William Bourcier | Lawrence Livermore National Lab (original) (raw)

Papers by William Bourcier

Energy Procedia, 2011

For industrial-scale CO2 injection in saline formations, pressure increase can be a limiting fact... more For industrial-scale CO2 injection in saline formations, pressure increase can be a limiting factor in storage capacity. To address this concern, we introduce Active CO2 Reservoir Management (ACRM), which combines brine extraction and residual-brine reinjection with CO2 injection, contrasting it with the conventional approach, which we call Passive CO2 Reservoir Management. ACRM reduces pressure buildup and CO2 and brine migration,

The objectives of this report are to develop, summarize, and interpret a series of detailed uncla... more The objectives of this report are to develop, summarize, and interpret a series of detailed unclassified simulations that forecast the nature and extent of radionuclide release and near-field migration in groundwater away from the CHESHIRE underground nuclear test at Pahute Mesa at the NTS over 1000 yrs. Collectively, these results are called the CHESHIRE Hydrologic Source Term (HST). The CHESHIRE underground nuclear test was one of 76 underground nuclear tests that were fired below or within 100 m of the water table between 1965 and 1992 in Areas 19 and 20 of the NTS. These areas now comprise the Pahute Mesa Corrective Action Unit (CAU) for which a separate subregional scale flow and transport model is being developed by the UGTA Project to forecast the larger-scale migration of radionuclides from underground tests on Pahute Mesa. The current simulations are being developed, on one hand, to more fully understand the complex coupled processes involved in radionuclide migration, with...

Environmental Geology, 2002

Increasing concern about radioactive contamination of groundwater from underground nuclear tests ... more Increasing concern about radioactive contamination of groundwater from underground nuclear tests has reinforced the need for a basic understanding of how the radionuclide inventories of such tests enter and migrate through groundwater. As a basis for studying these processes, the physically and thermally disturbed geologic environment produced by such tests and its relation to the post-test distribution of radionuclides is discussed from a conceptual perspective. These concepts are used to support the development of a reactive transport model to evaluate the nature and extent of radionuclide contamination within alluvium surrounding a specific underground nuclear test at the Nevada Test Site (NTS). Simulations are focused on determining the abundance and chemical nature of radionuclides that are introduced into groundwater, as well as the rate and extent of radionuclide migration and reaction in groundwater surrounding the working point of the test. Transport simulations based upon a streamline-based numerical model are used to illustrate the nature of radionuclide elution out of the near-field environment and illustrate the conceptual modeling process. The numerical approach allowed for relatively complex flow and chemical reactions to be considered in a computationally efficient manner. The results are particularly sensitive to the rate of melt glass dissolution, distribution of reactive minerals in the alluvium, and overall groundwater flow configuration. They provide a rational basis from which defensible migration assessments over larger spatial and temporal scales can proceed.

Environmental Science & Technology, 2012

Methane is the most important greenhouse gas after carbon dioxide, with particular influence on n... more Methane is the most important greenhouse gas after carbon dioxide, with particular influence on near-term climate change. It poses increasing risk in the future from both direct anthropogenic sources and potential rapid release from the Arctic. A range of mitigation (emissions control) technologies have been developed for anthropogenic sources that can be developed for further application, including to Arctic sources. Significant gaps in understanding remain of the mechanisms, magnitude, and likelihood of rapid methane release from the Arctic. Methane may be released by several pathways, including lakes, wetlands, and oceans, and may be either uniform over large areas or concentrated in patches. Across Arctic sources, bubbles originating in the sediment are the most important mechanism for methane to reach the atmosphere. Most known technologies operate on confined gas streams of 0.1% methane or more, and may be applicable to limited Arctic sources where methane is concentrated in pockets. However, some mitigation strategies developed for rice paddies and agricultural soils are promising for Arctic wetlands and thawing permafrost. Other mitigation strategies specific to the Arctic have been proposed but have yet to be studied. Overall, we identify four avenues of research and development that can serve the dual purposes of addressing current methane sources and potential Arctic sources: (1) methane release detection and quantification, (2) mitigation units for small and remote methane streams, (3) mitigation methods for dilute (<1000 ppm) methane streams, and (4) understanding methanotroph and methanogen ecology.

