Fukaya, Yuji; Goto, Minoru; Ohashi, Hirofumi
Annals of Nuclear Energy, 138, p.107182_1 - 107182_9, 2020/04
The investigation on self-shielding effect of double heterogeneity for plutonium burner High Temperature Gas-cooled Reactor (HTGR) design has been performed. Plutonium burner HTGR designed in the previous study by using the advantage of double heterogeneity to control excess reactivity. In the present study, the mechanism of the self-shielding effect is elucidated by the analysis of burn-up calculation and reactivity decomposition based on exact perturbation theory. As a result, it is revealed that the characteristics of burn-up reactivity are determined by resonance cross section peak at 1 eV of Pu due to the surface term of background cross section, this is, the characteristics of neutron leakage from fuel lump and collision to a moderator. Moreover, significant spectrum shift is caused during the burn-up period, and it enhances reactivity worth of Pu and Pu in EOL.
Gorlachev, I.*; Kharkin, P.*; Dyussembayeva, M.*; Lukashenko, S.*; Gluchshenko, G.*; Matiyenko, L.*; Zheltov, D.*; Kitamura, Akihiro; Khlebnikov, N.*
Journal of Environmental Radioactivity, 213, p.106110_1 - 106110_10, 2020/03
The main goal of the presented research activities is to determine the degree of water contamination of the largest waterway of the STS, the Shagan river, with heavy elements and artificial radionuclides. Such approach made it possible to identify the most significant elements-contaminants typical for the selected object, to determine the most dirty points of the Shagan riverbed, to compare the degree of water contamination with heavy metals and artificial radionuclides, and to calculate the complex indices of water contamination with heavy metals. According to the obtained data, the recommendations can be made for application of Shagan's water for household purpose.
Yamashita, Takayuki; Morooka, Satoshi; Harjo, S.; Kawasaki, Takuro; Koga, Norimitsu*; Umezawa, Osamu*
Scripta Materialia, 177, p.6 - 10, 2020/03
Okada, Yuji; Amaya, Masaki
Annals of Nuclear Energy, 136, p.107028_1 - 107028_9, 2020/02
Endo, Yukihiro*; Fukaya, Yuki; Mochizuki, Izumi*; Takayama, Akari*; Hyodo, Toshio*; Hasegawa, Shuji*
Carbon, 157, p.857 - 862, 2020/02
no abstracts in English
Kumagai, Yuta; Jonsson, M.*
Dalton Transactions (Internet), 49(6), p.1907 - 1914, 2020/02
This study aims to reveal possible involvements of organic acids in the oxidative dissolution of UO. Using phthalic acid as a model compound, we have measured adsorption on UO and investigated effects on the reaction between HO and UO and on oxidative dissolution induced by -irradiation. Significant adsorption of phthalic acid was observed even at neutral pH. However, the reaction between HO and UO in phthalic acid solution induced oxidative dissolution of U(VI) similarly to aqueous bicarbonate solution. These results indicate that even though phthalic acid adsorbs on the UO surface, it is not involved in the interfacial reaction by HO. In contrast, the dissolution of U by irradiation was inhibited in aqueous phthalic acid solution, whereas HO generated by radiolysis was consumed by UO. The inhibition suggests that radical species derived from phthalic acid was involved in the redox reaction process of UO.
Minato, Futoshi; Tanimura, Yusuke*
European Physical Journal A, 56(2), p.45_1 - 45_18, 2020/02
For nuclei, three-body model of inert core can provide an understanding of pairing correlations in the ground state and spin-isospin excitations. However, residual core-nucleon interactions can impact the core nucleus significantly. The effect of core excitations thus has to be included for the detailed understanding of the ground state and the spin-isospin properties. We solve the three-body problem including core vibrational states to obtain the ground state as well as the spin-excitations. By including the effect of core excitation, (a) magnetic moment, (b) the enegy difference between the first and the excited states, (c) B(M1) and B(GT), are improved. It was also found that the root mean squares of distances between proton and neutron, and the center of mass of valence prton and neutron and core slightly increase.
