Collaborative Laboratories for Advanced Decommissioning Science; Keio University*
JAEA-Review 2020-047, 63 Pages, 2021/01
JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2019, this report summarizes the research results of the "Study of corrosion and degradation of the objects in the nuclear reactor by microorganisms" conducted in FY2019.
Collaborative Laboratories for Advanced Decommissioning Science; University of Tsukuba*
JAEA-Review 2020-037, 53 Pages, 2020/12
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 "Upgrading of Recovery Method for Radioactive Microparticles by Heavy Liquid Separation Aiming to Volume Reduction of Contaminated Soil" conducted in FY2019.
Abe, Tomohisa; Ogiya, Takashi*; Shibata, Katsuya*; Hanawa, Tatsuaki*; Sanada, Yukihisa
JAEA-Data/Code 2020-004, 280 Pages, 2020/08
After the accidents at Fukushima Daiichi Nuclear Power Station (FDNPS), Japan Atomic Energy Agency has carried on survey for distribution situation of radiation materials under the direction of the Ministry of Education, Culture, Sports, Science and Technology (later the Nuclear Regulatory Agency) from June 2011 to FY2019. This report is mainly summarized as data-base of air dose rate, integrated dose and radionuclide concentration of some types of environmental sample (airborne dust, soil, pine needles) in the radiation monitoring in Fukushima Prefecture (20 km far from FDNPS). The results of radiation monitoring were analyzed for temporal change at each measurement site under the unification format. Furthermore, the effective half-life and the dispersion at each location and sample were evaluated based on these big data.
Tachi, Yukio; Sato, Tomofumi*; Akagi, Yosuke*; Kawamura, Makoto*; Nakane, Hideji*; Terashima, Motoki; Fujiwara, Kenso; Iijima, Kazuki
Science of the Total Environment, 724, p.138098_1 - 138098_11, 2020/07
To understand and predict radiocesium transport behaviors in the environment, highly contaminated sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on key factors controlling radiocesium sorption and fixation, including particle size, clay mineralogy and organic matter.
Tachi, Yukio; Sato, Tomofumi*; Takeda, Chizuko*; Ishidera, Takamitsu; Fujiwara, Kenso; Iijima, Kazuki
Science of the Total Environment, 724, p.138097_1 - 138097_10, 2020/07
To understand and predict radiocesium transport behaviors in the environment, sorption and fixation behaviors of radiocesium on river sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on Cs sorption and fixation mechanisms and their relationship with Cs concentrations and sediment properties including clay mineralogy and organic matter.
Collaborative Laboratories for Advanced Decommissioning Science; University of Tsukuba*
JAEA-Review 2019-023, 33 Pages, 2020/01
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 'Upgrading of Recovery Method for Radioactive Microparticles by Heavy Liquid Separation Aiming to Volume Reduction of Contaminated Soil'. After the accident of the Fukushima Daiichi Nuclear Power Station, radioactive cesium has been heterogeneously distributed in surface soil due to the existence of radioactive microparticles and clay minerals. Therefore, the selective removal of these microparticles will lead to the volume reduction of contaminated soil. The present study examines methods for selectively removing radioactive microparticles from soil. Also, in order to reduce the volume of contaminated soil, we search a possibility to practically apply the separation method that uses the difference in specific gravity of particles (heavy liquid separation method).
Wakiyama, Yoshifumi*; Onda, Yuichi*; Yoshimura, Kazuya; Igarashi, Yasunori*; Kato, Hiroaki*
Journal of Environmental Radioactivity, 210, p.105990_1 - 105990_12, 2019/12
Muto, Kotomi; Atarashi-Andoh, Mariko; Matsunaga, Takeshi*; Koarashi, Jun
Journal of Environmental Radioactivity, 208-209, p.106040_1 - 106040_10, 2019/11
Vertical distributions of Cs in the soil profile were observed at five forest sites with different vegetation types for 4.4 years after the Fukushima Dai-ichi Nuclear Power Plant accident, and Cs migration in the organic layer and mineral soil was analyzed based on a comparison of models and observations. Cesium-137 migration from the organic layer was faster than that observed in European forests, suggesting that the mobility and bioavailability of Cs could be suppressed rapidly in Japanese forests. The diffusion coefficients of Cs in the mineral soil were estimated to be 0.042-0.55 cmy, which were roughly comparable with those of European forest soils affected by the Chernobyl Nuclear Power Plant accident. Model predictions indicated Cs mainly distributed in the surface mineral soil at 10 years after the accident. It suggest that the Cs deposited onto Japanese forest ecosystems will be retained in the surface layers of mineral soil for a long time.
