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DOE OSTI2024

DECOVALEX-2023: Task D Final Report

Task D of DECOVALEX-2023 is focused on the simulation of the coupled thermal hydraulic-mechanical (THM) behaviour in the full-scale engineered barrier system (EBS). The Horonobe EBS experiment is the demonstration of the full-scale EBS in the underground research laboratory (URL) (performed by JAEA in the Horonobe URL in Japan). Task D consisted of the three steps, a preliminary step (Step 0), simulation of the laboratory tests (Step 1) and simulation of the in-situ full-scale EBS experiment (Step 2). Since the Horonobe EBS experiment demonstrates the vertical emplacement option of the EBS, the experiment gallery is also backfilled with the backfill material. Therefore, interaction between the EBS and the backfill material can also be demonstrated, such as deformation (change of density) of the buffer material. The underground water in the Horonobe URL is saline. This fact adds chemical processes to THM behaviour. For example, mechanical properties (such as swelling pressure of the buffer material and backfill material) and hydraulic properties (such as permeability of the buffer material and backfill material) change depending on the water chemistry. Task D was therefore a challenging Task focused on not only the relatively simple THM behaviour but also complex THM behaviour including chemical processes. Six research teams (BGR, CAS, JAEA, KAERI, SNL and Taipower) participated the Task D. BGR, CAS, JAEA, KAERI and Taipower research teams selected a THM approach, while the SNL research team selected a TH approach. Step 1 involved the simulation of laboratory test results and was important to check the numerical codes developed by the research teams. Step 1 was divided into four sub steps. The simulation results through the Step 1 identified the parameters for simulation of the Step 2. Basic parameters of the materials (buffer material, backfill material, rock mass, concrete, sand) were provided by JAEA. Special parameters which research team needed were identified by back analysis of Step 1. Most notably the mechanical behaviour of swelling and displacement depended on the applied model (elastic model or elastoplastic model). Parameters such as Young’s modulus were found to need smaller values than characterised in the fundamental laboratory test results (Step 1-1, 1-2) for the elastic model. Although laboratory experiments are usually simple, test results contained some error. For example, if the saturation level is 100 % or higher, it should be considered an error. This situation was presented in the Step 1-3. A possible reason is that the buffer material is a mixture of bentonite and silica sand. When a specimen is cut to measure volume or weight, sand grains will affect the measurement data. In Step 2, boundary conditions such as temperature on the surface of the simulated overpack, heater power of the electrical heaters installed in the simulated overpack, injection pressure and inflow rate of the test water, were applied. The outer boundary conditions can be selected using measured data (injection pressure and inflow rate of the test water that is controlled by the injection systems installed in the sand layer around the buffer material and in the boundary between backfill material and concrete support). Since such measured data has some noise, research teams developed their own simplified boundary conditions. Inner boundary conditions can be selected using measured data as heater power and temperature on the surface of the simulated overpack. These data also contain some noise, so research teams developed their own simplified developed boundary conditions. Task D validated various approaches thorough the simulation of the in-situ full scale EBS system including backfill of the gallery: variations in the coupling processes (THM or THC), analysis codes, and boundary conditions. Temperature distribution in the buffer material was simulated well by all research teams. This means thermal behaviour is not sensitive to the simulation approaches. Although the water content distribution on the outside of the buffer material was well simulated by all research teams, the simulation results differ from the measured values inside the buffer material (at the centre and inside, near the simulated overpack). The buffer material is made from tap water, but in the in-situ experiment, saline groundwater infiltrates the buffer material. Therefore, the selection of the hydraulic parameters of the buffer material greatly affects the simulation results of the re saturation behaviour of the buffer material. In the Horonobe EBS experiment, measured values suitable for validating the simulation results were not obtained near the simulated overpack. When simulating the pressure and deformation of the buffer material, the measurement data is easily affected by the installation conditions of the measurement sensors, so verifying the measurement data itself remains an issue. Mechanical simulation results differ depending on whether they are considered as elastic or elastoplastic phenomena. The accuracy of measured in-situ data can be assessed by detailed analysis comparing sampling specimen analysis and measured data. The Horonobe EBS experiment is scheduled to be dismantled in the future (FY2026 and 2027). This detailed dismantling investigation will finally confirm the measured data.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS1985

Water permeation and dielectric breakdown. Water permeability in Pub Tedlar. Pub/Tedlar as a function of temperature and humidity

Moisture transport and dielectric breakdown of polyvinyl butyral (PVB), Tedlar, and PVB/Tedlar composites were addressed. Data for the temperature range between 20 and 80 C showed that the moisture flux through the composite is governed by the slower material; and that the composite permeability is intermediate to those of the component material, as predicted by theory. Data for Tedlar at 71 C, showing the dependence of moisture flux on relative humidity, was also presented. Dielectric breakdown data were less precise and less conclusive. The generally applied theoretical model does not match the experimental data. The PVB/Tedlar composite exhibited greater voltage breakdown resistance than either component. Testing of EVA and EVA/Tedlar composites is underway.

