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Journal Articles

Sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ ions onto sedimentary rock in the presence of gamma-irradiated humic acid

Zhao, Q.*; Saito, Takeshi*; Miyakawa, Kazuya; Sasamoto, Hiroshi; Kobayashi, Taishi*; Sasaki, Takayuki*

Journal of Hazardous Materials, 428, p.128211_1 - 128211_10, 2022/04

 Times Cited Count:0 Percentile:0.01(Engineering, Environmental)

The influence of humic acid and its radiological degradation on the sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ by sedimentary rock was investigated to understand the sorption process of metal ions and humic substances. Aldrich humic acid (HA) solution was irradiated with different doses of gamma irradiation using a Co-60 gamma-ray source prior to the contact between the metal ions and the solid sorbent. The HA molecule decomposed to smaller molecules with a lower complexation affinity. Batch sorption experiments were performed to evaluate the effect of gamma-irradiated HA on the sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ ions. The addition of non-irradiated HA weakened the sorption of Eu because of the lower sorption of the neutral or negatively charged Eu-HA complexes compared with free Eu ions. The sorption of monovalent Cs ions was barely affected by the presence of HA and its gamma irradiation. The concentration ratio of HA complexed species and non-complexed species in the solid and liquid phases was evaluated by sequential filtration and chemical equilibrium calculations. The ratios supported the minimal contribution of HA to Cs sorption. However, the concentration ratio for Eu$$^{3+}$$ in the liquid phase was high, indicating that the complexing ability of HA to Eu$$^{3+}$$ was higher than that of HA to Cs$$^{+}$$ ions. Therefore, the sorption of free Eu$$^{3+}$$ would predominate with the gamma irradiation dose applied to the HA solution under a radiation field near the HLW package.

Journal Articles

Radiocaesium accumulation capacity of epiphytic lichens and adjacent barks collected at the perimeter boundary site of the Fukushima Dai-ichi Nuclear Power Station

Dohi, Terumi; Omura, Yoshihito*; Yoshimura, Kazuya; Sasaki, Takayuki*; Fujiwara, Kenso; Kanaizuka, Seiichi*; Nakama, Shigeo; Iijima, Kazuki

PLOS ONE (Internet), 16(5), p.e0251828_1 - e0251828_16, 2021/05

 Times Cited Count:2 Percentile:49.98(Multidisciplinary Sciences)

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.

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

Applied research for the establishment of radiation monitoring and evaluation of exposure dose of residence at the zone designated for reconstruction and recovery

Funaki, Hironori; Takahara, Shogo; Sasaki, Miyuki; Yoshimura, Kazuya; Nakama, Shigeo; Sanada, Yukihisa

JAEA-Research 2018-016, 48 Pages, 2019/03

JAEA-Research-2018-016.pdf:29.73MB

Cabinet Office Nuclear Emergency Response Headquarters starts to consider radiation protection in the "specific reconstruction reproduction base area" of which evacuation order will be lifted by 2023. It is essential to grab the present situations of radiation contamination and evaluate exposure dose in the area to realize the plan. Many surveys have evaluated the distributions of air dose rate and exposure dose has been estimated based on the results since the Fukushima Daiichi Nuclear Power Plant accident. Nevertheless, more detailed information on exposure is needed for the areas because its radiation level is relatively high. That is also to help make prudent evaluation plan. This study aimed to evaluate the detailed contamination situation there and estimate exposure dose with considering areal circumstances. Investigations were carried out for (1) airborne survey of air dose rate using an unmanned helicopter (2) evaluation of airborne radiocesium and (3) estimation of external/internal effective doses for typical activity patterns assumed. Additionally, we applied new methods for the airborne survey to evaluate exposure dose. Our study showed a detailed three-dimensional map of air dose rate and clarified the distribution pattern in the areas. Results of effective dose estimation suggested that the internal effective dose due to inhalation accounts for less than 1% of the external effective dose.

