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At least 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Sludge Removal: Success and Partnership with T Plant - 20510

U.S. DOE contractor CH2M Hill Plateau Remediation Company (CHPRC) has safely and efficiently managed the removal of highly radioactive sludge from the 105-K West Reactor fuel storage basin (105- KW Basin) near the Columbia River. In mid-September 2019, sludge retrieval was completed after 21 storage containers were safely loaded with highly radioactive sludge and transported approximately 13 miles from the 105-KW Basin to T Plant, located in the 200 West Area on the Central Plateau of the Hanford Site. Sludge removal represents the last major source term reduction necessary before the K West Reactor and fuel storage basin can transition to closure activities in preparation for final deactivation and demolition. The technical complexity of the sludge retrieval process, coupled with the challenging physical and radiological characteristics of the waste, necessitated a methodical and deliberate approach using unique design and operational solutions to safely conduct the work. This challenge was further complicated by the need to plan and conduct the work in two separate facilities, each subject to the controls and requirements of its own nuclear facility safety basis. The project overcame these challenges through creating an integrated team that actively engaged, communicated and coordinated each phase of the project to ensure successful completion. This paper will cover how these key elements of the Sludge Removal Project led to its success: - Integrating project planning and management; - Lessons learned from design and construction; - Preparing for a successful campaign (lessons learned from testing and start-up); - Lessons learned from operating in two separate facilities, transporting sludge containers on the Hanford Site and ensuring compliance with a range of regulatory and safety basis requirements. The establishment of an integrated group spanning two facilities and multiple organizations created a team capable of overcoming the challenges necessary to successfully plan and execute the sludge retrieval mission. Sharing lessons learned from this successful project can enhance the ability of teams across the DOE complex to successfully plan and execute complex projects. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Effect of hydrocarbon adsorption on the wettability of rare earth oxide ceramics

Vapor condensation is routinely used as an effective means of transferring heat, with dropwise condensation exhibiting a 5 − 7x heat transfer improvement compared to filmwise condensation. However, state-of-the-art techniques to promote dropwise condensation rely on functional hydrophobic coatings, which are often not robust and therefore undesirable for industrial implementation. Natural surface contamination due to hydrocarbon adsorption, particularly on noble metals, has been explored as an alternative approach to realize stable dropwise condensing surfaces. While noble metals are prohibitively expensive, the recent discovery of robust rare earth oxide (REO) hydrophobicity has generated interest for dropwise condensation applications due to material costs approaching 1% of gold; however, the underlying mechanism of REO hydrophobicity remains under debate. In this work, we show through careful experiments and modeling that REO hydrophobicity occurs due to the same hydrocarbon adsorption mechanism seen previously on noble metals. To investigate adsorption dynamics, we studied holmia and ceria REOs, along with control samples of gold and silica, via X-Ray photoelectron spectroscopy (XPS) and dynamic time-resolved contact angle measurements. The contact angle and surface carbon percent started at ≈0 on in-situ argon-plasma-cleaned samples and increased asymptotically over time after exposure to laboratory air, with the rare earth oxides displaying hydrophobic (>90°) advancing contact angle behavior at long times (>4 days). The results indicate that REOs are in fact hydrophilic when clean and become hydrophobic due to hydrocarbon adsorption. Furthermore, this study provides insight into how REOs can be used to promote stable dropwise condensation, which is important for the development of enhanced phase change surfaces.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Adaptive linear predictor FIR filter based on the Cyclone V FPGA with HPS to reduce narrow band RFI in AERA radio detection of cosmic rays