Orehotsky, J.↗

DOE OSTI2021

Convergence of micro-geochemistry and micro-geomechanics towards understanding proppant shale rock interaction: A Caney shale case study in southern Oklahoma, USA

As a direct outcome of economic development coupled with an increase in population, global energy demand will continue to rise in the coming decades. Although renewable energy sources are increasingly investigated for optimal production, the immediate needs require focus on energy sources that are currently available and reliable, with a minimal environmental impact; the efficient exploration and production of unconventional hydrocarbon resources is bridging the energy needs and energy aspirations, during the current energy transition period. The main challenges are related to the accurate quantification of the critical rock properties that influence production, their heterogeneity and the multiscale driven physico-chemical nature of rock–fluid interactions. A key feature of shale reservoirs is their low permeability due to dominating nanoporosity of the clay-rich matrix. As a means of producing these reservoirs in a cost-effective manner, a prerequisite is creation of hydraulic fracture networks capable of the highest level of continued conductivity. Fracturing fluid chemical design, formation brine geochemical composition, and rock mineralogy all contribute to swelling-induced conductivity damage. The Caney Shale is an organic-rich, often calcareous mudrock. Many studies have examined the impact that clay has on different kinds of shale productivity but there is currently no data reported on the Caney Shale in relation to horizontal drilling; all reported data on the Caney Shale is on vertical wells which are shallow, compared to an emerging play that is at double the depth. Here, in this work we develop geochemical–geomechanical integration of rock properties at micro-and nanoscales that can provide insights into the potential proppant embedment and its mitigation. The novel methodology amalgamates the following: computed X-ray tomography, scanning electron microscopy, energy dispersive spectroscopy, micro-indentation, and Raman spectroscopy techniques. Here, our results show that due to the multiscale heterogeneity in the Caney Shale, these geochemical and structural properties translate into a variation in mechanical properties that will impact interaction between the proppant and the host shale rock.

03 NATURAL GAS↗

DOE OSTI2018

Late-stage diagenetic concretions in the Murray formation, Gale crater, Mars

Concretions are prevalent features in the generally lacustrine deposits of the Murray formation in Gale crater. Here, we document the morphologic, textural, and chemical properties of these concretions throughout 300 m of Murray formation stratigraphy from Mars Science Laboratory observations between Sols 750–1900. We interpret these observations to constrain the timing and composition of post-depositional fluid events at Gale crater. We determine that the overall diversity of concretion morphology, size, texture, and chemistry throughout the Murray formation indicates that concretions formed in multiple, likely late diagenetic, episodes with varying fluid chemistries. Four major concretion assemblages are observed at distinct stratigraphic intervals and approximately correlate with major distinct chemical enrichments in Mg-S-Ni-Cl, Mn-P, and Ca-S, among other local enrichments. Different concretion size populations and complex relationships between concretions and veins also suggest multiple precipitation events at Gale crater. Many concretions likely formed during late diagenesis after sediment compaction and lithification, based on observations of concretions preserving primary host rock laminations without differential compaction. An upsection decrease in overall concretion size corresponds to an inferred upsection decrease in porosity and permeability, thus constraining concretion formation as postdating fluid events that produced initial cementation and porosity loss. The combined observations of late diagenetic concretions and distinct chemical enrichments related to concretions allow constraints to be placed on the chemistry of late stage fluids at Gale crater. Collectively, concretion observations from this work and previous studies of other diagenetic features (veins, alteration halos) suggest at least six post-depositional events that occurred at Gale crater after the deposition of the Murray formation.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2025

Self-Assembled Oligomers Facilitate Amino Acid-Driven CO 2 Capture at the Air–Aqueous Interface

