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Papers by Florie Caporuscio

Chemical Geology, Sep 1, 2023

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Apr 1, 2019

EGU General Assembly Conference Abstracts, Apr 1, 2019

EGU General Assembly Conference Abstracts, Apr 1, 2019

AGU Fall Meeting Abstracts, Dec 1, 2013

AGU Fall Meeting Abstracts, Dec 1, 2007

ABSTRACT For certain proposed new facilities at Los Alamos National Laboratory, located on the Pa... more ABSTRACT For certain proposed new facilities at Los Alamos National Laboratory, located on the Pajarito Plateau of northern New Mexico, completion of seismic hazards studies must precede any construction to ensure appropriate engineering for damaging earthquakes is included in building design. For one such study, a two-phase excavation exposed approximately 4000 sq. m (42,000 sq. ft) of the two uppermost subunits of the 1.22 Ma Tshirege Member of the Bandelier Tuff (Qbt3 and Qbt4) and interbedded pyroclastic surge in excavation walls for detailed geologic investigations. Using traditional paleoseismic trenching techniques in an unconventionally large setting, we obtained detailed data on exposed geologic features, including contacts, fractures, and faults. Geologic mapping at an approximate scale of 1:36 on digital photographs, coupled with high-precision geodetic surveys of identified features, place the data within a geospatial reference frame and provide an unparalleled 3- dimensional composite dataset of localized contact relationships and structure within Qbt3 and Qbt4. The majority of fracture orientations trend east-northeast, with an overwhelming predominance of vertical or near- vertical dips. The pyroclastic surge exhibits radical thickness changes over short distances. Qbt3 and Qbt4 are intensely fractured in places, with the fractures exhibiting variable amounts of vertical continuity and displacement across the pyroclastic surge in particular. Fractures are commonly curvilinear and terminate at the contact with the pyroclastic surge. Minor faults with less than 0.6 m (2 ft) of vertical displacement across the pyroclastic surge are present. Many of these small faults exhibit displacement only on the upper or lower contact of the surge deposit. In several locations, these small faults bound funnel-shaped, fines-depleted zones in Qbt3 with significant overlying shattering in Qbt4. Thus, very little of the observed deformation is apparently tectonic in origin; rather, most deformation probably occurred during cooling and compaction of the thick tuff deposit, and some pronounced deformation is associated with zones of localized paleo-fumarolic activity.

