| 학회 | 한국재료학회 |
| 학술대회 | 2021년 봄 (05/12 ~ 05/14, 광주 김대중컨벤션센터) |
| 권호 | 27권 1호 |
| 발표분야 | E. 환경/센서 재료 분과 |
| 제목 | Monte Carlo simulations integrated with first-principles to understanding early-stage oxidation process of UO2 in aqueous solution |
| 초록 | Safe control of used nuclear fuels disposed in deep underground is of paramount concern for modern society. Previously various scenarios of release of the radioactive materials via contact of groundwater at elevated temperature and pressure conditions were proposed. For example, oxidation of the spent nuclear fuels has been suggested [1] without clear elucidation of underlying mechanism. In this study, we study early-stage process of UO2 oxidation reaction using first-principles density functional theory calculations and Monte Carlo simulations. Thermodynamically most stable surface of UO2 is identified with surface energy calculations. Atomistic level of surface oxidation of UO2 is described by Monte Carlo simulations, in which the interaction potentials between adsorbate O and UO2 are obtained by cluster expansion theory. Furthermore, the potentials enable us to calculate not only surface Pourbaix diagram but also cyclic voltammetry of UO2+x exposed to aqueous solution, which are invaluable for understanding the oxidation mechanism and characterizing detailed structures. Our calculated Pourbaix diagram indicate that oxidation potential of UO2+x surface is lower than bulk for the same stoichiometric oxide (i.e., easier oxidation). In Monte Carlo simulations, it is shown how the surface oxidation evolves with varying oxygen chemical potential and temperature. Our results are very consistent what were reported by experiment, and detailed oxidation mechanism is clearly identified for the early-stage reaction. It will provide a useful guide for safe management of disposed used nuclear fuel in underground. References 1. Ziyan Zhu, Shoesmith, David W and Noël James J, Electronic Thesis and Dissertation Repository, 5787 (2018). |
| 저자 | 김준엽, 권초아, 한병찬 |
| 소속 | 연세대 |
| 키워드 | <P>monte carlo simulations; cluster expansion; spent nuclear fuels; pourbaix diagram; cyclic voltammetry</P> |
