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Machida, Masahiko; Yamada, Susumu; Kim, M.; Okumura, Masahiko; Miyamura, Hiroko; Shikaze, Yoshiaki; Sato, Tomoki*; Numata, Yoshiaki*; Tobita, Yasuhiro*; Yamaguchi, Takashi; et al.
RIST News, (69), p.2 - 18, 2023/09
The contamination of radioactive materials leaked from the reactor has resulted in numerous hot spots in the Fukushima Daiichi Nuclear Power Station (1F) building, posing obstacles to its decommissioning. In order to solve this problem, JAEA has conducted research and development of the digital technique for inverse estimation of radiation source distribution and countermeasures against the estimated source in virtual space for two years from 2021 based on the subsidy program "Project of Decommissioning and Contaminated Water Management" performed by the funds from the Ministry of Economy, Trade and Industry. In this article, we introduce the results of the project and the plan of the renewal project started in April 2023. For the former project, we report the derivative method for LASSO method considering the complex structure inside the building and the character of the source and show the result of the inverse estimation using the method in the real reactor building. Moreover, we explain the platform software "3D-ADRES-Indoor" which integrates these achievements. Finally, we introduce the plan of the latter project.
Kim, M.; Malins, A.; Machida, Masahiko; Yoshimura, Kazuya; Saito, Kimiaki; Yoshida, Hiroko*; Yanagi, Hideaki*; Yoshida, Toru*; Hasegawa, Yukihiro*
RIST News, (67), p.3 - 15, 2021/09
no abstracts in English
Suno, Hiroya; Machida, Masahiko
RIST News, (66), p.3 - 16, 2020/10
no abstracts in English
Kim, M.; Malins, A.; Sakuma, Kazuyuki; Kitamura, Akihiro; Machida, Masahiko; Hasegawa, Yukihiro*; Yanagi, Hideaki*
RIST News, (64), p.3 - 16, 2018/09
To improve the accuracy of simulations for air dose rates over fallout contaminated areas, the distribution of the radionuclides within the environment should be modelled realistically, e.g. considering differences in radioactivity levels between agricultural land, urban surfaces, and forest compartments. Moreover simulations should model the shielding of 
rays by buildings, trees and land topography. Here we outline a system for generating three dimensional models of urban and rural areas in Fukushima Prefecture. The 
Cs and 
Cs radioactivity distribution can be set flexibly across the different components of the model. The models incorporate realistic representations of local buildings, based on nine common Japanese designs, individual conifer and broadleaf trees, and the topography of the land surface. Models are generated from Digital Elevation Model (DEM) and Digital Surface Model (DSM) datasets, and refined by users assisted with ortho-photographs of target sites. Completed models are exported from the system in a format suitable for the Particle and Heavy Ion Transport code System (PHITS) for the calculation of air dose rates and other radiological quantities. The system is demonstrated by modelling a suburban area 4 km from the Fukushima Daiichi Nuclear Power Plant that has yet to be decontaminated. Air dose rates calculated in PHITS were correlated with measurements taken across the site in a car-borne survey.
Miura, Yukitoshi
RIST News, (61), p.1 - 2, 2016/07
no abstracts in English
Muramatsu, Toshiharu
RIST News, (60), p.22 - 27, 2016/01
no abstracts in English
Sato, Kaoru; Takahashi, Fumiaki; Endo, Akira; Ono, Koji*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Yoshitake, Takayasu*; Ban, Nobuhiko*; Kai, Michiaki*
RIST News, (58), p.25 - 32, 2015/01
The Japan Atomic Energy Agency (JAEA) are now developing WAZA-ARI for improvement of management of exposure doses due to CT examination under the joint research with the Oita University of Nursing and Health Sciences. The trial version of WAZA-ARI has been released on 21 December 2012. In trial version, users can perform dose assessment by using organ dose database based on the average adult Japanese male (JM-103) and female (JF-103) voxel phantoms and a 4 years old female voxel phantom (UFF4). The homepage of WAZA-ARI has been accessed over 1000 times per month and 28421 times by the end of September 2014. We are developing WAZA-ARI version 2 as the extension version of dose calculation functions of WAZA-ARI. WAZA-ARI version 2 will be released by the end of March 2015. In WAZA-ARI version 2. Users can upload dose calculation results to WAZA-ARI version 2 server, and utilize improvement of the dose management of patients and the optimization of CT scan conditions.
