The Summary of Petrophysical Analysis of Olkiluoto Core Samples 1990 - 2008

In 2001, Olkiluoto Island was selected as the site for the final disposal of spent nuclear fuel in Finland. Since 1990 petrophysical samples have been taken from drillcores. In total, 1438 samples from 46 drillholes have been collected and analysed for different purposes. The aim of this study is to form a summary of petrophysical laboratory analysis from samples. The study was ordered by Posiva Oy. The purpose of analysis is to provide background information on how the geophysical measurements in different scales characterise the rock mass at Olkiluoto. In order to examine differences between rock types and correlations between parameters, distributions and dependencies were analysed. Frequency and cumulative distributions of every rock type and all samples were plotted. Scatterplots of every parameter combination by rock type were also drawn. Results define the key petrophysical character of the non-broken rock mass in Olkiluoto. This also provides an estimate of the range of values in altered or deformed rock domains. The analysis has provided useful information on correlation of petrophysical parameters to lithological, alteration and deformation properties of the rock mass. The results will aid feature recognition from geophysical drillhole logging data, site scale geophysical soundings and site scale mapping.