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At least 541 records · Page 30

Digitalization, Management and Synthesis of Thermal Hydraulic Legacy Data Using Dynamical System Scaling

A unique attribute of the nuclear industry is the extent by which designers, developers, operators, and regulators pay attention to demonstrating the safety case. The safety case for nuclear systems is a written, traceable expression of safety, demonstrating the system’s protective measures against uncontrolled radiological releases. The nuclear installation resiliency or safety takes overriding priority over function and performance. The preparation of the safety case heavily relies on extensive experimental campaigns that challenge the target design under a spectrum of postulated accident scenarios. For safety reasons, these experiments are typically conducted in sub-scale test apparatuses intended to reproduce the postulated accident scenarios and event sequences realistically but subject to proven similarity criteria, often referred to as scaling analyses. Since the dawn of the nuclear industry, significant resources have been committed to the construction and operation of such test facilities and a massive amount of data has been generated. Such test data have been and are still used to validate the fundamental assumptions of nuclear power plant phenomena. As we move into the digital world, capturing this multi-decades worth of information in a transparent, easily accessible, and usable manner for the public and industry stakeholders is of paramount importance. Over the last few years FPoliSolutions has been actively developing an enterprise digital data ontology platform (FPoliDON) intended to do just that. The concept was introduced in a paper at the previous NURETH edition and has been significantly enhanced since. With the vision of helping designers use the data to assess their safety case evaluation models, the platform was designed not only to ontologically organize the experimental data, but also to guide the user in the complex analytics associated with the interpretation and use of such test results. A new feature which has been recently added is the ability for the user to access a library of sophisticated mathematical procedures for performing scaling analyses. For this purpose, the Dynamical System Scaling (DSS) procedure invented by Dr. Jose’ Reyes was formulated as one of the services in the digital platform. These methods have been demonstrated to provide an excelled mathematical apparatus to identify similarity criteria or quantify distortions between measured data and the target prototypical conditions. Moreover, DSS can provide a level of synthesis across SETs and IETs which has the promise to yield efficiency in the evaluation code assessment activities. This is often a daunting and expensive task to set up evaluation models that support the safety case of current and future nuclear power plants.

Reyes, Jose↗

Bench-Scale Testing of Monolithic PPI Structured Contactors for Direct Air Capture of CO 2

The overall project objective was to develop, optimize and bench-scale test the integrated embodiment of a leading direct air capture (DAC) sorbent composition, linear-poly(propylenimine) (l-PPI), in a structured material system, specifically a monolithic contactor for achieving low pressure drop, to justify its further scale-up in a subsequent program. The project team was led by CORMETECH, a leading monolithic gas/solid contactor manufacturer for environmental applications, and included Global Thermostat, a well-known DAC start-up, and Georgia Tech, a prominent US academic institution in carbon capture and DAC. The monolithic contactor for l-PPI in this project employed an advanced, cost-effective fabrication technique from CORMETECH, namely a porous monolith substrate directly impregnated with the amine, an approach contrasting to the traditional wash-coating methods used for activating monoliths. The l-PPI monolithic contractor is targeted for use in DAC systems such as the Global Thermostat DAC process, which involves the cyclic operation of ambient air flow over a monolithic amine contactor followed by steam-mediated thermal desorption and CO 2 collection, maximizing volumetric productivity while reducing the auxiliary power required to capture CO 2 from air. The Global Thermostat DAC process currently utilizes poly(ethyleneimine) (PEI) materials as baseline sorbents, which are subject to oxidative degradation and slow capacity fade at the elevated temperature required for efficient CO 2 removal. Georgia Tech, with Global Thermostat, had discovered in lab-scale efforts that l-PPI had superior resistance to oxidative degradation compared to PEI, with similar CO 2 adsorption capacity. While the novel l-PPI sorbent offers significant advantages over PEI for DAC, including potential design simplification and increased process efficiency, it is not commercially available, and prior to this project, had not yet been evaluated on the bench-scale in a structured contactor.

36 MATERIALS SCIENCE↗

Development And Initial Testing Of Off-Gas Recycle Liquid From The WTP Low Activity Waste Vitrification Process - 14333