Direct air capture of CO 2 using amino acid absorbents, such as glycine or sarcosine, is constrained by the relatively slow mass transfer of CO 2 through the air–aqueous interface. Our recent study showed a marked improvement in CO 2 capture by introducing CO 2 -permeable oligo-dimethylsiloxane (ODMS-MIM + ) oligomers with cationic (imidazolium, MIM + ) headgroups. Here, in this work, we have employed all-atom molecular dynamics simulations in combination with subensemble analysis using network theory to provide a detailed molecular picture of the behavior of CO 2 and the glycinate anions (Gly – ) at the ODMS-MIM + decorated air–aqueous interfaces. We show that the cationic head groups of the surfactants enhance the concentration and lifetime of Gly – in the interfacial region, while ODMS tails promote the physisorption of CO 2 in the interfacial region. Together, these two factors increase the effective region of contact and the probability of interactions between CO 2 and Gly – compared to that of the pure air–aqueous interface. The fundamental insights gained in this work establish essential foundations for developing hybrid systems with oligomer-decorated interfaces to maximize the overall CO 2 capture rates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS2003

Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

Park, Cheol↗

DOE OSTI2016

Sic-Sic Composite Interphase Evaluation via Small Scale Mechanical Testing

Silicon carbide (SiC) has emerged as a highly capable engineering material for extreme environment applications. It has proven particularly useful for high temperature applications where it exhibits exceptional strength, relative chemical inertness, and low coefficient of thermal expansion. Recent studies have shown that SiC also has excellent neutronic properties including low thermal neutron absorption, low tritium permeability, and high radiation tolerance. As a result, SiC-SiC composites are being considered for application in accident tolerant fuel cladding and other structural components for fission and fusion reactors. The standard crystalline form of SiC is inherently brittle and therefore subject to low damage tolerance. In order to increase the material toughness, SiC-SiC fiber-matrix composites have been developed. These composites are divided into three constituents; a highly crystalline and near stoichiometric SiC fiber (commonly Hi-Nicalon{sup TM} Type-S or Tyranno{sup TM}-SA), a (layered) interphase of graphitized pyrolytic carbon (PyC) around the fiber, and a chemical vapor infiltrated (CVI) SiC matrix that consolidates the material. Increased toughness is achieved through two primary mechanisms: increasing the crack length by introducing more barriers, and fiber pullout via interphase shear within the matrix. As a result, it has become critically important to understand the fundamental properties of SiC-SiC composites. However, comprehensive material properties are difficult to predict unless we have an in depth knowledge of the individual constituents (fiber, matrix, interphase) and how their properties interact with one another at the micro-scale. Of specific interest to this work are the interfacial properties of the fiber-matrix interface. This includes the internal friction coefficient and interfacial debond shear stress. (authors)

36 MATERIALS SCIENCE↗

DOE OSTI2015

Protective effects of methane-rich saline on diabetic retinopathy via anti-inflammation in a streptozotocin-induced diabetic rat model

As the commonest complication of diabetes mellitus (DM), diabetic retinopathy (DR) is a neuro-vascular disease with chronic inflammatory. Methane could exert potential therapeutic interest in inflammatory pathologies in previous studies. Our study aims to evaluate the protective effects of methane-rich saline on DR and investigate the potential role of related MicroRNA (miRNA) in diabetic rats. Streptozotocin-induced diabetic Sprague–Dawley rats were injected intraperitoneally with methane-rich or normal saline (5 ml/kg) daily for eight weeks. Morphology changes and blood-retinal barrier (BRB) permeability were assessed by hematoxylin eosin staining and Evans blue leakage. Retinal inflammatory cytokines levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL1-β) were evaluated by immunohistochemistry. Retinal protein expressions of glial fibrillary acidic protein (GFAP) and vascular endothelial growth factor (VEGF) were determined by western blotting. Retinal miRNA expressions were examined by miRNA-specific microarray, verified by quantitative RT-PCR and predicted by GO enrichment and KEGG pathway analysis. There was no significant changes in blood glucose level and body weight of diabetic rats with methane-rich or normal saline treatment, but the decreased retinal thickness, retinal ganglial cell loss and BRB breakdown were all significantly suppressed by methane treatment. DM-induced retinal overexpressions of TNF-α, IL-1β, GFAP and VEGF were also significantly ameliorated. Moreover, the methane treatment significantly up-regulated retinal levels of miR-192-5p (related to apoptosis and tyrosine kinase signaling pathway) and miR-335 (related to proliferation, oxidative stress and leukocyte). Methane exerts protective effect on DR via anti-inflammation, which may be related to the regulatory mechanism of miRNAs. - Highlights: • Methane exerts protective effect on diabetic retinopathy via anti-inflammation. • Therapeutic effect of methane is related to the regulatory mechanism of miRNAs. • As a therapeutic gas, methane will be a bright future.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Role of miR-155 in fluorooctane sulfonate-induced oxidative hepatic damage via the Nrf2-dependent pathway