EGU General Assembly Conference Abstracts, Apr 1, 2019

Over the past seven years the Spent Fuel and Waste Science and Technology has investigated Engine... more Over the past seven years the Spent Fuel and Waste Science and Technology has investigated Engineered Barrier Systems (EBS) at higher heat loads (200 to 300 °C) and pressure (150 bar). This document presents the summary of Opalinus Clay experiments (EBS-14 to EBS-26). These results include clay mineral analyses, authigenic mineral formation, and steel interface and corrosion results. The past few years of experimental work focused on the interactions of Opalinus Clay wall rock and EBS components (e.g., bentonite, metal, and cement) at repository conditions and steel corrosion rates. Starting in FY-18, ordinary Portland Cement was added to the experimental system. A series of eight-week experiments were run in FY-18 (EBS-23 and EBS-24) and FY-19 (EBS-25 and EBS-26). Various types of stainless steel (316SS, 304SS, and LCS) were added to the experiments; future characterization will quantify the corrosion rates. This report documents the geochemical and mineralogical results of experiments EBS-14 through EBS-22, which included Opalinus Clay ± Wyoming Bentonite ± metal (Cu, 316SS, 304SS, and LCS). These experiments were conducted at 200 to 300 °C, 150 bar, and 6 weeks to 6 months. The aqueous solutions at 300 °C remained undersaturated with respect to quartz. Montmorillonite remained stable at 200 and 300 °C and very minor illite/illite-smectite was observed. Clay minerals in the Opalinus Clay fragments experienced significant changes at 300 °C, including the formation of illite, illite-smectite, and chlorite-smectite. Authigenic analcimewairakite was a major mineralogical product that formed at 300 °C along fractures and edges of Opalinus Clay fragments and within the bentonite matrix, but was not observed in the 200 °C products. The analcime-wairakite composition varies with the bulk composition of the system. Montmorillonite illitization within the Wyoming Bentonite EBS material was likely limited by the bulk chemistry of the system (i.e., low potassium and aluminum). Authigenic illite was likely limited to the Opalinus Clay fragments and nucleated on pre-existing illite in the shale. Previous experiments with only Wyoming Bentonite documented the transformation of precursor clinoptilolite into analcime with a sodium-and silica-rich composition. Results from Opalinus Clay-only 300 °C experiments indicate that the dissolution and re-precipitation of other phases, such as kaolinite, calcite, and smectite, may also contribute to zeolite formation, as Opalinus Clay does not contain the clinoptilolite precursor. Further, the low permeability limited authigenic analcime formation to fractures and edges of the Opalinus Clay fragments. Preliminary characterization of reaction products from the 200 °C Opalinus Clay-Wyoming Bentonite-Portland Cement experiment series are presented. Significant mineralogical changes occur with the introduction of cement. Structural degradation of the smectite mineral structure from within Wyoming Bentonite, due formation of interlayered illite, silica cementation, and/or CSH mineral intergrowth, resulted in ~10% reduction in expandability. Quantitative X-ray diffraction results indicate that combined illite, illite-smectite, and smectite in the bulk system was reduced by ~12 to 19 wt.%. Abundant Ca-rich silicate mineral formation was, including Ca-rich analcime, tobermorite (calcium silicate hydrate), and garronite (a rare Ca zeolite). QXRD results indicate these authigenic silicate phases make up ~15 to 17 wt.% of the reaction products. Amorphous material (gel) comprises 9-25% of the reaction products. The composition of analcime determined by electron microprobe reveals a wide range of Ca and Na compositions and lower Si/Al values than observed in previous EBS experiments. Steel corrosion and interface mineralogy was previously investigated for selected Opalinus Clay and Wyoming Bentonite experiments; roughly 4300 measurements of corrosion depth were taken. Low carbon steel (LCS) coupons exhibit pit corrosion and an average FY19 Argillite Disposal R&D-LANL May 30, 2019 corrosion rate of 1.95 µm/day. Goethite, an iron-bearing hydroxide, formed in the pits of the LCS. Other steel types (316SS and 304SS) have lower corrosion rates (0.23 and 0.37 µm/day, respectively) with less pitting and more general corrosion. Fe-saponite formed at the clay-steel interface for all three steel types in Opalinus Clay-Wyoming Bentonite systems. Early in FY-20, steel corrosion measurements will be made on coupons for all three types of steel that were included in Opalinus Clay-Wyoming Bentonite-Ordinary Portland Cement experiments. Preliminary mineralogical observations in the cement experiments indicate that major differences in mineralization at the steel coupon interface. Iron-rich clay phases (e.g., Fe-saponite) are not observed, and, instead, the surface is characterized by a layer of Fe-oxides, with minor Fe-Ni-Croxides and sulfides. Zeolites and CSH minerals are also observed at the steel surface. In one experiment, analcime is slightly enriched in iron. The results from the Opalinus Clay experiment series are significant for understanding zeolite formation, clay mineral stability, silica saturation, and steel corrosion within EBS materials of a high-temperature argillite-hosted repository. Our experimental results document the wide-ranging effects of bulk composition in the mineralogical and geochemical evolution of the repository environment.

