Report on laboratory tests of drying and rewetting of intact rocks from the drift-scale and single-heater tests

The primary focus of this report is measurement of moisture-retention curves of tuff as a function of temperature for both drying and rewetting conditions. The report contains descriptions of experimental designs and procedures, data, observations, preliminary analyses, and future work. Knowledge of unsaturated transport properties is critical for understanding the movement of water through the unsaturated zone. Evaluation of the performance of a potential nuclear waste repository also depends on knowledge of these properties. Moisture-retention data are important input for numerical models of moisture movement in unsaturated porous media. Also important is the effect of sample history on the moisture-retention curves and whether there is significant hysteresis between wetting and drying measurements. This report presents the moisture-retention curves of the Single-Heater Test (SHT) and Drift-Scale Test (DST) core samples measured thus far. We have completed the measurement of the moisture-retention curves of those core samples in the wetting phase at 95{degrees}C. The moisture-retention curves at 95{degrees}C in the drying phase will be determined in the next quarter. The highest temperature at which the moisture-retention curves will be determined will be 95{degrees}C. Previous measurements of the matrix potential of tuff are reported by Roberts and Lin (1995) and in the Near-Field and Altered-Zone Environment Report (Wilder, 1996)