The Waste Treatment and Immobilization Plant (WTP) process flow was designed to pre-treat feed from the Hanford tank farms, separate it into a High Level Waste (HLW) and Low Activity Waste (LAW) fraction and vitrify each fraction in separate facilities. Vitrification of the waste generates an aqueous condensate stream from the off-gas processes. This stream originates from two off-gas treatment unit operations, the Submerged Bed Scrubber (SBS) and the Wet Electrospray Precipitator (WESP). Currently, the baseline plan for disposition of the stream from the LAW melter is to recycle it to the Pretreatment facility where it gets evaporated and processed into the LAW melter again. If the Pretreatment facility is not available, the baseline disposition pathway is not viable. Additionally, some components in the stream are volatile at melter temperatures, thereby accumulating to high concentrations in the scrubbed stream. It would be highly beneficial to divert this stream to an alternate disposition path to alleviate the close-coupled operation of the LAW vitrification and Pretreatment facilities, and to improve long-term throughput and efficiency of the WTP system. In order to determine an alternate disposition path for the LAW SBS/WESP Recycle stream, a range of options are being studied. A simulant of the LAW Off-Gas Condensate was developed, based on the projected composition of this stream, and comparison with pilot-scale testing. The primary radionuclide that vaporizes and accumulates in the stream is Tc-99, but small amounts of several other radionuclides are also projected to be present in this stream. The processes being investigated for managing this stream includes evaporation and radionuclide removal via precipitation and adsorption. During evaporation, it is of interest to investigate the formation of insoluble solids to avoid scaling and plugging of equipment. Key parameters for radionuclide removal include identifying effective precipitation or ion adsorption chemicals, solid-liquid separation methods, and achievable decontamination factors. Results of the radionuclide removal testing indicate that the radionuclides, including Tc-99, can be removed with inorganic sorbents and precipitating agents. Evaporation test results indicate that the simulant can be evaporated to fairly high concentration prior to formation of appreciable solids, but corrosion has not yet been examined.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Technical Basis and Implementation of Groundwater Pathway Models Used for INL's RH LLW Disposal Facility Performance Assessment - 19440

The Idaho National Laboratory's (INL's) Remote-Handled Low-Level Waste (RH LLW) Disposal Facility has been designed and constructed to receive waste generated by INL in support of the Office of Nuclear Energy (NE) and Naval Reactors (NR) missions. RH LLW is generated on the INL site from spent nuclear fuel handling and operations at the Naval Reactors Facility (NRF), the Advanced Test Reactor (ATR), and at the Material and Fuels Complex (MFC) in addition to other miscellaneous research activities. The facility has been designed to receive RH LLW currently in storage at INL facilities and new waste generated by nuclear research programs. RH LLW received at the facility is solid waste consisting of surface contaminated materials, ion exchange resins used to purify cooling water, and activated metals generated during reactor core change outs, Naval spent fuel management, and nuclear R and D. The facility has been designed to meet the requirements of DOE Order 435.1, Radioactive Waste Management for all-pathways including groundwater and air, radon emissions limits, and inadvertent intrusion limits. The facility design includes a vault system incorporating robust concrete vaults oriented vertically in close-packed arrays, a hydraulic drainage system designed to limit water contact with the stainless steel waste canisters and concrete vaults, and a robust monitoring system. Per the environmental assessment (EA), all waste will be disposed of in stainless steel waste canisters. During facility design and construction, site-specific data was collected to provide laboratory and field scale performance characteristics for the concrete vault and hydraulic drainage systems. Field-scale infiltration tests were conducted and monitoring data was interpreted using numerical simulation. Based on interpretation of the observed laboratory and field test data, the facility performance assessment (PA) was developed. The PA groundwater pathway source release model differentially credits release from surface contaminated waste, ion exchange resins, and activated metals. It also credits steel waste canisters with failure rates based on actual corrosion data. Once released, radionuclide transport through the vadose zone and aquifer to downgradient receptor locations was simulated in the PA using a one-dimensional modeling approach based on three-dimensional modeling of historically-contaminated INL sites. This paper provides an overview of the groundwater pathway source release models and their technical implementation in the PA. It also describes the one-dimensional transport model used for the vadose zone and multi-dimensional model used for the aquifer. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Design and Optimization of Structured Multi-Functional Trapping Catalysts for Conversion of Hydrocarbons and NOx from Diesel and Advanced Combustion Engines