Francisco, P. C. M.; Mitsui, Seiichiro; Ishidera, Takamitsu; Tachi, Yukio; Doi, Reisuke; Shiwaku, Hideaki
Geochimica et Cosmochimica Acta, 270, p.1 - 20, 2020/02
Sugiyama, Masaaki*; Inoue, Rintaro*; Nakagawa, Hiroshi; Saio, Tomohide*
Hamon, 30(1), p.16 - 25, 2020/02
Neutron has distinct features as a scattering probe to analyze structure and dynamics of biological macromolecules. The theme of this review is to try to describe how we did/do utilize them. And "How we should utilize them more effectively in the trend of integrative structural biology?" with solution scattering.
Hamon, 30(1), p.7 - 8, 2020/02
Safety review of JRR-3 under the New Regulatory Requirements was completed on 7th November 2018. Neutron beam will come back in early 2021 after reinforcement works of the roof of the reactor building, the peripheral structures like a stack, a cooling tower, and the experimental hall. The future of neutron sciences using the research reactor strongly depends on how many impacted researches using JRR-3 are achieved after restarting JRR-3. At this stage, we can learn a lot of things from the back numbers of HAMON.
Metoki, Naoto; Aoki, Dai*; Griveau, J.-C.*; Otsuki, Junya*
Journal of the Physical Society of Japan, 89(2), p.024707_1 - 024707_6, 2020/02
The pseudo triplet ground state in the heavy-fermion superconductor NpPdAl was concluded. The magnetic susceptibility can be reproduced by the singlet ground state with the main component of and the first excited doublet dominated by at ,K. The magnetization curve can be explained from the effective local hamiltonian for pseudo spin =1 with () equivalent to the quadrupole operator . The specific heat can be described with the Kondo model normalized to give the entropy R, corresponding to the pseudo triplet state. The derived Kondo temperature ,K comparable to the level splitting ,K indicates the contribution of the excited doublet to the possible multi-channel Kondo effect.
Nomura, Takuji*; Yamamoto, Yuji*; Yoshii, Kenji
Journal of the Physical Society of Japan, 89(2), p.024704_1 - 024704_10, 2020/02
We report a mean-field theoretical study of a triangular magnet NiGaS. Using the localized Wannier functions obtained from a band calculation, the most stable magnetic state was found to be spiral with the incommensurate structure, consistent with the result from neutron diffraction. The Ni-site Coulomb interaction was not strong (U about 2 eV). The spin value at the Ni site was also not so large about 1.1 mb. These results mean that the hybridization between Ni and S may play an important role. The dynamical spin correlation function was found to in accord with the results from neutron scattering.
Journal of the Physical Society of Japan, 89(2), p.025001_1 - 025001_2, 2020/02
Good correspondence of the and - coupling scheme can be realized in the -electron states of the heavy-fermion superconductor NpPdAl and the isostructural family. The rare-earth and actinide elements are under a common strong uniaxial point charge potential with tetragonal point symmetry . The systematic development of the -electron states can be understood in the coupling scheme of configuration (the number of electrons ). We can find the corresponding states in - coupling scheme with three -orbitals , and determined from CePdAl with configuration.
Nakamura, Shota*; Hyodo, Kazushi*; Matsumoto, Yuji*; Haga, Yoshinori; Sato, Hitoshi*; Ueda, Shigenori*; Mimura, Kojiro*; Saiki, Katsuyoshi*; Iso, Kosei*; Yamashita, Minoru*; et al.
