锕系氮化物燃料的结构缺陷形成与扩散机理的理论研究

项目名称： 锕系氮化物燃料的结构缺陷形成与扩散机理的理论研究

项目编号： No.11505006

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 张玉娟

作者单位： 北京科技大学

项目金额： 23万元

中文摘要： 锕系氮化物作为未来先进核燃料循环体系的潜在核燃料近年来备受科学界关注。本项目拟结合DFT+U和从头算分子动力学方法，研究锕系氮化物的基态性质和电子结构特性及主要裂变产物缺陷行为。在严格考虑磁性和强关联电子作用的模型基础上，阐释5f电子行为对锕系材料磁性、结构稳定性等基本性质的影响，重点获取主要裂变产物的溶解扩散行为及其与体材料物性变化的内在关联。模拟不同组分的锕系氮化物的电子结构、热力学及缺陷行为；模拟固态裂变产物造成的材料的微观结构和体积的影响，预测固态裂变产物的稳定存在形态；寻找裂变气体聚集扩散的能量最优路径，计算扩散势垒、结合能和活化能，给出扩散系数，从而揭示氦、氙等裂变气泡的形成和生长、聚集过程。本项目的实施将加深对先进核燃料锕系氮化物材料的理解和认识，为发展锕系氮化物燃料中裂变产物有效控制方法提供基础数据和理论指导。

中文关键词： 锕系氮化物；裂变产物；第一性原理；从头算分子动力学；缺陷行为

英文摘要： Actinide nitrides, as the potential nuclear fuels in future advanced nuclear circulation systems, have attracted much attention in recent years. Combining DFT+U method and ab initio molecular dynamics simulations, the present project will perform investigations on the electronic structures and thermodynamic properties of actinide nitrides, and solution and diffusion behaviors of their fission products. On the basis of strict consideration of magnetism and strong-correlation electronic mechanism, we intend to clarify the influence of the 5f electrons on the electronic structures, magnetism and phase stabilities of actinide nitrides, and acquire the solution and diffusion behaviors of main fission products and their connections with the changes of bulk materials, concretely including: Simulating the electronic structures, thermodynamic properties and defect behaviors of actinide nitrides with different components; Simulating the thermal expansion process due to the solid fission products, and predicting the stable phase of the solid fission products; Finding the optimal segregation and diffusion paths of gas fission products, calculating the migration energy, incorporation energy and activation energy, providing the diffusion coefficients, and hence elucidating the physical mechanism of the formation, growing, and segregation process of gas fission products He and Xe bubbles in actinide nitrides. We expect that the present work will deepen the knowledge of actinide nitrides advanced nuclear fuels, and provide theoretical guidance for seeking efficient ways to suppress the detrimental effects of gas fission products.

英文关键词： actinide nitride;fission product;first-principle;ab initio molecular dynamics;defect behavior