Oxides of nitrogen in the form of nitric oxide (NO) and nitrogen dioxide (NO 2 ) commonly referred to as NOx, is one of the two chemical precursors that lead to ground-level ozone, a ubiquitous air pollutant in urban areas. A major source of NOx is generated by equipment and vehicles powered by diesel engines, which have a combustion exhaust that contains NOx in the presence of excess O 2 . Vehicular emission control catalysts are ineffective in eliminating CO, hydrocarbons, and NOx during engine cold-start when exhaust temperatures are below 200°C. The objective of the project was to develop and demonstrate a multi-functional, catalyzed trap that enables vehicles with advanced combustion strategies to meet Tier 3 emissions standards while achieving the 150 °C challenge for sustained co-oxidation of HCs and CO and ≥90% NO trapping and release during warmup. Specifically, the multi-functional Lean HC+NOx (LHCNT) was developed for application in the exhaust aftertreatment of conventional diesel engines and engines having low temperature combustion (LTC) regimes. Activities included the design and synthesis of adsorbents and catalysts, screening and evaluation. Passive NOx absorbers (PNA), hydrocarbon (HC) traps, and oxidation catalysts (OC) were evaluated for use in series or as integrated devices. Predictive tools were developed utilizing the characterization and analysis of these materials, and an emission system was designed and optimized utilizing the catalyst systems. Microkinetic models were developed for the PNA for the simple NO-only feed and complex feed containing CO, H 2 , and model hydrocarbons (ethylene and dodecane). A first-principles, mechanistic-based model of the PNA was developed which utilized molecular-scale estimates (density functional theory) of energy barriers, mechanistic-based kinetics and realistic treatments of the flow and transport processes. Two new oxidation catalysts were developed (PdCu alloy, mixed copper-ceria-cobalt oxide), both of which significantly lessened the detrimental inhibition by CO on hydrocarbon and NO oxidation. A method for lessening the detrimental impact of CO on PNA activity was developed that involves use of an oxidation catalyst upstream of the PNA. The SwRI Ectolab TM burner system was applied to evaluate the baseline PNA material and confirmed performance comparable to the benchflow PNA studies using simulated exhaust. Spatially-resolved mass spectrometry (SpaciMS) was used to measure the transient spatial profiles of reacting species spanning the length of a three-function LHCNT containing PNA, HCT, and OC. The findings from this study provide diesel vehicle and catalyst companies valuable information to develop more cost effective emission control catalysts which helps to expand the use of more fuel efficient diesel power. The fundamental modeling and experimental tools and findings from this project can be applied to catalyst technologies used in the energy and chemical industries. The project led to 14 publications in the peer-reviewed literature with 2 additional currently under review. Finally, the project also led to training of several doctoral students who were placed in research jobs in industry and academia. Specifically, Mugdha Ambast (UH) has joined Cummins, Kevin Gu (UVa) has joined GM, and Abhay Gupta (UH) is to join Caterpillar.

02 PETROLEUM↗

Design and Optimization of Structured Multi-Functional Trapping Catalysts for Conversion of Hydrocarbons and NOx from Diesel and Advanced Combustion Engines

Oxides of nitrogen in the form of nitric oxide (NO) and nitrogen dioxide (NO 2 ) commonly referred to as NOx, is one of the two chemical precursors that lead to ground-level ozone, a ubiquitous air pollutant in urban areas. A major source of NOx is generated by equipment and vehicles powered by diesel engines, which have a combustion exhaust that contains NOx in the presence of excess O 2 . Vehicular emission control catalysts are ineffective in eliminating CO, hydrocarbons, and NO x during engine cold-start when exhaust temperatures are below 200°C. The objective of the project was to develop and demonstrate a multi-functional, catalyzed trap that enables vehicles with advanced combustion strategies to meet Tier 3 emissions standards while achieving the 150 °C challenge for sustained co-oxidation of HCs and CO and ≥90% NO trapping and release during warmup. Specifically, the multi-functional Lean HC+NOx (LHCNT) was developed for application in the exhaust aftertreatment of conventional diesel engines and engines having low temperature combustion (LTC) regimes. Activities included the design and synthesis of adsorbents and catalysts, screening and evaluation. Passive NOx absorbers (PNA), hydrocarbon (HC) traps, and oxidation catalysts (OC) were evaluated for use in series or as integrated devices. Predictive tools were developed utilizing the characterization and analysis of these materials, and an emission system was designed and optimized utilizing the catalyst systems. Microkinetic models were developed for the PNA for the simple NO-only feed and complex feed containing CO, H 2 , and model hydrocarbons (ethylene and dodecane). A first-principles, mechanistic-based model of the PNA was developed which utilized molecular-scale estimates (density functional theory) of energy barriers, mechanistic-based kinetics and realistic treatments of the flow and transport processes. Two new oxidation catalysts were developed (PdCu alloy, mixed copper-ceria-cobalt oxide), both of which significantly lessened the detrimental inhibition by CO on hydrocarbon and NO oxidation. A method for lessening the detrimental impact of CO on PNA activity was developed that involves use of an oxidation catalyst upstream of the PNA. The SwRI Ectolab TM burner system was applied to evaluate the baseline PNA material and confirmed performance comparable to the benchflow PNA studies using simulated exhaust. Spatially-resolved mass spectrometry (SpaciMS) was used to measure the transient spatial profiles of reacting species spanning the length of a three-function LHCNT containing PNA, HCT, and OC. The findings from this study provide diesel vehicle and catalyst companies valuable information to develop more cost effective emission control catalysts which helps to expand the use of more fuel efficient diesel power. The fundamental modeling and experimental tools and findings from this project can be applied to catalyst technologies used in the energy and chemical industries. The project led to 14 publications in the peer-reviewed literature with 2 additional currently under review. Finally, the project also led to training of several doctoral students who were placed in research jobs in industry and academia. Specifically, Mugdha Ambast (UH) has joined Cummins, Kevin Gu (UVa) has joined GM, and Abhay Gupta (UH) is to join Caterpillar.