We present the new approach to a filtering of radio frequency interferences (RFI) in the Auger Engineering Radio Array (AERA) which study the electromagnetic part of the Extensive Air Showers. The radio stations can observe radio signals caused by coherent emissions due to geomagnetic radiation and charge excess processes. AERA observes frequency band from 30 to 80 MHz. This range is highly contaminated by human-made RFI. In order to improve the signal to noise ratio RFI filters are used in AERA to suppress this contamination. The first kind of filter used by AERA was the Median one, based on the Fast Fourier Transform (FFT) technique. The second one, which is currently in use, is the infinite impulse response (IIR) notch filter. The proposed new filter is a finite impulse response (FIR) filter based on a linear prediction (LP). A periodic contamination hidden in a registered signal (digitized in the ADC) can be extracted and next subtracted to make signal cleaner. The FIR filter requires a calculation of n=32, 64 or even 128 coefficients (dependent on a required speed or accuracy) by solving of n linear equations with coefficients built from the covariance Toeplitz matrix. This matrix can be solved by the Levinson recursion, which is much faster than the Gauss procedure. The filter has been already tested in the real AERA radio stations on Argentinean pampas with a very successful results. The linear equations were solved either in the virtual soft-core NIOSR processor (implemented in the FPGA chip as a net of logic elements) or in the external Voipac PXA270M ARM processor. The NIOS processor is relatively slow (50 MHz internal clock), calculations performed in an external processor consume a significant amount of time for data exchange between the FPGA and the processor. Test showed a very good efficiency of the RFI suppression for stationary (long-term) contaminations. However, we observed a short-time contaminations, which could not be suppressed either by the IIR-notch filter or by the FIR filter based on the linear predictions. For the LP FIR filter the refreshment time of the filter coefficients was to long and filter did not keep up with the changes of a contamination structure, mainly due to a long calculation time in a slow processors. We propose to use the Cyclone V SE chip with embedded micro-controller operating with 925 MHz internal clock to significantly reduce a refreshment time of the FIR coefficients. The lab results are promising. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

DECOMMISSIONING AND ENVRIONMENTAL CLEANUP OF SMALL ARMS TRAINING FACILITY

USDOE performed a (CERCLA) non-time critical removal (NTCR) action at the Small Arms Training Area (SATA) Site Evaluation Area (SEA) located at the Savannah River Site (SRS), in Aiken, South Carolina. From 1951 to May 2010, the SATA was used as a small weapons practice and qualifying firing range. The SATA consisted of 870.1 ha (2,150 ac) of woodlands and open field, of which approximately 2.9 ha (7.3 ac) were used as a firing range. The SATA facility was comprised of three small arms ranges (one static and two interactive), storage buildings for supplies, a weapons cleaning building, and a control building. Additionally, a 113- m (370-ft) long earthen berm was used as a target backstop during live-fire exercises. The berm soils accumulated a large amount of spent lead bullets in the berm face during the facilities 59- years of operation. The accumulation of lead was such that soil concentrations exceeded the U.S. Environmental Protection Agency (USEPA) residential and industrial worker regional screening levels (RSLs). The RSL threshold values are based on standardized exposure scenarios that estimate contaminant concentrations in soil that the USEPA considers protective of humans over a lifetime. For the SATA facility, lead was present in soil at concentrations that exceed both the current residential (400 mg/kg) and industrial (800 mg/kg) RSLs. In addition, the concentration of lead in the soil exceeded the Toxicity Characteristic Leaching Procedure (TCLP) (40 Code of Federal Regulations [CFR] 261.24) regulatory limit. The TCLP analysis simulates landfill conditions and is designed to determine the mobility of contaminants in waste. In addition, a principal threat source material (PTSM) evaluation, human health risk assessment (HHRA), and contaminant migration (CM) analysis were conducted to evaluate soil contamination at the SATA SEA. This evaluation determined that there were no contaminants present that constitute PTSM and the CM analysis revealed that no constituents posed a migration risk to groundwater. The NTCR action involved removal of approximately 12,092 m3 (15,816 yd3) of spent bullets and lead-impacted soil and off-site disposal. The removal action included soils from the berm area, a fill area that received scraped soils from the berm, and soil from a drainage ditch located on the edge of the berm area. Also included in the removal action was a mixture of soil, concrete, and asphalt from the other three range areas. Under this action, 11,796 m3 (15,429 yd3) of hazardous waste and impacted soil were removed from the SATA and transported to a permitted hazardous waste disposal facility (Lone Mountain Facility in Oklahoma) and 296 m3 (387 yd3) of nonhazardous waste (primarily concrete debris) were removed and transported to a local