Minerals, Dec 1, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

The tuffs of Yucca Mountain at the Nevada Test Site are currently under investigation as a possib... more The tuffs of Yucca Mountain at the Nevada Test Site are currently under investigation as a possible deep burial site for highlevel radioactive waste disposal. One of the main concerns is the effect of oxidizing groundwater on the transport of radionuclides. Rock components that may affect the oxygen content of groundwater include Fe-Ti oxides, Mn oxides, and glasses that contain ferrous iron. Some phenocryst Fe-Ti oxides at Yucca Mountain are in reduced states, whereas groundmass Fe-Ti oxides have been oxidized to hematite, rutile, and pseudobrookite (Fe 3+-bearing phases) exclusively. Estimates of Fa 2+-bearing oxides indicate that less than 0.33 vol% phenocryst c. is available to act as solid buffering agents of Eh. Of this percentage, significant amounts of Fe-Ti oxides, are isolated from effective interaction with groundwater because they occur in densely welded, devitrified tuffs that have low interstitial permeability. Manganese oxides occur primarily along fractures in the ashflow tuffs. Because the Mn oxides are concentrated along the same pathways (fractures) where transport has occurred in the past, these small volume percentages could act as buffers. However, the oxidation states of actual Mn-oxide phases are high (Mn 1 * 4 '), and these minerals have virtually no potential for reducing groundwater Eh. Manganese oxides may even act as oxidizing agents. However, regardless of their poor capabilities as reducing agents, the Mn oxides could be important as sorbents of heavy metals at Yucca Mountain. The lack of accessible, pristine Fe-Ti oxides and the generally high oxidation states of Mn oxides seem to rule out bhese oxides as Eh buffers of the Yucca Mountain groundwater system. Reduction of ferrous iron within glassy tuffs may have some effect on Eh, but further study is needed. At present it is prudent to assume that minerals and glasses have little or no capacity for reducing oxygen-rich groundwater at Yucca Mountain.

Portions of this document may be illegible electronic image products. Images are produced from th... more Portions of this document may be illegible electronic image products. Images are produced from the best available original document.

The Topopah Spring Member of the Paintbrush Tuff and the Lithic-rich tuff are two Tertiary volcan... more The Topopah Spring Member of the Paintbrush Tuff and the Lithic-rich tuff are two Tertiary volcanic units that occur in cores from drill holes UE25a-l and USW-Gl at Yucca Moun¬ tain, Nevada. Recently they have been suggested as possibly suitable for the permanent storage of high-level radioactive waste. This report augments earlier petrologic characteriza¬ tion of these units. The Topopah Spring Member (approximately 350 m thick) has two compound cooling units. The upper, thinner unit is densely welded to vitrophyric. The lower unit ranges from norwelded to vitrophyric, and its nonwelded base is exten¬ sively zeolitized to clinoptilolite and mordenite. Heulandite occurs as fracture fill in the overlying vitrophyric part, but zeolites are absent above that vitrophyre. Here primary devitrification plus vapor-phase crystallization dominate the mineralogy. Vapor-phase effects are especially prominent between the two vitrophyres in both cores and in¬ clude numerous large lithophysal cavities throughout most of this moderately to densely welded tuff. The Lithic-rich tuff extends from 1203 to 1506 m in the USW-Gl drill core. It is nonwelded to partly welded but is well indurated due to pervasive intergrowths of authigenic minerals. Thesr phases are analcime, albite, alkali feld¬ spar, sericite, chlorite and quartz. The transition from analcime to secondary albite corresponds to Iijima's zeolite Zone IV boundary, and this boundary appears in USW-Gl at 1326 m. However, analcime remains as a prominent phase through most of the Lithic-rich tuff. Further work is necessary to assess the suitability of either of these horizons for a waste repository. In the Topopah Spring Member, both mechanical and hydrologic proper¬ ties of the thick lithophysal zone must be studied, as well as the complete sequence of fracture fill. For both units, zeolite and clay mineral stabilities need to be investigated.

