Pu-239在粘土岩地质处置环境中的水化学行为及迁移机理研究

如何长期安全处置高放废物是人类可持续发展亟待解决的难题。粘土岩由于具有自封闭性、渗透率低等其他岩石类型不可比拟的优点，已经成为了高放废物处置围岩的热点研究对象。高放废物中的关键核素Pu-239具有剧毒性、长寿命、高敏感性及多种价态共存等特殊性，其在粘土岩中的物理化学性质、水化学行为、以及输运机理等方面的基础科学信息较为匮乏，尤其是在分子层面上Pu-239与粘土岩地质材料的界面相互作用机理尚不明确，该机理是帮助我们控制其迁移的关键。本项目拟通过研究Pu-239在处置地质环境中的水化学行为，及其与粘土岩在分子层面上的地球化学动力学过程与反应机理，来深入了解Pu-239在粘土岩地质环境中的输运行为。通过建立基于分子层面地球化学过程的输运模型，有效预测Pu-239在高放废物处置环境中的迁移数量和速率。并以此为基础提出有效阻滞Pu-239输运的有力科学依据与方法。

How to dispose safely and effectively High Level Radioactive Waste (HLW) is a challenging issue for the sustainable development of human being. Chinese government adopta "deep geological disposal of HLW" method. Clay rock has become a intense research direction as surrounding rock around HLW due to its self sealing and low permeability compare to other rock types. In the HLW, Pu-239 is one of the most particular key nuclides because of its highly toxic longevity, high sensitivity and various valence state of coexistence. In clay rock, its basic physical and chemical properties, aqueous chemical behavior, and migration mechanism have not yet been well understood, especially the molecular level mechanism at the interface between geological media of clay rock and Pu-239 is not clear at all. The mechanism is the key to help us to minimize the migration of Pu-239. This project aims to fully understand the migration behavior of Pu-239 in clay rock by studying aqueous chemical behavior of 239Pu in disposal geological media, and the molecular-level geochemical interaction mechanism of Pu-239 on the surface of clay rock. By developing reactive transport model incorporated the molecular-level geochemical processes, the amount and speed of the migration of Pu-239 in the environment will be accurately predicted. The relevant results could provide reliable scientific support and method which can effectively minimize the transport of Pu-239.