Hydrochemical investigations in characterizing the unsaturated zone at Yucca Mountain, Nevada

Abstract

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, compietentss, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any spccific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not nccessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors exptessed herein do not nccessarily state or reflect those of the United States Government or any agency thereof. ~~ ~~ Calico Hills Figure 1. Hydrogeologic units at Yucca Mountain, Nevada [modified from Montazer and Wilson (1984), table 11. MD, moderately to densely welded; NP, nonwelded to partially welded; B, bedded; (V), vitric; (D), devitrified.

Calibration of Yucca Mountain unsaturated zone flow and transport model using porewater chloride data

“…The detailed description of these data was given in several reports (Yang et al, 1998, Fabryka-Martin et al, 1998 …”

“…Porewater chemical concentration data have been used to calibrate the UZ model to bound the infiltration flux, flow pathways, and transport time (Fabryka-Martin et al, 1994;Johnson and Depaolo, 1994;Meijer, 1995;Flint et al, 1996;Triay et al, 1996;Yang et al, 1996Yang et al, , 1998Fabryka-Martin et al, 1997;Sonnenthal and Bodvarsson, 1999;Scanlon, 2000). The distribution of chloride in the UZ is useful because this information integrates the effects of a variety of factors, such as hydrological processes of surface precipitation, evapotranspiration, the fracture-matrix interactions of flow and transport, large-scale mixing via lateral transport, and the history of climate changes and recharge.…”

Implications of halide leaching on 36Cl studies at Yucca Mountain, Nevada

“…The matrix permeability of the PTn is generally several orders of magnitude greater than that of the TCw and TSw, but the degree of fracturing is substantially less [LeCain, 1997]. Pore waters generally have higher Cl concentrations in the TCw and PTn units and lower concentrations in the TSw unit [Sonnenthal and Bodvarsson, 1999;Yang et al, 1998aYang et al, , 1998bYang et al, , 1996.…”

Stochastic simulations of steady state unsaturated flow in a three-layer, heterogeneous, dual continuum model of fractured rock

“…Elevated levels of the isotopes 36 Cl and 99 Tc observed at the repository level in the Exploratory Studies Facility (ESF) (Fabryka-Martin et al, 1996, 1997 and tritium in the Calico Hills unit (Yang et al, 1996(Yang et al, , 1998 indicate travel times to the repository horizon of 50 years or less. This conceptual model for rapid fracture flow is further supported by secondary calcite deposits observed in fractures throughout the exploratory studies facility (ESF), indicating significant fracture flow (Paces et al, 1996).…”