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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Ghostbusters for Batteries

End-of-life lithium-ion batteries are Class 9 hazardous materials due to flammability of electrolyte and lithium. It is why the transportation cost ranges from $2.49/kg - $7.20/kg for civilian and defense disposition, that is over 50% of the cost of recycling. Damaged batteries have many times greater transportation cost. Dead batteries require costly bunker-storage that occupies real estate and personnel that could be used for productive purposes. Insurance is expensive and accidents are almost assured even with relatively low volumes of waste. Tipping fees on top of this adds an unpredictable, inflated cost for the EV industry, which is very cost sensitive for survival. Transforming lithium-ion into a class of non-hazardous material reduces transportation cost to $0.10/kg, providing a value opportunity of ~$2/kg to ~$6/kg for civilian and defense disposition respectively. OnTo can eliminate the risk of thermal runaway with a brief, non-toxic treatment to eliminate flammability and toxic risks in most any battery, except Pb, which is inherently toxic. With the service, OnTo also can provide rigorous certainty that cells are rendered inert. OnTo’s patented and patent pending deactivation technology improves the cost and safety for disposition of end-of-life lithium-ion battery packs and cells. Deactivation uses non-toxic chemical processing to remove inherent risks in lithium-ion and other primary and secondary chemistries. The technology has been demonstrated and developed through DOE contract with OnTo Technology LLC (EE0008475).

25 ENERGY STORAGE↗
DOE OSTI2015

The U.S. DOE-EM international program - 15026

The U.S. Department of Energy (DOE) Office of Environmental Management (EM) conducts international collaboration activities in support of U.S. policies and objectives regarding the accelerated risk reduction and remediation of the environmental cleanup legacy resulting from the nations' nuclear weapons program and government sponsored nuclear energy research. The EM International Program, supported out of the EM Office of the Associate Principal Deputy Assistant Secretary pursues collaborations with foreign government organizations, educational institutions and private industry to assist in identifying technologies and promote international collaborations that leverage resources and link international experience and expertise. The primary objective of the International Program is to work closely with the various technical program offices within EM (e.g., tank waste and nuclear materials management, groundwater and soil remediation, deactivation and decommissioning) to identify collaborative opportunities related to innovative technologies, as well as best management practices, that support successful completion of the EM mission. This objective is directly aligned with the current DOE Strategic Plan 2014 - 2018, issued in April 2014. In mid-fiscal year (FY) 2014, the International Program awarded several collaborative projects for work scope spanning waste management, tank waste management, groundwater and soil remediation, deactivation and decommissioning (D and D), disposal operations, and nuclear materials disposition initiatives to nine foreign organizations. These projects include both technical and non-technical activities, with opportunities for continuation into FY 2015 and beyond. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Preparing for safe and compliant open air demolition at Hanford's plutonium finishing plant - 15100

The Plutonium Finishing Plant (PFP), located in the 200 West Area of the U.S. Department of Energy (DOE) Hanford Site, began operations in 1949 and produced plutonium metal during the Cold War. Production was stopped in 1989, the facility was formally shut-down in 1996, and material stabilization completed in 2004. DOE contractor CH2M HILL Plateau Remediation Company (CH2M HILL) is tasked with the plant's deactivation, decommissioning, decontamination and demolition, to be completed by September 30, 2016. The project team, partnering with DOE-Richland Operations Office (DOE-RL), is exploring, evaluating and implementing efficiencies to safely and compliantly prepare the facility for demolition. Since 2008, employees have prepared approximately 75 percent of the complex for demolition. More than 90 percent of the 232 glove boxes have been removed from ventilation and more than 80 percent of pencil tank units have been dispositioned. As decontamination, deactivation and removal nears completion on the remaining glove boxes, pencil tanks and other radiological and chemical processing infrastructure, CH2M HILL and DOE-RL are making preparations to demolish PFP itself, a Hazardous Category II nuclear facility (HazCat II). Conventional techniques used to demolish buildings heavily contaminated with radiological hazards typically involve extensive hands-on work to remove Material at Risk (MAR) and decontaminate the building to low levels before conventional demolition techniques can be used to remove the building. A safe and more cost effective approach is packaging MAR located in hard to access areas of the plant and removing it during demolition. That process, combined with affixing remaining contamination to walls, floors and equipment, performing detailed air dispersion modeling before demolition and air monitoring and dust suppression during demolition, will reduce employee risk and is more efficient in demolishing a HazCat II facility. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Results of Modeling and Simulation Support to Specia Nuclear Material Handling Facility Operations - 16053

