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Journal Articles

Evaluation of particulate $$^{137}$$Cs discharge from a mountainous forested catchment using reservoir sediments and sinking particles

Funaki, Hironori; Yoshimura, Kazuya; Sakuma, Kazuyuki; Iri, Shatei; Oda, Yoshihiro

Journal of Environmental Radioactivity, 189, p.48 - 56, 2018/09

 Times Cited Count:4 Percentile:57.32(Environmental Sciences)

Journal Articles

Mathematical Modeling of Radioactive Contaminants in the Fukushima Environment

Kitamura, Akihiro; Kurikami, Hiroshi; Yamaguchi, Masaaki; Oda, Yoshihiro; Saito, Tatsuo; Kato, Tomoko; Niizato, Tadafumi; Iijima, Kazuki; Sato, Haruo; Yui, Mikazu; et al.

Nuclear Science and Engineering, 179(1), p.104 - 118, 2015/01

 Times Cited Count:6 Percentile:38.07(Nuclear Science & Technology)

The prediction of the distribution and fate of radioactive materials eventually deposited at surface in the Fukushima area is one of the main objectives and expected to be achieved in an efficient manner. In order to make such prediction, a number of mathematical models of radioactive contaminants, with particular attention on cesium, on the land and in rivers, lakes, and estuaries in the Fukushima area are developed. Simulation results are examined with the field investigations simultaneously implemented. The basic studies of the adsorption/absorption mechanism of cesium and soils have been performed to shed light on estimating distribution coefficient between dissolved contaminant and particulate contaminant.

Journal Articles

Predicting the long-term $$^{137}$$Cs distribution in Fukushima after the Fukushima Dai-ichi Nuclear Power Plant accident; A Parameter sensitivity analysis

Yamaguchi, Masaaki; Kitamura, Akihiro; Oda, Yoshihiro; Onishi, Yasuo*

Journal of Environmental Radioactivity, 135, p.135 - 146, 2014/09

 Times Cited Count:33 Percentile:17.66(Environmental Sciences)

We applied a model, to predict long term cesium distribution on Fukushima area, based on the USLE and simple sediment discharge formulas. Sensitivity analysis was conducted here to narrow the range of the output results due to the uncertainties of parameters. The preliminary calculation indicated significant deposition of sand portion within river basins. On the other hand the most of the eroded silt and clay portions were transported downstream to the river mouths. Annual sediment outflow into the ocean from Abukuma River and its total from the other 13 river basins vary between calculation cases based on the variation of land use, landform or precipitation. On the other hand, contributions of those parameters are relatively small for $$^{137}$$Cs concentration within transported soil. This indicates the total amount of $$^{137}$$Cs outflow into the ocean could be controlled by amount of soil erosion and transport, and total amount of $$^{137}$$Cs remaining within the basin.

Journal Articles

Simulating long-term $$^{137}$$Cs distribution on territory of Fukushima

Kitamura, Akihiro; Yamaguchi, Masaaki; Oda, Yoshihiro; Kurikami, Hiroshi; Onishi, Yasuo*

Transactions of the American Nuclear Society, 109(1), p.153 - 155, 2013/11

Long term $$^{137}$$Cs transport and its future distribution on the territory of Fukushima were predicted based on the USLE and the GIS. By modeling the soil erosion, transport, and deposition, we simulated the future distributions of air dose rates of $$^{137}$$Cs in mSv/h for 2, 6 and 21 years after the accident. The predictions made by METI were compared with the present results. The predictions of relatively high air dose rate areas were consistently matched between the two models over time. However, our model seemed to predict the decreasing rate of the $$^{137}$$Cs concentration with time to be slightly less than that of METI prediction. Some portions of the results obtained in the present study were used to provide influxes of sediments and $$^{137}$$Cs as boundary conditions and lateral inflows for the hydraulic river model.