Journal Articles

Quantitative analysis of radiocesium retention onto birnessite and todorokite

Yu, Q.*; Onuki, Toshihiko*; Kozai, Naofumi; Sakamoto, Fuminori; Tanaka, Kazuya; Sasaki, Keiko*

Chemical Geology, 470, p.141 - 151, 2017/10

 Times Cited Count:10 Percentile:42.48(Geochemistry & Geophysics)

In this work, the Cs retention onto two types of Mn oxide was investigated. We found that Todorokite has sorption sites with a higher selectivity for Cs than birnessite. When the initial Cs concentration was 10$$^{-9}$$ mol/L for the sorption experiments, approximately 34% of the sorbed Cs was residual in the todorokite after the extraction using 1 M NaCl and NH$$_{4}$$Cl; this value was much higher than the results for the Cs-sorbed birnessite. These results strongly suggest that todorokite contributes to the fixation of radioactive Cs in soils.

Journal Articles

Determination of dissolved natural thorium and uranium in Horonobe and Mizunami Underground Research Laboratory groundwater and its thermodynamic analysis

Sasaki, Takayuki*; Kokami, Takayuki*; Kobayashi, Taishi*; Kirishima, Akira*; Murakami, Hiroaki; Amano, Yuki; Mizuno, Takashi; Iwatsuki, Teruki; Sasamoto, Hiroshi; Miyakawa, Kazuya

Journal of Nuclear Science and Technology, 54(3), p.373 - 381, 2017/03

Trace amounts of natural thorium and uranium in deep groundwater were investigated at two underground research laboratories situated at Horonobe and Mizunami, Japan. The groundwater was sampled from underground boreholes, and the colloid contribution was checked by in situ two size-fractionated ultrafiltration systems. A decrease in the concentration after in situ filtration suggested the presence of natural colloids and suspended matter that were carriers of a portion of the elements. The result of the Th and U concentrations in groundwater after 10 kDa filtration was analyzed thermodynamically using existing hydrogeological and geochemical data such as the mineral components in the groundwater at a given pH, ionic strength, concentration of co-existing ions, redox potential, and solid phase assumed. A crystalline solid phase made the solubility very low compared with that of the amorphous phase, and the solubility agreed well with the concentrations measured.

Journal Articles

Interaction of rare earth elements and components of the Horonobe deep groundwater

Kirishima, Akira*; Kuno, Atsushi*; Amamiya, Hiroki; Kubota, Takumi*; Kimuro, Shingo*; Amano, Yuki; Miyakawa, Kazuya; Iwatsuki, Teruki; Mizuno, Takashi; Sasaki, Takayuki*; et al.

Chemosphere, 168, p.798 - 806, 2017/02

 Times Cited Count:3 Percentile:13.25(Environmental Sciences)

For better understanding of the migration behavior of minor actinides (MA) in deep groundwater, the interaction of doped rare earth elements (REEs) and components in Horonobe deep groundwater was studied. Appx. 10 ppb of rare earth elements, i.e., Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm and Yb were doped to the sample groundwater collected from a packed sections in borehole drilled from 140 m depth experiment drift of Horonobe underground research laboratory (URL), Hokkaido, Japan. Then, that groundwater was sequentially filtrated by 0.2 micron pore filter, 10 kDa, 3 kDa and 1 kDa of nominal molecular weight limit (NMWL) ultrafilters by keeping inert condition. After that, the filtrate solutions were analyzed by ICP-MS to determine the concentrations of retained REEs at each filtration steps, while the used filters were analyzed by the neutron activation analysis (NAA) and TOF-SIMS element mapping to know the amount and chemical speciation of trapped fraction of the REEs on each filter. A remarkable relation between the retention ratios of REEs in the filtrate solutions and the ionic radius was observed, i.e., smaller rare earth element solves more in liquid phase under the Horonobe groundwater condition. NAA and TOF-SIMS analyses revealed that certain portions of REEs were trapped by 0.2 micron pore filters as rare earth phosphates which corresponded with the predicted predominant species by a chemical equilibrium calculation for the Horonobe groundwater condition, while small portions of colloidal REEs were trapped by 10 kDa and 3 kDa NMWL ultrafilters. The result suggested that phosphate anion plays an important role in the chemical behavior of REEs in saline (seawater based) groundwater, which could be referred for the prediction of migration behavior of trivalent actinide released from the repository of radioactive waste in far future.