42 ENGINEERING↗

Representative-cell-based Modeling of HTTF in SAM

Although the current nuclear power market is primarily occupied by the light water reactors (LWRs), the TRISO-fueled helium-cooled graphite-moderated high temperature gas reactors (HTGRs) are drawing growing attention as the nuclear power industry marches towards more advanced systems. Compared to that of conventional LWRs, the thermal hydraulics of HTGR cores show extra complexity from their multi-scale heat transfer mechanisms with varying importance during different operation modes or transient stages. The modeling of HTGR cores for the system analysis purpose therefore faces the challenge of reaching reasonable fidelity and accuracy while maintaining sufficient simplicity. Previous development and validation efforts have demonstrated that a “2-D ring model” with reasonable performance can be implemented in the System Analysis Module (SAM) for prismatic HTGR cores. In the current project, an alternative modeling methodology based on “representative cells” is proposed for the typical prismatic core of HTGRs. Different from the previous ring model approach, the proposed methodology first separately models and then combines the small- and large-scale thermal conductions, by connecting representative local heat transfer units (cells) with effective core- wise thermal resistance. A modeling practice for an integral high-temperature test facility (HTTF) elaborates the modeling details. Steady-state validation of the resultant candidate model is performed against a higher-resolution benchmark from a 3D-1D coupled simulation, which shows satisfactory prediction with reasonably captured global parameters and well-represented temperature fields. A postulated pressurized conduction cooldown (PCC) is also simulated and analyzed, demonstrating the model’s capability of transient prediction with physically captured phenomena resolved in both small and large temporal and spatial scales. In general, the current work achieves a preliminary success in proposing a methodology using representative cells to model prismatic HTGR cores in SAM. Future efforts are envisioned with more validation activities and with potential modeling improvements to eventually achieve the high confidence on a high-fidelity robust modeling methodology with reasonable accuracy.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Technical Basis and Implementation of Groundwater Pathway Models Used for INL’s RH LLW Disposal Facility Performance Assessment

The Idaho National Laboratory’s (INL’s) Remote-Handled Low-Level Waste (RH LLW) Disposal Facility has been designed and constructed to receive waste generated on INL in support of the Office of Nuclear Energy (NE) and Naval Reactors (NR) missions. RH LLW is generated on the INL site from spent nuclear fuel handling and operations at the Naval Reactors Facility (NRF), the Advanced Test Reactor (ATR), and at the Material and Fuels Complex (MFC) in addition to other miscellaneous research activities. The facility has been designed to receive RH LLW currently in storage at INL facilities and new waste generated by nuclear research programs. RH LLW received at the facility is solid waste consisting of surface contaminated debris, ion exchange resins used to purify cooling water, and activated metals generated during reactor core change outs, Naval spent fuel management, and nuclear R&D. The facility has been designed to meet the requirements of DOE Order 435.1, Radioactive Waste Management [1] for all-pathways including groundwater and air, radon emissions limits, and inadvertent intrusion limits. The facility design includes a vault system incorporating robust concrete vaults oriented vertically in close-packed arrays, a hydraulic drainage system designed to limit water contact with the stainless steel waste canisters/liners and concrete vaults, and a robust monitoring system. Per the environmental assessment (EA) [2], all waste will be disposed of in stainless steel waste canisters/liners. During facility design and construction, site-specific data was collected to provide laboratory and field scale performance characteristics for the concrete vault and hydraulic drainage systems. Field-scale infiltration tests were conducted and monitored and the data was interpreted using numerical simulation. Based on interpretation of the observed laboratory and field test data, the facility performance assessment (PA) was developed. The PA groundwater pathway source release model differentially credits release from surface contaminated debris, ion exchange resins, and activated metals. It also credits failure of the steel waste canisters/liners with failure rates based on actual corrosion data. Once released, transport through the vadose zone and aquifer to downgradient receptor locations was simulated in the PA using a one-dimensional modeling approach based on historical three-dimensional modeling of historically-contaminated INL sites. This paper provides an overview of the groundwater pathway source release models and their technical implementation in the PA. It also describes the one-dimensional transport model used for the vadose zone and multi-dimensional model used for the aquifer.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Improved CO 2 Capture Performance of Electrochemically Mediated Amine Regeneration Processes with Ionic Surfactant Additives