Journal Articles

Suppression of heavy-ion induced current in SOI device

Ogura, Shunta*; Komiyama, Takahiro*; Takahashi, Yoshihiro*; Makino, Takahiro; Onoda, Shinobu; Hirao, Toshio*; Oshima, Takeshi

Proceedings of 10th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-10) (Internet), p.127 - 129, 2012/12

We have investigated the transient current in a SOI p$$^+$$n junction diode induced by single heavy-ions. The amount of radiation induced total collected charge exceeds the generated charge in active SOI layer because some of generated charge in handle substrate is collected through a BOX layer by displacement current. The displacement current is caused by the charges collected at surface of handle substrate due to an electric field in depletion layer. In this paper, we show that the amount of collected charge can be suppressed by reducing the width of depletion layer at the surface of handle substrate.

JAEA Reports

Research and development for treatment and disposal technologies of TRU waste; JFY 2010 annual report

Kamei, Gento; Honda, Akira; Oda, Chie; Hirano, Fumio; Ichige, Satoru; Kurimoto, Yoshitaka; Hoshino, Seiichi; Akagi, Yosuke; Sato, Nobuyuki; Takahashi, Kuniaki; et al.

JAEA-Research 2012-010, 80 Pages, 2012/06

JAEA-Research-2012-010.pdf:7.45MB

Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H22 (2010) Japanese fiscal year and their products during the last 5 years. These include (1) evaluation of long-term mechanical stability in the near-field including development of a creep mode of rock and analyses of mechanical behavior of TRU waste repository, (2) performance assessment of the disposal system including cementitious material alteration, bentonite and hostrock alteration with alkaline solution and nitrate effect, and (3) alternative technology development including decomposition of nitrate.

Journal Articles

X-ray study of radiation damage in UO$$_{2}$$ irradiated with high-energy heavy ions

Ishikawa, Norito; Sonoda, Takeshi*; Okamoto, Yoshihiro; Sawabe, Takashi*; Takegahara, Keisuke; Kosugi, Shinya*; Iwase, Akihiro*

Journal of Nuclear Materials, 419(1-3), p.392 - 396, 2011/12

 Times Cited Count:7 Percentile:43.63(Materials Science, Multidisciplinary)

In order to characterize the radiation damage due to ion-track formation in UO$$_{2}$$, polycrystalline samples have been irradiated with 210-MeV Xe ions, and measured with XRD (X-ray diffraction) technique using Cu X-ray. We have also tried EXAFS (extended X-ray absorption fine structure) measurement using X-ray near U L$$_{3}$$-edge. The results show that XRD technique detects damage at relatively low fluence of 10$$^{16}$$ ions/m$$^{2}$$ and higher, while the irradiation-induced change of EXAFS spectra is not observed even at highest fluence of 10$$^{19}$$ ions/m$$^{2}$$. The damage detection may be critically influenced by the depth profile of X-ray penetration.

Journal Articles

Optical measurement of the salinity distribution by saltwater intrusion experiment

Oda, Yoshihiro; Takasu, Tamio*; Sato, Hisashi; Sawada, Atsushi; Watahiki, Takanori*

Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 67(2), p.186 - 197, 2011/04

Because of the density difference between fresh groundwater and saline groundwater, the groundwater behaves complicated flow. It is well known that the expected barrier functions such as candidate buffer materials and others for high level radioactive waste geological isolation are inhibited by the saline water. The simulations have been required to evaluate the groundwater flow, because the available data by in-situ investigation of the saline and fresh ground water flows is very limited. In the simulation, the complex coupled process of advection-dispersion, seepage flow and density drive flow should be implemented in the simulation codes. The extensive verification studies have been done for modeling and simulation codes until now, but those results were compared only with qualitative experimental data. For the quantitative evaluations, we developed the quantitative measurement technique by optical method for saltwater intrusion, especially for the saltwater concentration distribution in transition zone, on laboratory experiment. We have obtained the quantitative data of the shape of saltwater wedge and saltwater concentration distribution at both transient and steady states.

JAEA Reports

Research and development for treatment and disposal technologies of TRU waste; JFY 2009 annual report

Kamei, Gento; Honda, Akira; Mihara, Morihiro; Oda, Chie; Ichige, Satoru; Kurimoto, Yoshitaka; Hoshino, Seiichi; Akagi, Yosuke; Sato, Nobuyuki; Murakami, Hiroshi*; et al.

