Miyahara, Kaname; Kawase, Keiichi
Genshiryoku No Ima To Ashita, p.159 - 167, 2019/03
This manuscript overviews lessons learned from decontamination pilot projects towards implementation of regional remediation after the environmental contamination due to the Fukushima Daiichi Nuclear Power Plant Accidents.
Thwe, T. A.; Terada, Atsuhiko; Hino, Ryutaro
JAEA-Technology 2018-012, 45 Pages, 2019/01
Under long-term storage of nuclear wastes including low- and high-level wastes, hydrogen can be spontaneously generated from corrosion of metal wastes and container wall itself, and from radiolysis of water in the waste. For the sake of hydrogen safety and the risk reduction of environmental contamination, we have started to investigate the behavior and characteristics of hydrogen combustion and explosion in waste vessel. In this report, we performed numerical simulation to investigate the characteristics of methane combustion by applying OpenFOAM. For combustion scenario, FireFoam solver with LES frame was used. As the results, the average temperature increased when the container height and inlet size increased. The simulation of gas diffusion by FireFoam results showed that helium diffused faster than hydrogen and methane. By XiFoame solver, the simulation was performed to obtain flame propagation radius for hydrogen-air premixed flame.
Saegusa, Jun; Koma, Yoshikazu; Ashida, Takashi
JAEA-Review 2018-017, 259 Pages, 2018/12
Collaborative Laboratories for Advanced Decommissioning Science (CLADS) is responsible to promote international cooperation in the R&D activities on the decommissioning of Fukushima Daiichi Nuclear Power Station and to develop the necessary human resources. CLADS held the Fukushima Research Conference on Development of Analytical Techniques in Waste Management (FRCWM 2018) on 19th and 20th June, 2018. This report compiles the abstracts and the presentation materials in the above conference.
Garcia-Lodeiro, I.*; Lebon, R.*; Machoney, D.*; Zhang, B.*; Irisawa, Keita; Taniguchi, Takumi; Namiki, Masahiro*; Osugi, Takeshi; Meguro, Yoshihiro; Kinoshita, Hajime*
Proceedings of 3rd International Symposium on Cement-based Materials for Nuclear Wastes (NUWCEM 2018) (USB Flash Drive), 4 Pages, 2018/11
Tachi, Yukio; Ochs, M.*
Progress in Nuclear Science and Technology (Internet), 5, p.229 - 232, 2018/11
Various types of post-accident radioactive waste have been generated from cleanup and decommissioning activities at the Fukushima Daiichi Nuclear Power Plant. For the disposal of these wastes, perturbation effects resulting from co-existing substances (e.g., organic substances, boron, and salts) are needed to be considered. Such co-existing substances may influence on the radionuclide sorption parameters for the safety assessment of the disposal systems. The present study focuses on developing the methodology to quantify sorption parameters by considering such perturbation effects and illustrating example calculations regarding the sorption reduction factors (SRFs) due to the presence of organic ligands (ISA) for cement systems. Three approaches for the derivations of SRFs for cement-Am-ISA case were compared. These options should be applied as a stepwise manner according to the data availability for the perturbation effects resulting from the co-existing substances.
Sugiyama, Daisuke*; Kimura, Hideo; Tachikawa, Hirokazu*; Iimoto, Takeshi*; Kawata, Yosuke*; Ogino, Haruyuki*; Okoshi, Minoru*
Journal of Radiological Protection, 38(1), p.456 - 462, 2018/03
Experience after the accident at the Fukushima Daiichi Nuclear Power Station has shown that there is a need to establish radiation protection criteria for radioactive waste management consistent with the criteria adopted for the remediation of existing exposure situations. A stepwise approach to setting such criteria is proposed. Initially, a reference level for annual effective dose from waste management activities in the range 1-10 mSv should be set, with the reference level being less than the reference level for ambient dose. Subsequently, the reference level for annual effective dose from waste management activities should be reduced in one or more steps to achieve a final target value of 1 mSv. The dose criteria at each stage should be determined with relevant stakeholder involvement. Illustrative case studies show how this stepwise approach might be applied in practice.
Sano, Yuichi; Ashida, Takashi
JAEA-Review 2017-021, 180 Pages, 2017/11
Collaborative Laboratories for Advanced Decommissioning Science (CLADS) is responsible to promote international cooperation in the R&D activities on the decommissioning of Fukushima Daiichi Nuclear Power Station and to develop the necessary human resources. CLADS held the Research Conference on Cementitious Composites in Decommissioning and Waste Management (RCWM2017) on 20th and 21st June, 2017. This report compiles the abstracts and the presentation materials in the above conference.