Journal of Nuclear Materials, Dec 1, 2018

Hydrothermal experiments on engineered barrier system (EBS) materials were conducted to character... more Hydrothermal experiments on engineered barrier system (EBS) materials were conducted to characterize high temperature interactions between bentonite and candidate waste container steels (304SS, 316SS, low-C steel) for deep geological disposition of nuclear spent fuel. Hydrothermal experiments were performed using Dickson reaction cells at temperatures and pressure of up to 300 C and 15e16 MPa, respectively, for four to six weeks. Wyoming bentonite was saturated with a 1900 ppm K-Ca-Na-Cl solution in combination with stainless and low-C steel coupons. Authigenic Fe-saponite precipitated utilizing steel as a growth substrate with Fe being supplied by steel corrosion. Concurrent with Fe-saponite formation, sulfides precipitated from sulfide-bearing fluids, from pyrite dissolution, near the steel interface. Sulfide mineral formation is dependent on the steel substrate composition: stainless steel produced pentlandite ((Ni, Fe) 9 S 8) and millerite (NiS), whereas low C steel generated pyrrhotite (Fe 7 S 8). The presence of sulfides suggests highly reduced environments at the steel-clay barrier interface potentially influencing overall steel corrosion rates and (re)passivation mechanisms. Results of this research show that nuclear waste steel container material may act as a substrate for mineral growth in response to corrosion during hydrothermal interactions with bentonite barriers.

Developments in Petrology, 1984

Abstract Two corundum-bearing kyanite eclogites from the Bobbejaan Mine, South Africa have been i... more Abstract Two corundum-bearing kyanite eclogites from the Bobbejaan Mine, South Africa have been investigated by optical and electron microprobe techniques. The two samples, respectively, contain 35% and 25% omphacitic clino-pyroxene, 45% and 58% garnet (Gr 47 Py 38 Al 15 ), 18% and 14% kyanite, and 2% and 3% corundum. Clinopyroxene grains in each sample contain oriented exsolution lamellae of both kyanite and garnet, however electron microprobe analysis indicates virtually no excess Al VI in either sample. Reconstruction of the original hypothetical precursor pyroxene indicates that it was more aluminous (25wt% Al 2 O 3 ) than the garnet and that the rock originally contained 80% or more modal pyroxene. The rocks are hypothesized to be differentiates from eclogitic liquids within the upper mantle. Inferred solidus conditions are 1350-1550°C and 40 to 50 kbars. Substantial subsolidus recrystallization has taken place and the rocks appear to have equilibrated at 1050 to 1150°C and 35 to 45 kbar pressure. The existence of peraluminous pyroxenes above 1300°C implies that the density of eclogites may be strongly a function of temperature at pressures above 40 kbar.

American Journal of Science, Nov 1, 1978

[American Journal of Science, Vol. 278, November, 1978, P. 1334-1342] OCCURRENCE OF SAPPHIRINE PL... more [American Journal of Science, Vol. 278, November, 1978, P. 1334-1342] OCCURRENCE OF SAPPHIRINE PLUS QUARTZ AT PEEKSKILL, NEW YORK FA CAPORUSCIO and SA MORSE Department of Geology and Geography, University of Massachusetts, Amherst, ...

This report is a supplement to a July 1996 report that presented the results of an independent te... more This report is a supplement to a July 1996 report that presented the results of an independent technical peer review of the adequacy of 24 conceptual models representing features, events, and processes involved in assessing the long-term performance of the Waste Isolation Pilot Plant (WIPP). WIPP has been developed at a site near Carlsbad, New Mexico, to become the nation's geologic repository for disposal of transuranic waste resulting from nuclear weapons programs. This independent peer review is required by 40 Code of Federal Regulations 194.27 as part of the Compliance Certification Application prepared by the U.S. Department of Energy (DOE). The U.S. Environmental Protection Agency (EPA) will use the peer review to help ensure that an adequate scientific foundation exists for a national decision on whether to dispose of this waste at WIPP. The peer review was initially conducted from April through June 1996 at the DOE Sandia National Laboratories by a six-member interdisciplinary Review Panel having the requisite broad experience to address the range of issues associated with waste isolation over the 10,000-year regulatory time frame. The Panel selection process and the biographies of the Panel members are included in the July 1996 report. A conceptual model is a statement of how important features, events, and processes such as fluid flow, chemical processes, or intrusion scenarios, are represented in the performance assessment. The Panel originally reviewed in detail the 24 conceptual models against the criteria of the EPA and NUREG 1297, including the scientific information used to develop the model, the assumptions, alternative models considered, uncertainties, adequacy, accuracy, and validity of conclusions. The Panel then determined whether the conceptual model is adequate for Disposal System Geometry

