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Yamaguchi, Masatake; Ebihara, Kenichi; Tsuru, Tomohito; Itakura, Mitsuhiro
Materials Transactions, 64(11), p.2553 - 2559, 2023/11
Times Cited Count：1 Percentile：0(Materials Science, Multidisciplinary)We attempted to calculate the hydrogen trapping energies on the incoherent interfaces of MgZn
precipitates and MgSi crystallites in aluminum alloys from first-principles calculations. Since the unit cell containing the incoherent interface does not satisfy the periodic boundary condition, resulting in a discontinuity of crystal blocks, the hydrogen trapping energy was calculated in a region far from the discontinuity (vacuum) region. We found considerable trapping energies for hydrogen atoms at the incoherent interfaces consisting of assumed atomistic arrangement. We also conducted preliminary calculations of the reduction in the cohesive energy by hydrogen trapping on the incoherent interfaces of MgSi in the aluminum matrix.
Shimizu, Kazuyuki*; Toda, Hiroyuki*; Fujihara, Hiro*; Yamaguchi, Masatake; Uesugi, Masayuki*; Takeuchi, Akihisa*; Nishijima, Masahiko*; Kamada, Yasuhiro*
Corrosion, 79(8), p.818 - 830, 2023/08
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)7xxx aluminum alloys are representative high-strength aluminum alloys; however, mechanical property degradation due to hydrogen hinders further strengthening. We propose the dispersion of Mn-based second-phase particles as a novel technique for preventing 7xxx aluminum alloy hydrogen embrittlement. In this study, the deformation and fracture behaviors of high hydrogen 7xxx alloys containing 0.0% Mn and 0.6% Mn are observed in situ using synchrotron radiation X-ray tomography. The obtained macroscopic hydrogen embrittlement is quantitatively analyzed based on hydrogen partitioning in alloys. Adding 0.6% Mn, generating second-phase particles with high hydrogen trapping abilities, significantly suppresses hydrogen-induced quasicleavage fracture.
Abe, Shinichiro; Hashimoto, Masanori*; Liao, W.*; Kato, Takashi*; Asai, Hiroaki*; Shimbo, Kenichi*; Matsuyama, Hideya*; Sato, Tatsuhiko; Kobayashi, Kazutoshi*; Watanabe, Yukinobu*
IEEE Transactions on Nuclear Science, 70(8, Part 1), p.1652 - 1657, 2023/08
Times Cited Count：0 Percentile：0.01(Engineering, Electrical & Electronic)Single event upsets (SEUs) caused by neutrons is a reliability problem for microelectronic devices in the terrestrial environment. Acceleration tests using white neutron beam provide realistic soft error rates (SERs), but only a few facilities can provide white neutron beam in the world. If single-source irradiation applicable to diverse neutron source can be utilized for the evaluation of the SER in the terrestrial environment, it contributes to solve the shortage of beam time. In this study, we investigated the feasibility of the SER estimation in the terrestrial environment by any one of these measured data with the SEU cross sections obtained by PHITS simulation. It was found that the SERs estimated by our proposed method are within a factor of 2.7 of that estimated by the Weibull function. We also investigated the effect of simplification which reduce the computational cost in simulation to the SER estimation.
Nakayama, Shinsuke; Furutachi, Naoya; Iwamoto, Osamu; Watanabe, Yukinobu*
NEA/NSC/R(2020)4 (Internet), p.345 - 349, 2022/10
Long-lived fission products (LLFPs) generated in nuclear reactors are strongly desired to be converted to stable or short-lived nuclides. Recently, it has been considered to transmute LLFPs by spallation reactions with high energy particles, and some experimental studies revealed that spallation reaction cross-sections induced by deuteron are larger than proton-induced ones. These results suggest the possibility that nuclear transmutation of LLFPs using deuteron beams is more efficient than one using proton beams. On the other hand, we have been developing a code system dedicated for deuteron-induced reactions, called DEURACS. DEURACS has been originally developed to contribute to the design of deuteron accelerator neutron sources. In the present study, we apply DEURACS to calculation of deuteron-induced spallation reactions on LLFPs. Through comparison with measured data, the applicability of DEURACS will be discussed.
Kunieda, Satoshi; Furutachi, Naoya*; Minato, Futoshi; Iwamoto, Nobuyuki; Iwamoto, Osamu
NEA/NSC/R(2020)4 (Internet), p.329 - 331, 2022/10
A new nuclear data library, ImPACT/LLFP-2018, is developed for an innovative study on the transmutation of long-lived fission products. In this work, we estimated cross-sections based on a nuclear model code CCONE, reflecting new knowledge on the nuclear structure theory and cross-section measurement. For instance, we used microscopic nuclear model to improve a phenomenological level density model. The pre-equilibrium model parameters are also optimized based on new experimental data of RIKEN/RIBF. Present library stores neutron and proton-induced cross-sections up to 200 MeV for 160 stable/unstable nuclei covering the long-lived fission products such as 
Se, 
Zr, 
Pd and 
Cs. Through a comparison with available experimental data on the stable isotopes, it is found that the present data gives predictions of cross-sections better than those from JENDL-4.0/HE, TENDL-2017 and the INCL model.
