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Journal Articles

Spin excitations of the $$S$$=1/2 one-dimensional Ising-like antiferromagnet BaCo$$_{2}$$V$$_{2}$$O$$_{8}$$ in transverse magnetic fields

Okutani, Akira*; Onishi, Hiroaki; Kimura, Shojiro*; Takeuchi, Tetsuya*; Kida, Takanori*; Mori, Michiyasu; Miyake, Atsushi*; Tokunaga, Masashi*; Kindo, Koichi*; Hagiwara, Masayuki*

Journal of the Physical Society of Japan, 90(4), p.044704_1 - 044704_9, 2021/04

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2019

Ishimaru, Tsuneari; Ogata, Nobuhisa; Kokubu, Yoko; Shimada, Koji; Hanamuro, Takahiro; Shimada, Akiomi; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; et al.

JAEA-Research 2020-011, 67 Pages, 2020/10

JAEA-Research-2020-011.pdf:3.87MB

This annual report documents the progress of research and development (R&D) in the 5th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. The current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Japanese population dose from natural radiation

Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*

Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09

 Times Cited Count:6 Percentile:77(Environmental Sciences)

UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.

Journal Articles

Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.

Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08

 Times Cited Count:1 Percentile:24.67(Physics, Applied)

To clarify the existence of cation vacancies in Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Journal Articles

Production of $$^{266}$$Bh in the $$^{248}$$Cm($$^{23}$$Na,5$$n$$)$$^{266}$$Bh reaction and its decay properties

Haba, Hiromitsu*; Fan, F.*; Kaji, Daiya*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Komori, Yukiko*; Kondo, Narumi*; Kudo, Hisaaki*; Morimoto, Koji*; Morita, Kosuke*; et al.

Physical Review C, 102(2), p.024625_1 - 024625_12, 2020/08

 Times Cited Count:2 Percentile:57.67(Physics, Nuclear)

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2020)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Koji; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; Komatsu, Tetsuya; Yokoyama, Tatsunori; et al.

JAEA-Review 2020-010, 46 Pages, 2020/07

JAEA-Review-2020-010.pdf:1.89MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2020. The objectives and contents in fiscal year 2020 are described in detail based on the JAEA 3rd Medium- and Long-term Plan (fiscal years 2015-2021). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2018

Ishimaru, Tsuneari; Ogata, Nobuhisa; Hanamuro, Takahiro; Shimada, Akiomi; Kokubu, Yoko; Asamori, Koichi; Niwa, Masakazu; Shimada, Koji; Watanabe, Takahiro; Saiga, Atsushi; et al.

JAEA-Research 2019-006, 66 Pages, 2019/11

JAEA-Research-2019-006.pdf:4.39MB

This annual report documents the progress of research and development (R&D) in the 4th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. In this report, the current status of R&D activities with previous scientific and technological progress is summarized.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2019)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Hanamuro, Takahiro; Shimada, Akiomi; Kokubu, Yoko; Asamori, Koichi; Niwa, Masakazu; Shimada, Koji; Watanabe, Takahiro; Sueoka, Shigeru; et al.

JAEA-Review 2019-010, 46 Pages, 2019/09

JAEA-Review-2019-010.pdf:2.45MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency, in fiscal year 2019. The objectives and contents in fiscal year 2019 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2017

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Akiomi; Asamori, Koichi; Kokubu, Yoko; Niwa, Masakazu; Watanabe, Takahiro; Saiga, Atsushi; Sueoka, Shigeru; Komatsu, Tetsuya; et al.

JAEA-Research 2018-015, 89 Pages, 2019/03

JAEA-Research-2018-015.pdf:14.43MB

This annual report documents the progress of research and development (R&D) in the 3rd fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. In this report, the current status of R&D activities with previous scientific and technological progress is summarized.

JAEA Reports

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific Program for fiscal year 2018)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Akiomi; Asamori, Koichi; Kokubu, Yoko; Niwa, Masakazu; Watanabe, Takahiro; Saiga, Atsushi; Sueoka, Shigeru; Komatsu, Tetsuya; et al.