solid waste landfill for disposal. During the excavation process, the extent was continuously assessed through the use of a hand-held, field-portable X-ray fluorescence unit with results verified using confirmation sampling with certified laboratory analysis. Following the completion of the excavation and confirmation sampling, final contouring, grading, and establishment of vegetative cover was performed to stabilize the affected areas. The NTCR action began on August 17, 2010, and mechanical completion was achieved on April 27, 2011. The selected removal action met the removal action objectives (RAOs), is protective of human health and the environment both in the short- and long-term, was successful in removing potential ecological risks, and is protective of surface water and groundwater. Furthermore, the selected NTCR action met residential cleanup goals and resulted in the release of the SEA from restricted use contributing to the overall footprint reduction at SRS.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Pilot-Scale Testing of an Integrated Circuit for the Extraction of Rare Earth Minerals and Elements from Coal and Coal Byproducts Using Advanced Separation Technologies

The primary objective of this project was to develop and demonstrate an integrated pilot-scale circuitry for recovering high-value rare earth elements (REEs) from coal and coal byproducts. The target performance was to produce a mixed REE product with content of at least two percent by weight on a dry mass basis in a cost-effective and environmentally benign manner. During the first nine months of the project period (Phase 2 Budget Period 2), pilot plant construction was completed including all field site startup activities such as permitting, engineering design, procurement/bidding, unit fabrication, site construction, equipment installation, module assembly, safety training, and circuit shakedown. During the remaining 21 months of project period (Phase 2 Budget Period 3), detailed field-testing activities were performed including feedstock sample collection and preparation, exploratory testing, circuit modification, detailed parametric study, and performance optimization. A detailed techno-economic analysis was performed based on the pilot plant testing findings which provided various scenarios for REE production. The project successfully accomplished the proposed target performance by producing mixed rare earth oxide (REO) with greater than 90% purity by weight in a continuous pilot scale operation from two distinctly different coarse refuse materials (i.e., West Kentucky No. 13 and Fire Clay coal seams), and at least three secondary sources (i.e., heap leach process and naturally formed acid mine drainage system). Project partners included the University of Kentucky, Virginia Tech, West Virginia University, Alliance Coal, Blackhawk Mining, Mineral Refining Company, and Mineral Separation Technologies. The pilot scale test facility was constructed at a former mining complex owned by Alliance Natural Resource Partners (Alliance Coal). The site was rehabilitated to accommodate the equipment installation, construction and fabrication, electrical power requirement, water line management and containment. The process units constructed and installed included X-ray sorting unit, crushing and grinding unit, physical separation unit, acid leaching unit, solvent extraction unit, and wastewater management unit. A rare earth mineral concentration unit was constructed as a standalone unit for flexible operation. A detailed environmental assessment and control plan was carried out to identify and quantify any potential impacts of the pilot-scale processing circuitry on the human and eco-system health and well-being. Corresponding mitigation strategies and control measures were provided. A conceptual flowsheet was developed to effectively remove thorium and uranium from high purity rare earth oxide mix or any potential radionuclide enriched stream. The two distinct feedstock materials were secured from the Blackhawk Mining Complex in eastern Kentucky where the Fire Clay (Hazard No. 4) seam is processed. The West Kentucky No. 13 (Baker) coarse refuse material was collected from an active process stream at an Alliance coal preparation plant located in western Kentucky. Characterization analysis indicated that both of feed materials generated from the two sources contained >300 ppm of TREEs on a dry whole mass basis which met the requirements for a qualified feed stock. The two feedstocks were further upgraded using a dual x-ray sorter to prepare the feed material for hydrometallurgical circuit. Thermal treatment on feed material prior to leaching was found to: 1) improve the leaching recovery of REEs, 2) increase the leaching kinetics, and 3) allow the leaching reaction to occur at lower acidity. Roasting at 600°C was selected as the pre-treatment condition for both West Kentucky No. 13 and Fire Clay coarse refuse material. Over 