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Fedkin, M. V.*; Shin, Y. K.*; Dasgupta, N.*; Yeon, J.*; Zhang, W.*; van Duin, D.*; Van Duin, A. C. T.*; Mori, Kento*; Fujiwara, Atsushi*; Machida, Masahiko; et al.
Journal of Physical Chemistry A, 123(10), p.2125 - 2141, 2019/03
Times Cited Count：44 Percentile：94.92(Chemistry, Physical)no abstracts in English
Machida, Masahiko; Nakamura, Hiroki; Srinivasan, S. G.*; Van Duin, A. C. T.*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05
Zircalloy has been widely employed as an excellent material covering the fuel rod. The mechanical and thermal properties have been explored by various experiments. In terms of its use as the fuel cladding, its response to oxidation reactions is an important topic when it is exposed to high temperature and high pressure steam during severe accidents. Especially, the hydrogen production accompanied by the oxidation is critical because it can lead to the crisis of the hydrogen explosion, as observed in the Fukushima Nuclear Power Plant accidents. Silicon carbide (SiC) has been considered as an alternative cladding material owing to an advantage that hydrogen production is much suppressed in the equivalent condition compared to Zircalloy. Therefore, we simulate the oxidation reaction for both materials, i.e. Zirconium metal and SiC in atomistic level by using the ReaxFF reactive force field method to simulate the chemical reaction molecular dynamics. Through such comparative studies between Zirconium and SiC in the same condition, we clarify how the temperature and the steam pressure accelerates the oxidation reaction and the resultant hydrogen production in both materials at typical severe accident conditions. The advantage using ReaxFF is that it allows us to directly trace the oxygen diffusion inside the Zirconium metal and SiC depending on the temperature and vapor pressure together with the oxidation reaction. We can compare the reaction processes in both materials. Especially, we paid attention to the rate of hydrogen production in both materials.
Machida, Masahiko; Nakamura, Hiroki; Srinivasan, S. G.*; Van Duin, A. C. T.*
no journal, ,
no abstracts in English
Machida, Masahiko; Nakamura, Hiroki; Srinivasan, S. G.*; Van Duin, A. C. T.*
no journal, ,
Zircalloy has been widely employed as an excellent material covering the fuel rod. The mechanical and thermal properties have been explored by various experiments. In terms of its use as the fuel cladding, the oxidation reaction is an important topic when exposed to high temperature and high pressure steam in severe accidents. Especially, the hydrogen nucleation accompanied by the oxidation is critical because it leads to the crisis of the hydrogen explosion as observed in the Fukushima Nuclear Power Plant accidents. Therefore, in this study, we simulate the oxidation reaction in atomistic level by using ReaxFF simulating the chemical reaction in addition to usual molecular dynamics and clarify how the surrounding situation as the temperature and steam pressure accelerates the oxidation reaction and resultant hydrogen nucleation. The advantage using ReaxFF is to directly trace the oxygen diffusion inside Zircalloy depending on the temperature and vapour pressure together with the oxidation reaction. The calculation results reveal that the oxygen diffusion from the top surface to internal area occurs and nucleated hydrogen molecules move out when increasing the temperature above a certain temperature and pressure.