Journal Articles

The Effects of ion beam irradiation on variation in the M$$_{1}$$ generation of two strains of ${{it Delphinium grandiflorum}}$ var. ${{it chinense}}$

Honda, Kazushige*; Taneichi, Shuhei*; Maeda, Tomoo*; Goto, Satoshi*; Shikanai, Yasuhiro*; Sasaki, Kazuya*; Nozawa, Shigeki; Hase, Yoshihiro

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 107, 2016/02

no abstracts in English

Journal Articles

Cobalt(II) oxidation by biogenic Mn oxide produced by $$Pseudomonas$$ sp. strain NGY-1

Tanaka, Kazuya*; Yu, Q.; Sasaki, Keiko*; Onuki, Toshihiko

Geomicrobiology Journal, 30(10), p.874 - 885, 2013/08

 Times Cited Count:10 Percentile:32.82(Environmental Sciences)

no abstracts in English

Journal Articles

Zinc sorption during bio-oxidation and precipitation of manganese modifies the layer stacking of biogenic birnessite

Yu, Q.; Sasaki, Keiko*; Tanaka, Kazuya*; Onuki, Toshihiko; Hirajima, Tsuyoshi*

Geomicrobiology Journal, 30(9), p.829 - 839, 2013/07

 Times Cited Count:28 Percentile:69.17(Environmental Sciences)

no abstracts in English

Journal Articles

Structural factors of biogenic birnessite produced by fungus ${it Paraconiothyrium}$ sp. WL-2 strain affecting sorption of Co$$^{2+}$$

Yu, Q.*; Sasaki, Keiko*; Tanaka, Kazuya*; Onuki, Toshihiko; Hirajima, Tsuyoshi*

Chemical Geology, 310-311, p.106 - 113, 2012/06

 Times Cited Count:49 Percentile:82.31(Geochemistry & Geophysics)

These results strongly suggested that the interlayer Mn(III) can oxidize the adsorbed Co$$^{2+}$$ to Co$$^{3+}$$, resulting in specific adsorption of Co$$^{2+}$$ by biogenic birnessite.

Journal Articles

Development of advanced tritium breeding material with added lithium for ITER-TBM

Hoshino, Tsuyoshi; Kato, Kenichi*; Natori, Yuri*; Oikawa, Fumiaki; Nakano, Natsuko*; Nakamura, Mutsumi*; Sasaki, Kazuya*; Suzuki, Akihiro*; Terai, Takayuki*; Tatenuma, Katsuyoshi*

Journal of Nuclear Materials, 417(1-3), p.684 - 687, 2011/10

 Times Cited Count:41 Percentile:95.3(Materials Science, Multidisciplinary)

Lithium titanate (Li$$_{2}$$TiO$$_{3}$$) is one of the most promising candidates among tritium breeding materials because of its good tritium release. Addition of H$$_{2}$$ to inert sweep gas has been proposed for enhancing the tritium release from tritium breeding materials. However, the mass of Li$$_{2}$$TiO$$_{3}$$ was decreased with time in the hydrogen atmosphere. It is assumed that the mass decrease indicates the loss of the oxygen contained in the sample caused by the change from Ti $$^{4+}$$ to Ti $$^{3+}$$, and that the partial pressures of Li-containing species were increased in the hydrogen atmosphere. In order to decrease the mass-change at high temperature, advanced tritium breeding material with added Li should be developed to improve the physical and chemical stability in hydrogen atmosphere. In the case of the Li$$_{2+x}$$TiO$$_{3+y}$$ samples used by the present study, LiOHH$$_{2}$$O and H$$_{2}$$TiO$$_{3}$$ were proportionally mixed with the molar ratio Li/Ti of either 2.0 and 2.2. These samples are designated as L20 (Li/Ti = 2.0) and L22 (Li/Ti = 2.2), respectively. The results of XRD measurement showed that the phases in advanced tritium breeding material were as follows. L22 existed as non-stoichiometric compound Li$$_{2+x}$$TiO$$_{3+y}$$.