Newport News Shipbuilding (NNS) is the sole designer and provider of nuclear powered aircraft carriers and one of only two companies in the United States to build nuclear powered submarines. As part of the upkeep of aircraft carriers, the ships return to NNS once in their lifetime for a complex overhaul and to be refueled. In support of overhaul operations NNS maintains a state of the art Special Nuclear Material (SNM) handling facility. Due to the complex nature of the operations that occur within this facility, during the design and initial operation of the building NNS developed a facility simulation model to provide decision support during the project planning and operational phases. This tool allows users to experiment with process times, process order, equipment utilization, personnel utilization and spatial utilization. By capturing the planned operations, time distributions for operations, equipment sizes and uses and personnel requirements, the tool accurately reflects the planned use of the facility. This realism allows the user to experiment with any aspect of the facility, in a controlled and cost effective space, and determine how changes or potential delays may impact overall facility operations. Thus the model allows for rapid exploration of multiple scenarios to determine likely outcomes, allowing a user to identify risks well ahead of their realization and explore mitigation strategies in a controlled space, to determine the ideal path forward. The tool was successful during the initial operation of the facility in helping to identify and mitigate risks related to the complex operations occurring during SNM handling. The tool is now in use to support planning for the next series of operations that will occur within the facility. The initial operations the model supported occurred during the deactivation of the USS Enterprise, and future operation will focus on the overhaul of Nimitz class aircraft carriers. The NNS planning team is currently using the tool to assess potential risks and challenges that are identified as potentially impacting the schedule and timelines for these overhaul processes. In addition, the NNS development team is working to add new operational steps to the model, capturing work that is occurring near the facility, but which directly impacts the facilities operational abilities. In conjuncture with the engineering planning division, the NNS development team has run over 20 complex scenarios through the tool. The team has provided output from these scenarios to both NNS personnel and government representatives. To date the model has successfully supported the identification of several feasible paths to incorporate new processes, dictated by the work to support a overhaul vs a deactivation. The model also provides a spatial arrangement component that allows users to experiment with different equipment placement within the facility. Due to the fidelity of the model, arranging equipment with the spatial component allows a user to set up the facility in an experimental layout and run the processes inside the facility to determine if the layout will be feasible, or if it would impact operational capabilities. Additionally, the spatial component allows for visual collaboration between stakeholders to ensure all operational personnel are aware of the current and planned layout, and that they do not locate equipment or work stations in locations that would interfere with facility operations. The spatial component, in combination with the simulation component, has resulted in several documented improvements in process. These include: the identification of additional equipment which could be stored outside the facility, without impacting operations, to increase space; confirmation of the ideal placement of a large water tank; and identification of several risks related to planned equipment storage area, allowing the team to develop new plans and avoid realizing the risk. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Testing and Deployment of Remote Systems to Remove Highly Radioactive Soil at Hanford's 324 Building - 18043