Studies demonstrated that perfluorooctane sulfonate (PFOS) tends to accumulate in the liver and is capable to cause hepatomegaly. In the present study, we investigated the roles of miR-155 in PFOS-induced hepatotoxicity in SD rats and HepG2 cells. Male SD rats were orally administrated with PFOS at 1 or 10 mg/kg/day for 28 days while HepG2 cells were treated with 0–50 μM of PFOS for 24 h or 50 μM of PFOS for 1, 3, 6, 12 or 24 h, respectively. We found that PFOS significantly increased the liver weight and serum alanine transaminase (ALT) and aspartate amino transferase (AST) levels in rats. Morphologically, PFOS caused actin filament remodeling and endothelial permeability changes in the liver. Moreover, PFOS triggered reactive oxygen species (ROS) generation and induced apoptosis in both in vivo and in vitro assays. Immunoblotting data showed that NF-E2-related factor-2 (Nrf2) expression and activation and its target genes were all suppressed by PFOS in the liver and HepG2 cells. However, PFOS significantly increased miR-155 expression. Further studies showed that pretreatment of HepG2 cells with catalase significantly decreased miR-155 expression and substantially increased Nrf2 expression and activation, resulting in reduction of PFOS-induced cytotoxicity and oxidative stress. Taken together, these results indicated that miR-155 plays an important role in the PFOS-induced hepatotoxicity by disrupting Nrf2/ARE signaling pathway. - Highlights: • PFOS is capable to cause hepatotoxicity. • PFOS triggers ROS generation and induces apoptosis both in vivo and in vitro assays. • PFOS-induced ROS inhibits Nrf2 expression and its transactivation function. • PFOS promotes miR155 expression in liver and HepG2 cells. • miR-155 is involved in PFOS-induced hepatotoxicity by disrupting Nrf2/ARE pathway.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2024

Cellulose acetate membranes exhibit exceptional monovalent to divalent cation selectivities

Salt transport properties of cellulose acetate membranes are reported for a series of chloride salts with mono- valent and divalent cations (LiCl, NaCl, MgCl 2 , CaCl 2 ). Measurements include salt permeability and sorption, with diffusivity values calculated from the permeability and sorption results. We report an exceptionally high LiCl/MgCl 2 selectivity of 750:1. Salts with similar valence (LiCl and NaCl; MgCl 2 and CaCl 2 ) have similar transport properties. The high monovalent/divalent selectivity arises from differences in both sorption and diffusion, with a LiCl/MgCl 2 solubility selectivity of about 11 and a diffusivity selectivity of about 70. Atomistic molecular dynamics simulations show that ions tend to reside in isolated clusters of water. Increasing ion charge strengthens ion–water interactions relative to ion–polymer interactions, explaining the reduced sorption of divalent ions. Diffusion of ions through the membrane occurs via hop-like motion between water clusters. Lithium diffuses faster than magnesium due to weaker ion–water coordination for lithium, which allows for greater mobility within water clusters and more frequent hopping. Altogether, our atomistic simulations suggest that the high LiCl/MgCl 2 selectivity is linked to cellulose acetate’s high water/salt selectivity and is a consequence of low water content and relatively uniform water distribution.

