Spent fuel dissolution in Belgian Supercontainer conditions: source term and compatibility

摘要

In the frame of the Safety and Feasibility Case 1 development, the Belgian agency for radioactive waste (ONDRAF/NIRAS) has to demonstrate that the geological disposal of spent nuclear fuel in the Boom Clay host rock following the Supercontainer design provides sufficient radiological safety in the long term. This safety relies on the containment of the radionuclides by the overpack, the limitation of radionuclide release from the waste matrix, the diffusion controlled transport of the radionuclides, and their low solubility and sorption on the Boom Clay host rock. This paper presents an evaluation of the main processes considered for the limitation of radionuclide release by the Spent Fuel in Supercontainer conditions, characterized by the presence of a concrete buffer and hyperalkaline pore water. We present a description of the main expected processes with their potential impact on the fuel alteration mechanisms, and potential reference fuel matrix alteration rates and effective fuel surface areas for use in safety and performance assessment models.