Journal Articles

Development of energy and environmental education in the Kids' Science Museum of Photons; Activities associated with regional administrative offices, educational institutions, and schools

Hoshiya, Taiji; Nishimura, Akihiko; Sasaki, Kazuya*; Nishikawa, Masahiro*

Enerugi Kankyo Kyoiku Kenkyu, 4(2), p.49 - 56, 2010/07

The Kids' Science Museum of Photons (KSMP), which was established in a blanch of the Kansai Photon Science Institute (KPSI), can provide us with the mysteries of light through various exhibits, theater, and science experimental events, as quite an unique museum, to be focused on the photon science. The goal of this museum is also to develop "Heart of Science" in children who can join and experience. In this phase, the KSMP has been promoting various activities of public understanding of science and technology, such as the collaboration seminar, the science festival and the teacher education program, to be associated with regional administrative offices, educational institutions, and schools. It can be explained the outline of systematically trial activities on the energy and environmental education, the collaboration lecture, the experimental village and the science-walker, from the viewpoint of the degree of understanding, the search mind and effects.

Journal Articles

Phosphate conversion behaviors of FP chlorides with spent electrolyte recycling

Kofuji, Hirohide; Amamoto, Ippei; Sasaki, Kazuya*; Yasumoto, Masaru*; Takasaki, Yasushi*; Myochin, Munetaka; Terai, Takayuki*

Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 77(8), p.597 - 600, 2009/08

 Times Cited Count:0 Percentile:0.01(Electrochemistry)

The process flow of the phosphate conversion technique has been developed for the reduction of high-level radioactive waste (HLW) generated from the metal-electrorefining process. In this study, the results of thermodynamic calculations for the phosphate conversion reactions were examined by the basic experiments. The chlorides of rare earth elements (REE) turned out to be converted into phosphates easily. Furthermore, as the additive for the phosphate conversion reaction, high temperature behavior of lithium phosphate was evaluated to elucidate the thermodynamic property.

Journal Articles

New synthesis method of advanced lithium titanate with Li$$_{4}$$TiO$$_{4}$$ additives for ITER-TBM

Hoshino, Tsuyoshi; Kato, Kenichi*; Natori, Yuri*; Nakamura, Mutsumi*; Sasaki, Kazuya*; Hayashi, Kimio; Terai, Takayuki*; Tatenuma, Katsuyoshi*

Fusion Engineering and Design, 84(2-6), p.956 - 959, 2009/06

 Times Cited Count:41 Percentile:93.78(Nuclear Science & Technology)

Li$$_{2}$$TiO$$_{3}$$ is one of the most promising candidates among the proposed solid breeder materials for fusion reactors. Addition of H$$_{2}$$ to inert sweep gas has been proposed for enhancing the release of bred tritium from breeder material. However, the mass of Li$$_{2}$$TiO$$_{3}$$ was found to decrease with time in the hydrogen atmosphere. This mass change indicates that the oxygen content of the sample decreased, suggesting the change from Ti$$^{4+}$$ to Ti$$^{3+}$$. In order to control the mass change at the time of high temperature use, the development of lithium titanate which has Li$$_{4}$$TiO$$_{4}$$ additive is expected to be effective.