JAEA-Review 2018-020, 46 Pages, 2019/01

JAEA-Review-2018-020.pdf:1.25MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency, in fiscal year 2018. The objectives and contents in fiscal year 2018 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

Journal Articles

Electron-tracking Compton camera imaging of technetium-95m

Hatsukawa, Yuichi*; Hayakawa, Takehito*; Tsukada, Kazuaki; Hashimoto, Kazuyuki*; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Tanimori, Toru*; Sonoda, Shinya*; Kabuki, Shigeto*; et al.

PLOS ONE (Internet), 13(12), p.e0208909_1 - e0208909_12, 2018/12

 Times Cited Count:0 Percentile:0.01(Multidisciplinary Sciences)

Imaging of $$^{95m}$$Tc radioisotope was conducted using an electron tracking-Compton camera (ETCC). $$^{95m}$$Tc emits 204, 582, and 835 keV $$gamma$$ rays, and was produced in the $$^{95}$$Mo(p,n)$$^{95m}$$Tc reaction with a $$^{95}$$Mo-enriched target. The recycling of the $$^{95}$$Mo-enriched molybdenum trioxide was investigated, and the recycled yield of $$^{95}$$Mo was achieved to be 70% - 90%. The images were obtained with each of the three $$gamma$$ rays. Results showed that the spatial resolution increases with increasing $$gamma$$-ray energy, and suggested that the ETCC with high-energy $$gamma$$-ray emitters such as $$^{95m}$$Tc is useful for the medical imaging of deep tissue and organs in the human body.

Journal Articles

Online chemical adsorption studies of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA

Lens, L.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Asai, Masato; Ballof, J.*; Block, M.*; David, H. M.*; Despotopulos, J.*; Di Nitto, A.*; Eberhardt, K.*; et al.

Radiochimica Acta, 106(12), p.949 - 962, 2018/12

 Times Cited Count:2 Percentile:33.17(Chemistry, Inorganic & Nuclear)

Online gas-solid adsorption studies with single atom quantities of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces were carried out using short-lived radioisotopes with half-lives in the range of 4-49 s. This is a model study to measure adsorption enthalpies of superheavy elements Cn, Nh, and Fl. The short-lived isotopes were produced and separated by the gas-filled recoil separator TASCA at GSI. The products were stopped in He gas, and flushed into gas chromatography columns made of Si detectors whose surfaces were covered by SiO$$_{2}$$ or Au. The short-lived Tl and Pb were successfully measured by the Si detectors with the SiO$$_{2}$$ surface at room temperature. On the other hand, the Hg did not adsorb on the SiO$$_{2}$$ surface, but adsorbed on the Au surface. The results demonstrated that the adsorption properties of short-lived Hg, Tl, and Pb could be studied with this setup, and that this method is applicable to the experiment for Cn, Nh, and Fl.

Journal Articles

A Refined analysis on the power reactivity loss measurement in Monju

Taninaka, Hiroshi; Takegoshi, Atsushi; Kishimoto, Yasufumi*; Mori, Tetsuya; Usami, Shin

Progress in Nuclear Energy, 101(Part C), p.329 - 337, 2017/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The present paper describes the evaluation of the power reactivity loss data obtained in the Japanese prototype fast breeder reactor Monju. The most recent analysis on the power reactivity loss measurement (Takano, et al., 2008) is updated considering the following findings: (a) in-core temperature distribution effect, (b) crystalline binding effect, (c) logarithmic averaging of the fuel temperature, (d) localized fuel thermal elongation effect, (e) updated Japanese Evaluated Nuclear Data Library, JENDL-4.0, and (f) refined corrections on the measured value. The influences of the updates are quantitatively identified and the most precise and probable C/E value is derived together with a thorough uncertainty evaluation. As a result, it is revealed that the analysis overestimates the measurement by 4.6% for the measurement uncertainty of 2.0%. The discrepancy is reduced to as small as 1.1% when the core bowing effect is considered, which implies the importance of the core bowing effect in the calculation of the power reactivity loss.