Nakamura, Hiroki; Okumura, Masahiko; Machida, Masahiko
RIST News, (58), p.33 - 46, 2015/01
no abstracts in English
Maeyama, Shinya
RIST News, (57), p.15 - 23, 2014/07
no abstracts in English
Sato, Tatsuhiko; Niita, Koji*; Matsuda, Norihiro; Hashimoto, Shintaro; Iwamoto, Yosuke; Noda, Shusaku; Ogawa, Tatsuhiko; Nakashima, Hiroshi; Fukahori, Tokio; Okumura, Keisuke; et al.
RIST News, (54), p.14 - 24, 2013/01
Features of the latest version of the PHITS code (version 2.52) is described.
Nishida, Akemi; Suzuki, Yoshio; Yamada, Tomonori; Kino, Chiaki; Uzawa, Ken*; Miyamura, Hiroko; Kawamura, Takuma; Takemiya, Hiroshi; Nakajima, Norihiro
RIST News, (54), p.33 - 37, 2013/01
Nuclear plants are complicated and huge structures and consist of a large number of parts. To simulate the behavior of such a complicated huge structure, it becomes important the viewpoint as a general system including pre-post-processing. Therefore, the CCSE proposed an approach for assembly structure analysis and implemented a framework of a full-scale 3D vibration simulator for an entire nuclear plant. Until now, we performed numerical experiments using the data of a building and equipment of HTTR, Oarai R&D Center, JAEA, and demonstrated that earthquake response simulation of large-scale structure as an entire nuclear plant was possible so far. In this report, the framework of the full-scale 3D vibration simulator, the assembly structure analysis approach and visualization technology for an evaluation of the results are shown. And finally, an example of application of the simulator for probabilistic risk assessment, PRA, started from 2011, is shown.
Satoh, Daiki; Oizumi, Akito; Matsuda, Norihiro; Kojima, Kensuke; Kugo, Teruhiko; Sakamoto, Yukio*; Endo, Akira; Okajima, Shigeaki
RIST News, (53), p.12 - 23, 2012/09
Decontamination planning based on a computer simulation code CDE is discussed in this paper. Large amount of radionuclides had been discharged to environment in the accident of the Tokyo Electronic Power Corporation Fukushima Dai-ichi Nuclear Power Plant. CDE has been developed to support planning the decontamination. From the present study, it is validated that the computer simulation is very useful to predict the effect of the scenario before actions, and to plan the decontamination.
Sato, Tatsuhiko
RIST News, (51), p.13 - 19, 2011/07
We review the recent development and release of the PHITS code.
Nakamura, Hideo
RIST News, (51), p.30 - 42, 2011/07
Long-term core cooling against any possible accident situations should be firmly secured and confirmed by the safety analyses using computer codes during the design phase of nuclear power plant. The accident at Fukushima Daiichi made us duly aware of incompleteness in the assumptions made for the safety analyses as well as the importance of the computer codes that accurately analyze such accidents. This paper tries to remind kinds, methods of utilization and development status of the computer codes for safety analysis, and to briefly review recent development efforts of such computer codes in Korea and China, both to re-consider how our code development should be in Japan.
Sukegawa, Atsuhiko; Okuno, Koichi*; Kawasaki, Hiromitsu*
RIST News, (51), p.20 - 29, 2011/07
no abstracts in English
Kureta, Masatoshi
RIST News, (48), p.24 - 37, 2009/12
Neutron visual sensing technique is one of the nondestructive visualization and image-sensing techniques. In this article, some advanced neutron visual sensing techniques are introduced. The most up-to-date high-speed neutron radiography, neutron 3D CT, high-speed scanning neutron 3D/4D CT and multi-beam neutron 4D CT techniques are included with some fundamental application results. Oil flow in a car engine was visualized by high-speed neutron radiography technique to make clear the unknown phenomena. 4D visualization of painted sand in the sand glass was reported as the demonstration of the high-speed scanning neutron 4D CT technique. The purposes of the development of these techniques are to make clear the unknown phenomena and to measure the void fraction, velocity etc. with high-speed or 3D/4D for many industrial applications.
Nakashima, Hiroshi
RIST News, (47), p.3 - 14, 2009/06
Recently high energy particle accelerators are widely used in various fields from basic science to medical application. In these accelerator facilities, in order to apply radiation shielding design methods to the facility shielding design, the methods are developed and their accuracy are evaluated. Therefore I summarize the present status of the radiation shielding design methods for the high energy accelerator facilities and their benchmarking in this paper.
Takase, Kazuyuki; Yoshida, Hiroyuki
RIST News, (45), p.3 - 9, 2008/05
no abstracts in English
Suzuki, Yoshio
RIST News, (44), p.9 - 16, 2007/10
no abstracts in English
Ozeki, Takahisa
RIST News, (44), p.3 - 8, 2007/10
no abstracts in English