Miwa, Kazuji; Takeda, Seiji; Iimoto, Takeshi*
Radiation Protection Dosimetry, 184(3-4), p.372 - 375, 2019/10
The Ministry of the Environment has indicated the policy of recycling the contaminated soil generated by decontamination activity after the Fukushima accident. By recycling to coastal reclamation which is one of effective recycling application, dissolved radiocesium and absorbed radiocesium on soil particles will flow out to the ocean by construction, therefore evaluating radiocesium transition in ocean considering the both types of radiocesium is important for safety assessment. In this study, the radiocesium outflow during constructing and after constructing is modeled, and radiocesium transition in ocean is evaluated by Sediment model suggested in OECD/NEA. The adaptability of sediment model is confirmed by reproducing evaluation of the coastal area of Fukushima. We incorporate the sediment model to PASCLR2 code system to evaluate the doses from radiocesium in ocean.
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.
Strlevern Rappot 2018:4 (Internet), p.62 - 64, 2018/04
The widespread environment was contaminated by radioactive cesium discharged by the severe accident of the Fukushima Daiichi Nuclear Power Station. Decontamination measures have been implemented extensively, resulting in the generation of large volume of decontamination soil that has been placed in temporary storage. To reduce the volume of decontamination soil, it can be effective to recycle the soil as construction material. This report shows the concept of safety assessment method for recycle to public projects in which the management system and allocation of responsibility are clarified, scenario construction and parameter selection, and also the results of safe assessment for the recycle to coastal levees.
Azami, Kazuhiro*; Otagaki, Takahiro*; Ishida, Mutsushi; Sanada, Yukihisa
Landscape and Ecological Engineering, 14(1), p.3 - 15, 2018/01
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.
Global Environmental Research (Internet), 20(1&2), p.83 - 90, 2017/03
Major challenges to implementing full-scale environmental decontamination were the absence of real-world examples and also lack of experience in planning and implementing decontamination technology appropriate to the physical and social boundary conditions in both Japan and Fukushima. The Japan Atomic Energy Agency was thus charged with conducting a range of Decontamination Pilot Project to examine the applicability of decontamination technologies, with a special focus on reducing dose rates and thus allowing evacuees to return to re-establish their normal lifestyles as quickly as possible, whilst simultaneously maintaining worker safety. In this report, re-edit the report of the Decontamination Pilot Project (Nakayama et al.,2014), do the commentary for the decontamination technology.
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.
Yang, B.*; Onda, Yuichi*; Wakiyama, Yoshifumi*; Yoshimura, Kazuya; Sekimoto, Hitoshi*; Ha, Y.*
Environmental Pollution, 208(Part B), p.562 - 570, 2016/01
Konoplev, A.*; Golosov, V.*; Laptev, G.*; Namba, Kenji*; Onda, Yuichi*; Takase, Tsugiko*; Wakiyama, Yoshifumi*; Yoshimura, Kazuya
Journal of Environmental Radioactivity, 151(Part 3), p.568 - 578, 2016/01
Yamashita, Yuji*; Yanase, Nobuyuki; Nagano, Tetsushi; Mitamura, Hisayoshi; Naganawa, Hirochika
Journal of Radioanalytical and Nuclear Chemistry, 305(2), p.583 - 587, 2015/08
We propose a method for the decontamination and waste volume reduction of cesium-contaminated soil. The soils were solidified with an interpolyelectrolyte complex solution and classified into several size fractions by wet sieving. -ray spectrometry of these fractions showed that the distribution ratio of the activity concentration of coarse soil particles decreased, whereas that of soil particles under 0.075 mm increased relative to reference samples. Results show that the fine soil particles, on which radioactive cesium accumulates, were removed from the surface of the coarse soil particles during, and remained in the washing water.
Takayama, Yusuke; Sato, Toshinori; Onoe, Hironori; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onuki, Kenji
Dai-43-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.313 - 318, 2015/01
In the Mizunami Underground Research Laboratory, groundwater recovery experiment is being conducted to construct the method to understand the transition of geological environment due to groundwater recovery at the -500m access and research gallery-north. As a part of this experiment, backfill test is planned using drilling pits filled with artificial materials (clay and concrete) to evaluate the influence on the surrounding rock mass due to the interaction of rock and artificial materials. In this study, numerical simulation of the backfill test has been carried out to predict the qualitative hydro-mechanical behavior.
RIST News, (39), p.10 - 22, 2005/03
A new atmosphere-soil-vegetation model named SOLVEG2 (SOLVEG version 2) was developed to study the heat, water, and CO exchanges between the atmosphere and land-surface. The model consists of one-dimensional multilayer sub-models for the atmosphere, soil, and vegetation. It also includes sophisticated processes for solar and long-wave radiation transmission in vegetation canopy and CO exchanges among the atmosphere, soil, and vegetation. Although the model usually simulates only vertical variation of variables in the surface-layer atmosphere, soil, and vegetation canopy by using meteorological data as top boundary conditions, it can be used by coupling with a three-dimensional atmosphere model.