed with the number of ensemble members being 10.