Chemical Geology, Sep 1, 2023

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Apr 1, 2019

EGU General Assembly Conference Abstracts, Apr 1, 2019

EGU General Assembly Conference Abstracts, Apr 1, 2019

AGU Fall Meeting Abstracts, Dec 1, 2013

AGU Fall Meeting Abstracts, Dec 1, 2007

ABSTRACT For certain proposed new facilities at Los Alamos National Laboratory, located on the Pa... more ABSTRACT For certain proposed new facilities at Los Alamos National Laboratory, located on the Pajarito Plateau of northern New Mexico, completion of seismic hazards studies must precede any construction to ensure appropriate engineering for damaging earthquakes is included in building design. For one such study, a two-phase excavation exposed approximately 4000 sq. m (42,000 sq. ft) of the two uppermost subunits of the 1.22 Ma Tshirege Member of the Bandelier Tuff (Qbt3 and Qbt4) and interbedded pyroclastic surge in excavation walls for detailed geologic investigations. Using traditional paleoseismic trenching techniques in an unconventionally large setting, we obtained detailed data on exposed geologic features, including contacts, fractures, and faults. Geologic mapping at an approximate scale of 1:36 on digital photographs, coupled with high-precision geodetic surveys of identified features, place the data within a geospatial reference frame and provide an unparalleled 3- dimensional composite dataset of localized contact relationships and structure within Qbt3 and Qbt4. The majority of fracture orientations trend east-northeast, with an overwhelming predominance of vertical or near- vertical dips. The pyroclastic surge exhibits radical thickness changes over short distances. Qbt3 and Qbt4 are intensely fractured in places, with the fractures exhibiting variable amounts of vertical continuity and displacement across the pyroclastic surge in particular. Fractures are commonly curvilinear and terminate at the contact with the pyroclastic surge. Minor faults with less than 0.6 m (2 ft) of vertical displacement across the pyroclastic surge are present. Many of these small faults exhibit displacement only on the upper or lower contact of the surge deposit. In several locations, these small faults bound funnel-shaped, fines-depleted zones in Qbt3 with significant overlying shattering in Qbt4. Thus, very little of the observed deformation is apparently tectonic in origin; rather, most deformation probably occurred during cooling and compaction of the thick tuff deposit, and some pronounced deformation is associated with zones of localized paleo-fumarolic activity.

