Computer simulation of defect evolution in lanthanum doped cerium dioxide under irradiation

Radiation Damage;Cerium Oxide;Nuclear Fuel Material;Molecular Dynamics;Molecular Statics;Dislocation Loop;Defect Migration

Miao, Yinbin ; Stubbins ; James F.

关键词: Radiation Damage;    Cerium Oxide;    Nuclear Fuel Material;    Molecular Dynamics;    Molecular Statics;    Dislocation Loop;    Defect Migration;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/29577/Miao_Yinbin.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Uranium dioxide is the most common choice for fuel material in fission reactors. However, the radioactivity of uranium limits the experimental approaches on the oxide fuel material. Fortunately, cerium dioxide has been shown to be a good surrogate of uranium dioxide in many aspects. To better understand the experimental results of irradiated cerium dioxide and to clarify the similarities and differences in radiation resistance properties between ceria and urania, computer modeling methods are applied to explore the defect evolution in cerium dioxide under irradiation condition. In this study, conventional atomic potential for the cerium dioxide system with xenon, implanted as an important fission product, and lanthanum, doped to simulate trivalent solid fission products or mixed oxide fuel (MOX), is developed for both molecular statics (MS) and molecular dynamics (MD) simulations. Then the single xenon incorporation and migration behaviors in ceria are examined using MS calculation. Although the vacancy cluster with only one cerium vacancy is found to be a stable site for a single xenon atom, only in the vacancy cluster including two cerium vacancies can a xenon atom migrate through the vacancy-assisted mechanism. The structure of the dislocation loop observed in TEM images are determined to be the planar interstitial cluster in {111} planes. Also, the loop formation and growth mechanisms are studied by means of both the Frenkel pair evolution simulation and the overlapped displacement cascades simulation to explain the growth rate difference in various lanthanum doping conditions.