Journal Articles

Evaluation of phosphate thermodynamic properties for spent electrolyte recycle

Kofuji, Hirohide; Amamoto, Ippei; Yasumoto, Masaru*; Sasaki, Kazuya*; Myochin, Munetaka; Terai, Takayuki*

Journal of Nuclear Materials, 389(1), p.173 - 178, 2009/05

 Times Cited Count:4 Percentile:32.2(Materials Science, Multidisciplinary)

Adaptation of the phosphate conversion technique was undertaken and evaluated for application to the recycle process of the spent electrolyte generated from metal electrorefining process which is a kind of pyrochemical reprocessing technologies. The conceptual flow sheet has been discussed based on the thermodynamic properties of constituent. However few data have been published relating to the phosphate, therefore, the thermodynamic data were attempted to be obtained by the calorimetry and vapor pressure measurements. The measurements have been started with pure substance such as lithium phosphate. Through the measurements of HTMS and TG-DTA, it was clarified that decomposition or phase transition of Li$$_{3}$$PO$$_{4}$$ occurred at specific temperatures below the melting point of Li$$_{3}$$PO$$_{4}$$. To avoid the influence of fragment substances which have high vapour pressures, improved method of the HTMS measurement was examined.

Journal Articles

Crystal structure of advanced lithium titanate with lithium oxide additives

Hoshino, Tsuyoshi; Sasaki, Kazuya*; Tsuchiya, Kunihiko; Hayashi, Kimio; Suzuki, Akihiro*; Hashimoto, Takuya*; Terai, Takayuki*

Journal of Nuclear Materials, 386-388, p.1098 - 1101, 2009/04

no abstracts in English

Journal Articles

The Performance of photons rainbow-colored energy experimental lecture schools in the Kids' Science Museum of Photons

Hoshiya, Taiji; Sasaki, Kazuya*; Nishikawa, Masahiro

Reza Kenkyu, 36(4), p.221 - 225, 2008/04

The Kansai Photon Science Institute (KPSI) of Japan Atomic Energy Agency (JAEA) has been promoting various activities of public understanding of science and technology, to be focused on the photon science, which is characterized by activities on science lectures and science events based on science and experiment classrooms, by utilizing the science museum of the JAEA (The Kids' Science Museum of Photons). In this phase, the KPSI extends systematically trial activities of the science museum to be as an experimental apparatus for studying on science and technology, including the program for promoting activities on public understanding of science and technology at the region. In this report, the photons rainbow-colored energy experiments lecture schools were held on the energy conversion. About ninety percent of 142 participants can enjoy each school and get the motivation to have attraction for these fields, and these schools can be useful for elementary school members.

JAEA Reports

Guidance of operation practice and nuclear physics experiments using JRR-4

Yokoo, Kenji; Horiguchi, Hironori; Yagi, Masahiro; Nagadomi, Hideki; Yamamoto, Kazuyoshi; Sasajima, Fumio; Oyama, Koji; Ishikuro, Yasuhiro; Sasaki, Tsutomu; Hirane, Nobuhiko; et al.

JAEA-Technology 2007-018, 104 Pages, 2007/03

JAEA-Technology-2007-018.pdf:5.92MB

Reactor operation training using JRR-4 (Japan Research Reactor No.4) was started in FY 1969, one of the curriculums of Nuclear Technology and Education Center (NuTEC). After that, the program was updated and carried out for reactor operation training, control rod calibration, and measurement of various kind of characteristics. JRR-4 has been contributed for nuclear engineer training that is over 1,700 trainees from bother domestic and foreign countries. JRR-4 can be used for experiment from zero power to 3500kW, and the trainees can make experience to operate the reactor from start up to shut down, not only zero-power experiments (critical approach, control rod calibration, reactivity measurement, etc.) but also other experiments under high power operation (xenon effect, temperature effects, reactor power calibration, etc.). This report is based on various kinds of guidance texts using for training, and collected for operation and experiments for reactor physics.

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