36 MATERIALS SCIENCE↗

NASA NTRSDate not supplied

TRIDENT Drill Validation at Mars and Lunar Analog Field Sites

Drilling on Earth is typically a human-intensive activity. Drilling on other planets is further complicated by the lack of prior local field surveys of their target area, hence blindly drilling into uncertain target rocks. Field conditions on the Moon or Mars are also different than for shallow drilling on Earth: lower temperatures and pressures, less power available, low masses (hence less weight-on-bit). Given the cost of transport from Earth, no drilling muds or working fluids are likely to be available to carry away cuttings. And impact-gardened regolith and dust vary mechanically and texturally from most terrestrial soils. The Regolith and Ice Drill for Exploration of New Terrains (TRIDENT) is a rotary-percussive 1m-class drill from Honeybee Robotics. It is low-power (rotary and percussive actuators are 200 W each) and lightweight (<20 kg) with the maximum weight on bit limited to 200 N. TRIDENT has been manifested for the Volatiles Investigating Polar Exploration Rover (VIPER) and PRIME-1 lunar south pole missions in 2024, has previously been field tested at a hot, dry analog site in the Atacama Desert, and in lunar conditions in thermal vacuum chamber tests. TRIDENT was also part of the 2019 Icebreaker Mars Discovery proposal, as well as in the Mars Life Explorer concept. During ARADS tests, drill control and fault recovery automation software enabled hands-off operations of a rover-mounted TRIDENT drill. TRIDENT Drill Analog Site Validation: Past TRIDENT tests in thermal vacuum (TVAC) chambers targeted containers of manufactured lunar simulants with added volatiles. 2022 TRIDENT ambient testing at NASA Ames drilled into cemented lunar simulant materials. Low cuttings-permeability led to cuttings buildup, and drill choking and binding was observed. The Atacama analog site in ARADS had desiccated unconsolidated sediments that did not challenge the TRIDENT design. However, lunar polar regolith is expected to be diverse and heterogeneous with varying clast sizes, with abundant impactites and perhaps subsurface ice deposits. Neither the simulants nor Atacama testing had completely covered the TRIDENT-targeted field characteristics, motivating further analog tests prior to the planned lunar missions. To gain more insight into the behavior of the TRIDENT hardware in diverse impactites and subsurface ice, and to verify the software automation in that environment, in August 2023 TRIDENT was brought to Haughton Crater, a field analog site in the Canadian Arctic. In September 2023 the same drill was brought to the Bishop Tuff in southern California to verify whether drilling binding behaviors previously seen in lunar simulant testing would be observed in naturally occurring fine-grained massive layers. The ~22 Ma Haughton Crater impact structure is located at 75 ̊22’ N, 89 ̊41’ W, on northwestern Devon Island, Nunavut, Canada. Numerous deposits of pale-grey crater-fill polymictic impact-melt breccia are found within the crater with a typical thickness reaching ~125 m or greater and covering ~60 km -2 . An approximately 600m-thick permafrost layer is also present with ice typically found within 0.5-0.6m of the surface. The volcanic tableland north of Bishop, CA exposes densely welded tuff laid down during the eruption that created the Long Valley Caldera at approximately 0.76 Ma. Extensional faults and the Owens River gorge expose cross-sections across the plateau. The area is viewed as an analog site for Mars features believed to be of pyroclastic origin. Results: Haughton Crater.Drilling tests were conducted 8-13 August 2023 at a previously undisturbed area separated 5-10 m from past years’ Drill Hill test sites (75.4208, -089.7613). In six days, TRIDENT drilled 8 holes to nearly 1 m depth each, totaling 7.80 m. The active layer/ice boundary was at ~67 cm depth, with a total of approximately 2.4 m drilled into ice or ice-cemented impact breccia. During drilling, five drill fault states were observed and successfully recovered. Holes 23-1, 4 and 7 were drilled under manual control, using Honeybee’s Thorax user interface. Holes 23-5, 6, and 8 were drilled with the Ames IBexec automated drilling control software. TRIDENT was observed to have little difficulty in the thawed uncemented impact breccia above the active layer boundary, but required percussion to make slower headway in the ice-cemented breccia. In Hole 23-7 (Fig.1), drilling slowed down in a massive unit just above the active-layer boundary (perhaps a large rock extending into the ice-cementation?), with only 7cm progress made in 27 minutes of high auger torque and constant percussion, leading to a choking fault and then a binding fault. A similar pattern had been observed in TRIDENT Rio Tinto test data from 2017 [6] as well as in the 2022laboratory tests.Bishop Tuff.A team from NASA Ames and the US Geological Survey deployed the same TRIDENT drill to Bishop Sites 1B and 1C (37.4203, -118.4289; 37.4265, -118.4215) on 13-16 September 2023, on the Bishop Tuff plateau. A third drill site was used 17-18 September 2023(37.4598, -118.3667) in an abandoned pumice mine. Four holes (totaling 2.5m depth) were drilled into the fine-grained, meters-thick tuff units at Sites 1B and 1C, and a further two boreholes (totaling 1.98m depth) were made at the pumice site. Drill behavior in the tuff below 10 cm depth was similar to that seen at 65-74 cm depth in Haughton Hole 23-7 (Fig. 1) and that seen in the 2022 lab simulant drilling. Drill safety torque limits were exceeded multiple times resulting in drill stops downhole. These freezes then required external added torques (with a pipe wrench) to resume rotation, to unstick the drill for withdrawal. To prevent this choking and binding behavior we found that more-frequent cuttings removal was necessary, e.g., reducing the “drill bite” size from the nominal 10 cm to 2 cm per bite --bringing the auger up to the surface more frequently, as seen in Bishop Site 1C Hole 2 (Fig.2). This permitted slow progress without drill binding and without external interventions. Conversely, TRIDENT drilling in the more porous pumice target material showed no cuttings buildup issue, and single bites as large as 40 cm were demonstrated. Discussion: We observed that TRIDENT easily penetrated unconsolidated heterogeneous soils (both above the active layer boundary at Haughton and previously in the Atacama). Cemented or consolidated targets that were cuttings-permeable (icy impact breccia, pumice) required more energy applied and percussion. However, in non-cuttings-permeable targets (welded microporous tuff, cemented simulants, boulder) TRIDENT was observed to be prone to excessive cuttings accumulation leading to choking/binding faults and stalling. The wedge cutting bit, used by TRIDENT in field tests and in its flight versions, pulverizes the target rock and creates fine cuttings that ideally are transported up the auger spirals for removal. In porous, fractured or vesicular target materials (such as at the Bishop pumice site) a significant portion of the cuttings are pushed aside, but for non-fractured, microporous targets the cuttings remain in the borehole and accumulate. Rock powder is relatively incompressible as a working fluid at only 100-200N downward force (TRIDENT limits) and hence eventual drilling progress slows or stops. Our recommended strategy for improving TRIDENT cuttings removal in massive target units with low cuttings-permeability is to reduce TRIDENT bite sizes when encountering these units, from 10cm to as little as 1-2cm, to effectively bail the accumulating cuttings. This approach was demonstrated to reduce choking and allowed slow progress to continue in cuttings-impermeable microporous target units (viz. the Bishop tuff in our September 2023 tests or cemented simulants in 2022 ambient tests).