U.S. Department of Energy (DOE) contractor CH2M HILL Plateau Remediation Company (CHPRC) is in the process of procuring, testing and deploying remotely operated tools to safely remove highly contaminated soil from beneath the 324 Building on the Hanford Site in southeastern Washington State. The 324 Building operated for more than 40 years, completing a variety of high-dose engineering development and demonstration activities inside six hot cells that shielded the workers from the highly radioactive materials. Activities to decommission, decontaminate and demolish the facility began in 2008. In 2010, soil contamination was found in the soil under one of the hot cells, and building deactivation was paused to evaluate the soil contamination. Sampling efforts, using borehole technology, revealed significant under-building contamination with dose rates measuring has high as 130 Sv/hr (13,000 R/hr). The highly-contaminated soil has to be removed before traditional open air deactivation activities can continue. CHPRC completed proof of concept testing and built a full-scale test facility to demonstrate the effectiveness of three primary tools that will accomplish the floor and soil removal. The tools include a commercially available concrete saw, and a commercially available excavator arm that have been modified to operate remotely in the high-radiation environment within the hot-cell. In order to reduce the wear on the hot-cell overhead cranes, a remote operated rail and cart system has been designed to transport soil and debris out of the hot-cell to an airlock area where the waste will be separated, according to its level of radioactivity. A camera and light system has been designed to provide visual and audio coverage of the hot-cell area that will allow the operations to proceed from remote control stations. This paper will describe the primary remote operated equipment designed for the project and the challenges and processes for developing, testing and deploying the equipment necessary to excavate the soil from below the 324 Building. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

C-400 and C-409 Criticality Incredible Road Map

Many guides and standards describe a process for evaluating process operations with known quantities of fissile material. The accepted industry guides and standards for performing criticality evaluations for fissile material operations are not well suited for operating systems that may contain residual fissile material. The Paducah Site deactivation activities includes large process components that have unfavorable geometries for the {sup 235}U enrichment levels present. The fissile material holdup in these components can range from negligible residual quantities to significant deposits weighing several hundred pounds. The purpose of this white paper is to outline a methodology that can be used to declare a facility as criticality incredible (CI). For the purpose of this paper, criticality incredible means that the inventory and its form and distribution within the facility does not need Nuclear Criticality Safety Evaluation (NCSE) type (e.g., administrative or engineered) controls. This assumes of course that certain project assumptions are maintained. For example in the facilities that will be discussed within this paper, wet decontamination is not part of the planned demolition and disposal operations. The proposed methodology for deactivation of a facility to the point that criticality incredible can be declared will be applied to the C-400 Chemical Cleaning Building and to the C-409 Decontamination Facility at the Paducah Gaseous Diffusion Plant (PGDP). The purpose and intent of the CI declaration is to release a facility from Nuclear Criticality Safety (NCS) requirements and simplify the demolition of the facility. In practical terms, this means the facility can be re-categorized as < a Hazard Category 3 facility per DOE-STD-1027-92 Hazard Categorization and Accident Analysis Techniques for compliance with DOE Order 5480.23, Nuclear Safety Analysis Reports, NCS controls are not needed, and the Criticality Accident Alarm Systems (CAAS) can be removed from service. The only involvement from the site NCS program following the declaration would be to ensure that the underlying assumptions are not violated through discovered conditions or project changes. This includes the institutional control of preventing new fissile material from being introduced into the facility. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Molten Salt Reactor Experiment (MSRE) Lay-Up - 19187

UCOR, an AECOM-led partnership with Jacobs, manages the cleanup of the 2,200-acre East Tennessee Technology Park for its client, the U.S. Department of Energy (DOE), in Oak Ridge, Tennessee. The site was contaminated with radioactive, hazardous and industrial wastes generated by more than 40 years of national defense and energy missions. 2019 is the 50. anniversary of the shutdown of the Molten Salt Reactor Experiment (MSRE). MSRE ran a brief four years in the 1960's but earned an enduring legacy as an innovative reactor technology concept which has enjoyed a renewal of global interest in the past several years. In 2018, it was given elevated status among advanced reactor programs within DoE's Nuclear Energy office. The MSRE was a graphite-moderated, liquid fueled reactor that operated from June 1965 through December 1969. Although it was shut down nearly 50 years ago, certain systems within the reactor have continued to operate to maintain the facility in a safe and stable condition until it can be demolished as part of the comprehensive cleanup of the Oak Ridge Reservation. These systems are composed of a complex network of pipes, valves, gauges and associated equipment that control air filtration and pressure buildup resulting from fluorine gas generated through radiolysis of the fluoride salt which once fueled the reactor. In 2016, an MSRE Engineering Evaluation Team was chartered to assess current facility conditions and develop recommendations to maintain the facility in a safe state until deactivation and demolition commences. Plans are now underway to 'lay up' the MSRE facility until deactivation and demolition can occur. The proposed MSRE Facility Layup will minimize maintenance costs, reduce personnel risk of injury and exposure, provide reliable electric service to the facility and require zero personnel occupancy at MSRE. In the proposed layup approach a new source of electrical power to required loads will be routed through the facility, and new gas processing and ventilation systems will be installed that will be optimized for safe processing of the constituent hazardous gasses that exist in the legacy vessels at MSRE. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Panel Session 120B: DOE Portsmouth Paducah Project Office (PPPO) Update

