Use of Chlorine Isotope Measurements to Trace Water Movements at Yucca Mountain.

摘要

The rates of water movements in the tuffs at Yucca Mountain are important for assessing the performance of a potential high-level nuclear waste repository. Measurements of cosmogenic 3.0 (times) 10(sup 5) yr (36)Cl in tuff from the unsaturated zone and in water from the saturated zone can provide information about water movements over times of 10(sup 15) to 10(sup 6) years. The data derived from the analysis of cuttings from a dry-drilled hole at Yucca Mountain indicate the presence of a (sup 36)Cl background that must be taken into account for proper interpretation of the (36)Cl interpretation of the (36)Cl results. Similarly, the (36)Cl measured in water from the saturated zone requires additional work for correct interpretation. Fallout of (36)Cl from nuclear weapons tests between 1952 and 1962 provided a tracer for an infiltration study. Measurements of the (36)Cl bomb pulse in tuffs from the unsaturated zone show potential for tracing recent water flow in faults and fractures. 5 refs.