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Journal Articles

Hydrogen trapping in Mg$$_2$$Si and Al$$_7$$FeCu$$_2$$ intermetallic compounds in aluminum alloy; First-principles calculations

Yamaguchi, Masatake; Tsuru, Tomohito; Ebihara, Kenichi; Itakura, Mitsuhiro; Matsuda, Kenji*; Shimizu, Kazuyuki*; Toda, Hiroyuki*

Materials Transactions, 61(10), p.1907 - 1911, 2020/10

no abstracts in English

Journal Articles

Recent progress of a code system DEURACS toward deuteron nuclear data evaluation

Nakayama, Shinsuke; Iwamoto, Osamu; Watanabe, Yukinobu*

EPJ Web of Conferences, 239, p.03014_1 - 03014_4, 2020/09

Intensive neutron sources using deuteron accelerators have been proposed for various applications such as irradiation test for fusion reactor materials and production of radioisotopes for medical use. In addition, transmutation system using deuteron-induced spallation reactions has been recently proposed for LLFPs. Accurate and comprehensive deuteron nuclear data are indispensable in the design study of such facilities. Under the above situations, we have been developing a code system dedicated for deuteron-induced reactions, which is called DEURACS. In the present work, calculations using DEURACS are compared with available experimental data up to 200 MeV such as DDXs for emission of neutron or light charged particles. We also analyze isotopic production cross sections of residual nuclei. Validation of the present modelling in DEURACS is discussed through comparison with the experimental data.

Journal Articles

Measurement of cesium isotopic ratio by thermal ionization mass spectrometry for neutron capture reaction studies on $$^{135}$$Cs

Shibahara, Yuji*; Nakamura, Shoji; Uehara, Akihiro*; Fujii, Toshiyuki*; Fukutani, Satoshi*; Kimura, Atsushi; Iwamoto, Osamu

Journal of Radioanalytical and Nuclear Chemistry, 325(1), p.155 - 165, 2020/07

 Times Cited Count:0 Percentile:100(Chemistry, Analytical)

The measurements of isotopic ratios of Cs samples by thermal ionization mass spectrometry were performed for the analysis of their samples used to evaluate nuclear data obtained for $$^{135}$$Cs. To obtain a high intensity and stable ion beam, the effects of additive agents on the ionization of Cs were examined. The effect of silicotungstic acid on the ionization of Cs was the largest among the additive agents studied in the present study, while the silicotungstic acid also showed the largest isobaric interference of polyatomic ions. It was demonstrated that as small as 2$$times$$10$$^{-13}$$ g of a Cs sample was sufficient to achieve the analytical precision required to measure the $$^{135}$$Cs/$$^{137}$$Cs ratio in the case where an additive agent of TaO/glucose was employed. After examining of the analytical conditions, such as the interference effect due to Ba, the measurements of the isotopic ratios of two Cs samples used in our study using TIMS were conducted, and it was discussed how much the ratios contributed to evaluation of the neutron capture cross-section of $$^{135}$$Cs.

Journal Articles

Measurements of thermal-neutron capture cross-section of cesium-135 by applying mass spectrometry

Nakamura, Shoji; Shibahara, Yuji*; Kimura, Atsushi; Iwamoto, Osamu; Uehara, Akihiro*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 57(4), p.388 - 400, 2020/04

 Times Cited Count:1 Percentile:100(Nuclear Science & Technology)

The thermal-neutron capture cross-section ($$sigma_{0}$$) and resonance integral(I$$_{0}$$) were measured for the $$^{135}$$Cs(n,$$gamma$$)$$^{136}$$Cs reaction by an activation method and mass spectrometry. We used $$^{135}$$Cs contained as an impurity in a normally available $$^{137}$$Cs standard solution. An isotope ratio of $$^{135}$$Cs and $$^{137}$$Cs in a standard $$^{137}$$Cs solution was measured by mass spectrometry to quantify $$^{135}$$Cs. The analyzed $$^{137}$$Cs samples were irradiated at the hydraulic conveyer of the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as neutron monitors to measure thermal-neutron fluxes and epi-thermal Westcott's indices at an irradiation position. A gadolinium filter was used to measure the $$sigma_{0}$$, and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of $$^{137}$$Cs, $$^{136}$$Cs and monitor wires. On the basis of Westcott's convention, the $$sigma_{0}$$ and I$$_{0}$$ values were derived as 8.57$$pm$$0.25 barn, and 45.3$$pm$$3.2 barn, respectively. The $$sigma_{0}$$ obtained in the present study agreed within the limits of uncertainties with the past reported value of 8.3$$pm$$0.3 barn.

