Pu或Am含量对铀基混合氧化物的结构和能量及力学性质的影响

Effects of different Pu or Am contents on structure,energy and mechanical properties of uranium-based mixed oxides

U-Pu和U-Am混合氧化物中的Pu或Am含量对核反应堆燃料的高效循环利用至关重要.研究铀基混合氧化物中不同Pu或Am的含量对其结构、力学性质和能量的影响有助于理解和预测提高反应堆中燃料的行为以及与包层的化学或力学相互作用.本文通过DFT+U方法首先探索UO_(2)、PuO_(2)和AmO_(2)的结构和能量随U的变化关系,然后研究UO_(2)结构中不同Pu或Am含量对其结构和力学性质以及能量的影响.结果表明在UO_(2)结构中掺入不同Pu或Am的含量均使得体系晶格参数收缩,且与实验观测(U,Pu)O_(2)中Pu的含量结论是一致的.从能量角度观察,UO_(2)结构中掺入不同Pu或Am的含量使得体系形成能随掺入量的变化趋势明显不同.结果显示当UO_(2)结构中掺入Pu为25%时,U-Pu混合氧化物体系的形成能最低,而当UO_(2)结构中掺入Am为75%时,U-Am混合氧化物体系的形成能最低.此外,我们也探讨和分析了在UO_(2)结构中掺入不同Pu或Am含量的弹性参量的变化和差异.

The Pu or Am content in U-Pu and U-Am mixed oxides is crucial for the efficient recycling of nu⁃clear reactor fuel.The effects of different Pu or Am contents in uranium-based mixed oxides on their structures,mechanical properties and energies can help to understand and predict the behavior of fuel in boost reactors and the chemical or mechanical interactions with the cladding.Therefore,in this work,the DFT+U method based on density functional theory is used to explore the relationships between the structure and energy of UO_(2),PuO_(2)and AmO_(2)with U,and then study the effect of different Pu or Am contents in the UO_(2)structure on its structure,mechanical properties and energy.The results show that the incorporation of Pu or Am into the UO_(2)structure re⁃duces the lattice parameters,and both are between UO_(2)and PuO_(2)or AmO_(2).From the energy point of view,the different contents of Pu or Am into UO_(2)structure makes the variation trend of the formation energy of the system significantly different with the amount of doping.The formation energy of the U-Pu mixed oxide system is the low⁃est when the UO_(2)structure is doped with 25%Pu,while the U-Am mixed oxide system has the lowest formation energy when the UO_(2)structure is doped with 75%Am.In addition,we also discussed and analyzed the variation and difference of elastic parameters with different Pu or Am contents incorporated into the UO_(2)structure.