JAEA-Research 2011-002, 82 Pages, 2011/03

JAEA-Research-2011-002.pdf:5.64MB

Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H20 (2008) Japanese fiscal year, which are (1) evaluation of long-term mechanical stability in the near-field including development of a creep mode of rock and analyses of mechanical behavior of TRU waste repository, (2) performance assessment of the disposal system including data acquisition and preparation on radionuclides migration, cementitious material alteration, bentonite and hostrock alteration with alkaline solution and nitrate effect, and (3) alternative technology development including decomposition of nitrate.

Journal Articles

Double loss-of-function mutation in ${it EARLY FLOWERING 3}$ and ${it CRYPTOCHROME 2}$ genes delays flowering under continuous light but accelerates it under long days and short days; An Important role for ${it Arabidopsis}$ CRY2 to accelerate flowering time in continuous light

Nefissi, R.*; Natsui, Yu*; Miyata, Kana*; Oda, Atsushi*; Hase, Yoshihiro; Nakagawa, Mayu*; Ghorbel, A.*; Mizoguchi, Tsuyoshi*

Journal of Experimental Botany, 62(8), p.2731 - 2744, 2011/02

 Times Cited Count:14 Percentile:48.54(Plant Sciences)

no abstracts in English

Journal Articles

Isolation and characterization of suppressors of the ${it early flowering 3}$ in ${it Arabidopsis thaliana}$

Natsui, Yu*; Nefissi, R.*; Miyata, Kana*; Oda, Atsushi*; Hase, Yoshihiro; Nakagawa, Mayu*; Mizoguchi, Tsuyoshi*

Plant Biotechnology, 27(5), p.463 - 468, 2010/12

 Times Cited Count:3 Percentile:85.61(Biotechnology & Applied Microbiology)

EARLY FLOWERING 3 (ELF3) is a circadian clock protein with a major role in maintaining circadian rhythms in plants. In this work, ${it elf3-101}$ was mutagenized by EMS in plants of the Lansberg ${it erecta}$ background to isolate suppressors of ${it elf3}$ and to understand the molecular mechanisms of flowering time controlled by ELF3. Two suppressors, ${it sel106}$ obtained from this screen and ${it sel5}$ from a precious study, were chosen for further analysis. Genetic mapping, gene expression analysis, and sequencing identified ${it sel106}$ and ${it sel5}$ as new alleles of ${it gi}$ and ${it fca}$, respectively. Genetic interactions between ${it elf3}$ and ${it gi}$ and between ${it elf3}$ and ${it fca}$ in the control of the floral activator ${it FLOWERING LOCUS T}$ were also investigated. Six suppressor of ${it elf3}$ were classified at least into four subgroups based on the expression of such floral regulators as GI, CO, FT, SVP, and FLC, and on their flowering times under LL, LD, and SD. This classification scheme is useful for the characterization of unidentified suppressor mutations.

JAEA Reports

Study on flow and mass transport through fractured sedimentary rocks (Joint research)

Shimo, Michito*; Kumamoto, So*; Ito, Akira*; Karasaki, Kenji*; Sawada, Atsushi; Oda, Yoshihiro; Sato, Hisashi

JAEA-Research 2010-040, 57 Pages, 2010/11

JAEA-Research-2010-040.pdf:5.12MB

In safety analysis of geological disposal of the high-level nuclear waste, it is important to evaluate appropriately the mass transport characteristics of the bedrock as the natural barrier. Especially, it has been found that the porosity of the rock matrix is high and fractured zones are developing and therefore the mass transport characteristics will be the mixture of those for porous media and the fractured media. In this work, we conducted, (1) a study on the method to mine out the rock block sample of tens of-centimeter to maximum 1 m scale, (2) a study on a method of the tracer test using a rock block sample and a series of scoping analysis. We also examined the uncertainty associated the hydrogeological model using a method combining a forward and inverse analysis, based on the various type of data sets obtained at Horonobe site, such as the temperature distribution and hydraulic head and salinity distribution.