For the effective reduction of global CO 2 emissions, it is essential to develop and deploy efficient and cost-effective technologies for CO 2 capture, especially from large point sources. We recently developed an electrochemically mediated amine regeneration (EMAR) system to replace traditional thermal desorption for the capture of CO 2 from post-combustion flue gases. Despite EMAR effectiveness on a laboratory scale, concerns regarding the high gas-to-liquid ratio in the electrochemical cell and long-term instability of the electrodes need to be addressed before further scale-up of the process to a pilot plant and beyond can be entertained. Accordingly, we investigated the effect of using sodium dodecyl sulfate (SDS) as an anionic surfactant and dodecyltrimethylammonium bromide (DTAB) as a cationic surfactant on the process operation. It was found that it is advantageous to use an anionic surfactant for a system such as EMAR that contains hydrophilic electrodes and a positively charged electrochemically active species. The overall cell resistance was notably reduced when SDS anionic surfactant was used. The precipitation of copper particles observed in the anode outlet when no surfactant was used was effectively avoided when SDS was added to the electrolyte, resulting in electrode stability. In addition, smaller gas bubbles were produced in the presence of the SDS surfactant, which resulted in less blockage of the electrode by the gas with a resultant lower cell potential under constant current conditions, driving more efficient CO 2 desorption. This led to an ~25% reduction in the electrochemical energy requirement, the lowest ever achieved experimentally for the EMAR process. Altogether, the addition of a very low concentration of SDS resulted in the successful circumvention of the important problems faced by the EMAR system regarding further scale-up.

36 MATERIALS SCIENCE↗

N and OH-Immobilized Cu 3 Clusters In Situ Reconstructed from Single-Metal Sites for Efficient CO 2 Electromethanation in Bicontinuous Mesochannels

Cu-based catalysts hold promise for electrifying CO 2 to produce methane, an extensively used fuel. However, the activity and selectivity remain insufficient due to the lack of catalyst design principles to steer complex CO 2 reduction pathways. Herein, we develop a concept to design carbon-supported Cu catalysts by regulating Cu active sites’ atomic-scale structures and engineering the carbon support’s mesoscale architecture. This aims to provide a favorable local reaction microenvironment for a selective CO 2 reduction pathway to methane. In situ X-ray absorption and Raman spectroscopy analyses reveal the dynamic reconstruction of nitrogen and hydroxyl-immobilized Cu 3 (N,OH-Cu 3 ) clusters derived from atomically dispersed Cu–N 3 sites under realistic CO 2 reduction conditions. The N,OH-Cu 3 sites possess moderate *CO adsorption affinity and a low barrier for *CO hydrogenation, enabling intrinsically selective CO 2 -to-CH 4 reduction compared to the C–C coupling with a high energy barrier. Importantly, a block copolymer-derived carbon fiber support with interconnected mesopores is constructed. The unique long-range mesochannels offer an H 2 O-deficient microenvironment and prolong the transport path for the CO intermediate, which could suppress the hydrogen evolution reaction and favor deep CO 2 reduction toward methane formation. Thus, the newly developed catalyst consisting of in situ constructed N,OH-Cu 3 active sites embedded into bicontinuous carbon mesochannels achieved an unprecedented Faradaic efficiency of 74.2% for the CO 2 reduction to methane at an industry-level current density of 300 mA cm –2 . In conclusion, this work explores effective concepts for steering desirable reaction pathways in complex interfacial catalytic systems via modulating active site structures at the atomic level and engineering pore architectures of supports on the mesoscale to create favorable microenvironments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Water use in the development and operation of geothermal power plants.

Geothermal energy is increasingly recognized for its potential to reduce carbon emissions and U.S. dependence on foreign oil. Energy and environmental analyses are critical to developing a robust set of geothermal energy technologies. This report summarizes what is currently known about the life cycle water requirements of geothermal electric power-generating systems and the water quality of geothermal waters. It is part of a larger effort to compare the life cycle impacts of large-scale geothermal electricity generation with other power generation technologies. The results of the life cycle analysis are summarized in a companion report, Life Cycle Analysis Results of Geothermal Systems in Comparison to Other Power Systems. This report is divided into six chapters. Chapter 1 gives the background of the project and its purpose, which is to inform power plant design and operations. Chapter 2 summarizes the geothermal electricity generation technologies evaluated in this study, which include conventional hydrothermal flash and binary systems, as well as enhanced geothermal systems (EGS) that rely on engineering a productive reservoir where heat exists but water availability or permeability may be limited. Chapter 3 describes the methods and approach to this work and identifies the four power plant scenarios evaluated: a 20-MW EGS plant, a 50-MW EGS plant, a 10-MW binary plant, and a 50-MW flash plant. The two EGS scenarios include hydraulic stimulation activities within the construction stage of the life cycle and assume binary power generation during operations. The EGS and binary scenarios are assumed to be air-cooled power plants, whereas the flash plant is assumed to rely on evaporative cooling. The well field and power plant design for the scenario were based on simulations using DOE's Geothermal Economic Technology Evaluation Model (GETEM). Chapter 4 presents the water requirements for the power plant life cycle for the scenarios evaluated. Geology, reservoir characteristics, and local climate have various effects on elements such as drilling rate, the number of production wells, and production flow rates. Over the life cycle of a geothermal power plant, from construction through 30 years of operation, plant operations is where the vast majority of water consumption occurs. Water consumption refers to the water that is withdrawn from a resource such as a river, lake, or non-geothermal aquifer that is not returned to that resource. For the EGS scenarios, plant operations consume between 0.29 and 0.72 gal/kWh. The binary plant experiences similar operational consumption, at 0.27 gal/kWh. Far less water, just 0.01 gal/kWh, is consumed during operations of the flash plant because geofluid is used for cooling and is not replaced. While the makeup water requirements are far less for a hydrothermal flash plant, the long-term sustainability of the reservoir is less certain due to estimated evaporative losses of 14.5-33% of produced geofluid at operating flash plants. For the hydrothermal flash scenario, the average loss of geofluid due to evaporation, drift, and blowdown is 2.7 gal/kWh. The construction stage requires considerably less water: 0.001 gal/kWh for both the binary and flash plant scenarios and 0.01 gal/kWh for the EGS scenarios. The additional water requirements for the EGS scenarios are caused by a combination of factors, including lower flow rates per well, which increases the total number of wells needed per plant, the assumed well depths, and the hydraulic stimulation required to engineer the reservoir. Water quality results are presented in Chapter 5. The chemical composition of geofluid has important implications for plant operations and the potential environmental impacts of geothermal energy production. An extensive dataset containing more than 53,000 geothermal geochemical data points was compiled and analyzed for general trends and statistics for typical geofluids. Geofluid composition was found to vary significantly both among and within geothermal fields. Seven main chemical constituents were found to account for 95-99% of the dissolved solids in typical geofluids. In order of abundance, they were chloride, sodium, bicarbonate, sulfate, silica, calcium, and potassium. The potential for water and soil contamination from accidents and spills was analyzed by comparing geofluid composition with U.S. drinking water standards. Geofluids were found to present a potential risk to drinking water, if released, due to high concentrations of antimony, arsenic, lead, and mercury. That risk could be mitigated through proper design and engineering controls. The concentration and impact of noncondensible gases (NCG) dissolved in the geofluid was evaluated. The majority of NCG was either nitrogen or carbon dioxide, but a small number of geofluids contain potentially recoverable concentrations of hydrogen or methane.