Journal Articles

Complex chemistry with complex compounds

Eichler, R.*; Asai, Masato; Brand, H.*; Chiera, N. M.*; Di Nitto, A.*; Dressler, R.*; D$"u$llmann, Ch. E.*; Even, J.*; Fangli, F.*; Goetz, M.*; et al.

EPJ Web of Conferences, 131, p.07005_1 - 07005_7, 2016/12

 Times Cited Count:1 Percentile:48.51

In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the productions and investigations of fragile single molecular species of superheavy elements. The latest highlight is the formation of very volatile hexacarbonyl compound of element 106, Sg(CO)$$_{6}$$. Following this success, second-generation experiments were performed to measure the first bond dissociation energy between the central metal atom and the surrounding ligand. The method using a tubular decomposition reactor was developed and successfully applied to short-lived Mo(CO)$$_{6}$$, W(CO)$$_{6}$$, and Sg(CO)$$_{6}$$.

Journal Articles

Heat transport analysis in a district heating system applying waste heat from GTHTR300, a commercial design of high-temperature gas-cooled reactor

Kasahara, Seiji; Murata, Tetsuya*; Kamiji, Yu; Terada, Atsuhiko; Yan, X.; Inagaki, Yoshiyuki; Mori, Michitsugu*

Mechanical Engineering Journal (Internet), 3(3), p.15-00616_1 - 15-00616_16, 2016/06

A district heating system for household heating and road snow melting utilizing waste heat from GTHTR300, a heat-electricity cogeneration design of high temperature gas-cooled reactor, was analyzed. The application area was Sapporo and Ishikari, cities with heavy snowfall in northern Japan. The heat transport analyses were performed by modeling components to estimate heat supply profile; the secondary loops between the GTHTR300s and the heat-application area; heat exchangers connecting the secondary loops to the tertiary loops of the district-heating pipes; and the tertiary loops between the heat exchangers and houses and roads. Though double pipes for the secondary loops were advantageous for having less heat loss and a smaller excavation area, these advantages did not compensate for the higher construct cost of the pipes. To satisfy heat demand in the month of maximum requirement, 520-529 MW of heat were supplied by 3 GTHTR300s and delivered by 6 secondary loops, 3,450 heat exchangers about 90 m long, and 3,450 tertiary loops. Heat loss to the ground from the tertiary loops comprised 80%-90% of the heat loss. More than 90% of the construction cost went into thermal insulators. The thickness and properties of the thermal insulator must be reevaluated for economical heat delivery.

Journal Articles

A Scrutinized analysis on the power reactivity loss measurement in Monju

Taninaka, Hiroshi; Kishimoto, Yasufumi; Mori, Tetsuya; Usami, Shin

Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.2610 - 2621, 2016/05

Reactivity loss due to power ascension (power reactivity loss or power coefficient of reactivity) is thus an important design parameter for determining the number of CRs and plutonium content or inventory in the SFR core design, along with the burnup reactivity loss. Measurements on these reactivity losses were therefore performed during the system startup tests in the Japanese prototype SFR Monju in 1995 and analyses have been carried out for several times. The most recent analysis on the power coefficient measurement in Monju was presented by Takano (Takano, et al., 2008). The following latest findings, which have not been taken into account in the past analyses, are available at present and may affect the existing results: (a) in-core temperature distribution effect, (b) crystalline binding effect, (c) logarithmic averaging of the fuel temperature, (d) localized fuel thermal elongation effect, (e) updated Japanese Evaluated Nuclear Data Library, JENDL-4.0, and (f) refined corrections on the measured value. The influences of refining the calculational models and measured value corrections were therefore quantitatively identified in this study by considering all of these new findings. As a result, it was revealed that the analysis overestimates the experiment by 8.1% for the total uncertainty of 5.9%. Therefore, an additional effect, that is the core bowing effect, was considered in the calculation, and the discrepancy was reduced to 2.9%. The possibility of a significant contribution from the core bowing or deformation effect was thus suggested.

