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
Japanese Flag 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.

Diffusion - Long Term Diffusion project (LTD)

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.

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Long Term Diffusion project (LTD) Experiment Diffusion - Long Term Diffusion project (LTD)

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.