15 GEOTHERMAL ENERGY↗

Testing the Accuracy of Data-driven MHD Simulations of Active Region Evolution

Models for the evolution of the solar coronal magnetic field are vital for understanding solar activity, yet the best measurements of the magnetic field lie at the photosphere, necessitating the development of coronal models which are “data-driven” at the photosphere. We present an investigation to determine the feasibility and accuracy of such methods. Our validation framework uses a simulation of active region (AR) formation, modeling the emergence of magnetic flux from the convection zone to the corona, as a ground-truth data set, to supply both the photospheric information and to perform the validation of the data-driven method. We focus our investigation on how the accuracy of the data-driven model depends on the temporal frequency of the driving data. The Helioseismic and Magnetic Imager on NASA’s Solar Dynamics Observatory produces full-disk vector magnetic field measurements at a 12-minute cadence. Using our framework we show that ARs that emerge over 25 hr can be modeled by the data-driving method with only ∼1% error in the free magnetic energy, assuming the photospheric information is specified every 12 minutes. However, for rapidly evolving features, under-sampling of the dynamics at this cadence leads to a strobe effect, generating large electric currents and incorrect coronal morphology and energies. We derive a sampling condition for the driving cadence based on the evolution of these small-scale features, and show that higher-cadence driving can lead to acceptable errors. Future work will investigate the source of errors associated with deriving plasma variables from the photospheric magnetograms as well as other sources of errors, such as reduced resolution, instrument bias, and noise.

79 ASTRONOMY AND ASTROPHYSICS↗

Intelligent Software Agents: Sensor Integration and Response

Abstract In a post Macondo world the buzzwords are Integrity Management and Incident Response Management. The twin processes are not new but the opportunity to link the two is novel. Intelligent software agents can be used with sensor networks in distributed and centralized computing systems to enhance real-time monitoring of system integrity as well as manage the follow-on incident response to changing, and potentially hazardous, environmental conditions. The software components are embedded at the sensor network nodes in surveillance systems used for monitoring unusual events. When an event occurs, the software agents establish a new concept of operation at the sensing node, post the event status to a blackboard for software agents at other nodes to see , and then react quickly and efficiently to monitor the scale of the event. The technology addresses a current challenge in sensor networks that prevents a rapid and efficient response when a sensor measurement indicates that an event has occurred. By using intelligent software agents - which can be stationary or mobile, interact socially, and adapt to changing situations - the technology offers features that are particularly important when systems need to adapt to active circumstances. For example, when a release is detected, the local software agent collaborates with other agents at the node to exercise the appropriate operation, such as: targeted detection, increased detection frequency, decreased detection frequency for other non-alarming sensors, and determination of environmental conditions so that adjacent nodes can be informed that an event is occurring and when it will arrive. The software agents at the nodes can also post the data in a targeted manner, so that agents at other nodes and the command center can exercise appropriate operations to recalibrate the overall sensor network and associated intelligence systems. The paper describes the concepts and provides examples of real-world implementations including the Threat Detection and Analysis System (TDAS) at the International Port of Memphis and the Biological Warning and Incident Characterization System (BWIC) Environmental Monitoring (EM) Component. Technologies developed for these 24/7 operational systems have applications for improved real-time system integrity awareness as well as provide incident response (as needed) for production and field applications.