Cantarel, V.; Motooka, Takafumi; Yamagishi, Isao
JAEA-Review 2017-014, 36 Pages, 2017/06
After a necessary decay time, the zeolites used for the water decontamination will eventually be conditioned for their long-term storage. Geopolymer is considered as a potential matrix to manage radioactive cesium and strontium containing waste. For such applications, a correct comprehension of the binder structure, its macroscopic properties, its interactions with the waste and the physico-chemical phenomena occurring in the waste form is needed to be able to judge of the soundness and viability of the material. Although the geopolymer is a young binder, a lot of research has been carried out over the last fifty years and our understanding of this matrix and its potential applications is progressing fast. This review aims at gathering the actual knowledge on geopolymer studies about geopolymer composites, geopolymer as a confinement matrix for nuclear wastes and geopolymer under irradiation. This information will finally provide guidance for the future studies and experiments.
Miyahara, Kaname; Ohara, Toshimasa*
Nippon Genshiryoku Gakkai-Shi, 59(5), p.282 - 286, 2017/05
This review highlights JAEA and NIES's challenges for enhancing Fukushima environmental resilience based on carrying out multifaceted research working with many public and private sector organizations and academia.
Motooka, Takafumi; Yamagishi, Isao
JAEA-Review 2017-004, 157 Pages, 2017/03
Collaborative Laboratories for Advanced Decommissioning Science (CLADS) is responsible to promote international cooperation in the R&D activities on the decommissioning of Fukushima Daiichi Nuclear Power Station and to develop the necessary human resources. CLADS held the Research Conference on Post-accident Waste Management Safety (RCWM2016) was held on November 7th, 2016 and the Technical Seminar on Safety Research for Radioactive Waste Storage was held on November 8th, 2016. This report compiles the abstracts and the presentation materials in the above conference and seminar.
Ohara, Toshimasa*; Miyahara, Kaname
Global Environmental Research (Internet), 20(1&2), p.3 - 13, 2017/03
Toward the environmental regeneration in Fukushima Prefecture and other areas after the Fukushima Daiichi Nuclear Power Station accidents, JAEA and NIES working with many public and private sector organizations and academia have carried out multifaceted research that will help to restore the environment of affected areas. These challenging efforts need to be further strengthened.
Shibata, Atsuhiro; Koma, Yoshikazu; Oi, Takao
Journal of Nuclear Science and Technology, 53(12), p.1933 - 1942, 2016/12
ISTC/STCU Fukushima Initiative Technical Review Committee; Fukushima Initiative Technical Review Committee
JAEA-Conf 2016-003, 107 Pages, 2016/07
The final ISTC/STCU Technical Review Committee Meeting "On the environmental assessment for long term monitoring and remediation in and around Fukushima" was held in Hitotsubashi University Hall, Tokyo, on November 5-6, 2015. This report consists of summary reports of Fukushima Initiative projects, which were presented at the meeting. As regarding to the sections those which will be published elsewhere, only their executive summaries are included.
ISTC/STCU Fukushima Initiative Technical Review Committee; Fukushima Initiative Technical Review Committee
JAEA-Conf 2016-002, 111 Pages, 2016/06
The final ISTC/STCU Technical Review Committee Meeting "On the environmental assessment for long term monitoring and remediation in and around Fukushima" was held in Hitotsubashi University Hall, Tokyo, on December 5-6, 2015. This report consists of summary reports of Fukushima Initiative projects, which were presented at the meeting. As regarding to the sections those which will be published elsewhere, only their executive summaries are included.
Kato, Jun; Meguro, Yoshihiro
E-Journal of Advanced Maintenance (Internet), 7(2), p.138 - 144, 2015/08
Concentration of Cs in radioactive wastes such as used cesium adsorption vessels and sludge generated from the cesium adsorption device, the 2nd cesium adsorption device, and the decontamination device, which have operated or been suspended as a part of the contaminated water treatment system in Fukushima Daiichi Nuclear Power Stations, was calculated by using analysis data of the contaminated water. The total decontamination amount of Cs from Jun 6, 2011 to Aug 12, 2014 was estimated.
