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Journal Articles

Visual analysis of geospatial multivariate data for investigating radioactive deposition processes

Takahashi, Shigeo*; Sakurai, Daisuke*; Sasaki, Miyuki; Miyamura, Hiroko; Sanada, Yukihisa

Visual Computer, 37(12), p.3039 - 3050, 2021/12

 Times Cited Count:0 Percentile:0.01(Computer Science, Software Engineering)

The Fukushima nuclear accident in 2011 raised awareness on the importance of radioactive deposition processes, especially for proposing aerosol measures against possible air pollution. However, identifying these types of processes is often difficult due to complicated terrains. This paper presents an application study for identifying radioactive deposition processes by taking advantage of visual interaction with topographic data. The idea is to visually investigate the correspondence of the spatial positions to the air dose rate along with relevant attributes. This is accomplished by composing scatterplots of pairwise attributes, onto which we project terrain areas to interactively find specific patterns of such attributes. We applied our approach to the analysis of air dose rate distribution data around the Fukushima nuclear plant after the accident. Our visualization technique clearly distinguished contamination areas derived from different deposition processes, and thus is useful for elucidation of the deposition process.

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:1 Percentile:0(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

Nanoscopic structural investigation of physically cross-linked nanogels formed from self-associating polymers

Sekine, Yurina; Endo, Hitoshi*; Iwase, Hiroki*; Takeda, Shigeo*; Mukai, Sadaatsu*; Fukazawa, Hiroshi; Littrell, K. C.*; Sasaki, Yoshihiro*; Akiyoshi, Kazunari*

Journal of Physical Chemistry B, 120(46), p.11996 - 12002, 2016/11

 Times Cited Count:9 Percentile:32.16(Chemistry, Physical)

The detailed structure of a nanogel formed by self-association of cholesterol-bearing pullulans (CHP) was determined by contrast variation small-angle neutron scattering. The decomposition of scattering intensities into partial scattering functions of each CHP nanogel component, i.e., pullulan, cholesterol, and the cross-term between the pullulan and the cholesterol allows us to investigate the internal structure of the nanogel. The effective spherical radius of the skeleton formed by pullulan chains was found to be about 8.1 nm. In the CHP nanogel, there are about 19 cross-linking points where a cross-linking point is formed by aggregation of trimer cholesterol molecules with the spatially inhomogeneous distribution of the mass fractal dimension of 2.6. The average radius of the partial chains can also be determined to be 1.7 nm. As the result, the complex structure of the nanogels is coherently revealed at the nanoscopical level.

Journal Articles

Radioactivity evaluation of the secondary sodium in DRACS of the Japan Sodium-cooled Fast Reactor

Sasaki, Kenji*; Naito, Katsuaki*; Oki, Shigeo; Okubo, Tsutomu; Kotake, Shoji*

Progress in Nuclear Science and Technology (Internet), 4, p.94 - 98, 2014/04

This paper evaluates the amount of activation of the secondary sodium in Direct Heat Exchanger (DHX) by neutrons leaked from the core, the radioactivity density, and the dose rate around the secondary sodium pipes in Direct Reactor Auxiliary Cooling System (DRACS) and confirms that the requirements in radioactivity free areas are satisfied by improving the exactness of calculation model with Monte Carlo Methodology.

Journal Articles

Raman and UV-visible absorption spectroscopy of rare-earth hydride under high pressure

Kume, Tetsuji*; Machida, Akihiko; Aoki, Katsutoshi; Sasaki, Shigeo*; Shimizu, Hiroyasu*

Koatsuryoku No Kagaku To Gijutsu, 21(3), p.184 - 189, 2011/09

Raman and visible absorption spectra of rare earth trihydrides have been measured at high pressures, in order to investigate the structural and electronic phase transitions. The successive phase transitions of hcp-intermediatefcc phase were confirmed by Raman measurements. From the visible absorption experiments, the band gap energy was estimated. The gap closure was found to occur on the transition from the intermediate to the fcc phase.

Journal Articles

High-pressure study of ScH$$_{3}$$; Raman, infrared, and visible absorption spectroscopy

Kume, Tetsuji*; Oura, Hiroyuki*; Takeichi, Tomoo*; Omura, Ayako*; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Sasaki, Shigeo*; Shimizu, Hiroyasu*; Takemura, Kenichi*

Physical Review B, 84(6), p.064132_1 - 064132_7, 2011/08

 Times Cited Count:13 Percentile:53.09(Materials Science, Multidisciplinary)

Raman, IR, and visible absorption spectra of scandium trihydride (ScH$$_{3}$$) have been measured at high pressures up to 50 GPa at room temperature. The structural and electronic phase transitions were investigated. Successive hcp-intermediate-fcc phase transitions took place at 25 and 46 GPa. It was suggested that the intermediate phase of ScH$$_{3}$$ has the same structure as that of YH$$_{3}$$. The energy gap of ScH$$_{3}$$ is 1.7 eV at the ambient condition and is closed around 50 GPa, at which the crystal structure transforms to fcc.