emergency response↗

Atomically dispersed metal–nitrogen–carbon catalysts for fuel cells: advances in catalyst design, electrode performance, and durability improvement

The urgent need to address the high-cost issue of proton-exchange membrane fuel cell (PEMFC) technologies, particularly for transportation applications, drives the development of simultaneously highly active and durable platinum group metal-free (PGM-free) catalysts and electrodes. The past decade has witnessed remarkable progress in exploring PGM-free cathode catalysts for the oxygen reduction reaction (ORR) to overcome sluggish kinetics and catalyst instability in acids. Among others, scientists have identified the newly emerging atomically dispersed transition metal (M: Fe, Co, or/and Mn) and nitrogen co-doped carbon (M–N–C) catalysts as the most promising alternative to PGM catalysts. Here, we provide a comprehensive review of significant breakthroughs, remaining challenges, and perspectives regarding the M–N–C catalysts in terms of catalyst activity, stability, and membrane electrode assembly (MEA) performance. A variety of novel synthetic strategies demonstrated effectiveness in improving intrinsic activity, increasing active site density, and attaining optimal porous structures of catalysts. Rationally designing and engineering the coordination environment of single metal MN x sites and their local structures are crucial for enhancing intrinsic activity. Increasing the site density relies on the innovative strategies of restricting the migration and agglomeration of single metal sites into metallic clusters. Relevant understandings provide the correlations among the nature of active sites, nanostructures, and catalytic activity of M–N–C catalysts at the atomic scale through a combination of experimentation and theory. Current knowledge of the transferring catalytic properties of M–N–C catalysts to MEA performance is limited. Rationally designing morphologic features of M–N–C catalysts play a vital role in boosting electrode performance through exposing more accessible active sites, realizing uniform ionomer distribution, and facilitating mass/proton transports. We outline future research directions concerning the comprehensive evaluation of M–N–C catalysts in MEAs. The most considerable challenge of current M–N–C catalysts is the unsatisfied stability and rapid performance degradation in MEAs. Therefore, we further discuss practical methods and strategies to mitigate catalyst and electrode degradation, which is fundamentally essential to make M–N–C catalysts viable in PEMFC technologies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Pyramid Resource Center-Green Energy Center

There are currently over 3,500 USA/Canadian landfills listed by the EPA/EC and like numbers in Europe that are producing methane-rich landfill gas (LFG). This gas is typically made up of 50-percent methane (CH4), 35-percent carbon dioxide (CO2), and 2 to 25% nitrogen and oxygen (N2 & O2), plus dozens of dilute contaminants. LFG is classified as a renewable fuel, because it is generated via biological decay of municipal solid waste, a constant byproduct of human activity. To date, most LFG has been allowed to escape into the atmosphere. On account of its high CH4 content, LFG may contribute to climate change, as CH4 is one of the most harmful greenhouse gases with 21 times the global warming potential of CO2. Of the landfills that collect LFG, most simply flare it. In the past decade, some landfills have begun to use LFG for electricity generation or for direct combustion as low Btu gas. Very few landfills upgrade LFG to high Btu gas. A patented CO2 WashTM process developed by Acrion Technologies Inc., and licensed to Firm Green Inc. shows promise as an economically and environmentally sustainable process to recover energy and prevent pollution from landfills. The CO2 WashTM has already been proven at lab-scale. It upgrades LFG, which consists of 50% methane (CH4) + 35% carbon dioxide (CO2) + 2 to 25% nitrogen + oxygen (N2+O2), 1 to 2% water vapor, and dozens of contaminants (which total a few hundred to a few thousand parts per million). CH4, which by itself has an energy content of 1,012 British thermal units (Btu) per standard cubic foot (SCF), is the only component in LFG that contributes to its energy content, which is therefore about 400-550 Btu/SCF. Accordingly, raw LFG is usually referred to as medium-Btu gas. To be salable, it is necessary to remove essentially all the components besides CH4, while keeping the vast majority of the revenue producing CH4. This is high-Btu gas, yielding 850 to 1,000 Btu/SCF. The CO2 WashTM process upgrades LFG to about 930 Btu/SCF, and reduces the contaminants to levels that make it salable as a vehicle fuel in the form of compressed natural gas (CNG).