Energy Procedia, 2014

Micro-encapsulated Carbon Sorbents (MECS) are a new class of carbon capture materials consisting ... more Micro-encapsulated Carbon Sorbents (MECS) are a new class of carbon capture materials consisting of a CO 2absorbing liquid solvent contained within solid, CO 2 -permeable, polymer shells. MECS enhance the rate of CO 2 absorption for solvents with slow kinetics and prevent solid precipitates from scaling and fouling equipment, two factors that have previously limited the use of sodium carbonate solution for carbon capture. Here, we examine the thermodynamics of sodium carbonate slurries for carbon capture. We model the vapour-liquid-solid equilibria of sodium carbonate and find several features that can contribute to an energy-efficient capture process: very high CO 2 pressures in stripping conditions, relatively low water vapour pressures in stripping conditions, and good swing capacity. The potential energy savings compared with an MEA system are discussed.

Commercial Demands vs. Water, Wildlife, and Human Ecosystems, 2013

Fractures and fracture networks are the principal pathways for migration of water and contaminant... more Fractures and fracture networks are the principal pathways for migration of water and contaminants in groundwater systems, fluids in enhanced geothermal systems (EGS), oil and gas in petroleum reservoirs, carbon dioxide leakage from geological carbon sequestration, and radioactive and toxic industrial wastes from underground storage repositories. When dealing with EGS fracture networks, there are several major issues to consider, e.g., the minimization of hydraulic short circuits and losses of injected geothermal fluid to the surrounding formation, which in turn maximize heat extraction and economic production. Gel deployments to direct and control fluid flow have been extensively and successfully used in the oil industry for enhanced oil recovery. However, to the best of our knowledge, gels have not been applied to EGS to enhance heat extraction. Insitu gelling systems can either be organic or inorganic. Organic polymer gels are generally not thermostable to the typical temperatures of EGS systems. Inorganic gels, such as colloidal silica gels, however, may be ideal blocking agents for EGS systems if suitable gelation times can be achieved. In the current study, we explore colloidal silica gelation times and rheology as a function of SiO 2 concentration, pH, salt concentration, and temperature, with preliminary results in the twophase field above 100 °C. Results at 25 °C show that it may be possible to choose formulations that will gel in a reasonable and predictable amount of time at the temperatures of EGS systems.

Titanate-based ceramic waste forms for the disposal of nuclear wastes have been the subjects of n... more Titanate-based ceramic waste forms for the disposal of nuclear wastes have been the subjects of numerous studies over the past decades. In order to assess the performance of this ceramic in a potential Yucca Mountain high-level waste (HLW) repository, it is necessary to understand the kinetics and mechanisms of corrosion of the ceramic under repository conditions. To this end, we are conducting single pass flow-through (SPFT) dissolution tests on ceramics relevant to Pu disposition. .

ABSTRACT Transmission electron microscopy results from a sintered ceramics with stoichiometry of ... more ABSTRACT Transmission electron microscopy results from a sintered ceramics with stoichiometry of Ca(U0.5Ce0.25Hf0.25)Ti 2O7 show the material contains both pyrochlore and zirconolite phases and structural intergrowth of zirconolite lamellae within pyrochlore. (001) plane of zirconolite is parallel to (111) plane of pyrochlore because of their structural similarities. The pyrochlore is relatively rich in U, Ce, and Ca with respect to the coexisting zirconolite. Average compositions for the coexisting pyrochlore and zirconolite at 1350 °C are Ca 1.01(Ce3+0.13Ce4+0.19U0.52Hf0.18)(Ti1.95Hf 0.05)O7 (with U/(U+Hf) = 0.72) and (Ca 0.91Ce0.09)(Ce3+0.08U 0.26Hf0.66Ti0.01)Ti2.00O 7 (with U/(U+Hf) = 0.28) respectively. A single pyrochlore (Ca(U,Hf)Ti2O7) phase may be synthesized at 1350 °C if the ratio of U/(U+Hf) is greater than 0.72, and a single zirconolite (Ca(Hf,U)Ti2O7) phase may be synthesized at 1350 °C if the ratio of U/(U+Hf) is less than 0.28. An amorphous leached layer that is rich in Ti and Hf forms on the surface after the ceramics has been leached in pH 4 buffered solution. The thickness of the layer ranges from 5 nm to 15 nm. The leached layer functions as a protective layer and therefore reduces the leaching rate.