This panel focused on the Portsmouth/Paducah Project Office (PPPO) of the US DOE Office of Environmental Management, Lexington, Kentucky, the US DOE Featured Site for Thursday. It showcased recent progress, challenges and planned efforts in radioactive waste management, waste disposition, environmental remediation and D and D at the Portsmouth (Ohio) and Paducah (KY) Gaseous Diffusion Plant Sites, as well as the Depleted Uranium Hexafluoride (DUF6) Conversion Project with facilities at both sites Presentations proposed include: 1 - Portsmouth/Paducah Project Office (PPPO) (Joel Bradburne, US DOE Portsmouth/Paducah Project Office (USA)); 2 - Portsmouth (Jeff Bettinger, US DOE Portsmouth/Paducah Project Office (USA)); 3 - Paducah (Jennifer Woodard, US DOE Portsmouth/Paducah Project Office (USA)); 4 - Depleted Uranium Hexafluoride Conversion Project (Reinhard Knerr, US DOE Portsmouth/Paducah Project Office (USA)); 5 - Portsmouth Deactivation and Demolition Project (Bob Smith, Fluor-BWXT Portsmouth (USA)); 6 - Paducah Deactivation and Remediation Project (Jeff Bradford, Four Rivers Nuclear Partnership - FRNP (USA)); 7 - Seven Lines-One Project (Zack Smith, SNC Lavalin (USA))

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Comparing Ecological Risk between D and D Facilities and Operating Facilities at the Hanford Site - 19531

Many countries are faced with a large remediation task resulting from World War II, the Cold War, and subsequent industrial development. In the U.S. the Department of Energy (DOE) faces the largest hazardous waste remediation tasks, with a commitment to protect human health and the environment during and following remediation. DoE's biggest challenge is remediation of the many remaining cleanup areas at the Hanford Site, Washington. Some Hanford sites have extensive ecological resources and ecosystems that require protection or restoration. We briefly 1) describe a rapid evaluation method for ecological resources on units slated for cleanup that allows comparison among the different areas at the Hanford Site, 2) examine some D4 (deactivation, decommissioning, decontamination and demolition) facilities and Operating facilities that require remediation, 3) describe potential ecological harm to resources on these sites, and 4) compare how risks from potential harm vary at the Hanford Site. The ecological evaluation includes three phases: 1) general steps (identify resource categories, identify cleanup areas), 2) ecological descriptions (describe resources on the site to be cleaned up), and 3) ecological ratings (rate the value of the resources on a scale that can be applied across remediation sites). After completion of these steps for the sites requiring cleanup, a comparison of potential risks can be made among types of facilities (e.g. D4 facilities, legacy waste sites, operating facilities). D4 facilities are those slated for deactivation, decommissioning, decontamination and demolition, while operating facilities at Hanford include waste treatment plants, sludge basins, waste trenches, Central Waste Complex, storage facilities, and disposal facilities, among others required to support the D4 and other remediation activities, before they too are remediated. Currently the potential harm to ecological (and eco-cultural) resources on the Hanford Site for remediation at D4 facilities is very low, but increases to very high (for reactors) during remediation when there is physical disruption, increased traffic and personnel, and possible increased contamination. Following remediation, the potential harm to ecological resources is low, and the value may increase due to restoration of native vegetation on sites that were largely industrial prior to remediation. In contrast, the potential harm to ecological resources at Operating Facilities was higher currently than for D4 facilities, but was low to medium following cleanup. The higher harm (risk) at D4 facilities partly derives from the location of the reactors near the Columbia River, a resource extremely important to Tribal Nations and to other peoples in the Northwestern United States, as well as for the iconic and threatened salmon populations. Methods described in this paper provide Congress, DOE managers, regulators, Tribes, and the general public with assurance that ecological and eco-cultural resources and the environment are being protected during and following remediation. The analysis of specific sites provides managers, regulators and the public with information to make cost-effective decisions about remediation that continues to enhance ecological value while protecting human health. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Performance Evaluation of Augmented Teleoperation of Contact Manipulation Tasks

