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JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018) (Translated document)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2020-007, 249 Pages, 2020/10

JAEA-Research-2020-007.pdf:15.83MB

The accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, Japan Atomic Energy Agency (JAEA) has been conducting "Long-term Assessment of Transport of Radioactive Contaminants in the Environment of Fukushima" concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Journal Articles

Estimation of air dose rate using measurement results of monitoring posts in Fukushima Prefecture

Seki, Akiyuki; Mayumi, Akie; Wainwright-Murakami, Haruko*; Saito, Kimiaki; Takemiya, Hiroshi; Idomura, Yasuhiro

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.158 - 164, 2020/10

We developed a method to estimate the temporal change of the air dose rate at the location with sparse (in time) measurements by using the continuous measurement data from the nearby monitoring post. This method determines an observation model from the correlation between sparse data at the target location and dense data at the monitoring post based on a hierarchical Bayesian model. The developed method was validated against the air dose rate measured at the monitoring posts in Fukushima prefecture from 2012 to 2017. The results showed that the developed method can predict the air dose rate at almost all target locations with an error rate of less than 10%.

Journal Articles

Optimizing long-term monitoring of radiation air-dose rates after the Fukushima Daiichi Nuclear Power Plant

Sun, D.*; Wainwright-Murakami, Haruko*; Oroza, C. A.*; Seki, Akiyuki; Mikami, Satoshi; Takemiya, Hiroshi; Saito, Kimiaki

Journal of Environmental Radioactivity, 220-221, p.106281_1 - 106281_8, 2020/09

 Times Cited Count:4 Percentile:62.5(Environmental Sciences)

We have developed a methodology for optimizing the monitoring locations of radiation air dose-rate monitoring. For the method, we use a Gaussian mixture model to identify the representative locations among multiple environmental variables, such as elevation and land-cover types. Next, we use a Gaussian process model to capture and estimate the heterogeneity of air-dose rates across the domain. Our results have shown that this approach allows us to select monitoring locations in a systematic manner such that the heterogeneity of air dose rates is captured by the minimal number of monitoring locations.

Journal Articles

Summary of temporal changes in air dose rates and radionuclide deposition densities in the 80 km zone over five years after the Fukushima Nuclear Power Plant accident

Saito, Kimiaki; Mikami, Satoshi; Ando, Masaki; Matsuda, Norihiro; Kinase, Sakae; Tsuda, Shuichi; Yoshida, Tadayoshi; Sato, Tetsuro*; Seki, Akiyuki; Yamamoto, Hideaki*; et al.

Journal of Environmental Radioactivity, 210, p.105878_1 - 105878_12, 2019/12

 Times Cited Count:20 Percentile:87.21(Environmental Sciences)

Journal Articles

Temporal change in radiological environments on land after the Fukushima Daiichi Nuclear Power Plant accident

Saito, Kimiaki; Mikami, Satoshi; Ando, Masaki; Matsuda, Norihiro; Kinase, Sakae; Tsuda, Shuichi; Sato, Tetsuro*; Seki, Akiyuki; Sanada, Yukihisa; Wainwright-Murakami, Haruko*; et al.

Journal of Radiation Protection and Research, 44(4), p.128 - 148, 2019/12

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2019-002, 235 Pages, 2019/08

JAEA-Research-2019-002.pdf:21.04MB

The accident of the Fukushima Daiichi Nuclear Power Station (hereinafter referred to 1F), Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, JAEA has been conducting Long-term Environmental Dynamics Research concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

JAEA Reports

Comprehensive evaluation system for environmental remediation of Fukushima; Toward integration of three components as a whole system

Saito, Hiroshi; Nozawa, Takashi; Takemiya, Hiroshi; Seki, Akiyuki; Matsubara, Takeshi; Saito, Kimiaki; Kitamura, Akihiro

JAEA-Review 2017-040, 34 Pages, 2018/03

JAEA-Review-2017-040.pdf:9.52MB

The accidents at Fukushima Daiichi Nuclear Power Station on March 11th 2011, released significant amount of radionuclide to the environment. It has migrated to the human habitation and raised concerns of possible effect on human health, and for that a lot of researches have been performed. JAEA created and opened "Database for Radioactive Substance Monitoring Data" for usage of obtained data. For accurate modelling and future forecast using numerical code and the data, "Supporting Environment for Processing Simulation Codes" has been operated. In addition, research results have been opened as Q&A style "Knowledge Base for Environmental Remediation" in JAEA's website. The "Comprehensive Evaluation System" composed of these components, should act more interrelated and integrated as one system. Besides, information dissemination is not enough to the outside. The report summarizes the current status, remaining issues and expected improvement of each component and the system.

