Yang, J.*; Ren, W.*; Zhao, X.*; Kikuchi, Tatsuya*; Miao, P.*; Nakajima, Kenji; Li, B.*; Zhang, Z.*
Journal of Materials Science and Technology, 99, p.55 - 60, 2022/02
High-entropy alloys are characteristic of extensive atomic occupational disorder on high-symmetric lattices, differing from traditional alloys. Here, we investigate magnetic and thermal transport properties of the prototype face-centered-cubic high-entropy alloy CrMnFeCoNi by combining physical properties measurements and neutron scattering. Direct-current (dc) and alternating-current (ac) magnetizations measurements indicate a mictomagnetic behavior with coexisting antiferromagnetic and ferromagnetic interactions in the entire temperature region and three anomalies are found at about 80, 50, and 20 K, which are related to the paramagnetic to antiferromagnetic transition, the antiferromagnetic to ferromagnetic transition, and the spin freezing, respectively. The electrical and thermal conductivities are significantly reduced compared to Ni and the temperature dependence of lattice thermal conductivity exhibits a glass-like plateau. Inelastic neutron scattering measurements suggest weak anharmonicity so that the thermal transport is expected to be dominated by the defect scattering.
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 58(10), p.1061 - 1070, 2021/10
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 20.50.4 barn, which supported the evaluated value of 20.40.3 barn. The Ta nuclide could be useful as a flux monitor that complements the sensitivity between Au and Mo monitors.
Takamizawa, Hisashi; Nishiyama, Yutaka
Journal of Pressure Vessel Technology, 143(5), p.051502_1 - 051502_8, 2021/10
no abstracts in English
Nakayama, Hiromasa; Satoh, Daiki; Nagai, Haruyasu; Terada, Hiroaki
Journal of Nuclear Science and Technology, 58(9), p.949 - 969, 2021/09
We introduced a detailed dose calculation method considering building shielding effects into LOcal-scale High-resolution atmospheric DIspersion Model using LES (LOHDIM-LES). To estimate quickly and accurately dose distributions considering shielding effects of buildings, we employed the calculation method using dose-response matrices which were evaluated by photon transport simulations with Particle and Heavy-Ion Transport code System (PHITS). Compared to the air dose rate data obtained from monitoring posts in an actual nuclear facility, it was shown that the calculated dose rate is reasonably simulated well. It is concluded that LOHDIM-LES equipped with the calculation method using dose-response matrices can reasonably estimate the air dose rates considering shielding effects of individual buildings and structures.
Pshenichnikov, A.; Kurata, Masaki; Nagae, Yuji
Journal of Nuclear Science and Technology, 58(9), p.1025 - 1037, 2021/09
Okita, Shoichiro; Nagaya, Yasunobu; Fukaya, Yuji
Journal of Nuclear Science and Technology, 58(9), p.992 - 998, 2021/09
Sun, Haomin; Shibamoto, Yasuteru; Hirose, Yoshiyasu; Kukita, Yutaka
Journal of Nuclear Science and Technology, 58(9), p.1048 - 1057, 2021/09
no abstracts in English
Mihara, Takeshi; Udagawa, Yutaka; Sugiyama, Tomoyuki; Amaya, Masaki
Journal of Nuclear Science and Technology, 58(8), p.872 - 885, 2021/08
Li, Y.; Katsumata, Genshichiro*; Masaki, Koichi; Hayashi, Shotaro*; Itabashi, Yu*; Nagai, Masaki*; Suzuki, Masahide*; Kanto, Yasuhiro*
Journal of Pressure Vessel Technology, 143(4), p.041501_1 - 041501_8, 2021/08
Nakayama, Shinsuke; Iwamoto, Osamu; Watanabe, Yukinobu*; Ogata, Kazuyuki*
Journal of Nuclear Science and Technology, 58(7), p.805 - 821, 2021/07
Intensive fast neutron sources using deuteron accelerators have been proposed for various applications. To contribute to the design study of such neutron sources, a deuteron nuclear data library for Li, Be, and C up to 200 MeV, JENDL/DEU-2020 is developed. The evaluation of JENDL/DEU-2020 are performed by employing the code system DEURACS with particular attention to neutron production data. Toward the evaluation of JENDL/DEU-2020, some modifications are made to DEURACS. The validation of the library is performed though simulation with the Monte Carlo transport calculation codes. From the simulation, it is shown that the calculation results based on JENDL/DEU-2020 reproduce the measured neutron production data well in the incident energies up to 200 MeV. The new library is expected to make a large contribution to diverse design studies of deuteron accelerator neutron sources.
Kawase, Shoichiro*; Kimura, Atsushi; Harada, Hideo; Iwamoto, Nobuyuki; Iwamoto, Osamu; Nakamura, Shoji; Segawa, Mariko; Toh, Yosuke
Journal of Nuclear Science and Technology, 58(7), p.764 - 786, 2021/07
Kusaka, Ryoji; Kumagai, Yuta; Yomogida, Takumi; Takano, Masahide; Watanabe, Masayuki; Sasaki, Takayuki*; Akiyama, Daisuke*; Sato, Nobuaki*; Kirishima, Akira*
Journal of Nuclear Science and Technology, 58(6), p.629 - 634, 2021/06
Lu, K.; Katsuyama, Jinya; Masaki, Koichi; Watanabe, Tadashi*; Li, Y.