At Argonne National Laboratory, an enhanced telerobotic concept has been suggested by providing augmented virtual fixtures for precise and dexterous manipulation. The proposed technology incorporated a human-robot interface that can assist personnel on the processes of Deactivation and Decommissioning in sites of high radiation. It has been implemented on a dual-arm robot system, known as Baxter, by integrating the Robotic Operating System (ROS) with 3D sensors and visual-haptic operator interface. However, what remained before its practical utilization is the capability for precisely placing the virtual fixtures. To this end, the objectives involved camera calibration, which required hardware fabrication and setup, as well as modification and implementation of ROS. The goal of this Research and Development is to develop an augmented-reality- based operator interface for human-inclusive, intelligent, and autonomous robotic system for the Deactivation and Decommissioning (D and D) of radioactive sites. The objectives are to develop: Collaborative Robot; Multi-modal Mixed-Reality Human-Robot Interface; Intelligent and Autonomous Behaviors. In order to achieve this, Baxter's Head-Kinect camera and Left-Hand camera need to be calibrated to overlap the real environment with the simulated environment. Camera calibration, which is crucial for precisely placing the virtual fixtures, was successful after running the simulations. The real and simulated environments overlapped, permitting the utilization of augmented teleoperation and the dexterous manipulation of Baxter for D and D applications in nuclear sites. Future steps: Performance evaluation of augmented teleoperation of contact manipulation tasks: Multiple-Camera 3D Reconstruction and Automation. Oculus Interface: Augmented reality and machine learning for enhanced telerobotic operation (Augmented Tele-autonomy): Machine-learning techniques for complex and flexible autonomous robotic behaviors. Interactive remote operation of robotic systems. Mesh cutting with simulation and real robot.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Session 077 - Panel: Wednesday US DOE Featured Site: Lexington, KY Office (Portsmouth and Paducah Sites) (R1.14)

This panel featured the DoE's Portsmouth Paducah Project Office (PPPO), which is responsible for the management and cleanup of at the Portsmouth, Ohio and Paducah, Kentucky former Gaseous Diffusion Plant sites. Portsmouth is primed for the first major skyline change at the site the upcoming demolition of the X-326 process building and initial operations of the Onsite Waste Disposal Facility. The Paducah site is working on the C-400 city block initiative allowing DOE to tackle the main source of groundwater contamination at the site, in conjunction with deactivation and demolition of the C-400 Cleaning Building. PPPO's DUF6 conversion plants have 7 lines in continuous operation at both sites providing the opportunity to ramp up cylinder processing. Panelists with presentations: DOE PPO Update (Robert Edwards, Joel Bradburne); Portsmouth/Paducah Project Office (PPPO) (Joel Bradburne, Robert Edwards); PADUCAH (Jennifer Woodard, Myrna Espinosa Redfield); Depleted Uranium Hexafluoride Conversion Project (Reinhard Knerr, Zack Smith); Paducah Deactivation and Remediation Project (Myrna Espinosa Redfield); Mid-America Conversion Services - Seven Lines One Project (Zack Smith)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Is there a Perfect D and D Plan - 20100