Journal Articles

Heat transport analysis in a district heating and snow melting system in Sapporo and Ishikari, Hokkaido applying waste heat from GTHTR300

Kasahara, Seiji; Murata, Tetsuya*; Kamiji, Yu; Terada, Atsuhiko; Yan, X.; Inagaki, Yoshiyuki; Mori, Michitsugu*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 11 Pages, 2015/05

A heat transport analysis of a district heating and snow melting system in Sapporo and Ishikari, Hokkaido was carried out assuming application of waste heat from GTHTR300, a design of high temperature gas-cooled reactor. The following components in the system were modeled; pipelines of the water loops between GTHTR300 and heat demand district and heat exchangers to transport the heat from the water loops to water loops in the district. Double pipes for the pipeline has disadvantage that pumping electricity consumption was 2.74 times to that of single pipes due to pressure loss in annulus channel. On the other hand, the double pipe was advantageous in less heat loss and excavation load. Heat loss was 33% smaller because heat loss from inner tube was recovered in annulus channel. Excavation area was 23% smaller because water loop was made by one double pipe. Total heat loss from the GTHTR300s to the water loop in the district was 4.2% and ratio of pump electricity to power generation from the GTHTR300s was 0.8%. In January, the maximum heat demand in a year, 97.0% of the heat demand was supplied by 2 GTHTRs. Less distance between GTHTR300 and heat demand district from 40 km to 20 km would make cost of the heat transfer system 22% smaller.

Journal Articles

Production of $$^{rm 95m}$$Tc for Compton camera imaging

Hatsukawa, Yuichi; Hashimoto, Kazuyuki; Tsukada, Kazuaki; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Nagai, Yasuki; Tanimori, Toru*; Sonoda, Shinya*; Kabuki, Shigeto*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1283 - 1285, 2015/02

 Times Cited Count:2 Percentile:22.25(Chemistry, Analytical)

Technetium-99m ($$^{rm 99m}$$Tc) is used in radioactive medical diagonostic tests, for example as a radioactive tracer that medical equipment can detect in the human body. It is well suited to the role because it emits readily detectable 141 keV $$gamma$$ rays, and its half-life is 6.01 hours (meaning that about 94% of it decays to technetium-99 in 24 hours). There are at least 31 commonly used radiopharmaceuticals based on technetium-99m for imaging and functional studies of the brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood, and tumors. Recent years, with the develop-ment of the Compton camera which can realize high position resolution, technetium isotopes emitting high energy $$gamma$$-rays are required. In this study, technetium-95m which emits some $$gamma$$ rays around 800 keV was produced by the $$^{95}$$Mo(p,n)$$^{rm 95m}$$Tc reaction.

Journal Articles

High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; Koga, J. K.; Mori, Michiaki; Kawase, Keigo*; et al.

RAL-TR-2015-025, P. 22, 2015/00

Journal Articles

Probing strongly correlated 4$$f$$-orbital symmetry of the ground state in Yb compounds by linear dichroism in core-level photoemission

Mori, Takeo*; Kitayama, Satoshi*; Kanai, Yuina*; Naimen, Sho*; Fujiwara, Hidenori*; Higashiya, Atsushi*; Tamasaku, Kenji*; Tanaka, Arata*; Terashima, Kensei*; Imada, Shin*; et al.

Journal of the Physical Society of Japan, 83(12), p.123702_1 - 123702_5, 2014/12

 Times Cited Count:15 Percentile:71.43(Physics, Multidisciplinary)

We show that the strongly correlated 4$$f$$-orbital symmetry of the ground state is revealed by linear dichroism in core-level photoemission spectra, as we have discovered for YbRh$$_{2}$$Si$$_{2}$$ and YbCu$$_{2}$$Si$$_{2}$$. Theoretical analysis shows us that the linear dichroism reflects the anisotropic charge distributions resulting from a crystalline electric field. We have successfully determined the ground-state 4$$f$$ symmetry for both compounds from the polarization-dependent angle resolved core-level spectra at a temperature well below the first excitation energy. The excited-state symmetry is also probed by temperature dependence of the linear dichroism where the high measurement temperatures are on the order of the crystal-field-splitting energies.

154 (Records 1-20 displayed on this page)