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Sakamoto, Kan*; Adachi, Mika*; Tokushima, Kazuyuki*; Aomi, Masaki*; Shibata, Hiroki; Nagae, Yuji; Kurata, Masaki
Zirconium in the Nuclear Industry; 20th International Symposium (ASTM STP 1645), p.411 - 432, 2023/11
Yamashita, Susumu; Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Yoshida, Hiroyuki
Journal of Nuclear Science and Technology, 60(9), p.1029 - 1045, 2023/09
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Shirasu, Noriko; Sato, Takumi; Suzuki, Akihiro*; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Science and Technology, 60(6), p.697 - 714, 2023/06
Times Cited Count:2 Percentile:51.90(Nuclear Science & Technology)Interaction tests between UO and Zr were performed at precisely controlled high temperatures between 1840 and 2000
C to understand the interaction mechanism in detail. A Zr rod was inserted in a UO
crucible and then heat-treated at a fixed temperature in Ar-gas flow for 10 min. After heating in the range of 1890 to 1930
C, the Zr rod was deformed to a round shape, in which the post-analysis detected the significant diffusion of U into the Zr region and the formation of a dominant
-Zr(O) matrix and a small amount of U-Zr-O precipitates. The abrupt progress of liquefaction was observed in the sample heated at around 1940
C or higher. The higher oxygen concentration in the
-Zr(O) matrix suppressed the liquefaction progress, due to the variation in the equilibrium state. The U-Zr-O melt formation progressed by the selective dissolution of Zr from the matrix, and the selective diffusion of U could occur via the U-Zr-O melt.
Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Quaini, A.*; Guneau, C.*
CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 79, p.102481_1 - 102481_11, 2022/12
Times Cited Count:1 Percentile:8.33(Thermodynamics)Pshenichnikov, A.; Kurata, Masaki; Nagae, Yuji
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10
The CLADS-MADE-04 is the next test in the series aiming at understanding of the melt propagation behaviour in the lower core region. In this contribution, recent results of the post-test analysis including microstructure of metallic debris investigated by Electron Probe Micro Analyzer (EPMA) are discussed. During the test, melting of the control blade happened with sudden wave of strong heat release relatively slowly (several cm/min) spread from the hottest area downwards along the degrading control blade and channel box consuming the walls made of Zircaloy-4. A significant damage happened with the sample supporting plate as well. The investigation of microstructure of such metallic debris would allow understanding of a mechanism of enhanced local core degradation. The nature of strong heat release and possibility of spreading to the surrounding materials is to be confirmed after thorough phase identification by EPMA. The difference between Fe-B eutectic debris and Zr-Fe eutectic debris will be outlined. It is especially important for understanding of the lower core plate melt-through and a possibility of a Zr-Fe molten material progression into the lower plenum.
Ohgi, Hiroshi; Nagae, Yuji; Kurata, Masaki
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10
Pshenichnikov, A.; Shibata, Hiroki; Yamashita, Takuya; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Science and Technology, 59(3), p.267 - 291, 2022/03
Times Cited Count:3 Percentile:33.11(Nuclear Science & Technology)Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki
Proceedings of TopFuel 2021 (Internet), 12 Pages, 2021/10
Pshenichnikov, A.; Kurata, Masaki; Nagae, Yuji
Journal of Nuclear Science and Technology, 58(9), p.1025 - 1037, 2021/09
Times Cited Count:5 Percentile:42.67(Nuclear Science & Technology)Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 7 Pages, 2021/08
Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Science and Technology, 58(4), p.416 - 425, 2021/04
Times Cited Count:15 Percentile:81.27(Nuclear Science & Technology)Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki
Mechanical Engineering Journal (Internet), 7(3), p.19-00503_1 - 19-00503_10, 2020/06
Sudo, Ayako; Meszaros, B.*; Poznyak, I.*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Materials, 533, p.152093_1 - 152093_8, 2020/05
Times Cited Count:4 Percentile:36.46(Materials Science, Multidisciplinary)Pshenichnikov, A.; Kurata, Masaki; Bottomley, D.; Sato, Ikken; Nagae, Yuji; Yamazaki, Saishun
Journal of Nuclear Science and Technology, 57(4), p.370 - 379, 2020/04
Times Cited Count:16 Percentile:68.47(Nuclear Science & Technology)Pshenichnikov, A.; Nagae, Yuji; Kurata, Masaki
Mechanical Engineering Journal (Internet), 7(2), p.19-00477_1 - 19-00477_8, 2020/04
Pham, V. H.; Nagae, Yuji; Kurata, Masaki; Bottomley, D.; Furumoto, Kenichiro*
Journal of Nuclear Materials, 529, p.151939_1 - 151939_8, 2020/02
Times Cited Count:18 Percentile:86.22(Materials Science, Multidisciplinary)Pham, V. H.; Nagae, Yuji; Kurata, Masaki; Furumoto, Kenichiro*; Sato, Hisaki*; Ishibashi, Ryo*; Yamashita, Shinichiro
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.670 - 674, 2019/09
Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(3), p.111 - 118, 2019/08
Cooling rate of molten core materials during solidification significantly affects the segregation of major constituents of fuel debris. To understand general tendency of the segregation, liquefaction/solidification tests of simulated corium (UO, ZrO
, FeO, B
C and sim-FP oxides) were performed. Simulated corium was heated up to 2600
C under Ar atmosphere and then cooled down with two different cooling processes; furnace cooling (average cooling rate is approximately 744
C/min) and slow cooling (cooling rate in 2600
C
2300
C is 5
C/min and in 2300
C
1120
C is approximately 788
C/min). Element analysis detected three oxide phases with different composition and one metal phase in both solidified samples. Solubility of FeO in these oxide phases was mostly fixed to be 12
5at% in both samples, which is in reasonable accordance with the value estimated from UO
-ZrO
-FeO phase diagrams. However, a significant grain-growth of one oxide phase, rich in Zr-oxide, was detected only in the slowly cooled sample. The composition of this particular oxide phase is comparable to the initial average composition. The condensation is considered to be caused by the connection of remaining liquid agglomerates during slow solidification.
Pshenichnikov, A.; Kurata, Masaki; Nagae, Yuji
Dai-24-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (USB Flash Drive), 4 Pages, 2019/06
Pshenichnikov, A.; Yamazaki, Saishun; Bottomley, D.; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Science and Technology, 56(5), p.440 - 453, 2019/05
Times Cited Count:19 Percentile:86.90(Nuclear Science & Technology)