• Date: 2024. 09. 12(THU)

    • Time: 16:30~17:30PM

    • Venue: Research Building I, #310

    • Speaker: Prof. Youngheum Jo(Hanyang University)

    • Title: Complexation and Sorption of Radionuclides (V/VI) in Nuclear Waste Repository

    • Abstract:

The migration of radionuclides within natural aquifers and engineered barrier systems of nuclear waste repositories is predominantly governed by chemical processes such as complexation and sorption. A thorough mechanistic understanding and reliable geochemical data regarding the migration behavior of long-lived radionuclides are essential for the long-term performance assessment of nuclear waste disposal.

This presentation focuses on the migration behavior of radionuclides with high oxidation states within nuclear waste repository systems, specifically examining two distinct groups: actinides(VI) and niobium(V). Actinides are significant contributors to the long-term radiotoxicity of spent nuclear fuel. In the environmental chemistry of uranium, the complexation of calcium-uranyl(VI)-carbonate plays a critical role in determining uranium mobility within natural systems. The experimental results on the temperature effects on this complexation to model uranium migration in deep geological repositories under elevated temperatures is discussed. Beyond the uranyl system, this presentation introduces the first experimental evidence of ternary complexation involving neptunyl(VI) and plutonyl(VI).

For niobium(V), one of the main contributor to the dose in low- and intermediate-level radioactive waste (LILW) repositories, its solubility and sorption in cementitious systems—key components of LILW repositories—is examined. Furthermore, the impact of organic materials, such as isosaccharinic acid, on niobium migration is discussed.