Journal of Pressure Vessel Technology, 143(3), p.031704_1 - 031704_8, 2021/06
Takei, Hayanori; Tsutsumi, Kazuyoshi*; Meigo, Shinichiro
Journal of Nuclear Science and Technology, 58(5), p.588 - 603, 2021/05
The Japan Atomic Energy Agency (JAEA) has designed a Transmutation Physics Experimental Facility (TEF-P) as an experimental facility in the Japan Proton Accelerator Research Complex (J-PARC). The TEF-P is a critical assembly driven by a low-power proton beam, a maximum of 10 W, which is extracted from a high-power beam source, such as 250 kW of 400 MeV proton beam of the J-PARC Linac. To extract such a low-power proton beam from the high-power proton beam, we developed a laser charge exchange (LCE) device and employed its technique, which is one of the non-contact beam extraction techniques. For the proof of performance of the LCE device to the TEF-P, a low-power proton beam was extracted using a negative-hydrogen (H) Linac having an energy of 3 MeV, and a bright continuous laser. Proton beam with the power of 0.57 mW was successfully extracted with a laser stripping efficiency of . These experimental values are in good agreement with the estimated ones.
Kaneko, Masashi; Sasaki, Yuji; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Journal of Nuclear Science and Technology, 58(5), p.515 - 526, 2021/05
Density-functional theory calculations were applied to molecular structure and complex formation reaction modelings of metal ion complexes with diethylenetriaminepentaacetic acid (DTPA) and its bisamide (DTPABA) chelates to understand the metal ions selectivity between Am and Eu. The calculated complexes with DTPA and DTPABA chelates reproduced the coordination geometries of experimental crystal structures. Calculated Gibbs free energies of the complex formation reactions indicated that Am ion forms higher stable complexes with both chelates than Eu ion, being consistent with the experimental results. The higher Am selectivity over Eu was suggested to originate in the larger bond overlap between Am 5f-orbital and N 2s, 2p-orbital. This mean that the covalent contribution between metal ion and donor atoms differentiates the complex formation stabilities, leading to the Am/Eu selectivity. We expect that this study contributes to systematize the origin of metal ions selectivity and to accelerate novel ligands exploration.
Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Science and Technology, 58(4), p.416 - 425, 2021/04
Onishi, Takashi; Maeda, Koji; Katsuyama, Kozo
Journal of Nuclear Science and Technology, 58(4), p.383 - 398, 2021/04
Tanaka, Sota; Kakinuma, Hotaru*; Adachi, Taro*; Atarashi-Andoh, Mariko; Koarashi, Jun
Journal of Nuclear Science and Technology, 58(4), p.507 - 514, 2021/04
Understanding the pathways of Cs transfer to predatory spiders is useful to assess long-term behavior of Cs in the environment, because spiders obtain food resources from both the grazing and detritus food chains in terrestrial-aquatic linking forest ecosystems. In the present study, we collected spider samples at forest interior and riverside. The sample collection was approximately 6.5 years after the FDNPP accident. Moreover, a transfer factor value (T) for Cs in spiders was quantified. Stable carbon and nitrogen isotope ratios (C and N) of the spiders were also investigated to estimate the transfer pathways of Cs to the spiders.
Sugiyama, Daisuke*; Nakabayashi, Ryo*; Tanaka, Shingo*; Koma, Yoshikazu; Takahatake, Yoko
Journal of Nuclear Science and Technology, 58(4), p.493 - 506, 2021/04
Sudo, Ayako; Sato, Takumi; Ogi, Hiroshi; Takano, Masahide
Journal of Nuclear Science and Technology, 58(4), p.473 - 481, 2021/04
Dissolution behavior of Sr and Ba is crucial for evaluating secondary source terms via coolant water from ex-vessel debris accumulated at Fukushima Daiichi Nuclear Power Plant. To understand the mechanism, knowing the distribution of Sr and Ba in the ex-vessel debris is necessary. As a result of reaction tests between simulated corium and concrete materials, two layered structures were observed in the solidified sample, (A) a silicate glass-based ((Si-Al-Ca-Fe-Zr-Cr-U-Sr-Ba)-O) phase-rich layer in the upper surface region and (B) a (U,Zr)O particle-rich layer at the inner region. Measurable concentrations of Sr and Ba were observed in layer (A) (approximately 1.7 times that in the layer (B)). According to thermodynamic analysis, (U,Zr)O is predicted to solidify, in advance, in the concrete-based melt around 2177 C. Then, the residual melt is solidified as a silicate glass, and Sr and Ba are preferentially dissolved into the silicate glass. During the tests, (U,Zr)O particles sank, in advance, in the melt because of its higher density, and the silicate glass phase relocated to the surface layer. On the other hand, silicate glass containing Sr and Ba is predicted to be hardly soluble in water and chemically stable.