Yamaguchi, Masatake; Itakura, Mitsuhiro; Tsuru, Tomohito; Ebihara, Kenichi
Materials Transactions, 62(5), p.582 - 589, 2021/05
Times Cited Count：13 Percentile：73.14(Materials Science, Multidisciplinary)no abstracts in English
Si and Al
FeCu intermetallic compounds in aluminum alloy; First-principles calculationsYamaguchi, Masatake; Tsuru, Tomohito; Ebihara, Kenichi; Itakura, Mitsuhiro; Matsuda, Kenji*; Shimizu, Kazuyuki*; Toda, Hiroyuki*
Materials Transactions, 61(10), p.1907 - 1911, 2020/10
Times Cited Count：11 Percentile：55.63(Materials Science, Multidisciplinary)no abstracts in English
Kanamura, Shohei*; Takahashi, Yuya*; Omori, Takashi*; Nohira, Toshiyuki*; Sakamura, Yoshiharu*; Matsumura, Tatsuro
Denki Kagaku, 88(3), p.289 - 290, 2020/09
no abstracts in English
Nakayama, Shinsuke; Iwamoto, Osamu; Watanabe, Yukinobu*
EPJ Web of Conferences, 239, p.03014_1 - 03014_4, 2020/09
Times Cited Count：2 Percentile：86.93(Nuclear Science & Technology)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.
CsShibahara, 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：8 Percentile：71.58(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 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
10
g of a Cs sample was sufficient to achieve the analytical precision required to measure the Cs/
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 Cs.
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：3 Percentile：31.89(Nuclear Science & Technology)The thermal-neutron capture cross-section (
) and resonance integral(I
) were measured for the Cs(n,
)
Cs reaction by an activation method and mass spectrometry. We used Cs contained as an impurity in a normally available Cs standard solution. An isotope ratio of Cs and Cs in a standard Cs solution was measured by mass spectrometry to quantify Cs. The analyzed 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 , and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of Cs, Cs and monitor wires. On the basis of Westcott's convention, the and I values were derived as 8.57
0.25 barn, and 45.33.2 barn, respectively. The obtained in the present study agreed within the limits of uncertainties with the past reported value of 8.30.3 barn.
Abe, Shinichiro; Sato, Tatsuhiko; Kuroda, Junya*; Manabe, Seiya*; Watanabe, Yukinobu*; Liao, W.*; Ito, Kojiro*; Hashimoto, Masanori*; Harada, Masahide; Oikawa, Kenichi; et al.
Proceedings of IEEE International Reliability Physics Symposium (IRPS 2020) (Internet), 6 Pages, 2020/04
Times Cited Count：2 Percentile：64.23(Engineering, Electrical & Electronic)Single event upsets (SEUs) caused by neutrons have been recognized as a serious reliability problem for microelectronic devices on the ground level. In our previous work, it was found that hydride placed in front of the memory chip has considerably impact on SEU cross sections because H ions generated via elastic scattering of neutrons with hydrogen atoms are only emitted in a forward direction. In this study, the effect of components neighboring transistors on neutron-induced SEUs was investigated for 65-nm bulk SRAMs by using PHITS. It was found that the shape of the SEU cross section around few MeV comes from the thickness and the position of components placed in front of transistors when that components do not contains hydrogen atoms. By considering components adjoin memory cells in the test board used in the simulation, measured data at J-PARC BL10 were reproduced well. In addition, it was found that the effect of components neighboring transistors on neutron-induced SERs does not negligible in terrestrial environment.
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：31 Percentile：82.42(Multidisciplinary Sciences)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.
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：8 Percentile：66.68(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 Se, Zr, Pd and 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.
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：19 Percentile：78.27(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 
orientation relationship between the -MgZn phase and the Al lattice with the following orientation relationship (0001) 
(120)
and (
) (001), plate on (120). The precipitate interfaces were observed and analyzed along two projections 90
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.
Morita, Keisuke; Suzuki, Hideya; Matsumura, Tatsuro; Takahashi, Yuya*; Omori, Takashi*; Kaneko, Masaaki*; Asano, Kazuhito*
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.464 - 468, 2019/09
High level liquid waste (HLLW) contains several radionuclides with half-lives longer than 10
year. For reduce environmental burden of waste disposal, minor actinoids and long-lived fission products will to be partitioned and transmuted. JAEA and Toshiba developed process for recovering Se, Zr, Pd and Cs from HLLW. Solvent extraction for Zr with novel extractant, 
-didodecyl-2-hydroxyacetoamide (HAA) was detailed. The HAA system showed high selectivity for Zr, as indicated by the extraction order of Zr 
Mo Pd Ag 
Sb Sn Lns Fe. The extracted species was determined as Zr(HAA)
(NO)
(HNO)
. A continuous countercurrent extraction with HAA was applied to a simulated, concentrated HLLW after Pd, Se, and Cs removal, where the quantitative extraction of Zr and Mo was effectively demonstrated.
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 (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 Cs at the Kyoto University Research Reactor (KUR).
Matsuda, Kenji*; Yasumoto, Toru*; Bendo, A.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Marioara, C. D.*; Lervik, A.*; Holmestad, R.*; et al.
Materials Transactions, 60(8), p.1688 - 1696, 2019/08
Times Cited Count：14 Percentile：63.04(Materials Science, Multidisciplinary)no abstracts in English
Inagaki, Yoshiyuki; Sakaba, Nariaki; Tanaka, Nobuyuki; Nomura, Mikihiro*; Sawada, Shinichi*; Yamaki, Tetsuya*
Nihon 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.
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：8 Percentile：56.2(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 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.