Environmental Science & Technology, 2004

A durable titanate ceramic waste form (Synroc) with pyrochlore (Ca(U,Pu)Ti2O7) and zirconolite (C... more A durable titanate ceramic waste form (Synroc) with pyrochlore (Ca(U,Pu)Ti2O7) and zirconolite (CaZrTi2O7) as major crystalline phases has been considered to be a candidate for immobilizing various high-level wastes containing fissile elements (239Pu and 235U). Transmission electron microscopy study of a sintered ceramic with stoichiometry of Ca(U(0.5)Ce(0.25)Hf(0.25))Ti2O7 shows the material contains both pyrochlore and zirconolite phases and structural intergrowth of zirconolite lamellae within pyrochlore. The (001) plane of zirconolite is parallel to the (111) plane of pyrochlore because of their structural similarities. The pyrochlore is relatively rich in U, Ce, and Ca with respect to the coexisting zirconolite. Average compositions for the coexisting pyrochlore and zirconolite at 1350 degrees C are Ca(1.01)(Ce3+(0.13)Ce4+(0.19)U(0.52)Hf(0.18))(Ti(1.95)Hf(0.05))O7 (with U/(U + Hf) = 0.72) and (Ca(0.91)Ce(0.09))(Ce3+(0.08)U(0.26)Hf(0.66)Ti(0.01))Ti(2.00)O7 (with U/(U + Hf) = 0.28), respectively. A single pyrochlore (Ca(U,Hf)Ti2O7) phase may be synthesized at 1350 degrees C if the ratio of U/(U + Hf) is greater than 0.72, and a single zirconolite (Ca(Hf,U)Ti2O7) phase may be synthesized at 1350 degrees C if the ratio of U/(U + Hf) is less than 0.28. The synthesized products were used for dissolution tests. The single-pass flow-through dissolution tests show that the dissolution of the U-bearing pyrochlore is incongruent. All the elements are released at differing rates. The dissolution data also show a decrease in rate with run time. The results indicate that a diffusion-controlled process may play a key role during the release of U. TEM observation of the leached pyrochlore directly proves that an amorphous leached layer that is rich in Ti and Hf formed on the surface after the ceramic was leached in pH 4 buffered solution for 835 days. The thickness of the layer ranges from 6 to 10 nm. A nanocrystalline TiO2 phase also forms in the leached layer. The U leaching rate (g/(m2 day)) in acidic solutions can be expressed as log(NR) = -5.36-0.20 pH, where NR is the normalized rate. Conservative leaching rates of uranium [log(NR)] for the U-bearing ceramic at pH 2 and pH 4 solutions are -5.76 and -6.16 g/(m2 day), respectively. The results show that the U release rate of the ceramic waste is 10 times slower than that of defense high-level waste glass and about 1000 times slower than that of spent fuel. The pyrochlore-based ceramic is an ideal waste form for immobilizing long-lived radionuclides of 239Pu and 235U due to the Ti- and Hf-rich leached layer that forms on the ceramic surface. The leached layer functions as a protective layer and therefore reduces the leaching rate as thickness of the leached layer increases.

The present invention provides a new method and apparatus/system for purifying ionic solutions, s... more The present invention provides a new method and apparatus/system for purifying ionic solutions, such as, for example, desalinating water, using engineered charged surfaces to sorb ions from such solutions. Surface charge is applied externally, and is synchronized with oscillatory fluid movements between substantially parallel charged plates. Ions are held in place during fluid movement in one direction (because they are

$Research paper thumbnail of Direct observation of reactive flow in a single fracture$

Water Resources Research, 2001

We carried out a laboratory experiment to examine the relationship between local rate of dissolut... more We carried out a laboratory experiment to examine the relationship between local rate of dissolution and local aperture during flow of a slightly acidic aqueous solution through a rough fracture in Carrara marble under a confining pressure of 0.2 MPa. Fracture surfaces were digitized in three dimensions before the fluid flow tests and after the tests. Digital reconstruction of the aperture then allowed numerical simulation of flow patterns, and digital comparison of surfaces before and after dissolution allowed mapping of patterns of dissolution. We observed that both mean aperture and fracture permeability decreased as a result of dissolution. Despite the low confining pressure, the experiments thus simulate dissolution in deeply buried formations, in contrast to the gaping and karst formation that occur under vanishingly low confining pressure in the shallow crust. We observed that the growth of new pathways for flow changed from stable to unstable as length scale increased. At the millimeter scale the fracture aperture evolved in stable fashion from a strongly heterogeneous arrangement of tortuous flow channels to a smoother topography, while at the scale of the full rock (50 mm), the aperture developed a single, broad flow channel. The scale dependence of the dissolution pattern may be the result of changes with scale in extent of reaction (i.e., the Damk6hler number) and in the relative importance of diffusion (the Peclet number). Finally, we also see evidence of a negative relationship between local fluid flux and local rate of dissolution in some locations in the fracture.

