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Tonna, Ryutaro*; Sasaki, Takayuki*; Kodama, Yuji*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Kumagai, Yuta; Kusaka, Ryoji; Watanabe, Masayuki
Nuclear Engineering and Technology, 55(4), p.1300 - 1309, 2023/04
Times Cited Count:0 Percentile:75.85(Nuclear Science & Technology)Simulated debris was synthesized using UO, Zr, and stainless steel and a heat treatment method under inert or oxidizing conditions. The primary U solid phase of the debris synthesized at 1473 K under inert conditions was UO, whereas a (U,Zr)O solid solution formed at 1873 K. Under oxidizing conditions, a mixture of UO and (Fe,Cr)UO phases formed at 1473 K whereas a (U,Zr)O solid solution formed at 1873 K. The leaching behavior of the fission products from the simulated debris was evaluated using two methods: the irradiation method, for which fission products were produced via neutron irradiation, and the doping method, for which trace amounts of non-radioactive elements were doped into the debris. The dissolution behavior of U depended on the properties of the debris and aqueous medium the debris was immersed in. Cs, Sr, and Ba leached out regardless of the primary solid phases. The leaching of high-valence Eu and Ru ions was suppressed, possibly owing to their solid-solution reaction with or incorporation into the uranium compounds of the simulated debris.
Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03
The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.
Furuta, Takuya; Sato, Tatsuhiko; Ogawa, Tatsuhiko; Niita, Koji*; Ishikawa, Kenichi*; Noda, Shigeho*; Takagi, Shu*; Maeyama, Takuya*; Fukunishi, Nobuhisa*; Fukasaku, Kazuaki*; et al.
Proceedings of Joint International Conference on Mathematics and Computation, Supercomputing in Nuclear Applications and the Monte Carlo Method (M&C + SNA + MC 2015) (CD-ROM), 9 Pages, 2015/04
In Particle and Heavy Ion Transport code System PHITS, two parallel computing functions are prepared to reduce the computational time. One is the distributed-memory parallelization using message passing interface (MPI) and the other is the shared-memory parallelization using OpenMP directives. Each function has advantages and disadvantages, and thus, by adopting both functions in PHITS, it is possible to conduct parallel computing suited for needs of users. It is also possible to conduct the hybrid parallelization by the intra-node OpenMP parallelization and the inter-node MPI parallelization in supercomputer systems. Each parallelization functions were explained together with some application results obtained using a workstation and a supercomputer system, K computer at RIKEN.
Sato, Ryutaro*; Saito, Hiroyuki; Endo, Naruki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Aoki, Katsutoshi; Orimo, Shinichi*
Applied Physics Letters, 102(9), p.091901_1 - 091901_4, 2013/03
Times Cited Count:23 Percentile:73.58(Physics, Applied)Takagi, Shigeyuki*; Saito, Hiroyuki; Endo, Naruki; Sato, Ryutaro*; Ikeshoji, Tamio*; Matsuo, Motoaki*; Miwa, Kazutoshi*; Aoki, Katsutoshi; Orimo, Shinichi*
Physical Review B, 87(12), p.125134_1 - 125134_6, 2013/03
Times Cited Count:12 Percentile:53.67(Materials Science, Multidisciplinary)Matsuo, Motoaki*; Saito, Hiroyuki; Machida, Akihiko; Sato, Ryutaro*; Takagi, Shigeyuki*; Miwa, Kazutoshi*; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Orimo, Shinichi*
RSC Advances (Internet), 3(4), p.1013 - 1016, 2013/01
Times Cited Count:16 Percentile:52.39(Chemistry, Multidisciplinary)Sakamoto, Keishi; Takahashi, Koji; Kasugai, Atsushi; Minami, Ryutaro; Kobayashi, Noriyuki*; Nishio, Satoshi; Sato, Masayasu; Tobita, Kenji
Fusion Engineering and Design, 81(8-14), p.1263 - 1270, 2006/02
Times Cited Count:5 Percentile:36.44(Nuclear Science & Technology)no abstracts in English
Nakamura, Kazuyuki; Akiba, Masato; Araki, Masanori; Dairaku, Masayuki; Sato, Kazuyoshi; ; ; Ando, Toshiro; *; Saido, Masahiro; et al.
