钚自辐照老化过程中氦效应理论研究进展

钚因放射性衰变而出现自辐照老化效应。钚中氦行为是理解钚自辐照老化效应的一个基础和前提。运用分子动力学模拟技术，计算研究了钚中缺陷行为、氦与缺陷的相互作用、氦泡的初始形核过程、氦泡的长大过程以及氦泡对钚材料宏观性能的影响等。其中，钚-钚、钚-氦和氦-氦相互作用势分别采用修正嵌入原子多体势（modifiedembeddedatommethod，MEAM）、Morse对势和Lennard-Jones对势。主要的计算结果表明，氦原子与空位的结合能较大，在钚的自辐照过程中，两者易于结合并形成氦-空位团簇，成为氦泡的前驱体；氦泡可通过冲出位错环的机制而长大；氦泡的压力在GPa量级，且氦泡引起的基体膨胀很小。

Advances in Theoretical Research of Helium Effects in Plutonium During Aging Process of Self-radiation Damage

Due to α radioactive decay plutonium is vulnerable to aging. The behavior of helium in plutonium is the foundation for understanding plutonium self-radiation damage aging. Molecular dynamics (MD) technique was performed to investigate the behavior of defects, the interaction between helium and defects, the processes of initial nucleation and growth of helium bubble, and the dependence of helium bubble on the macroscopical properties of plutonium. Modified embedded atom method (MEAM), Morse pair potential and the Lennard-Jones pair potential were used for describing the interactions of Pu-Pu, Pu-He and He-He, respectively. The main calculated results show that helium atoms can combine with vacancies to form helium-vacancy cluster (i.e. the precursor of helium bubble) during the process of self-radiation as a result of high binding energy of an interstitial helium atom to vacancy; helium bubble's growth can be dominated by the mechanism of punching out of dislocation loop; the pressures of helium bubble in plutonium are at the level of GPa and the swelling induced by helium bubble is very small.