The weathering of core samples

Teollisuuden Voima OY (TVO) is carrying out a thorough research project in the suitability of Finnish bedrock for the disposal of spent nuclear fuel. The site investigations will go on until the year 2000. Incident to the extension of the research, the controlling of the occurrence of any major changes in the core samples during their storage will contribute useful information for later sample analyses. The weathering of core samples was investigated by a comparison between various normally stored samples (oldest from 1918) and samples stored in nitrogen to prevent oxidation. The main point of interest were the possible chemical changes. In this preliminary work, the methods used were the analysis of the content of water measured as loss of ignition (LOI) and as total water (H20tot) and the analysis of the oxidation stages of iron. These analyses were completed in the Chemistry Laboratory at the Geological Survey of Finland. The energy dispersive spectrometry connected to the scanning electron microscope, X-ray fluorescence analysis, and polarization microscope were also used