robotic drilling↗

DOE OSTI2025

Formation of Composite SiC/SiC Joints by Embedded Wire Chemical Vapor Deposition

The joining of ceramic monoliths or composites to date has primarily been limited to the formation of brittle monolithic joints using heterogeneous (dissimilar) materials, similar to brazing in metals. The development of a damage-tolerant joint layer by SiC fiber reinforcements is demonstrated here. Tube workpieces made of SiC fiber-SiC matrix composite are joined using a nonwoven SiC fiber mat densified by embedded wire chemical vapor deposition (EWCVD), creating a fiber-reinforced weld-like joint by homogeneous joining. EWCVD uses a localized heating method to target deposition and growth to the joint region specifically, while minimizing thermal damage to the surrounding composite tube material. X-ray computed tomography (XCT) is used to nondestructively characterize as-made joints for relative density, adhesion, and composition. In situ XCT analysis during mechanical testing revealed crack deflections in the bonding layer, which indicates a toughening mechanism typical of ceramic matrix composite phase. Gas permeation testing of these proof-of-concept composite joints identified relatively high leak rates in comparison to fully coated SiC/SiC composite tube workpieces. In conclusion, the novelty of the composite joining method and current technology challenges, including gas permeability, are discussed in comparison with traditional ceramic joints and materials.

SiC↗

DOE OSTI2020

Co-ion specific effect on sodium halides sorption and transport in a cross-linked poly(p-styrene sulfonate-co-divinylbenzene) for membrane applications

Here, sodium halide sorption and transport in a cation exchange membrane based on cross-linked poly(p-styrene sulfonate-co-divinylbenzene) (CR61) were investigated experimentally and theoretically. At fixed co-ion valence, sodium halide partitioning between aqueous electrolyte solutions and ion exchange polymers is only minimally sensitive to co-ion chemical identity. NaCl, NaF and NaI exhibit similar solubility coefficients in CR61, which agrees reasonably well with predictions of the Donnan-Manning model, especially at high external salt concentrations. Ion activity coefficients in the membrane were evaluated and ion sorption thermodynamics were investigated. Ion diffusion coefficients in CR61 were predicted using a recently developed framework based on the Manning diffusion model, which accounts for electrostatic effects on ion diffusion, and the Mackie-Meares model, which accounts for tortuosity/area effects on ion diffusion in swollen polymers. Model predictions agree reasonably well with the experimental data, especially at high external salt concentrations. The observed decrease in salt diffusion coefficients in CR61 relative to values in aqueous solutions is due primarily to tortuosity/area effects. Salt diffusion coefficients correlate with co-ion hydrated radius and membrane water content. Finally, salt permeability coefficients predicted using the solution-diffusion model exhibit good agreement with experimental data, especially at external salt concentration greater than 0.1 mol/L.