EGU General Assembly Conference Abstracts, Apr 1, 2019

Over the past seven years the Spent Fuel and Waste Science and Technology has investigated Engine... more Over the past seven years the Spent Fuel and Waste Science and Technology has investigated Engineered Barrier Systems (EBS) at higher heat loads (200 to 300 °C) and pressure (150 bar). This document presents the summary of Opalinus Clay experiments (EBS-14 to EBS-26). These results include clay mineral analyses, authigenic mineral formation, and steel interface and corrosion results. The past few years of experimental work focused on the interactions of Opalinus Clay wall rock and EBS components (e.g., bentonite, metal, and cement) at repository conditions and steel corrosion rates. Starting in FY-18, ordinary Portland Cement was added to the experimental system. A series of eight-week experiments were run in FY-18 (EBS-23 and EBS-24) and FY-19 (EBS-25 and EBS-26). Various types of stainless steel (316SS, 304SS, and LCS) were added to the experiments; future characterization will quantify the corrosion rates. This report documents the geochemical and mineralogical results of experiments EBS-14 through EBS-22, which included Opalinus Clay ± Wyoming Bentonite ± metal (Cu, 316SS, 304SS, and LCS). These experiments were conducted at 200 to 300 °C, 150 bar, and 6 weeks to 6 months. The aqueous solutions at 300 °C remained undersaturated with respect to quartz. Montmorillonite remained stable at 200 and 300 °C and very minor illite/illite-smectite was observed. Clay minerals in the Opalinus Clay fragments experienced significant changes at 300 °C, including the formation of illite, illite-smectite, and chlorite-smectite. Authigenic analcimewairakite was a major mineralogical product that formed at 300 °C along fractures and edges of Opalinus Clay fragments and within the bentonite matrix, but was not observed in the 200 °C products. The analcime-wairakite composition varies with the bulk composition of the system. Montmorillonite illitization within the Wyoming Bentonite EBS material was likely limited by the bulk chemistry of the system (i.e., low potassium and aluminum). Authigenic illite was likely limited to the Opalinus Clay fragments and nucleated on pre-existing illite in the shale. Previous experiments with only Wyoming Bentonite documented the transformation of precursor clinoptilolite into analcime with a sodium-and silica-rich composition. Results from Opalinus Clay-only 300 °C experiments indicate that the dissolution and re-precipitation of other phases, such as kaolinite, calcite, and smectite, may also contribute to zeolite formation, as Opalinus Clay does not contain the clinoptilolite precursor. Further, the low permeability limited authigenic analcime formation to fractures and edges of the Opalinus Clay fragments. Preliminary characterization of reaction products from the 200 °C Opalinus Clay-Wyoming Bentonite-Portland Cement experiment series are presented. Significant mineralogical changes occur with the introduction of cement. Structural degradation of the smectite mineral structure from within Wyoming Bentonite, due formation of interlayered illite, silica cementation, and/or CSH mineral intergrowth, resulted in ~10% reduction in expandability. Quantitative X-ray diffraction results indicate that combined illite, illite-smectite, and smectite in the bulk system was reduced by ~12 to 19 wt.%. Abundant Ca-rich silicate mineral formation was, including Ca-rich analcime, tobermorite (calcium silicate hydrate), and garronite (a rare Ca zeolite). QXRD results indicate these authigenic silicate phases make up ~15 to 17 wt.% of the reaction products. Amorphous material (gel) comprises 9-25% of the reaction products. The composition of analcime determined by electron microprobe reveals a wide range of Ca and Na compositions and lower Si/Al values than observed in previous EBS experiments. Steel corrosion and interface mineralogy was previously investigated for selected Opalinus Clay and Wyoming Bentonite experiments; roughly 4300 measurements of corrosion depth were taken. Low carbon steel (LCS) coupons exhibit pit corrosion and an average FY19 Argillite Disposal R&D-LANL May 30, 2019 corrosion rate of 1.95 µm/day. Goethite, an iron-bearing hydroxide, formed in the pits of the LCS. Other steel types (316SS and 304SS) have lower corrosion rates (0.23 and 0.37 µm/day, respectively) with less pitting and more general corrosion. Fe-saponite formed at the clay-steel interface for all three steel types in Opalinus Clay-Wyoming Bentonite systems. Early in FY-20, steel corrosion measurements will be made on coupons for all three types of steel that were included in Opalinus Clay-Wyoming Bentonite-Ordinary Portland Cement experiments. Preliminary mineralogical observations in the cement experiments indicate that major differences in mineralization at the steel coupon interface. Iron-rich clay phases (e.g., Fe-saponite) are not observed, and, instead, the surface is characterized by a layer of Fe-oxides, with minor Fe-Ni-Croxides and sulfides. Zeolites and CSH minerals are also observed at the steel surface. In one experiment, analcime is slightly enriched in iron. The results from the Opalinus Clay experiment series are significant for understanding zeolite formation, clay mineral stability, silica saturation, and steel corrosion within EBS materials of a high-temperature argillite-hosted repository. Our experimental results document the wide-ranging effects of bulk composition in the mineralogical and geochemical evolution of the repository environment.

