Long Term Diffusion (LTD) - Introduction
University of Helsinki, Dept of Chemistry - Laboratory of Radiochemistry (HYRL), Finland
Japan Atomic Energy Agency (JAEA), Japan
National Research Institute (NRI) and the Radioactive Waste Repository Authority (RAWRA), Czech Republic
National Cooperative for the Disposal of Radioactive Waste (Nagra), Switzerland
Nuclear Waste Management Organization (NUMO), Japan
This is a long-term, large-scale experiment which aims to further examine in-situ matrix diffusion and pore space visualisation at the Grimsel Test Site.
Matrix diffusion is the process by which solute, flowing in distinct fractures, penetrates into the surrounding rock and is transported, through a connected system of pores or micro-fractures, into the rock matrix.
The importance of matrix diffusion in the context of a radioactive waste repository is that it provides a mechanism for greatly enlarging the area of rock surface in contact with advecting radionuclides, from that of the flow path surfaces (and infills), to a much larger portion of the bulk rock and increases the global pore volume which can retard radionuclides
This is especially crucial when considering the calculated contribution to dose from weakly- and non-sorbing radionuclides such as 129I and 14C and offers a more realistic dose reduction scenario than many of the exotic engineering solutions currently being proposed for the engineered barrier.
Long Term Diffusion project (LTD) Experiment