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Yoshida, Go*; Matsumura, Hiroshi*; Nakamura, Hajime*; Miura, Taichi*; Toyoda, Akihiro*; Masumoto, Kazuyoshi*; Nakabayashi, Takayuki*; Matsuda, Makoto
Journal of Nuclear Science and Technology, 61(10), p.1298 - 1307, 2024/10
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Watanabe, Miku*; Miyamoto, Goro*; Zhang, Y.*; Morooka, Satoshi; Harjo, S.; Kobayashi, Yasuhiro*; Furuhara, Tadashi*
ISIJ International, 64(9), p.1464 - 1476, 2024/07
Times Cited Count:1Li, L.*; Miyamoto, Goro*; Zhang, Y.*; Li, M.*; Morooka, Satoshi; Oikawa, Katsunari*; Tomota, Yo*; Furuhara, Tadashi*
Journal of Materials Science & Technology, 184, p.221 - 234, 2024/06
Times Cited Count:2 Percentile:33.88(Materials Science, Multidisciplinary)Nakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Hirota, Katsuya*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.L041602_1 - L041602_4, 2024/04
Times Cited Count:0 Percentile:0.00(Physics, Nuclear)Okudaira, Takuya*; Nakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.044606_1 - 044606_9, 2024/04
Times Cited Count:0 Percentile:0.00(Physics, Nuclear)Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 8 Pages, 2024/00
Fukuda, Kodai; Obara, Toru*; Suyama, Kenya
Nuclear Technology, 11 Pages, 2024/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 60(11), p.1361 - 1371, 2023/11
Times Cited Count:2 Percentile:57.39(Nuclear Science & Technology)The thermal-neutron capture cross section () and resonance integral (I
) for
Nb among nuclides for decommissioning were measured by an activation method and the half-life of
Nb by mass analysis. Niobium-93 samples were irradiated with a hydraulic conveyer installed in the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Gold-aluminum, cobalt-aluminum alloy wires were used to monitor thermal-neutron fluxes and epi-thermal Westcott's indexes at an irradiation position. A 25-
m-thick gadolinium foil was used to sort out reactions ascribe to thermal-and epi-thermal neutrons. Its thickness provided a cut-off energy of 0.133 eV. In order to attenuate radioactivity of
Ta due to impurities, the Nb samples were cooled for nearly 2 years. The induced radio activity in the monitors and Nb samples were measured by
-ray spectroscopy. In analysis based on Westcott's convention, the
and I
values were derived as 1.11
0.04 barn and 10.5
0.6 barn, respectively. After the
-ray measurements, mass analysis was applied to the Nb sample to obtain the reaction rate. By combining data obtained by both
-ray spectroscopy and mass analysis, the half-life of
Nb was derived as (2.00
0.15)
10
years.
Okita, Shoichiro; Goto, Minoru
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 10 Pages, 2023/10
Wu, P.*; Murai, Naoki; Li, T.*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Kofu, Maiko; Nakajima, Kenji; Xia, K.*; Peng, K.*; Zhang, Y.*; et al.
New Journal of Physics (Internet), 25(1), p.013032_1 - 013032_11, 2023/01
Times Cited Count:0 Percentile:0.00(Physics, Multidisciplinary)Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 59(11), p.1388 - 1398, 2022/11
Times Cited Count:1 Percentile:17.57(Nuclear Science & Technology)The present study selected Np among radioactive nuclides and aimed to measure the thermal-neutron capture cross-section for
Np in a well-thermalized neutron field by an activation method. A
Np standard solution was used for irradiation samples. A thermal-neutron flux at an irradiation position was measured with neutron flux monitors:
Sc,
Co,
Mo,
Ta and
Au. The
Np sample and flux monitors were irradiated together for 30 minutes in the graphite thermal column equipped with the Kyoto University Research Reactor. The similar irradiation was carried out twice. After the irradiations, the
Np samples were quantified using 312-keV gamma ray emitted from
Pa in a radiation equilibrium with
Np. The reaction rates of
Np were obtained from gamma-ray peak net counts given by
Np, and then the thermal-neutron capture cross-section of
Np was found to be 173.8
4.4 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within the limit of uncertainty.
Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2021, P. 93, 2022/07
In terms of nuclear transmutation studies of minor actinides in nuclear wastes, the present work selected Np among them and aimed to measure the thermal-neutron capture cross-section of
Np using a well-thermalized neutron field by a neutron activation method because there have been discrepancies among reported cross-section data. A
Np standard solution was used for irradiation samples. The thermal-neutron flux at an irradiation position was measured with flux monitors:
Sc,
Co,
Mo,
Ta and
Au. The
Np sample was irradiated together with the flux monitors for 30 minutes in the graphite thermal column equipped in the Kyoto University Research Reactor. The similar irradiation was repeated once more to confirm the reproducibility of the results. After irradiation, the
Np samples were quantified using 312-keV gamma-ray emitted from
Pa in radiation equilibrium with
Np. The reaction rates of
Np were obtained from the peak net counts of gamma-rays emitted from generated
Np, and then the thermal-neutron capture cross-section of
Np was found to be 173.8
4.7 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within a limit of uncertainty.