Fukushima Environmental Safety Center, Sector of Fukushima Research and Development
JAEA-Review 2014-051, 121 Pages, 2015/03
The Japan Atomic Energy Agency (JAEA) was charged with conducting a range of "Decontamination Pilot Project" to examine the applicability of decontamination technologies. The project was implemented at 16 sites in 11 municipalities within the evacuated zone. Despite tight boundary conditions in terms of timescale and resources, the project provides a good basis for developing recommendations on how to assure decontamination efficiency and worker safety whilst additionally constraining costs, subsequent waste management and environmental impacts. This report, based on the Japanese detailed reports that have been published elsewhere, consists of two volumes. This volume 1 summarises the Decontamination Pilot Project, providing the background required to put this work in context for an international audience. In volume 2, the subsequent application of output from these projects to regional remediation now being conducted by the Japanese government and municipalities, is discussed, along with a status update on such work, an overview of associated JAEA's R&D and international input to/review of regional environmental decontamination in Fukushima.
Arifi, E.*; Ishimatsu, Koichi*; Iizasa, Shinya*; Namihira, Takao*; Sakamoto, Hiroyuki*; Tachi, Yukio; Kato, Hiroyasu*; Shigeishi, Mitsuhiro*
Construction and Building Materials, 67(Part.B), p.192 - 196, 2014/09
The Fukushima Dai-ichi Nuclear Plant accident has resulted in a large amount of radioactively contaminated concrete. The possible application of the pulsed power discharge to reduce the amount of contaminated concrete as radioactive waste was investigated. The contaminated concrete was decontaminated by separating contaminated matrix from uncontaminated coarse aggregate under pulsed power discharge process. In this study, a stable Cs isotope was used to simulate radioactively contaminated concrete. As a result, while the volume of reclaimed aggregate from contaminated concrete could be reproduced was up to 60%, nevertheless Cs detected in the reclaimed aggregate was only approximately 3%. Thus most of the Cs were dissolved in water during the discharge process. It is expected that the pulsed power could reduce the contaminated concrete waste by reusing aggregate. Further investigations are requested to test the applicability of this method under the realistic conditions close to the actual waste.
Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo
Journal of Nuclear Science and Technology, 43(4), p.305 - 310, 2006/04
We are developing an resonance ionization spectrometric apparatus aiming at an analysis of a radioactive isotope of calcium (Ca) in nuclear waste materials. The developed system consists of the reference laser whose frequency was locked on a Doppler-free absorption line of 85Rb and the computer-controlled fringe offset lock system which transfer frequency stability of the reference laser to slave lasers for Ca excitation. With heterodyne spectroscopy and laser induced fluorescence spectroscopy of Ca, it was confirmed that the developed apparatus was suitable for resonance ionization spectrometric analysis.
Otaki, Kiyoshi*; Tanaka, Yoji*; Katsurai, Kiyomichi*; Aoki, Kazuo*
JAERI-Review 2005-035, 79 Pages, 2005/09
In order to collect technical information for the assessment on future nuclear power reactors and fuel cycle systems in Japan, investigation has been made on the characteristics and performance of future reactor options including reduced moderation water reactors (RMWRs) and their fuel cycle systems since the fiscal year 1998. The subjects of investigation are divided into three categories; breeder reactors and their fuel cycle, alternative to sodium-cooled FBR systems,plutonium recycling, spent fuel reprocessing and waste disposal. This report is a summary of the investigation carried out so far.
Mizukoshi, Seiji; Oshima, Soichiro; Shimada, Taro
JAERI-Tech 2005-011, 122 Pages, 2005/03
The radiological and physical characteristic on decommissioning, such as component and structure weights and radioactivity of the 1.1 MWe class reference nuclear power plants summarized in the NUREG reports of the US NRC were classified,arranged and compared with the domestic commercial nuclear power plants and JPDR from a view point of dismantling plan and waste management for decommissioning. As the results, it was found that the radioactive component and structure weights was about 28,000ton、and non-radioactive structure weights was about 124,000ton less than the domestic commercial BWR. And it was found that this differences has mainly influenced dismantling costs for decommissioning. Farther, it was found that the concrete element composition rates of B, Ni, Nb and so were differerence of one or more figures btween the reference nuclear power plants and the domestic commercial PWR or JPDR.Also,it was found that the this difference became about two or three times by radioactivity concentration and has mainly influenced transport and disposal costs for decommissioning.