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Miyazaki, Hidetoshi*; Akatsuka, Tatsuyoshi*; Kimura, Koji*; Egusa, Daisuke*; Sato, Yohei*; Itakura, Mitsuhiro; Takagi, Yasumasa*; Yasui, Akira*; Ozawa, Kenichi*; Mase, Kazuhiko*; et al.
Materials Transactions, 64(6), p.1194 - 1198, 2023/06
Times Cited Count:1 Percentile:54.26(Materials Science, Multidisciplinary)We investigated the electronic structure of the MgZnY alloy using hard and soft X-ray photoemission spectroscopy and electronic band structure calculations to understand the mechanism of the phase stability of this material. Electronic structure of the MgZnY alloy showed a semi-metallic electronic structure with a pseudo-gap at the Fermi level. The observed electronic structure of the MgZnY alloy suggests that the presence of a pseudogap structure is responsible for phase stability.
Nagai, Takayuki; Kobayashi, Hidekazu; Sasage, Kenichi; Ayame, Yasuo; Okamoto, Yoshihiro; Shiwaku, Hideaki; Matsuura, Haruaki*; Uchiyama, Takafumi*; Okada, Yukiko*; Nezu, Atsushi*; et al.
JAEA-Research 2016-015, 52 Pages, 2016/11
The local structure of waste elements in simulated waste glasses including V was estimated by using synchrotron XAFS measurement in this study. The results are as follows. (1) V has a high possibility which exists in the glass phase in the case of frit, and V can regard both samples as stable 4 coordination structure. (2) Zn, Ce, Nd, Zr, and Mo exist in the glass phase, and the difference is admitted by the percentage of Ce(III) and Ce(IV) by the composition. (3) Ru is separated from the glass phase as RuO crystalline, both of metal and oxide exist in Rh, and Pd is separated out as metal. (4) It was confirmed that the regularity of the local structure of Zr and Mo in the molten glasses retreats as a result of the XAFS measurement at high temperature. (5) The XAFS measurement of molten glasses were performed at 1200C, so it would be possible to acquire excellent data by improving the shapes of the sample cell.
Numakura, Masahiko*; Sato, Nobuaki*; Bessada, C.*; Okamoto, Yoshihiro; Akatsuka, Hiroshi*; Nezu, Atsushi*; Shimohara, Yasuaki*; Tajima, Keisuke*; Kawano, Hirokazu*; Nakahagi, Takeshi*; et al.
Progress in Nuclear Energy, 53(7), p.994 - 998, 2011/11
Times Cited Count:13 Percentile:69.64(Nuclear Science & Technology)X-ray absorption fine structure (XAFS) measurements on thorium fluoride in molten lithium-calcium fluoride mixtures and molecular dynamics (MD) simulation of zirconium and yttrium fluoride in molten lithium-calcium fluoride mixtures have been carried out. In the molten state, coordination number of thorium and inter ionic distances between thorium and fluorine in the first neighbor are nearly constant in all mixtures. However the fluctuation factors (Debye-Waller factor and C cumulant) increase until CaF = 0.17 and decrease by addition of excess CaF. It means that the local structure around Th is disordered until CaF=0.17 and stabilized over CaF = 0.17. The variation of fluctuation factors is related to the number density of F in ThF mixtures and the stability of local structure around Th increases with decreasing the number density of F in ThF mixtures. This tendency is common to those in the ZrF and YF mixtures.
Ozawa, Masaki; Suzuki, Tatsuya*; Koyama, Shinichi; Akatsuka, Hiroshi*; Mimura, Hitoshi*; Fujii, Yasuhiko*
Progress in Nuclear Energy, 50(2-6), p.476 - 482, 2008/03
Times Cited Count:38 Percentile:90.44(Nuclear Science & Technology)For the minimization of the ecological burden originated in nuclear fuel recycling, a new R&D strategy was filed as "Adv.-ORIENT cycle". In the context, mutual precise separation of -elements, such as minor actinide (MA)/lanthanides (Lns) and Am/Cm, are highly essential for enhancing the MA (Am) burning. The separation and utilization of rare metal fission products (RMFPs; Ru, Tc, etc) are a new direction in the partitioning and transmutation field. Separation of exothermic nuclides, Sr, Cs as well as MA, will significantly help to improve the repository tasks. A key separation media are ion exchange chromatography (IXC) by tertiary pyridine resin and a catalytic electrolytic extraction (CEE) by Pd. On challenging the isotope separation of LLFP, theoretical and laboratory studies were begun for Cs, Sn in the first priority.
Oshita, Hironori; Ozawa, Masaki; Ishikawa, Makoto; Koyama, Shinichi; Akatsuka, Hiroshi*
JAEA-Review 2007-031, 41 Pages, 2007/09
Recently establishment of self consistent nuclear fuel cycle has been required with respect to economical efficiency, safety and reduction of the load to the environment. Especially Cs included in spent fuel of nuclear power plants has extremely long half life (3.010y) and its water solubility leads to the anxiety of exudation into ground water in geologic disposal. Recent technology development of laser has come to make it possible in principle to excite a specific isotope and separate it making use of the intrinsic physical and chemical properties of the excited state. This document reports the review of the isotope separation principle and its application to Cs separation.
Suzuki, Masaaki*; Sekiguchi, Hidetoshi*; Akatsuka, Hiroshi*; Goto, Takanobu*; Osugi, Takeshi*; Kobayashi, Hiroaki; Nakazawa, Osamu
JNC TY8400 2002-016, 158 Pages, 2002/03
None
*; Akatsuka, Hiroshi*; *; Suzuki, Tatsuya*; *; *;
JNC TY9400 2000-009, 41 Pages, 2000/03
no abstracts in English
Numakura, Masahiko*; Bessada, C.*; Ory, S.*; Rakhamatullin, A.*; Akatsuka, Hiroshi*; Nezu, Atsushi*; Yaita, Tsuyoshi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Matsuura, Haruaki*
no journal, ,
To investigate the local structure of molten TbF - LiF (x[TbF = 0.2), X-ray absorption fine structure technique (XAFS) was applied using by BL11XU in SPring-8. By several analyses, e.g. X-ray diffraction and differential scanning calorimetry, it had been confirmed that TbF and boron nitride reacted at less than 1073 K even under helium gas flow environment, thus, we focused on the spectrum obtained below 1073 K. According to the curve fitting, the interionic distance obtained from the data of heating between 933 K and 1013 K was shorter than solid state. It would be surely molten state of TbF - LiF (x[TbF] = 0.2), since the value of distance obtained, i.e. 2.26 corresponds to the sum of ionic radii of Tb and F.