Journal Articles

Hydrogen-accelerated spontaneous microcracking in high-strength aluminium alloys

Tsuru, Tomohito; Shimizu, Kazuyuki*; Yamaguchi, Masatake; Itakura, Mitsuhiro; Ebihara, Kenichi; Bendo, A.*; Matsuda, Kenji*; Toda, Hiroyuki*

Scientific Reports (Internet), 10, p.1998_1 - 1998_8, 2020/04

 Times Cited Count:1

Age-hardening has been one and only process to achieve high strength aluminum alloys since unlike iron and titanium, pure aluminum does not have other solid phases during heat treatment. Highly-concentrated precipitations play therefore dominant role in mechanical properties and hydrogen embrittlement of aluminium alloys. It has been considered that the coherent interface between matrix and precipitation does not contribute to the crack initiation and embrittlement due to its coherency. Here, we discovered the origin of unprecedented quasi-cleavage fracture mode. Hydrogen partitioning at various defect sites is investigated comprehensively combined with experiment, theory and first-principles calculations. We demonstrate that despite low excess free volume, the aluminum-precipitation interface is more preferable trap site than void and grain boundary. The cohesivity of the interface deteriorates significantly with increasing occupancy while hydrogen atoms are trapped stably up to extremely high occupancy equivalent to spontaneous cleavage.

Journal Articles

JENDL/ImPACT-2018; A New nuclear data library for innovative studies on transmutation of long-lived fission products

Kunieda, Satoshi; Furutachi, Naoya; Minato, Futoshi; Iwamoto, Nobuyuki; Iwamoto, Osamu; Nakayama, Shinsuke; Ebata, Shuichiro*; Yoshida, Toru*; Nishihara, Kenji; Watanabe, Yukinobu*; et al.

Journal of Nuclear Science and Technology, 56(12), p.1073 - 1091, 2019/12

 Times Cited Count:1 Percentile:53.3(Nuclear Science & Technology)

A new nuclear data library, JENDL/ImPACT-2018, is developed for an innovative study on the transmutation of long-lived fission products. Nuclear reaction cross- sections are newly evaluated for incident neutrons and protons up to 200 MeV for 163 nuclides including long-lived nuclei such as $$^{79}$$Se, $$^{93}$$Zr, $$^{107}$$Pd and $$^{135}$$Cs. Our challenge is an evaluation of cross-sections for a number of unstable nuclei over a wide energy range where the experimental data are very scarce. We estimated cross- sections based on a nuclear model code CCONE that incorporates an advanced knowledge on the nuclear structure theory and a model-parameterization based on a new experimental cross-sections measured by the inverse kinematics. Through comparisons with available experimental data on the stable isotopes, it is found that the present data give predictions of cross-sections better than those in the existing libraries.

Journal Articles

An Unreported precipitate orientation relationship in Al-Zn-Mg based alloys

Bendo, A.*; Matsuda, Kenji*; Lervik, A.*; Tsuru, Tomohito; Nishimura, Katsuhiko*; Nunomura, Norio*; Holmestad, R.*; Marioara, C. D.*; Shimizu, Kazuyuki*; Toda, Hiroyuki*; et al.

Materials Characterization, 158, p.109958_1 - 109958_7, 2019/12

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

Characterization of precipitates in Al-Zn-Mg alloys, using a combination of electron diffraction, bright field transmission electron microscopy and atomic scale scanning transmission electron microscopy imaging revealed the presence of an unreported $$eta$$$$_{13}$$ orientation relationship between the $$eta$$-MgZn$$_2$$ phase and the Al lattice with the following orientation relationship (0001)$$eta$$ $$||$$ (120)$$_{rm Al}$$ and ($$2bar{1}bar{1}0$$)$$eta$$ $$||$$ (001)$$_{rm Al}$$, plate on (120)$$_{rm Al}$$. The precipitate interfaces were observed and analyzed along two projections 90$$^{circ}$$ to one-another. The precipitate coarsening was through the common thickening ledge mechanism. The ledges were significantly stepped along one lateral direction. An interface relaxation model using density functional theory was carried out to explain the precipitate behavior.

Journal Articles

Activation measurement for thermal-neutron capture cross-section of Cesium-135

Nakamura, Shoji; Kimura, Atsushi; Iwamoto, Osamu; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*

KURNS Progress Report 2018, P. 106, 2019/08

Under the ImPACT project, the neutron capture cross-section measurements of Cesium-135 ($$^{135}$$Cs) among the long-lived fission products have been performed at Kyoto University. This paper reports measurements of the thermal-neutron capture cross-section of $$^{135}$$Cs at the Kyoto University Research Reactor (KUR).