Hashimoto, Shunsuke*; Nakajima, Kenji; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Shibata, Kaoru; Yamada, Takeshi*
Journal of Molecular Liquids, 342, p.117580_1 - 117580_8, 2021/11
Times Cited Count:3 Percentile:18.93(Chemistry, Physical)Quasi-elastic neutron scattering (QENS) and pulsed-field-gradient nuclear magnetic resonance (PFGNMR) analyses of a nanofluid composed of silicon dioxide (SiO) nanoparticles and a base fluid of ethylene glycol aqueous solution were performed. The aim was to elucidate the mechanism increase in the thermal conductivity of the nanofluid above its theoretical value. The obtained experimental results indicate that SiO
particles may decrease the self-diffusion coefficient of the liquid molecules in the ethylene glycol aqueous solution because of their highly restricted motion around these nanoparticles. At a constant temperature, the thermal conductivity increases as the self-diffusion coefficient of the liquid molecules decreases in the SiO
nanofluids.
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 58(10), p.1061 - 1070, 2021/10
Times Cited Count:8 Percentile:71.07(Nuclear Science & Technology)In a well-thermalized neutron field, it is principally possible to drive a thermal-neutron capture cross-section without considering an epithermal neutron component. This was demonstrated by a neutron activation method using the graphite thermal column (TC-Pn) of the Kyoto University Research Reactor. First, in order to confirm that the graphite thermal column was a well-thermalized neutron field, neutron irradiation was performed with neutron flux monitors: Au,
Co,
Sc,
Cu, and
Mo. The TC-Pn was confirmed to be extremely thermalized on the basis of Westcott's convention, because the thermal-neutron flux component took a constant value regardless of the sensitivity of each flux monitor to epithermal neutrons. Next, as a demonstration, the thermal-neutron capture cross section of
Ta(n,
)
Ta reaction was measured using the graphite thermal column, and then derived to be 20.5
0.4 barn, which supported the evaluated value of 20.4
0.3 barn. The
Ta nuclide could be useful as a flux monitor that complements the sensitivity between
Au and
Mo monitors.
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 58(3), p.259 - 277, 2021/03
Times Cited Count:5 Percentile:45.87(Nuclear Science & Technology)Research and development were made for accuracy improvement of neutron capture cross section data on Am among minor actinides. First, the emission probabilities of decay
rays were obtained with high accuracy, and the amount of the ground state of
Am produced by reactor neutron irradiation of
Am was examined by
-ray measurement. Next, the total amount of isomer and ground states was examined by
-ray measurement. Thermal-neutron capture cross sections and resonance integrals were derived both for the
Am(n,
)
Am and for
Am(n,
)
Am reactions.
Okita, Shoichiro; Tasaki, Seiji*; Abe, Yutaka*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 19(3), p.178 - 184, 2020/09
The Kyoto University Accelerator-based Neutron Source (KUANS) is a compact neutron source that is mainly used for spectrometer and detector development. In addition, it is also suited for experiments to study the neutronic design of moderators owing to the relatively low neutron generation yield by Be(p,n). We present a neutronic design of the neutron moderator on a reentrant-hole configuration for KUANS to enhance the neutron emission, and some experiments are conducted at KUANS for verification. A polyethylene moderator on a reentrant-hole configuration is designed by PHITS calculation and is introduced to KUANS to obtain intense oblong neutron beams. The intensity of the pulsed neutron beam is experimentally measured. The results reveal that the intensity becomes approximately 1.9 times stronger than that of the conventional rectangular design. In addition, the ratio of its intensity to the conventional intensity increases to approximately threefold as the neutron wavelength increases. It is interesting to note that the longer the neutron wavelength, the more efficiently they are extracted from the inside of the moderator owing to the existence of the reentrant-hole configuration.
Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2019, P. 132, 2020/08
Research and development were made for accuracy improvement of neutron capture cross section data on Am among minor actinides. First, the emission probabilities of decay
rays were obtained with high accuracy, and the amount of the ground state of
Am produced by reactor neutron irradiation of
Am was examinded by
-ray measurement. Next, the total amount of isomer and ground states was examoned by
-ray measurement.
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:10 Percentile:71.82(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:27.62(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 45.3
3.2 barn, respectively. The
obtained in the present study agreed within the limits of uncertainties with the past reported value of 8.3
0.3 barn.
Ichihara, Akira
JAEA-Review 2019-046, 36 Pages, 2020/03
Toward the revision of JENDL-4.0, we conducted a literature survey on how to compute the cross section of thermal neutrons scattered by a liquid. This report summarizes the computational methods for evaluating thermal neutron cross sections with molecular dynamics simulations. The cross section can be expressed with a function called as scattering law. For light and heavy water, the scattering law data instead of the cross sections have been provided in nuclear databases. In this report we review the formulations of the scattering laws. The scattering laws can be derived from both the intermediate scattering function and the space-time correlation function. Features of the derived scattering laws are briefly explained. It is shown that the scattering law data can be evaluated using a molecular dynamics simulation of the liquid that is the target of thermal neutrons.