42 ENGINEERING↗

DOE OSTI2016

Critical dynamics of gravito-convective mixing in geological carbon sequestration

When CO 2 is injected in saline aquifers, dissolution causes a local increase in brine density that can cause Rayleigh-Taylor-type gravitational instabilities. Depending on the Rayleigh number, density-driven flow may mix dissolved CO 2 throughout the aquifer at fast advective time-scales through convective mixing. Heterogeneity can impact density-driven flow to different degrees. Zones with low effective vertical permeability may suppress fingering and reduce vertical spreading, while potentially increasing transverse mixing. In more complex heterogeneity, arising from the spatial organization of sedimentary facies, finger propagation is reduced in low permeability facies, but may be enhanced through more permeable facies. The connectivity of facies is critical in determining the large-scale transport of CO 2 -rich brine. We perform high-resolution finite element simulations of advection-diffusion transport of CO 2 with a focus on facies-based bimodal heterogeneity. Permeability fields are generated by a Markov Chain approach, which represent facies architecture by commonly observed characteristics such as volume fractions. CO 2 dissolution and phase behavior are modeled with the cubic-plus-association equation-of-state. Our results show that the organization of high-permeability facies and their connectivity control the dynamics of gravitationally unstable flow. Lastly, we discover new flow regimes in both homogeneous and heterogeneous media and present quantitative scaling relations for their temporal evolution.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2019

A Nonconventional CO 2 -EOR Target in the Illinois Basin: Oil Reservoirs of the Thick Cypress Sandstone

The Illinois State Geological Survey (ISGS) identified and quantified nonconventional carbon dioxide (CO 2 ) enhanced oil recovery (EOR) target opportunities within the thick Cypress Sandstone in the Illinois Basin. Up to 60 m thick Cypress Sandstone bodies define a northeast-southwest fairway that is approximately 230 km long and 100 km wide across the central portion of the Illinois Basin. These sandstones commonly contain relatively thin oil reservoirs and were found to have associated underlying residual oil zones (ROZs). The presence of a thick brine aquifer underlying the ROZ and high vertical permeability results in characteristic low primary oil recovery caused by excessive brine production from the aquifer. Nonconventional CO 2 -EOR in these oil reservoirs are expected to require more CO 2 to produce a unit of oil compared to conventional CO 2 -EOR. Consequently, nonconventional CO 2 -EOR will have a higher storage component and offer a unique storage opportunity. An integrated approach of detailed site-specific geologic reservoir characterization, three-dimensional geocellular modeling, and reservoir simulation of multiple development cases at Noble Field was employed to determine development strategies for CO 2 -EOR and storage. The findings of Noble Field research were leveraged to assess the regional CO 2 -EOR and associated storage resource within the nonconventional reservoirs of the thick Cypress Sandstone in the Illinois Basin. Regional characterization shows that thick, multistory fluvial facies of the Cypress Sandstone exhibits porosity from 15% to 21% and horizontal and vertical permeability up to approximately 0.98 µm 2 (1,000 mD). Oil saturation indicators screened from well records and well log analyses were used to map 27 brownfield and greenfield ROZ prospects with residual oil saturation (S OR ) values ranging from 14 to 35%. ROZ thickness varies from 2.7 to 21.6 m (9 to 71 ft). The 27 Cypress Sandstone ROZ prospects have approximately 290.8 million m 3 (1.8 billion barrels) of oil in place. Specific CO 2 -EOR development strategies depend on the goals of the project (prioritizing EOR performance vs. storage performance and NCNO) and geologic setting (brownfield vs greenfield), and company’s business strategies (economic metrics). Nevertheless, applying two unique development strategies derived from reservoir simulation of the depleted main pay zone and ROZ in the Cypress Sandstone at Noble Field, 31.1 million m 3 (196 million barrels) of oil is estimated to be recoverable using the 80-acre blanket WAG development strategy (which favors EOR and economic metrics, but is carbon positive) whereas 21.3 million m 3 (144 million barrels) of oil is estimated to be recoverable using the 40-acre high CO 2 injection rate development strategy (which favors storage and economic metrics and results in net carbon negative oil production). Storage of CO 2 associated with EOR in these ROZ prospects alone, not accounting for associated main pay zones, underlying brine formation, or intervals adjacent to or between prospects, is estimated to be up to 10.4 billion tonnes using the latter development strategy.

