核废料地质处置中含有大量中低水平放射性核素 79Se，其中地质材料的水化水泥Ca-Al-LDHs成分对长寿命SeO32-/SeO42-阴离子核素迁移扩散的起着阻滞作用，深入理解Ca-Al-LDHs与放射性阴离子核素之间的相互作用具有重要意义。本项目基于同步辐射PDF和XAFS及原位PDF实验技术，结合常规实验手段，研究Ca-Al-LDHs层状双金属氢氧化物与典型放射性SeO32-/SeO42-阴离子核素之间的相互作用，吸附位点和预测几何配位构型，深入理解其阻滞行为及放射性阴离子核素的迁移行为，为乏燃料地质处置工艺改进提供理论依据,同时推动PDF实验技术在环境放射化学领域的应用。

Radioactive waste contains considerable amounts of long-lived radionuclides 79Se in a cementitious repository. The cement barrier with additive components Ca-Al-LDHs is responsible for the retention of anionic radionuclides (SeO32-/SeO42-) from the repository. It is important to in-depth understand the interaction mechanism between Ca-Al-LDHs and anionic radionuclides SeO32-/SeO42-. In this project, combined with synchrotron-based PDF-XAFS and in-situ PDF techniques as well as conventional experimental characterizations, the interaction mechanism, adsorption sites and geometric coordination configurations of this anionic radionuclides with Ca-Al-LDHs were studied, further analyzing the retard behavior of Ca-Al-LDHs and the migration of anionic radionuclides, which provides the guidance for the improvement of nuclear waste geological disposal, and push forward to study the fundamental environmental radiochemistry issues by terms of PDF technique.