Minerals, Dec 1, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

The tuffs of Yucca Mountain at the Nevada Test Site are currently under investigation as a possib... more The tuffs of Yucca Mountain at the Nevada Test Site are currently under investigation as a possible deep burial site for highlevel radioactive waste disposal. One of the main concerns is the effect of oxidizing groundwater on the transport of radionuclides. Rock components that may affect the oxygen content of groundwater include Fe-Ti oxides, Mn oxides, and glasses that contain ferrous iron. Some phenocryst Fe-Ti oxides at Yucca Mountain are in reduced states, whereas groundmass Fe-Ti oxides have been oxidized to hematite, rutile, and pseudobrookite (Fe 3+-bearing phases) exclusively. Estimates of Fa 2+-bearing oxides indicate that less than 0.33 vol% phenocryst c. is available to act as solid buffering agents of Eh. Of this percentage, significant amounts of Fe-Ti oxides, are isolated from effective interaction with groundwater because they occur in densely welded, devitrified tuffs that have low interstitial permeability. Manganese oxides occur primarily along fractures in the ashflow tuffs. Because the Mn oxides are concentrated along the same pathways (fractures) where transport has occurred in the past, these small volume percentages could act as buffers. However, the oxidation states of actual Mn-oxide phases are high (Mn 1 * 4 '), and these minerals have virtually no potential for reducing groundwater Eh. Manganese oxides may even act as oxidizing agents. However, regardless of their poor capabilities as reducing agents, the Mn oxides could be important as sorbents of heavy metals at Yucca Mountain. The lack of accessible, pristine Fe-Ti oxides and the generally high oxidation states of Mn oxides seem to rule out bhese oxides as Eh buffers of the Yucca Mountain groundwater system. Reduction of ferrous iron within glassy tuffs may have some effect on Eh, but further study is needed. At present it is prudent to assume that minerals and glasses have little or no capacity for reducing oxygen-rich groundwater at Yucca Mountain.

Portions of this document may be illegible electronic image products. Images are produced from th... more Portions of this document may be illegible electronic image products. Images are produced from the best available original document.

The Topopah Spring Member of the Paintbrush Tuff and the Lithic-rich tuff are two Tertiary volcan... more The Topopah Spring Member of the Paintbrush Tuff and the Lithic-rich tuff are two Tertiary volcanic units that occur in cores from drill holes UE25a-l and USW-Gl at Yucca Moun¬ tain, Nevada. Recently they have been suggested as possibly suitable for the permanent storage of high-level radioactive waste. This report augments earlier petrologic characteriza¬ tion of these units. The Topopah Spring Member (approximately 350 m thick) has two compound cooling units. The upper, thinner unit is densely welded to vitrophyric. The lower unit ranges from norwelded to vitrophyric, and its nonwelded base is exten¬ sively zeolitized to clinoptilolite and mordenite. Heulandite occurs as fracture fill in the overlying vitrophyric part, but zeolites are absent above that vitrophyre. Here primary devitrification plus vapor-phase crystallization dominate the mineralogy. Vapor-phase effects are especially prominent between the two vitrophyres in both cores and in¬ clude numerous large lithophysal cavities throughout most of this moderately to densely welded tuff. The Lithic-rich tuff extends from 1203 to 1506 m in the USW-Gl drill core. It is nonwelded to partly welded but is well indurated due to pervasive intergrowths of authigenic minerals. Thesr phases are analcime, albite, alkali feld¬ spar, sericite, chlorite and quartz. The transition from analcime to secondary albite corresponds to Iijima's zeolite Zone IV boundary, and this boundary appears in USW-Gl at 1326 m. However, analcime remains as a prominent phase through most of the Lithic-rich tuff. Further work is necessary to assess the suitability of either of these horizons for a waste repository. In the Topopah Spring Member, both mechanical and hydrologic proper¬ ties of the thick lithophysal zone must be studied, as well as the complete sequence of fracture fill. For both units, zeolite and clay mineral stabilities need to be investigated.