02 PETROLEUM↗

DOE OSTI2021

Can we safely go to 200 °C? An integrated approach to assessing impacts to the engineered barrier system in a high-temperature repository

Abstract. This presentation gives on overview of the complex thermo-hydro-mechanical-chemical (THMC) processes occurring during the disposal of heat-producing high-level radioactive waste in geologic repositories. A specific focus is on the role of compacted bentonite, which is commonly used as an engineered backfill material for emplacement tunnels because of its low permeability, high swelling pressure, and radionuclide retention capacity. Laboratory and field tests integrated with THMC modeling have provided an effective way to deepen our understanding of temperature-related perturbations in the engineered barrier system; however, most of this work has been conducted for maximum temperatures around 100 ∘C. In contrast, some international disposal programs have recently started investigations to understand whether local temperatures in the bentonite of up to 200 ∘C could be tolerated with no significant changes to safety relevant properties. Raising the maximum temperature is attractive for economical and safety reasons but faces the challenge of exposing the bentonite to significant temperature increases. Strong thermal gradients may induce complex moisture transport processes while geochemical processes, such as cementation and perhaps also illitization effects may occur, all of which could strongly affect the bentonite and near-field rock properties. Here, we present initial investigations of repository behavior exposed to strongly elevated temperatures. We will start discussing our current knowledge base for temperature effects in repositories exposed to a maximum temperature of 100 ∘C, based on data and related modeling analysis from a large heater experiment conducted for over 18 years in the Grimsel Test Site in Switzerland. We then show results from coupled THMC simulations of a nuclear waste repository in a clay formation exposed to a maximum temperature of 200 ∘C. We also explore preliminary data from a bench-scale laboratory mock-up experiment, which was designed to represent the strong THMC gradients occurring in a “hot” repository, and we finally touch on a full-scale field heater test to be conducted soon in the Grimsel Test Site underground research laboratory in Switzerland (referred to as HotBENT).

Birkholzer, Jens T. (ORCID:0000000279891912)↗

NASA NTRS2001

Membrane Separation of Gases From The Martian Atmosphere

A test bed has been constructed to test membrane modules for separation of gases under temperature and pressure conditions normally encountered on the surface of Mars. The test bed allows independent control of (1) feed flow rates, (2) feed composition, (3) feed pressure, (4) permeate pressure, and (5) operating temperature. Preliminary data obtained at a nominal feed pressure of 760 torr and permeate pressure of 10 torr has demonstrated the ability of one membrane module to operate at temperatures as low as -70 C. At temperatures below -40 C, however, significant loss of carbon dioxide and argon was observed, probably indicating condensation at the relatively high pressure used. As expected, permeation flow rates decreased with decreasing temperature, the flow at -30 C approximately 37% of the value at +23 C. Values of permeability for individual gas components showed similar decreases with decreasing temperature, but permeability ratios changed significantly. For example, the ratio of the permeabilities of carbon dioxide and nitrogen increased from 2.6 at 23 C to 5.6 at -30 C. Additional data at lower operating pressures and temperatures must be obtained in order to optimize design of a usable separation system.

Jennings, Paul A.↗

NASA NTRS2002

Membrane Separation of Gases from the Martian Atmosphere

A test bed has been constructed to test membrane modules for separation of gases under temperature and pressure conditions normally encountered on the surface of Mars. The test bed allows independent control of: (1) feed flow rates, (2) feed composition, (3) feed pressure, (4) permeate pressure, and (5) operating temperature. Preliminary data obtained at a nominal feed pressure of 760 torr and permeate pressure of 10 torr has demonstrated the ability of one membrane module to operate at temperatures as low as -70 C. At temperatures below -40 C, however, significant loss of carbon dioxide and argon was observed, probably indicating condensation at the relatively high pressure used. As expected, permeation flow rates decreased with decreasing temperature, the flow at -30 C approximately 37% of the value at +23 C. Values of permeability for individual gas components showed similar decreases with decreasing temperature, but permeability ratios changed significantly. For example, the ratio of the permeabilities of carbon dioxide and nitrogen increased from 2.6 at 23 C to 5.6 at -30 C. Additional data at lower operating pressures and temperatures must be obtained in order to optimize design of a usable separation system.

Jennings, Paul A.↗