Journal Articles

Large-volume static compression using nano-polycrystalline diamond for opposed anvils in compact cells

Okuchi, Takuo*; Sasaki, Shigeo*; Osakabe, Toyotaka; Ono, Yoshiki*; Odake, Shoko*; Kagi, Hiroyuki*

Journal of Physics; Conference Series, 215, p.012188_1 - 012188_9, 2010/03

 Times Cited Count:5 Percentile:87.1

We prepared super-hard nano-polycrystalline diamond (NPD) anvils for large-volume compression for intrinsically low-sensitivity methods of measurement, such as neutron scattering and NMR. These anvils are harder, larger and stronger than single crystal diamond anvils, so that they could play an ideal role to accept the larger forces. We tested supported and unsupported anvil geometries separately by using two types of compact high-pressure cells and could generate the pressure of 14 GPa for the sample volume of 0.1 mm$$^{3}$$ or more. The test results demonstrate a large future potential of NPD anvils for large-volume compression.

Journal Articles

A High pressure experiment of powder neutron diffraction on the HRPD at JRR-3

Komatsu, Kazuki*; Arima, Hiroshi*; Kagi, Hiroyuki*; Okuchi, Takuo*; Sasaki, Shigeo*; Yamauchi, Hiroki; Fukazawa, Hiroshi; Igawa, Naoki; Utsumi, Wataru; Kamiyama, Takashi*

Koatsuryoku No Kagaku To Gijutsu, 18(2), p.170 - 172, 2008/05

In this short communication, we report neutron diffractions under high pressure from lead powder in a Paris-Edinburgh cell at the High Resolution Powder Diffractometer (HRPD) installed at JRR-3, Ibaraki, Japan. This is the kick-off experiment in Japan as a high pressure powder diffraction study using reactor neutron source.

Journal Articles

High-pressure study of YH$$_{3}$$ by Raman and visible absorption spectroscopy

Kume, Tetsuji*; Oura, Hiroyuki*; Sasaki, Shigeo*; Shimizu, Hiroyasu*; Omura, Ayako*; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Takemura, Kenichi*

Physical Review B, 76(2), p.024107_1 - 024107_5, 2007/07

 Times Cited Count:35 Percentile:79.4(Materials Science, Multidisciplinary)

Raman and visible absorption spectra of YH$$_{3}$$ were measured at high pressures, in order to clarify the structural and electronic phase transitions. The Raman results revealed the presence of an intermediate phase at 9-24 GPa between the low-pressure hexagonal and high-pressure fcc phases. The Y-framework structure and the positions of interstitial H atoms are changed on the transition to the intermediate phase. The results of the absorption measurements demonstrate that the optical band gap begins to close in response to the phase transition.

Journal Articles

Comparison of four bidentate phosphoric and diamide compounds for the extractability of actinides

Sasaki, Yuji; Umetani, Shigeo*

Journal of Nuclear Science and Technology, 43(7), p.794 - 797, 2006/07

 Times Cited Count:10 Percentile:59.81(Nuclear Science & Technology)

Using four bidentate phosphonate and diamide ligands (L), the extraction of Am(III), Th(IV), Np(V) and U(VI) was studied and their extraction species and extractability in these extractants were discussed. The extractant containing the phosphoric oxygen has stronger chelation than that with the carbonyl oxygen atoms. The molar ratios in the main chemical forms extracted are 1:3 for Am:L, 1:1 for Th:L and Np:L and 1:2 for U:L from the relationship between log D(An) and log [L]. The order of D in actinides with the different oxidation states is U(VI) $$>$$ Th(IV) $$>$$ Am(III) $$>$$ Np(V), which shows the different order from that for HDEHP and HTTA, namely Th(IV) $$>$$ U(VI) $$>$$ Am(III) $$>$$ Np(V). It is clear that BDPPM, a diphosphoric dioxide extractant, has high extractability towards all An used here.

