【摘要】 在高燃耗率时,作为裂变产物的镧系元素(主要为La,Ce,Pr,Nd,Pm,Sm)在合金燃料内部不断积累,并且逐渐迁移至包覆层-燃料界面,与包覆层主要化学元素(Fe,Cr,Ni)发生化学反应,生成低熔点金属间化合物。控制包覆层-燃料界面化学反应的有效措施之一是将特定化学元素掺入合金燃料中,与镧系元素发生化学反应,生成稳定的、难以迁移的化合物,从而显著减少或延迟包覆层-燃料界面化学反应的发生。铟(In)由于具有与合金燃料元素相容、对包覆层金属元素呈现化学惰性以及与镧系元素能够生成金属间化合物等特性,已作为合金燃料的化学掺杂剂而被研究。本工作通过第一性原理计算,研究了铟-镧系元素(In-La)金属间化合物(In La,Ce In3,αIn Pr,In3Nd)的基态性质以及在自旋-轨道耦合存在下的电子和磁性性质;此外,基于Debye-Slater模型,对In La、Ce In3、αIn Pr、In3Nd在不同温度和压力下的热力学性质进行了计算。该研究可更好地表征铟结合和稳定镧系裂变产物的功能。更多还原

【Abstract】 At high burnup,fission product lanthanide accumulate is substantial and obviously contributes to fuel-cladding chemical interaction upon migration to the Fe-based cladding interface. By doping with specific elements into the fuel alloy,the lanthanide accumulates may be precipitated into stable,non-migratory,and non-reactive phases within the fuel and thus significantly reduce and/or delay the onset of fuel-cladding chemical interaction. Experimentally,indium has been selected as the fuel dopant due to several attractive properties,such as its compatibility with the fuel,chemical inertness with cladding materials and reactivity with the lanthanides. In this study,first-principles calculations were performed to investigate ground-state properties of the indium-lanthanides(La,Ce,Pr and Nd) intermetallic compounds. The electronic and magnetic properties of In La,Ce In3,αIn Pr and In3 Nd have been calculated in the presence of spin-orbit coupling,and anti-ferromagnetic ground state structures have been found to be the most stable phases for these compounds. In addition,the thermodynamic properties of these four compounds at given temperatures and pressures have been calculated. The study may lead to a better understanding of the function of indium of binding and stabilizing lanthanide fission products.更多还原