Journal Articles

Heavy-ion induced current in SOI junction diode

Takahashi, Yoshihiro*; Takeyasu, Hidenori*; Okazaki, Yuji*; Hirao, Toshio; Onoda, Shinobu; Oshima, Takeshi

Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9), p.173 - 175, 2010/10

no abstracts in English

JAEA Reports

Advection dispersion and density flow simulation for salinity distribution on the transition zone of saltwater intrusion experiment

Oda, Yoshihiro; Watahiki, Takanori*; Sato, Hisashi; Sawada, Atsushi

JAEA-Research 2010-020, 23 Pages, 2010/08

JAEA-Research-2010-020.pdf:2.49MB

For the geological disposal of high level radioactive waste, it is important to know the groundwater flow to evaluate the geological isolation system. Simulation codes are used for the evaluation of the saline groundwater flow and distribution, because various and a lot of investigations and experiments are needed. At in-situ, simulation codes have to solve advection-dispersion flow coupling with density flow which occurs by the density difference between saline and fresh groundwater. But the results of laboratory experiments are qualitative data, then the verification cannot be done in quantitatively. The quantitative data of saltwater intrusion experiment, then we try to simulate saltwater intrusion by Dtransu2D-EL code which can calculate advection-dispersion flow coupled with density flow. Between the results of the simulation and the experiments, the toe point of wedge by the simulation shows good coincidence, but the top point is not good coincidence. As for the transition zone of saltwater intrusion, the band width of the experimental result decrease from the toe to the top, but the simulation result shows countertrend.

JAEA Reports

Study on flow and mass transport through fractured sedimentary rocks, 3

Shimo, Michito*; Kumamoto, So*; Ito, Akira*; Karasaki, Kenji*; Sawada, Atsushi; Oda, Yoshihiro; Sato, Hisashi

JAEA-Research 2009-060, 70 Pages, 2010/03

JAEA-Research-2009-060.pdf:14.26MB

It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground appropriately. Though it is considered that the mass transport in sedimentary rock occurs in pores between grains mainly, fractures of sedimentary rock can be main paths. In this study the following three tasks were carried out: (1) laboratory hydraulic and tracer experiments using the rock cores of Wakkanai formation, (2) a study on the tracer test and sampling technique for the larger scale, (3) a study on the reduction technique of uncertainty of the hydrogeological models using data from surface-based investigation. On the block scale tracer test technique, the sampling technique using wire saw and tracer test technique using block samples were suggested. As for the reduction technique of uncertainty of the hydrogeological model, availability of the information other than pressure data, such as the temperature and salinity and all, were presented.

JAEA Reports

Research and development for treatment and disposal technologies of TRU waste; JFY 2008 annual report

Kamei, Gento; Honda, Akira; Mihara, Morihiro; Oda, Chie; Murakami, Hiroshi; Masuda, Kenta; Yamaguchi, Kohei; Matsuda, Setsuro; Ichige, Satoru; Takahashi, Kuniaki; et al.

JAEA-Research 2009-046, 80 Pages, 2010/01

JAEA-Research-2009-046.pdf:9.1MB

Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H20 (2008) Japanese fiscal year.

Journal Articles

Change in ion beam induced current from Si metal-oxide-semiconductor capacitors after $$gamma$$-ray irradiation

Oshima, Takeshi; Onoda, Shinobu; Hirao, Toshio; Takahashi, Yoshihiro*; Vizkelethy, G.*; Doyle, B. L.*