Journal Articles

MOGRA-DB; Database system for migration prediction code MOGRA

Amano, Hikaru; Ikeda, Hiroshi*; Sasaki, Toshihisa*; Matsuoka, Shungo*; Kurosawa, Naohiro*; Takahashi, Tomoyuki*; Uchida, Shigeo*

KEK Proceedings 2003-11, p.239 - 244, 2003/11

A Code MOGRA (Migration Of GRound Additions) is a migration prediction code for toxic ground additions including radioactive materials in a terrestrial environment, which consists of computational codes that are applicable to various evaluation target systems, and can be used on personal computers. The computational code has the dynamic compartment analysis block at its core, the graphical user interface (GUI) for model formation, computation parameter settings, and results displays. The code MOGRA has varieties of databases, which is called MOGRA-DB. Another additional code MOGRA-MAP can take in graphic map and calculate the square measure about the target land.

JAEA Reports

Tono Regional Hydrogeological Study Project Annual Report 2002

Amano, Kenji; Iwatsuki, Teruki; Uehara, Daijiro; Sasaki, Keiichi; Takeuchi, Shinji; Nakama, Shigeo

JNC TN7400 2003-002, 40 Pages, 2003/04

JNC-TN7400-2003-002.pdf:23.2MB

Tono Geoscience Center, Japan Nuclear Cycle Development Institute has been conducting a wide range of geoscientific research in order to build firm scientific and technological basis for the research and development of geological disposal. One of the ongoing geoscientific research programme is a Regional Hydrogeological Study (RHS) project in the Tono region, central Japan. The main goal of the RHS project is to develop and demonstrate the surface-based investigation methodologies to characterize geological environments on regional scale in Japan. The RHS project was initiated in 1992. To date, remote sensing, geological mapping, airborne and ground geophysical investigations have been carried out and thirteen deep boreholes have been also drilled and investigations include geophysical logging, hydraulic tests etc. using these boreholes have been done in the study area of the RHS project (c. 100 km$$^{2}$$). Groundwater chemistry and hydraulic head monitoring is under way in these boreholes. Important results that have been obtained from these investigations include various information concerning the heterogeneity of lithological, hydrogeological and geochemical parameters, and evolution of the groundwater geochemistry. During fiscal year 2002, as the research for regional scale, groundwater simulation was carried out, and the domain setting method of modeling in regional scale was shown and the domain of local scale in the RHS project area was determined. The setting method of modeling/simulation of the local scale domain and its boundary condition were shown. Lineament investigation and reflection seismic survey were carried out in the local scale domain. VSP survey and some investigations concerning groundwater flow and chemistry were conducted in DH-2 borehole. Long-term groundwater monitoring using the existing boreholes was continued. Improvement of the instruments of hydraulic test and groundwater sampling was also continued.

JAEA Reports

Questionnaire on the measurement condition of distribution coefficient

Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Takahashi, Tomoyuki*; Yasuda, Hiroshi*; Uchida, Shigeo*; Mahara, Yasunori*; Saeki, Akiyoshi*; Sasaki, Noriyuki*; Ashikawa, Nobuo*; et al.

JAERI-Review 2001-015, 81 Pages, 2001/05

JAERI-Review-2001-015.pdf:5.94MB

no abstracts in English

Journal Articles

Intercomparison of measurements and questionnaire on the distribution coefficient

Takahashi, Tomoyuki*; Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Yasuda, Hiroshi*; Uchida, Shigeo*; Saeki, Akiyoshi*; Mahara, Yasunori*; Sasaki, Noriyuki*; Ashikawa, Nobuo*; et al.

KURRI-KR-44, p.169 - 176, 2000/02

no abstracts in English

JAEA Reports

Intercomparison on measurement of distribution coefficient; Investigation on differences of measured values between individuals

Takahashi, Tomoyuki; Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Yasuda, Hiroshi*; Uchida, Shigeo*; Saeki, Akiyoshi*; Mahara, Yasunori*; Sasaki, Noriyuki*; *; et al.

JAERI-Research 97-089, 25 Pages, 1997/12

JAERI-Research-97-089.pdf:1.11MB

no abstracts in English

JAEA Reports

Intercomparison of measurements of distribution coefficient; Investigation of factors affecting variability of measured values

Takahashi, Tomoyuki; Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Yasuda, Hiroshi*; Uchida, Shigeo*; Saeki, Akiyoshi*; Mahara, Yasunori*; Sasaki, Noriyuki*; *; et al.

JAERI-Research 97-066, 34 Pages, 1997/10

JAERI-Research-97-066.pdf:1.5MB

no abstracts in English

Oral presentation

Extractability of diamides and organophosphorus oxides for actinides

Sasaki, Yuji; Kimura, Takaumi; Umetani, Shigeo*

no journal, , 

no abstracts in English

33 (Records 1-20 displayed on this page)