Journal Articles

Challenges for enhancing Fukushima environmental resilience, 2; Features of radionuclide release and deposition with accident progress

Saito, Kimiaki; Nagai, Haruyasu; Kinase, Sakae; Takemiya, Hiroshi

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 59(6), p.40 - 44, 2017/06

no abstracts in English

Journal Articles

Algebraic design of multi-dimensional transfer function using transfer function synthesizer

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi

Journal of Visualization, 20(1), p.151 - 162, 2017/02

 Times Cited Count:2 Percentile:17.71(Computer Science, Interdisciplinary Applications)

In this paper, we propose a novel transfer function design interface for multivariate volume rendering. In the conventional multivariate volume rendering, GUI based transfer function design interfaces were limited to two-dimensional variables space. In order to design higher dimensional transfer functions in an interactive and intuitive manner, a Transfer Function Synthesizer (TFS) is developed. On the TFS, multi-dimensional transfer functions are generated by algebraic synthesis of one-dimensional transfer functions, which are designed based on the conventional GUIs or algebraic expressions. The TFS enables not only multivariate volume rendering but also general visualization techniques such as surface visualization and image composition within the framework of volume rendering. The TFS is implemented on the remote visualization system PBVR, and applied to various multivariate scalar volume data generated from nuclear applications.

Journal Articles

Level of detail control for environmental monitoring datasets

Miyamura, Hiroko; Takemiya, Hiroshi; Wu, H.-Y.*; Takahashi, Shigeo*

Kashika Joho Gakkai-Shi, 36(143), p.152 - 156, 2016/10

Broad survey on the distribution of the air dose rate has been performed after the accident at the Fukushima Daiichi Nuclear Power Plant continuously. The surveyed monitoring datasets are stored in a database and are made available to the public. Recently, the size of the datasets have been significantly increased as more detailed measurements in space and time are available, and effective reduction of the size of the datasets is necessary for visualizing and exploring such large scale datasets. However, if the datasets are not carefully reduced, we often miss a part of important features of the distribution data. Therefore, we develop an effective Level of Detail control (LoD) method for retaining critical features of the distribution. In the method, the global and local features of the distribution are extracted by means of differential topology analyses. Then, the simplified data is created by edge collapse operation with taking into account these features of the data.

Journal Articles

Visualization technique for large-scale data by particle-based volume rendering

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Imamura, Toshiyuki*; Takemiya, Hiroshi

Shisutemu Seigyo Joho Gakkai Rombunshi, 28(5), p.221 - 227, 2015/05

However remote volume visualization is important to obtain knowledge from complicated large-scale simulation results on supercomputer, the rendering speed and data transfer speed becomes bottleneck of the conventional Client/Server volume visualization techniques. Client/Server visualization system using particle-based volume rendering enables interactive volume visualization, which converts the original volume data to small size light particle data utilizing the supercomputer and transfer the data to Client PC. This system generated the particle data at a few seconds using parallel process on supercomputer Kei with strong scaling till 1000 processers.

Journal Articles

Development of a software platform for providing environmental monitoring data for the Fukushima Daiichi nuclear accident

Seki, Akiyuki; Saito, Osamu; Nago, Harutaka*; Suzuki, Kenta; Tomishima, Katsuya; Saito, Kimiaki; Takemiya, Hiroshi

Radiation Protection Dosimetry, 164(1-2), p.97 - 102, 2015/04

 Times Cited Count:4 Percentile:40.75(Environmental Sciences)

We have developed a software platform which supports working steps for providing large amount of diverse monitoring data. It was found that the platform is effective in reducing the time needed to publish the monitoring data. Reducing the cost and workload for publishing the monitoring data is also important, because monitoring should be continued over a few decades in the case of Fukushima accident. Our platform is expected to help to mitigate the problem, too.

Journal Articles

Measurements and evaluations of air dose rates around Fukushima, 4; Practical aspects of air dose rate measurements in the environment

Tsuda, Shuichi; Yoshida, Tadayoshi; Ando, Masaki; Matsuda, Norihiro; Mikami, Satoshi; Tanigaki, Minoru*; Okumura, Ryo*; Takamiya, Koichi*; Sato, Nobuhiro*; Seki, Akiyuki; et al.

Radioisotopes, 64(4), p.275 - 289, 2015/04

This article provides practically useful information on air dose rate measurements in the environments. The basic requirements for the accurate measurements are described giving actual data. The characteristics and some measured results are shown for reliable methods which are widely used in the environmental radiation measurements. Further, information is given on internet sites where air dose rates and related data obtained by official organizations can be browsed.

Journal Articles

Remote visualization system based on particle based volume rendering

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi; Sakamoto, Naohisa*; Koyamada, Koji*

Visualization and Data Analysis 2015 (Proceedings of SPIE Vol.9397) (Internet), p.93970S_1 - 93970S_8, 2015/02

 Times Cited Count:3 Percentile:86.38

In this paper, we propose a novel remote visualization system based on particle-based volume rendering (PBVR), which enables interactive analyses of extreme scale volume data located on remote computing systems. The remote PBVR system consists of Server, which generates particles for rendering, and Client, which processes volume rendering, and the particle data size becomes significantly smaller than the original volume data. Depending on network bandwidth, the level of detail of images is flexibly controlled to attain high frame rates. Server is highly parallelized on various parallel platforms with hybrid programing model. The mapping process is accelerated by two orders of magnitudes compared with a single CPU. The structured and unstructured volume data with 100 millions of cells is processed within a few seconds. Compared with commodity Client/Server visualization tools, the total processing cost is dramatically reduced by using proposed system.