Journal Articles

Contribution of membrane technology to hydrogen society; Development of membrane IS process

Inagaki, Yoshiyuki; Sakaba, Nariaki; Tanaka, Nobuyuki; Nomura, Mikihiro*; Sawada, Shinichi*; Yamaki, Tetsuya*

Nippon Kaisui Gakkai-Shi, 73(4), p.194 - 202, 2019/08

The thermochemical IS process is a promising hydrogen production method which can produce hydrogen in a large amount and stably with high efficiency by thermal splitting of water. Research and development on chemical reaction technology with membranes was conducted for the purpose of improving the efficiency of IS process and application of solar heat. The basic technology of ceramic membranes applied to decomposition reactions of hydrogen iodine and sulfuric acid was developed, and it is expected that the conversion rate on decomposition in each reaction can be remarkably improved. The basic technology of a cation exchange membrane applied to Bunsen reaction was developed with radiation-induced grafting technique, it is expected that the amount of iodine can be reduced to about one-fifth compared to the conventional method. These achievements are important technologies for practical use of the IS process.

Journal Articles

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.

Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07

 Times Cited Count:4 Percentile:28.2(Physics, Multidisciplinary)

Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for $$^{107}$$Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.

Journal Articles

Impact of irradiation side on neutron-induced single-event upsets in 65-nm Bulk SRAMs

Abe, Shinichiro; Liao, W.*; Manabe, Seiya*; Sato, Tatsuhiko; Hashimoto, Masanori*; Watanabe, Yukinobu*

IEEE Transactions on Nuclear Science, 66(7, Part2), p.1374 - 1380, 2019/07

 Times Cited Count:1 Percentile:53.3(Engineering, Electrical & Electronic)

Single event upsets (SEUs) caused by secondary cosmic-ray neutrons have recognized as a serious reliability problem for microelectronic devices. Acceleration tests at neutron facilities are convenient to validate soft error rates (SERs) quickly, but some corrections caused from measurement conditions are required to derive realistic SERs at actual environment or to compare other measured data. In this study, the effect of irradiation side on neutron-induced SEU cross sections was investigated by performing neutron transport simulation using PHITS. SERs for 65-nm bulk CMOS SRAMs are estimated using the sensitive volume model. It was found from simulation that SERs for the sealant side irradiation are 30-50% larger than those for the board side irradiation. This difference comes from the difference of production yield and angular distribution of secondary H and He ions, which are the main cause of SEUs. Thus the direction of neutron irradiation should be reported when the result of acceleration tests are published. This result also indicates that SERs can be reduced by equipping device with sealant side facing downward.

Journal Articles

Research and development on membrane IS process for hydrogen production using solar heat

Myagmarjav, O.; Iwatsuki, Jin; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ioka, Ikuo; Kubo, Shinji; Nomura, Mikihiro*; Yamaki, Tetsuya*; Sawada, Shinichi*; et al.

International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07

 Times Cited Count:6 Percentile:26.46(Chemistry, Physical)

Journal Articles

Characterisation of structural similarities of precipitates in Mg-Zn and Al-Zn-Mg alloys systems

Bendo, A.*; Maeda, Tomoyoshi*; Matsuda, Kenji*; Lervik, A.*; Holmestad, R.*; Marioara, C. D.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Toda, Hiroyuki*; Yamaguchi, Masatake; et al.

Philosophical Magazine, 99(21), p.2619 - 2635, 2019/07

 Times Cited Count:6 Percentile:15.42(Materials Science, Multidisciplinary)

Journal Articles

Spin Seebeck mechanical force

Harii, Kazuya; Seo, Y.-J.*; Tsutsumi, Yasumasa*; Chudo, Hiroyuki; Oyanagi, Koichi*; Matsuo, Mamoru; Shiomi, Yuki*; Ono, Takahito*; Maekawa, Sadamichi; Saito, Eiji

Nature Communications (Internet), 10(1), p.2616_1 - 2616_5, 2019/06

 Times Cited Count:8 Percentile:11.64(Multidisciplinary Sciences)

Journal Articles

Development of hydrogen production technology by thermal water splitting with solar heat

Inagaki, Yoshiyuki; Sakaba, Nariaki

Shokubai, 61(2), p.92 - 96, 2019/04

The outline of the membrane IS process to produce hydrogen by thermochemical water splitting using solar heat at around 650$$^{circ}$$C is described. The membrane technology has been applied to the three main reaction of the IS process to lower the reaction temperature and reduce the amount of circulation materials in the process. The key component technologies such as catalysts, membranes and corrosion resistant materials have been developed. The study was supported in part by the Council for Science, Technology and Innovation, Cross-ministerial Strategic Innovation Promotion Program, "Energy Carrier".