Journal of the Physical Society of Japan, 89(2), p.024705_1 - 024705_5, 2020/02
Kai, Tetsuya; Shinohara, Takenao; Matsumoto, Yoshihiro*
Kensa Gijutsu, 25(2), p.1 - 5, 2020/02
no abstracts in English
Oba, Yojiro; Ito, Daisuke*; Saito, Yasushi*; Onodera, Yohei*; Parker, J. D.*; Shinohara, Takenao; Oikawa, Kenichi
Materials Research Proceedings, Vol.15, p.160 - 164, 2020/02
Lead Bismuth eutectic (LBE) is a promising candidate of the coolant for accelerator driven system (ADS) and fast breeder reactor. Neutron transmission imaging is a powerful technique to investigate the LBE in flow channel. However, previous studies have focused on the analysis of the neutron transmission spectra due to Bragg diffraction (Bragg edge transmission) from the solid phase of the LBE. If the neutron transmission spectra due to the diffraction from a liquid phase can be observed, it is useful to study the behavior of the molten LBE in the flow channel. Therefore, the energy-resolved neutron transmission imaging measurements of the molten LBE was carried out. The observed neutron transmission spectra can be explained by those calculated from the scattering profiles of the molten LBE. This indicates that the structure of the molten LBE can be characterized and mapped using the neutron transmission imaging.
Komatsu, Kazuki*; Machida, Shinichi*; Noritake, Fumiya*; Hattori, Takanori; Sano, Asami; Yamane, Ryo*; Yamashita, Keishiro*; Kagi, Hiroyuki*
Nature Communications (Internet), 11(1), p.464_1 - 464_5, 2020/02
Water freezes below 0C at ambient pressure ordinarily to ice I, with hexagonal stacking sequence. Under certain conditions, ice with a cubic stacking sequence can also be formed, but ideal ice I without stacking-disorder has never been formed until recently. Here we demonstrate a route to obtain ice I without stacking-disorder by degassing hydrogen from the high-pressure form of hydrogen hydrate, C, which has a host framework isostructural with ice I. The stacking-disorder free ice I is formed from C via an intermediate amorphous or nano-crystalline form under decompression, unlike the direct transformations occurring in ice XVI from neon hydrate, or ice XVII from hydrogen hydrate. The obtained ice I shows remarkable thermal stability, until the phase transition to ice I at 250 K, originating from the lack of dislocations. This discovery of ideal ice I will promote understanding of the role of stacking-disorder on the physical properties of ice as a counter end-member of ice I.
Ueta, Shohei; Mizuta, Naoki; Fukaya, Yuji; Goto, Minoru; Tachibana, Yukio; Honda, Masaki*; Saiki, Yohei*; Takahashi, Masashi*; Ohira, Koichi*; Nakano, Masaaki*; et al.
Nuclear Engineering and Design, 357, p.110419_1 - 110419_10, 2020/02
The concept of a plutonium (Pu) burner HTGR is proposed to incarnate highly-effective Pu utilization by its inherent safety features. The security and safety fuel (3S-TRISO fuel) employs the coated fuel particle with a fuel kernel made of plutonium dioxide (PuO) and yttria stabilized zirconia (YSZ) as an inert matrix. This paper presents feasibility study of Pu burner HTGR and R&D on the 3S-TRISO fuel.
Malins, A.; Machida, Masahiko; Vu, T. D.; Aizawa, Kazuya; Ishida, Takekazu*
Nuclear Instruments and Methods in Physics Research A, 953, p.163130_1 - 163130_7, 2020/02
Ota, Masakazu; Terada, Hiroaki; Hasegawa, Hidenao*; Kakiuchi, Hideki*
Science of the Total Environment, 704, p.135319_1 - 135319_15, 2020/02
Land-surface transfers of I are modeled and incorporated into a land-surface model (SOLVEG-II), and the model was applied to the observed transfer of I at a vegetated field impacted by atmospheric releases of I from Rokkasho reprocessing plant during 2007 to investigate the importance of each I-transfer pathway. The model calculation revealed that contamination of leaves of wild bamboo grasses was mostly caused by foliar adsorption of I (81%) induced via wet deposition of I. Wet deposition of I was the main I-input to the soil, ten-fold the dry deposition of I; however, the deposition of I during 2007 was only 2% of the model-assumed I that pre-existed in the soil; indicating the importance of long-term accumulation of I in soils. The model calculation also revealed that root uptake of I, not methylation, control the long-term turnover of soil I.