Problems with many Deactivation and Demolition (D and D) projects arise not necessarily from the technical difficulty of the actions required in a given facility, but rather from lack of integration of the stove piped planning efforts; engineering, operations, environmental, radiological, human resources, etc. This paper will cover Polestar Technical Service, Inc. (Polestar) systems engineering approach to D and D planning based on the company's experience over the past 27 years. This systematic, four-pronged approach to planning is applicable to any D and D project and addresses several diverse topics in a cohesive and integrated manner. The four areas to be discussed are project scope, requirements, facility end state, work force and base operations. This approach progresses a facility through the typical DOE life-cycle from operations, through deactivation, into surveillance and maintenance (S and M) and to eventual demolition and site remediation. To achieve a final end state the approach brings together the efforts associated with identifying and managing the right set of requirements, detailing the scope of work, establishing the baseline, redefining the work processes, aligning the workforce resources with the work processes, and maintaining the base operations activities as the project progresses through the various life-cycle stages. Getting these building blocks right provides a solid framework for executing any D and D project. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Life cycle Management of 324 Project High-Activity, Mixed/Low-Level Radioactive Waste - 20506

U.S. DOE contractor CH2M Hill Plateau Remediation Company (CHPRC) manages the 324 Building and is preparing to remotely excavate and disposition the radioactive soil beneath the building to allow further deactivation of the building. The 324 Building is a non-reactor Category 2 Nuclear Facility located in the 300 Area of the Hanford Site. Records indicate that in October 1986, approximately 516 liters of a concentrated liquid waste stream containing cesium-137 ({sup 137}Cs) and strontium-90 ({sup 90}Sr) spilled onto the floor of a hot cell, B-Cell, in the 324 Building. The spill contained an estimated 1.3 million curies (Ci) of radioactivity. A breach in the sump of B-Cell was discovered in November 2009 during characterization of the soil under the building. Exposure rates in excess of 10,000 R/hr were detected through a system of access pipes installed under the hot cell, and an estimated 1.557 E+05 Ci of {sup 137}Cs and 6.842 E+04 Ci of {sup 90}Sr are in the soil beneath B-Cell. The magnitude of the soil contamination below B-Cell represents one of the most challenging remediation activities in the DOE complex. The objective of CHPRC's 324 Project is to remotely excavate and disposition the highly contaminated soil under the hot cell so building deactivation and stabilization activities can resume. Depending on the volume and radioactivity of contaminated soil under B-Cell, the material will be dispositioned either at the Hanford Site's Environmental Restoration Disposal Facility (ERDF) or in grout monoliths that will be created in the hot cells (A, C and D) next to B-Cell during future building demolition activities. The current project scope includes installing structural supports under the walls of B-Cell and using remotely operated equipment to remove debris from the hot cell, remove debris mixed with grout on the floor, saw through and remove the cell floor and liner, and excavate contaminated soil under B-Cell to a depth of up to 3.66 meters (12 feet). Addition or removal of debris in A-Cell may be required to support B-Cell cleanout and excavation activities. The base approach is to disposition debris and soil bins in the Radiochemical Engineering Cell (REC) monoliths, and subsequently disposition the monoliths during building demolition. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Aging Processes of Silver Mordenite and Silver Functionalized Aerogel in Dry Air, Humid Air and NO/N{sub 2}