Journal Articles

Magnetomechanical sensing based on delta-E effect in Y$$_3$$Fe$$_5$$O$$_{12}$$ micro bridge

Arisawa, Hiroki*; Daimon, Shunsuke*; Oikawa, Yasuyuki*; Seo, Y.-J.*; Harii, Kazuya; Oyanagi, Koichi*; Saito, Eiji

Applied Physics Letters, 114(12), p.122402_1 - 122402_5, 2019/03

 Times Cited Count:2 Percentile:50.59(Physics, Applied)

Journal Articles

Measurements of neutron capture reaction cross-sections at ANNRI of MLF in J-PARC

Iwamoto, Osamu

ImPACT Fujita Puroguramu Kokai Seika Hokokukai "Kaku Henkan Niyoru Koreberu Hoshasei Haikibutsu No Ohaba Na Teigen, Shigenka" Seika Hokokusho, Shiryoshu, p.78 - 81, 2019/03

Measurements of Neutron Capture Reaction Cross-Sections at ANNRI of MLF in J-PARC have been conducted as a part of the ImPACT Fujita Program titled "Reduction and Resource Recycling of High-level Radioactive Wastes through Nuclear Transmutation". A resonance cross section of the neutron capture reaction with Cs-135 was measured. In addition, a thermal cross section and a resonance integral have been deduced by an activation experiment at KUR. Summary of this study will be reported.

Journal Articles

Development of the standard evaluated database of nuclear reactions for long lived fission products

Iwamoto, Osamu

ImPACT Fujita Puroguramu Kokai Seika Hokokukai "Kaku Henkan Niyoru Koreberu Hoshasei Haikibutsu No Ohaba Na Teigen, Shigenka" Seika Hokokusho, Shiryoshu, p.102 - 105, 2019/03

Study on the development of the standard evaluated database of nuclear reactions for long lived fission products has been conducted as a part of the ImPACT Fujita Program titled "Reduction and Resource Recycling of High-level Radioactive Wastes through Nuclear Transmutation". The database of the neutron and proton induced reactions on LLFPs and their neighbor nuclei has been developed taking account of the up-to-date theoretical and experimental knowledges. In addition, the update of the calculation methods of deuteron induced reactions has also conducted. Summary of this study will be reported.

Journal Articles

Disposal and recycling; Safer disposal and reassuring recycling

Nishihara, Kenji

ImPACT Fujita Puroguramu Kokai Seika Hokokukai "Kaku Henkan Niyoru Koreberu Hoshasei Haikibutsu No Ohaba Na Teigen, Shigenka" Seika Hokokusho, Shiryoshu, p.28 - 31, 2019/03

In this project, long-lived fission products (LLFP) contained in conventional high-level radioactive wastes are separated and their life is reduced, and elements that can be used as resources are separated. By shortening the life of LLFP, it has been shown that it may be possible to dispose in intermediate depth of several tens of meters, meeting safety requirements, instead of geological disposal. In addition, for reassuring recycling of usable elements, possible exposure pathways were evaluated to estimate the safe concentration level of radioactivity.

Journal Articles

Investigation of system for volume-reduction and recycling of HLW

Nishihara, Kenji

ImPACT Fujita Puroguramu Kokai Seika Hokokukai "Kaku Henkan Niyoru Koreberu Hoshasei Haikibutsu No Ohaba Na Teigen, Shigenka" Seika Hokokusho, Shiryoshu, p.130 - 133, 2019/03

High level radioactive waste contains elements with various characteristics. It is possible to reduce the load on the disposal site by separating them according to those characteristics and appropriately dealing with them. In this project, we are working to shorten the life span of long-lived fission products (LLFP). When this technology is realized, high-level radioactive wastes will become new radioactive wastes with low radioactivity. As a result of investigation of disposal concept of new radioactive waste, it turned out that intermediate-depth disposal currently considered for low level radioactive waste may be suitable. Intermediate-depth disposal is a method of small-scale disposal in shallow locations as compared to geological disposal for conventional high-level radioactive waste. We conducted a safety assessment when this disposal is applied to new radioactive wastes, and found that it is possible to safely dispose of for the four LLFPs addressed by this project.

714 (Records 1-20 displayed on this page)