Journal Articles

The Air dose rate around the Fukushima Dai-ichi Nuclear Power Plant; Its spatial characteristics and temporal changes until December 2012

Mikami, Satoshi; Maeyama, Takeshi*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Sato, Shoji*; Okuda, Naotoshi*; Sato, Tetsuro*; Takemiya, Hiroshi; Saito, Kimiaki

Journal of Environmental Radioactivity, 139, p.250 - 259, 2015/01

 Times Cited Count:43 Percentile:86.58(Environmental Sciences)

Journal Articles

Spatial distributions of radionuclides deposited onto ground soil around the Fukushima Dai-ichi Nuclear Power Plant and their temporal change until December 2012

Mikami, Satoshi; Maeyama, Takeshi*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Sato, Shoji*; Okuda, Naotoshi*; Demongeot, S.*; Gurriaran, R.*; Uwamino, Yoshitomo*; Kato, Hiroaki*; et al.

Journal of Environmental Radioactivity, 139, p.320 - 343, 2015/01

 Times Cited Count:70 Percentile:94.06(Environmental Sciences)

Journal Articles

Detailed deposition density maps constructed by large-scale soil sampling for $$gamma$$-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident

Saito, Kimiaki; Tanihata, Isao*; Fujiwara, Mamoru; Saito, Takashi*; Shimoura, Susumu*; Otsuka, Takaharu*; Onda, Yuichi*; Hoshi, Masaharu*; Ikeuchi, Yoshihiro*; Takahashi, Fumiaki; et al.

Journal of Environmental Radioactivity, 139, p.308 - 319, 2015/01

 Times Cited Count:191 Percentile:99.23(Environmental Sciences)

Journal Articles

Fields of view for environmental radioactivity

Malins, A.; Okumura, Masahiko; Machida, Masahiko; Takemiya, Hiroshi; Saito, Kimiaki

Proceedings of International Symposium on Radiological Issues for Fukushima's Revitalized Future, p.28 - 34, 2015/00

The $$gamma$$ component of air radiation dose rates is a function of the amount and spread of radioactive nuclides in the environment. These radionuclides can be natural or anthropogenic in origin. The field of view describes the area of radionuclides on, or below, ground that is responsible for determining the air dose rate, and hence correspondingly the external radiation exposure. This work describes Monte Carlo radiation transport calculations for the field of view under a variety of situations. Presented first are results for natural 40K and thorium and uranium series radionuclides distributed homogeneously within the ground. Results are then described for atmospheric radioactive cesium fallout, such from the Fukushima Daiichi Nuclear Power Plant accident. Various stages of fallout evolution are considered through the depth distribution of $$^{134}$$Cs and $$^{137}$$Cs in soil. The fields of view for the natural radionuclides and radiocesium are different. This can affect the responses of radiation monitors to these nuclides if the detector is partially shielded from the ground within its field of view. The field of view also sets the maximum reduction in air dose rates that can be achieved through local decontamination or remediation measures. This maximum efficiency can be determined quickly from the data presented here for the air dose rate versus the spatial extent of radioactive source on the ground.

Journal Articles

Multivariate volume rendering using transfer function synthesizer implemented in remote visualization system PBVR

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi

Proceedings of SIGGRAPH Asia 2015 (SA 2015) (Internet), 4 Pages, 2015/00

In this paper, we propose a novel transfer function design technique for multivariate volume rendering. This technique generates a multidimensional transfer function by logical synthesis of variables and transfer functions. This technique enables analysts to extract correlation of variables and to combine multivariate surface and volume shapes. And this technique is implemented in Remote Visualization System PBVR optimized to several supercomputers. An experiment for the multi-phase fuel melting simulation result in the nuclear energy field shows the powerful ability of this technique enough by extracting complex behavior of molten materials.

Journal Articles

2-dimentional visualization technique for exploring region of interest in 4-dimensional data

Miyamura, Hiroko; Kawamura, Takuma; Suzuki, Yoshio; Idomura, Yasuhiro; Takemiya, Hiroshi

Joho Shori Gakkai Rombunshi, 55(9), p.2216 - 2224, 2014/09

In numerical simulations, variations of calculation results with respect to a variable axis are often observed. When the target model is given in 3D, the simulation results become 4D. Such a multi-dimensional dataset given in more than 4D space is analyzed by detailed explorations of regions of interest (ROIs) in multi-dimensional space. However, for high-dimensional and large-scale datasets, this approach requires enormous processing time and effort, and may have difficulty in capturing all the ROIs. Therefore, we propose a technique that is based on a concept of spatiotemporal image. In our technique, a space axis is created by octree, a variable axis is defined in the direction perpendicular to the space axis. Our technique is applied to the results of 3D seismic simulations of a nuclear plant, and regions with characteristic frequency responses of each region are analyzed. Through the analyses, it is demonstrated that our technique can effectively capture ROIs from 4D datasets.

190 (Records 1-20 displayed on this page)