One major problem in the treatment of nuclear-fuel reprocessing off-gas streams is the loss of capacity of the adsorbents exposed to off-gas streams containing air, I{sub 2} vapor, H{sub 2}O vapor, NO and NO{sub 2} over extended periods of time. These aging processes decrease the adsorption capacity of the reduced silver exchanged mordenite (Ag{sup 0}Z) and silver functionalized silica aerogel (Ag{sup 0}-aerogel) columns during the long processing time of iodine adsorption. Significant work has been performed over the past few years at ORNL on Ag{sup 0}Z and Ag{sup 0}-aerogel aging. The Ag{sup 0}Z and Ag{sup 0}-aerogel were aged in 4 different gas streams at 150 deg. C for periods of time up to 6 months. The aging samples were then loaded with I{sub 2} to determine the capacity loss after the aging. The results are summaries in Tab. 1. It was found that both Ag{sup 0}Z and Ag{sup 0}-aerogel had different amounts of capacity loss in different gases. For example, 40% and 22% capacity loss were observed for Ag{sup 0}Z and Ag{sup 0}-aerogel when aged in dry air for 6 months, while 78% and 43% capacity loss were observed when aged in 1% NO{sub 1} for 2 months. In addition, it was found that Ag{sup 0}Z and Ag{sup 0}-aerogel had a different capacity loss when aged at the same conditions. For example, after aged in 2% NO{sub 2} for 2 months, Ag{sup 0}Z lost 30% iodine capacity, but there was no capacity loss for Ag{sup 0}- aerogel. The differences in capacity loss should be due to different aging processes occurred when Ag{sup 0}Z and Ag{sup 0}- aerogel were exposed to different gases. The mechanisms of the aging processes have not been determined and need to be studied with proper chemical and physical characterization methods. Towards this objective, experimental work is proposed and on-going to obtain data to determine the mechanisms of the aging processes of Ag{sup 0}Z and Ag{sup 0}-aerogel in different aging gas streams. In addition, models will be developed to describe the deactivation process of the adsorbents when exposed to off gases. The deactivation model will be included in the transport models for predicting the adsorption processes over these long-time periods.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Monitoring Structural and Electronic Changes of Supported Metal Catalysts Using Combined X‐Ray Techniques

Supported metal nanoparticle catalysts have become increasingly crucial for many catalytic applications. However, long-term catalyst stability remains a problem due to catalyst deactivation caused by coke formation and sintering. The deposition of a thin overcoating via atomic layer deposition (ALD) onto metal-supported nanoparticles has shown to greatly inhibit catalyst deactivation. This work utilizes a model catalyst system comprised of Pt nanoparticles supported on Al 2 O 3 to demonstrate the effect of an atomically thin overcoating on supported metal nanoparticles. Continuous operando small-angle X-ray scattering (SAXS) and X-ray absorption near edge spectroscopy (XANES) monitor structural and electronic changes to the catalyst and overcoating during calcination. SAXS data fitting reveals the formation of nanopores in the overcoating at high temperatures, while XANES monitors the oxidation state of the Pt catalyst. Herein, the usefulness of combined X-ray techniques is demonstrated to characterize supported metal catalysts to further understanding of the synergistic effects of the ALD overcoating to aid in the design of new catalyst materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Coke formation in a zeolite crystal during the methanol-to-hydrocarbons reaction as studied with atom probe tomography

Understanding the formation of carbon deposits in zeolites is vital to developing new, superior materials for various applications, including oil and gas conversion processes. Herein, atom probe tomography (APT) has been used to spatially resolve the 3D compositional changes at the sub-nm length scale in a single zeolite ZSM-5 crystal, which has been partially deactivated by the methanol-to-hydrocarbons reaction using 13 C-labeled methanol. The results reveal the formation of coke in agglomerates that span length scales from tens of nanometers to atomic clusters with a median size of 30–60 13 C atoms. These clusters correlate with local increases in Brønsted acid site density, demonstrating that the formation of the first deactivating coke precursor molecules occurs in nanoscopic regions enriched in aluminum. Here, this nanoscale correlation underscores the importance of carefully engineering materials to suppress detrimental coke formation.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Bimetallic Ag-Pt Sub-nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts

A combined experimental and theoretical investigation of Ag-Pt sub-nanometer clusters as heterogeneous catalysts in the CO -> CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size-selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first-principles simulations at realistic coverage. Insitu GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano-aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O-2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species.

Ab initio calculations↗