Development of semantic survey map building system using semi-autonomous mobile robots for surveying of disaster area and gathering of information in nuclear power station (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Polytechnic University*

JAEA-Review 2022-011, 80 Pages, 2022/07

JAEA-Review-2022-011.pdf:5.42MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of semantic survey map building system using semi-autonomous mobile robots for surveying of disaster area and gathering of information in nuclear power station" conducted from FY2018 to FY2021 (this contract was extended to FY2021). Since the final year of this proposal was FY2021, the results for four fiscal years were summarized. The present study aims to research and develop semi-autonomous mobile robot systems (multi-sensor fusion system, semantic simultaneous localization and mapping (SLAM), system for traversable-route learning and safe traversable-route presentation, etc.) that simply, safely, and rapidly make semantic survey maps …

Development of semantic survey map building system using semi-autonomous mobile robots for surveying of disaster area and gathering of information in nuclear power station (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Polytechnic University*

JAEA-Review 2020-062, 47 Pages, 2021/01

JAEA-Review-2020-062.pdf:3.43MB

JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Semantic Survey Map Building System using Semi-autonomous Mobile Robots for Surveying of Disaster Area and Gathering of Information in Nuclear Power Station" conducted in FY2019.

Development of semantic survey map building system using semi-autonomous mobile robots for surveying of disaster area and gathering of information in nuclear power station (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Polytechnic University*

JAEA-Review 2019-022, 35 Pages, 2020/01

JAEA-Review-2019-022.pdf:2.71MB

CLADS, JAEA, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the Development of Semantic Survey Map Building System Using Semi-autonomous Mobile Robots for Surveying of Disaster Area and Gathering of Information in Nuclear Power Station. The objective of the present study is to research and develop semi-autonomous mobile robot systems (multi-sensor fusion system, semantic simultaneous localization and mapping (SLAM), system for traversable-route learning and safe traversable-route presentation, etc.) that simply, safely, and rapidly make semantic survey maps including multiple information (air dose rate, temperature, obstacles, etc.). The system will be applied to the investigation of the situation inside the building of the nuclear power station where people cannot access at the time of disaster.

Study of corrosion rate of carbon steel in diluted artificial seawater under simulated irradiation condition

Komatsu, Atsushi; Tsukada, Takashi; Ueno, Fumiyoshi; Yamamoto, Masahiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05

Effect of oxygen and hydrogen peroxide on corrosion rate of carbon steel in diluted artificial seawater was investigated by electrochemical methods. Diffusion coefficient and thickness of diffusion layer for oxygen and hydrogen peroxide were measured to estimate the diffusion limiting current density. Corrosion tests of carbon steel were also conducted in diluted artificial seawater containing oxygen and/or hydrogen peroxide at 323K. The diffusion coefficient of hydrogen peroxide was about 0.8 times lower than that of oxygen, and the thickness of diffusion layer was almost equivalent between oxygen and hydrogen peroxide. Diffusion limiting current density of hydrogen peroxide was estimated to be 0.4 times lower than that of oxygen in the same concentration at 323K. Plot of corrosion rate with the addition of concentration of oxygen and 0.4 times concentration of hydrogen peroxide showed good correlation.

Design study of a neutral beam injector for fusion DEMO plant at JAERI

Inoue, Takashi; Hanada, Masaya; Kashiwagi, Mieko; Nishio, Satoshi; Sakamoto, Keishi; Sato, Masayasu; Taniguchi, Masaki; Tobita, Kenji; Watanabe, Kazuhiro; DEMO Plant Design Team

Fusion Engineering and Design, 81(8-14), p.1291 - 1297, 2006/02

https://doi.org/10.1016/j.fusengdes.2005.08.074

Requirement and technical issues of the neutral beam inejctor (NBI) is discussed for fusion DEMO plant. The NBI for the fusion DEMO plant should be high efficiency, high energy and high reliability with long life. From the view point of high efficiency, use of conventional electrostatic accelerator is realistic. Due to operation under radiation environment, vacuum insulation is essential in the accelerator. According to the insulation design guideline, it was clarified that the beam energy of 1.52 MeV is possible in the accelerator. Development of filamentless, and cesium free ion source is required, based on the existing high current/high current density negative ion production technology. The gas neutralization is not applicable due to its low efficiency (60%). R&D on an advanced neutralization scheme such as plasma neutralization (efficiency: 80%) is required. Recently, development of cw high power semiconductor laser is in progress. The paper shows a conceptual design of a high efficiency laser neutralizer utilizing the new semiconductor laser array.

