2012:44 Technical Note, Review of Matrix Diffusion and related properties of intact rock in SKB’s Licence Application for a Spent Nuclear Fuel Repository in Forsmark, Sweden

This report summarizes a review of SKB’s theoretical development of matrix diffusion, its associated processes and parameters, and the data supporting calculations of matrix diffusion.  In addition to diffusion, this review covers matrix porosity, the formation factor, matrix diffusivity, penetration depth, and measurement of some of these parameters with electrical methods.  Sorption and the F-factor were specifically excluded from the review.  All or parts of 19 SKB reports and SKB-supported publications were read and considered in this review. 

In general, the quality of work is excellent.  SKB and SKB-supported researchers have been leaders in the topic of matrix diffusion for more than 30 years.  Studies conducted or supported by SKB have been some of the most important in the field. Consequently, the process is well understood both theoretically and practically.  As a result of extensive field and laboratory testing, the average value of the key parameters is well quantified.  SKB has pursued the development of electrical resistivity for measuring matrix diffusion properties.  This has resulted in several thousand data points that help to constrain both the value and the variability in matrix diffusion properties.