AIP Conference Proceedings 1099, p.1014 - 1017, 2009/03

Metal-Oxide-Semiconductor (MOS) capacitors were made on both n- and p-type Si substrates (n-MOS, and p-MOS). These MOS capacitors were irradiated with $$gamma$$-rays at a dose of 6.3 kGy (SiO$$_{2}$$) at room temperature. The capacitance-voltage characteristics for MOS capacitors were measured before and after irradiation. The flat band shift for n-MOS and p-MOS capacitors due to $$gamma$$-ray irradiation was -12.3 V and -15.2 V, respectively. As for the generation of interface traps, the values for n-MOS and p-MOS capacitors were estimated to be 0.5$$times$$10$$^{11}$$ and 1.7$$times$$10$$^{11}$$/cm$$^{2}$$, respectively. Transient Ion Beam Induced Current (TIBIC) obtained from these MOS capacitors were compared before and after $$gamma$$-ray irradiation. For n-MOS capacitors, the peak height of TIBIC signals decreased after $$gamma$$-ray irradiation. On the other hand, the peak height of TIBIC signals for p-MOS capacitors increased after $$gamma$$-ray irradiation. The applied bias dependence of the peak height of TIBIC signals for MOS capacitors irradiated with $$gamma$$-rays can be matched to that for ones before $$gamma$$-rays irradiation by shifting the voltage by -13 V for n-MOS capacitors and by -15 V for p-MOS capacitors. These voltage values are in good agreement with the flat band voltage shifts due to $$gamma$$-ray irradiation. Since flat band shift occurs due to the generation of positive charge trapped in gate oxide, the change in TIBIC signals observed for MOS capacitors due to $$gamma$$-ray irradiation can be interpreted in terms of positive charge generated in oxide.

JAEA Reports

Experiments of sodium nitrate liquid waste treatment by biological method

Takahashi, Kuniaki; Meguro, Yoshihiro; Kawato, Yoshimi; Kuroda, Kazuhiko*; Ogawa, Naoki*

JAEA-Technology 2008-084, 12 Pages, 2009/02

JAEA-Technology-2008-084.pdf:1.06MB

Low level liquid waste discharged from a Reprocessing Facility includes sodium nitrate. In the case that it is directly solidified with cement and so on and then the solidified waste are disposed under the ground, sodium nitrate soaks into the environment through underground water layer. We planned to apply the biological treatment system that many ordinary industrial plants are running in the field of waste water treatment to reduce nitrate. We carried out degradation experiments of nitrate for 4wt% sodium nitrate solution by biological method. To solve the assignments that biological treatment technology has, we tested and obtained the results as shown below; (1) The amount of sludge ash could be cut down a tenth as much as usual. The disposal cost reduction of secondary waste is just in sight. (2) Treatment performance could be improved up to 7 kg-N/m$$^{3}$$/d from 4 kg-N/m$$^{3}$$/d. It could be expected the more compact system by improvement of the membrane set into the biological treatment tanks.

JAEA Reports

Research and development for treatment and disposal technologies of TRU waste; JFY 2007 annual report

Kamei, Gento; Honda, Akira; Mihara, Morihiro; Oda, Chie; Murakami, Hiroshi; Masuda, Kenta; Yamaguchi, Kohei; Matsuda, Setsuro; Ichige, Satoru; Takahashi, Kuniaki; et al.

JAEA-Research 2008-082, 84 Pages, 2008/11

JAEA-Research-2008-082.pdf:2.52MB
JAEA-Research-2008-082(errata).pdf:0.15MB

Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H19 (2007) fiscal year, which are (1) treatment and packaging of TRU waste including applicability of calcination for unpacking and sorting of wastes, characterization and inspection methodology of TRU waste, (2) mechanical assessment for the near-field structure including model development and preparation, introduction of hostrock creep model and coupling analysis of deformation of hostrock and engineered barrier. (3) performance assessment of the disposal system including data acquisition and preparation on radionuclides migration, cementitious material alteration, bentonite and hostrock alteration with alkaline solution and nitrate effect, and (4) alternative technology development including decomposition of nitrate.

Journal Articles

Total dose effects on heavy-ion induced gate current in MOS structure

Takahashi, Yoshihiro*; Fugane, Masaru*; Imagawa, Ryo*; Owaki, Akihiro*; Hirao, Toshio; Onoda, Shinobu; Oshima, Takeshi

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 7, 2008/11

no abstracts in English

112 (Records 1-20 displayed on this page)