Open AccessStudy plan for water movement test: Site Characterization Plan Study 8.3.1.2.2.2
Author(s) -
A.E. Norris
Publication year - 1989
Language(s) - English
Resource type - Reports
DOI - 10.2172/137509
Subject(s) - precipitation , tracer , chlorine , groundwater , vadose zone , radioactive waste , chloride , percolation (cognitive psychology) , environmental science , soil water , hydrology (agriculture) , geology , radiochemistry , chemistry , meteorology , nuclear physics , soil science , nuclear chemistry , geography , physics , geotechnical engineering , organic chemistry , neuroscience , biology
The water movement tracer test is designed to produce information derived from isotopic measurements of soil and tuff samples collected from Yucca Mountain that is pertinent for assessing the performance of a nuclear waste repository. Measurements of chlorine isotropic distributions will help characterize the percolation of precipitation into the unsaturated zone. The {sup 36}Cl in the unsaturated zone occurs from atmospheric fallout of {sup 36}Cl produced by cosmic-ray secondaries reacting with {sup 40}Ar and, to a lesser extent, with {sup 36}Ar. It also occurs as global fallout from high-yield nuclear weapons tests conducted at the Pacific Proving Grounds between 1952 and 1962. When chloride ions at the surface are washed underground by precipitation, the radioactive decay of the {sup 36}Cl in the chloride can be used to time the rate of water movement. The {sup 36}l half-life of 301,000 yr permits the detection of water movement in the range of approximately 50,000 to 2 million years. These data are part of the input for developing numerical models of ground water flow at this site. 5 refs., 4 figs., 4 tabs