Hydrothermal interaction of solid wafers of Topopah Spring Tuff with J-13 water and distilled water at 90, 150, and 250{sup 0}C, using Dickson-type, gold-bag rocking autoclaves

Abstract

The Nevada Nuclear Waste Storage Investigations Project has conducted experi ments to study the hydrothermal interaction of rock and water representative of a poten tial high-level waste repository at Yucca Mountain, Nevada. The results of these experi ments help define the near-field repository environment during and shortly after the thermal period that results from the emplacement of nuclear waste. When considered in conjunction with results contained in companion reports, these results cm be used to assess our ability to accelerate tests using the surface area/volume parameter and/or temperature. These rock-water interaction experiments were conducted with solid polished wa fers cut from both drillcore and outcrop samples of Topopah tuff, using both a natural ground water and distilled water as the reacting fluid. Pre-and post-test characterization of the reacting materials was extensive. Post-test identification and chemical analysis of secondary phases resulting from the hvdrothermal interactions were aided by using monoliths of tuff rather than crushed material. All experiments were run in Dicksontvpe, gold-bag rocking autoclaves that were periodically sampled at in situ conditions. A total of nine short-term (up to 66-day) experiments were run in this series; these experi ments covered the range from 90 to 250°C and from 50 to 100 bar. The results obtained from the experiments have been used to evaluate the modeled results produced by cal culations using the geochemieal reaction process code EQ3/6.

Equilibrium Modeling of Clinoptilolite-Analcime Equilibria at Yucca Mountain, Nevada, USA

“…82 Heat capacity terms for equation Cp = k o + kiT -~ + k2 T-2 + k3~1 ~3 in units of J/mol.K estimated using Berman and Brown (1985). (Kerrisk 1987), well J-t3 water (Delany 1985), pore water obtained from Topopah Spring Tuff (Yang 1992) and projected water compositions using J-13 water equilibrated with Topopah Spring Tuff samples at elevated temperatures (Delany 1985;Peifer 1985, 1987;Knauss, Beiriger, Peifer and Piwinskii 1985;Knauss and Peifer 1986). Gray shading depicts the 90-~ data, black depicts the 150-~ data and striped depicts the 250-~ data.…”

“…Calculations assumed temperatures of 100 and 150 ~ and silica activities in equilibrium with cristobalite or quartz. Chemical compositions of J-13 water, measured pore water composition from Yang (1992), projected 90 and 150 ~ J-13 water compositions (Delany 1985;Peifer 1985, 1987;Knauss, Beiriger, Peifer and Piwinskii 1985;Knauss and Peifer 1986) and the chemical analyses of Yucca Mountain waters from Kerrisk (1987) are plotted on the figures for reference.…”

Results of plug-flow reactor experiments with crushed tuff at 280C and 300C

“…This phenocryst-poor (< 2%) tuff consists largely (-99 vol.%) of the former glassy matrix now devitrified to fine crystals of cristobalite, alkali feldspar, and quartz. Knauss and Wolery (1986) and Knauss et al (1985) provide detailed compositional data for both whole rock and individual mineral analyses performed on this material.…”

Stochastic hydrogeologic units and hydrogeologic properties development for total-system performance assessments. Yucca Mountain Site Characterization Project

“…Lahoud et al (1984) UE-25b #1 PA0001 1 Weeks and Wilson (1984) USW H-1 PA00012 Thordarson (1983) J-13 PA00013 Nimick et al (1987) USW G-2 PA00014 Anderson (1981a) UE-25a #1 PA00015 Anderson (1984) USW GU-3/G3 and USW G-4 PA00016 Lin and Daily (1984) Topopah Spring Tuff PA00017 Knauss et al (1985) Topopah Spring Tuff PA00018 Knauss and Peifer (1986) Topopah Spring Tuff PA00019 Schwartz (1990) Unsaturated zone tuffs PA00020 PA00021 Anderson (1981b) UE-25a #3 PA00023 Rush ef al. (1983) USW H-1 PA00025 Kume and Hammermeister (1990) usw uz-7 PA00029 Rutherford et al (1992) USW G-1, USW GU-3, and USW G-4 Figure 3-8 shows the histogram of the data and the beta-function PDF for unit 3 (Topopah Spring welded).…”