MRS Proceedings, 1992

We simulated the reaction of SRL-131 glass with equilibrated J-13 water in order to investigate t... more We simulated the reaction of SRL-131 glass with equilibrated J-13 water in order to investigate the effects of surface area to volume ratio (SA/V) on glass dissolution. We show that glass-fluid ion exchange causes solution pH to rise to progressively higher values as SA/V increases. Because the ion exchange is rapid relative to the duration of the glass dissolution experiment,

A kinetic model for the dissolution of borosilicate glass, incorporated into the EQ3/6 geochemica... more A kinetic model for the dissolution of borosilicate glass, incorporated into the EQ3/6 geochemical modeling code, is used to predict the dissolution rate of a nuclear waste glass. The glass dissolution rate is controlled by the rate of dissolution of an alkali-depleted amorphous surface gel layer. The good agreement between predicted and observed dissolution behavior suggests that the experimentally obtained non-linear glass release rates are not diffusion controlled, as previously believed, but are instead controlled by dissolution affinity. The model predicts that the long-term rate of glass dissolution will depend mainly on ion concentrations in solution, and therefore the secondary phased which precipitate and control ion concentrations. 4 refs., 5 figs., 1 tab.

Energy Procedia, 2011

... com/locate/XXX GHGT-10 Fresh water generation from aquifer-pressured carbon storage: feasibil... more ... com/locate/XXX GHGT-10 Fresh water generation from aquifer-pressured carbon storage: feasibility of treating saline formation waters Roger D. Aines a ... While not true in all cases, such pressure buildup is observed today at the In Salah and Cranfield sites (Havorka 2009 pers. ...

Nature communications, 2015

Drawbacks of current carbon dioxide capture methods include corrosivity, evaporative losses and f... more Drawbacks of current carbon dioxide capture methods include corrosivity, evaporative losses and fouling. Separating the capture solvent from infrastructure and effluent gases via microencapsulation provides possible solutions to these issues. Here we report carbon capture materials that may enable low-cost and energy-efficient capture of carbon dioxide from flue gas. Polymer microcapsules composed of liquid carbonate cores and highly permeable silicone shells are produced by microfluidic assembly. This motif couples the capacity and selectivity of liquid sorbents with high surface area to facilitate rapid and controlled carbon dioxide uptake and release over repeated cycles. While mass transport across the capsule shell is slightly lower relative to neat liquid sorbents, the surface area enhancement gained via encapsulation provides an order-of-magnitude increase in carbon dioxide absorption rates for a given sorbent mass. The microcapsules are stable under typical industrial operat...

A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was... more A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was undertaken in order to derive an estimate of glass reactive surface area. Reactive surface area is needed to model release rates of radionuclides from nuclear melt glass in the subsurface. Because of the limited availability of nuclear melt glasses, natural volcanic glass samples were collected which

Journal of Nuclear Materials, 2001

This paper presents experimental studies on the kinetics of U release from near single-phase zirc... more This paper presents experimental studies on the kinetics of U release from near single-phase zirconolite, pyrochlore, brannerite and pyrochlore-rich titanate ceramic materials. The dissolution tests were conducted at 20–75°C with initial pHs from 2 to 12, and flow rates from 10 to 80 ml d−1 in the open atmosphere. The U releases from these titanate materials are controlled by initial

Energy Procedia, 2011

Environmental Geology, 2002

Environmental Science & Technology, 2012

Energy Procedia, 2014

Commercial Demands vs. Water, Wildlife, and Human Ecosystems, 2013

Environmental Science & Technology, 2004

$Research paper thumbnail of Direct observation of reactive flow in a single fracture$

Water Resources Research, 2001

MRS Proceedings, 1992

Energy Procedia, 2011

Nature communications, 2015

Journal of Nuclear Materials, 2001