Journal of Nuclear Materials, Dec 1, 2018

Hydrothermal experiments on engineered barrier system (EBS) materials were conducted to character... more Hydrothermal experiments on engineered barrier system (EBS) materials were conducted to characterize high temperature interactions between bentonite and candidate waste container steels (304SS, 316SS, low-C steel) for deep geological disposition of nuclear spent fuel. Hydrothermal experiments were performed using Dickson reaction cells at temperatures and pressure of up to 300 C and 15e16 MPa, respectively, for four to six weeks. Wyoming bentonite was saturated with a 1900 ppm K-Ca-Na-Cl solution in combination with stainless and low-C steel coupons. Authigenic Fe-saponite precipitated utilizing steel as a growth substrate with Fe being supplied by steel corrosion. Concurrent with Fe-saponite formation, sulfides precipitated from sulfide-bearing fluids, from pyrite dissolution, near the steel interface. Sulfide mineral formation is dependent on the steel substrate composition: stainless steel produced pentlandite ((Ni, Fe) 9 S 8) and millerite (NiS), whereas low C steel generated pyrrhotite (Fe 7 S 8). The presence of sulfides suggests highly reduced environments at the steel-clay barrier interface potentially influencing overall steel corrosion rates and (re)passivation mechanisms. Results of this research show that nuclear waste steel container material may act as a substrate for mineral growth in response to corrosion during hydrothermal interactions with bentonite barriers.

Developments in Petrology, 1984

Abstract Two corundum-bearing kyanite eclogites from the Bobbejaan Mine, South Africa have been i... more Abstract Two corundum-bearing kyanite eclogites from the Bobbejaan Mine, South Africa have been investigated by optical and electron microprobe techniques. The two samples, respectively, contain 35% and 25% omphacitic clino-pyroxene, 45% and 58% garnet (Gr 47 Py 38 Al 15 ), 18% and 14% kyanite, and 2% and 3% corundum. Clinopyroxene grains in each sample contain oriented exsolution lamellae of both kyanite and garnet, however electron microprobe analysis indicates virtually no excess Al VI in either sample. Reconstruction of the original hypothetical precursor pyroxene indicates that it was more aluminous (25wt% Al 2 O 3 ) than the garnet and that the rock originally contained 80% or more modal pyroxene. The rocks are hypothesized to be differentiates from eclogitic liquids within the upper mantle. Inferred solidus conditions are 1350-1550°C and 40 to 50 kbars. Substantial subsolidus recrystallization has taken place and the rocks appear to have equilibrated at 1050 to 1150°C and 35 to 45 kbar pressure. The existence of peraluminous pyroxenes above 1300°C implies that the density of eclogites may be strongly a function of temperature at pressures above 40 kbar.

American Journal of Science, Nov 1, 1978

[American Journal of Science, Vol. 278, November, 1978, P. 1334-1342] OCCURRENCE OF SAPPHIRINE PL... more [American Journal of Science, Vol. 278, November, 1978, P. 1334-1342] OCCURRENCE OF SAPPHIRINE PLUS QUARTZ AT PEEKSKILL, NEW YORK FA CAPORUSCIO and SA MORSE Department of Geology and Geography, University of Massachusetts, Amherst, ...

This report is a supplement to a July 1996 report that presented the results of an independent te... more This report is a supplement to a July 1996 report that presented the results of an independent technical peer review of the adequacy of 24 conceptual models representing features, events, and processes involved in assessing the long-term performance of the Waste Isolation Pilot Plant (WIPP). WIPP has been developed at a site near Carlsbad, New Mexico, to become the nation's geologic repository for disposal of transuranic waste resulting from nuclear weapons programs. This independent peer review is required by 40 Code of Federal Regulations 194.27 as part of the Compliance Certification Application prepared by the U.S. Department of Energy (DOE). The U.S. Environmental Protection Agency (EPA) will use the peer review to help ensure that an adequate scientific foundation exists for a national decision on whether to dispose of this waste at WIPP. The peer review was initially conducted from April through June 1996 at the DOE Sandia National Laboratories by a six-member interdisciplinary Review Panel having the requisite broad experience to address the range of issues associated with waste isolation over the 10,000-year regulatory time frame. The Panel selection process and the biographies of the Panel members are included in the July 1996 report. A conceptual model is a statement of how important features, events, and processes such as fluid flow, chemical processes, or intrusion scenarios, are represented in the performance assessment. The Panel originally reviewed in detail the 24 conceptual models against the criteria of the EPA and NUREG 1297, including the scientific information used to develop the model, the assumptions, alternative models considered, uncertainties, adequacy, accuracy, and validity of conclusions. The Panel then determined whether the conceptual model is adequate for Disposal System Geometry