Annual report of Naka Fusion Research Establishment from April 1, 2004 to March 31, 2005

Naka Fusion Research Establishment

JAERI-Review 2005-046, 113 Pages, 2005/09

JAERI-Review-2005-046.pdf:24.35MB

This annual report provides an overview of research and development activities at Naka Fusion Research Establishment, including those performed in collaboration with other research establishments of JAERI, research institutes, and universities, during the period from 1 April, 2004 to 31 March, 2005. The activities in the Naka Fusion Research Establishment are highlighted by researches in JT-60 and JFT-2M, theoretical and analytical plasma researches, research and development of fusion reactor technologies towards ITER and fusion power demonstration plants, and activities in support of ITER design and construction.

Study of millimeter wave high-power gyrotron for long pulse operation

Kasugai, Atsushi; Sakamoto, Keishi; Minami, Ryutaro; Takahashi, Koji; Imai, Tsuyoshi

Nuclear Instruments and Methods in Physics Research A, 528(1-2), p.110 - 114, 2004/08

https://doi.org/10.1016/j.nima.2004.04.029

The development of the millimeter wave high power gyrotron with the development of a depressed collector, an over sized cavity and a synthesized diamond output window is under going in JAERI. The performances of 170 GHz, 0.9 MW for 9.2 s and 0.5 MW for 30 s were achieved up to now. It was clarified, however, that pulse extension of the gyrotron was limited by sudden outgassing due to stray RF power deposition to the bellows behind movable mirror. For suppression of stray RF power deposition, the structure of the bellows section was improved to avoid the direct power deposition and the surface of bellows was coated by copper for reduction of RF loss and increase of thermal conductivity. As a result of the modification, temperature increase of bellows was reduced to less than 1/10 and time constant of thermal diffusion shortened to 90 s from 270 s in comparison with before the modification. This indicates that the modification is quite effective for suppression of temperature increase.

Electric power flow in a nuclear fusion power plant

Matsukawa, Makoto; Tobita, Kenji; Chikaraishi, Hirotaka*; Sagara, Akio*; Norimatsu, Takayoshi*

Purazuma, Kaku Yugo Gakkai-Shi, 80(7), p.559 - 562, 2004/07

https://doi.org/10.1585/jspf.80.559

Final purpose of the fusion energy development is to utilize the produced fusion power mainly as electric power for the easiness of transmission and conversion. In spite of the type of fusion power plant, large circulating electric power should exist in the plant for the plasma heating, current drive. This paper describes the electric power flow in the nuclear fusion power plants to be built as the DEMO reactor beyond ITER. Here, the necessity of the local energy storage and high efficient converter will be also discussed.

Evaluation for the models of neutron diffusion theory in terms of power density distributions of the HTTR

Takamatsu, Kuniyoshi; Shimakawa, Satoshi; Nojiri, Naoki; Fujimoto, Nozomu

JAERI-Tech 2003-081, 49 Pages, 2003/10

JAERI-Tech-2003-081.pdf:2.6MB

In the case of evaluations for the highest temperature of the fuels in the HTTR, it is very important to expect the power density distributions accurately; therefore, it is necessary to improve the analytical model with the neutron diffusion and the burn-up theory. The power density distributions are analyzed in terms of two models, the one mixing the fuels and the burnable poisons homogeneously and the other modeling them heterogeneously. Moreover these analytical power density distributions are compared wtih the ones derived from the gross -ray measurements and the Monte Carlo calculational code with continuous energy. As a result the homogeneous mixed model isn't enough to expect the power density distributions of the core in the axial direction; on the other hand, the heterogeneous model improves the accuracy.

Thermofluid analysis of free surface liquid divertor in tokamak fusion reactor

Kurihara, Ryoichi

Fusion Engineering and Design, 61-62, p.209 - 216, 2002/11

https://doi.org/10.1016/S0920-3796(02)00171-0

To attain high fusion power density, the divertor must suffer high heat flux from the fusion plasma. It is very difficult to remove a high heat flux more than 20 MW/m using the only solid divertor plate from the viewpoint of severe mechanical state such as thermal stress and crack growth. Therefore, a concept of liquid divertor is proposed to remove high heat flux by liquid films flowing on a solid wall. This paper mainly descries a preliminary thermofluid analysis of the free surface liquid flow, made of the FliBe molten salt, using the finite element analysis code ADINA-F. The heat flux of 25100 MW/m was given on the free surface liquid of the flow. I explored a possibility of applying the secondary flow to enhance the heat transfer of the liquid flow suffering high heat flux. This analysis shows that the heat flux of 100 MW/m can be removed by inducing the secondary flow in the free surface liquid FLiBe. And this paper shows that the liquid divertor using solid-liquid multi-phase flow makes possible large heat removal by utilizing the latent heat of fusion of solid phase.