09 BIOMASS FUELS↗

Remote Robotic Equipment for Retrieval of High Level Waste to Support Environmental Closure - 18162

The Idaho Cleanup Project contractor, Fluor Idaho, LLC, is responsible for managing HLW calcine stored in the Calcined Solids Storage Facility at the Idaho Nuclear Technology and Engineering Center. The Idaho Nuclear Technology and Engineering Center is a DOE managed facility located at the INL Site in the remote portions of southeast Idaho. In 2016, DOE directed Fluor Idaho to develop and test a full-scale retrieval system to demonstrate the ability to safely retrieve HLW calcine from the Calcined Solids Storage Facility for future retrieval and processing. Removing HLW calcine from the State of Idaho is required by the 1995 Settlement Agreement, which mandates that DOE have HLW calcine ready to be moved out of Idaho by December 2035. Fluor Idaho is currently testing retrieval and transfer concepts to ensure that the Calcined Solids Storage Facility is placed in a final configuration that is protective of human health and the environment after HLW calcine has been removed to the maximum extent practical. This paper describes the full-scale prototype that will be used to prove retrieval and transfer system design capabilities, verify operating parameters, and establish a basis for calcine retrieval efficacy. Additionally, it describes the retrieval (bulk and residual) and visual monitoring systems that were designed and tested in 2017 and will continue to be tested with the full-scale prototype. Testing (i.e., full-scale mockup, bulk retrieval, residual clean-out, and visualization monitoring) performed by Fluor Idaho will demonstrate the maximum extent practical of HLW calcine removal that is achievable. This is critical to (1) establish criteria for ending calcine removal activities, (2) evaluate cost and benefits associated with performing additional removal, and (3) ensure clean up and closure standards under applicable requirements (e.g., statutes, orders, and agreements) are met. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Prediction of Adsorption Energies for Chemical Species on Metal Catalyst Surfaces Using Machine Learning

Computational catalyst screening has the potential to significantly accelerate heterogeneous catalyst discovery. Typically, this involves developing microkinetic reactor models that are based on parameters obtained from density functional theory and transition-state theory. To reduce the large computational cost involved in computing various adsorption and transition-state energies of all possible surface states on a large number of catalyst models, linear scaling relations for surface intermediates and transition states have been developed that only depend on a few, typically one or two descriptors, such as the carbon atom adsorption energy. As a result, only the descriptor values have to be computed for various active site models to generate volcano curves in activity or selectivity. Unfortunately, for more complex chemistries the predictability of linear scaling relations is unknown. Also, the selection of descriptors is essentially a trial and error process. Here, using a database of adsorption energies of the surface species involved in the decarboxylation and decarbonylation of propionic acid over eight monometalic transition-metal catalyst surfaces (Ni, Pt, Pd, Ru, Rh, Re, Cu, Ag), we tested if nonlinear machine learning (ML) models can outperform the linear scaling relations in prediction accuracy when predicting the adsorption energy for various species on a metal surface based on data from the rest of the metal surfaces. We found linear scaling relations to hold well for predictions across metals with a mean-absolute error of 0.12 eV, and ML methods being unable to outperform linear scaling relations when the training dataset contains a complete set of energies for all of the species on various metal surfaces. Only when the training dataset is incomplete, namely, contains a random subset of species’ energies for each metal, a currently unlikely scenario for catalyst screening, do kernel-based ML models significantly outperform linear scaling relations. We also found that simple coordinate-free species descriptors, such as bond counts, achieve as good results as sophisticated coordinate-based descriptors. Finally, we propose an approach for automatic discovery of appropriate metal descriptors using principal component analysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Landmark Report Analyzes Current State of U.S. Offshore Wind Industry (Fact Sheet)

New report assesses offshore wind industry, offshore wind resource, technology challenges, economics, permitting procedures, and potential risks and benefits. The National Renewable Energy Laboratory (NREL) recently published a new report that analyzes the current state of the offshore wind energy industry, Large-Scale Offshore Wind Power in the United States. It provides a broad understanding of the offshore wind resource, and details the associated technology challenges, economics, permitting procedures, and potential risks and benefits of developing this clean, domestic, renewable resource. The United States possesses large and accessible offshore wind energy resources. The availability of these strong offshore winds close to major U.S. coastal cities significantly reduces power transmission issues. The report estimates that U.S. offshore winds have a gross potential generating capacity four times greater than the nation's present electric capacity. According to the report, developing the offshore wind resource along U.S. coastlines and in the Great Lakes would help the nation: (1) Achieve 20% of its electricity from wind by 2030 - Offshore wind could supply 54 gigawatts of wind capacity to the nation's electrical grid, increasing energy security, reducing air and water pollution, and stimulating the domestic economy. (2) Provide clean power to its coastal demand centers - Wind power emits no carbon dioxide (CO2) and there are plentiful winds off the coasts of 26 states. (3) Revitalize its manufacturing sector - Building 54 GW of offshore wind energy facilities would generate an estimated $200 billion in new economic activity, and create more than 43,000 permanent, well-paid technical jobs in manufacturing, construction, engineering, operations and maintenance. NREL's report concludes that the development of the nation's offshore wind resources can provide many potential benefits, and with effective research, policies, and commitment, offshore wind energy can play a vital role in future U.S. energy markets.

14 SOLAR ENERGY↗