Fusion Engineering and Design, 30, p.291 - 298, 1995/00
Times Cited Count:2 Percentile:28.65(Nuclear Science & Technology)no abstracts in English
Nakamura, Kazuyuki; Ando, Toshiro; Akiba, Masato; Araki, Masanori; ; Sato, Kazuyoshi; ; Dairaku, Masayuki; Saido, Masahiro; *
Fusion Engineering and Design, 24, p.431 - 435, 1994/00
Times Cited Count:0 Percentile:0.49(Nuclear Science & Technology)no abstracts in English
Sasaki, Takayuki*; Tonna, Ryutaro*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Kumagai, Yuta; Kusaka, Ryoji; Watanabe, Masayuki
no journal, ,
Sasaki, Takayuki*; Kodama, Yuji*; Tonna, Ryutaro*; Kobayashi, Taishi*; Kumagai, Yuta; Kusaka, Ryoji; Watanabe, Masayuki; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; et al.
no journal, ,
no abstracts in English
Sasaki, Takayuki*; Tonna, Ryutaro*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Watanabe, Masayuki; Kumagai, Yuta; Kusaka, Ryoji
no journal, ,
We synthesized simulated fuel debris which containing stainless steel and zirconium. The fission of Uranium by the irradiation of thermal neutron or non-radioactive elements was fed in the simulated fuel debris as fission products (FP), and the sample was immersed in pure water or artificial sea water. In this presentation, we would report the behavior of the solubility of the FP and the interpretation of its results.
Sasaki, Takayuki*; Tonna, Ryutaro*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Watanabe, Masayuki; Kumagai, Yuta; Kusaka, Ryoji
no journal, ,
Fuel debris containing alloy phases is expected to be formed in the Fukushima Daiichi Nuclear Power Plant. In this study, two series of simulated debris samples comprising uranium-zirconium-stainless steel were synthesized. One series of the samples was prepared by the irradiation method, where the samples were irradiated by thermal neutron for fission generation. The other was prepared by the doping method, where stable isotopes of FPs were added during the synthesis. We performed leaching tests as an aging treatment, and then measured structural changes in the samples and the elution rates of U and FPs contained in the samples. Moreover, in order to evaluate the colloid formation of these elements, particle size distribution was analyzed by an ICP-MS method combined with filtration using different pore-size filters or size exclusion chromatography. Based on the results, the chemical stability of the simulated debris and the speciation of the eluted nuclides were discussed.
Tonna, Ryutaro*; Sasaki, Takayuki*; Okamoto, Yoshihiro; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*
no journal, ,
Since fuel debris recovered from the Fukushima Daiichi Nuclear Power Plant may be directly disposed of in deep geological strata, knowledge of dissolution reactions of fuel debris in water and chemical states of dissolved nuclides is essential for safety assessment of disposals. The chemical composition and physical properties of fuel debris depend on the atmosphere and temperature, but the formation of FeUO has been suggested at conditions under which air enters the reactor from outside. Uranium in FeUO is reported to be pentavalent, but no dissolution reaction in water has been investigated. In this study, FeUO was synthesized by heating at a predetermined temperature and oxygen pressure, immersed in nitric acid to remove unreacted uranium oxides, and then immersed in a solution of pH2-8. After the prescribed period, pH and Eh values were measured, and dissolved iron and uranium concentrations were measured by ICP-MS. X-ray absorption fine structure (XAFS) and powder X-ray diffraction (XRD) were used to evaluate the solid state before and after immersion. From these results, it was interpreted that the dissolution of FeUO was accompanied by a redox reaction between Fe(III)/Fe(II) and U(V)/U(VI) during dissolution.