Subsurface novel gas transport at the Nevada Test Site

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objective of our research was to explain the results of a groundwater pumping test done from 1975 to 1991 at the location of the nuclear test {open_quotes}Cambric{close_quotes} on the Nevada Test Site. The elution data from the pumped well indicated that krypton was delayed relative to tritium in the eluate and that less than half of the calculated Kr-85 source term was removed (though over 92% of the tritium was removed). We postulated an explanation for these observations and tested it with a mathematical model that simulated the movement of tritium and krypton at this site. The model showed that the hypothesis was consistent with the observed behavior; but the model was very sensitive to assumptions about initial radionuclide distributions and to hydrologic parameters. 1 ref