40% of leaching recovery was achieved by roasting West Kentucky No. 13 material having a top particle size of 3 mm in the pilot scale operation using 1.2M sulfuric acid leaching at 75OC. Initial pilot scale testing involved continuous operation of the pilot plant for 94 hours. The leaching unit was operated at solid-to-liquid ratio of 1 to 10 (w/v) using 0.5M sulfuric acid solution at a temperature of 75°C. The continuous solvent extraction circuit utilized rougher and cleaner units with DEHPA and TBP as the extractants. An innovative stripping circuit was developed to accumulate the REE concentration in the stripping solution to a level above 600 ppm. A bleed stream from the recycled strip solution was treated using oxalic acid precipitation which produced a high grade rare earth oxalate. The oxalate product was roasted to remove the oxalate which produced a rare earth oxide product having a purity greater 90%. Due to high concentrations of contaminant ions in the pregnant leach solution (PLS), a modified flowsheet was developed that involved pre-concentration of the REEs using multiple stages of precipitation and redissolution. The advantage of this process was improved removal of contamination before the downstream purification process and a significant cost reduction relative to the circuit that utilized the solvent extraction process. The modified circuitry included processes involving leaching, multistage precipitation, redissolution, and oxalate precipitation followed by roasting of the oxalate product. The circuit produced a mixed REO that was 92.96% pure from the initial test. A detailed parametric test plan was carried out which involved varying key parameters including solids feed rate, acid flowrate, acid concentration, multistage precipitation pH, redissolution pH, oxalate precipitation dosage and pH. The response variables included REE recovery, contaminant recovery, REO product grade and overall chemical consumption. Test results indicated that the acid-to-solid ratio is the key parameter to leaching efficiency as performance deteriorated with an increase in solids concentration. The optimal pH determined for REE precipitation and redissolution was 6.5 and 2.5, respectively. Additional tests were conducted to further improve the flowsheet. Recirculating a portion of the PLS to the feed of the leach tanks improved the leaching performance by lowering the pH of the leaching system and reducing the contamination recovery by shortening the residence time. Moreover, the removal of Al prior to REE precipitation significantly reduced the oxalic acid consumption in the oxalate precipitation circuit. The modified circuit produced over 90% grade REO by weight from both West Kentucky No. 13 and Fire Clay coarse refuse material in pilot scale continuous test programs. A case analysis model was developed to project the REE and major contaminants concentration in each PLS stream based on the leaching condition, pH cut point, and oxalic acid dosage. A correlation was established using empirical and semi-empirical models. Using the models, chemical consumption required for each stage was predicted based on the projected performance of the hydrometallurgy circuit. After identifying the optimum conditions, validation tests were carried out for the treatment of both West Kentucky No. 13 and Fire Clay coarse refuse materials in the pilot plant. The actual circuit performance and chemical consumptions were very close to the model predictions. Other than the two coarse refuse sources, several secondary feedstocks were also tested in the pilot plant facility. A “heap leach” system was constructed using the coarse refuse material generated from cleaning the West Kentucky No. 13 seam coal. Using the two stage SX rougher and cleaner circuit, a concentrate with a grade >90% REO was produced while recovering >97% of the REEs from the heap leach PLS. Naturally generated acid mine drainage (AMD) from West Kentucky No.13 mine was processed using the multistage precipitation circuit in the pilot plant in a test conducted for a period of 32 hours. The final grade of the mix RE oxide produced from the AMD was 90.84% with an overall circuit recovery of 64%. The primary source of REE was the selective precipitation steps involving iron and aluminum rejection. The hydrophobic-hydrophilic separation (HHS) process was proven to effectively recover coal from fine waste materials. For REM recovery, the HHS process was able to produce concentrates at grades of approximately 1.8% REE on an ash basis; however, recovery values were typically low, <10%, under the optimal conditions determined in the laboratory-scale testing. Staged testing of the pilot-scale HHS process for coal recovery and semi-continuous laboratory testing for REM testing showed that a total concentration ratio of more than 15x was observed for the REM recovery process. A circuit simulation package was developed for REE extraction and purification using a spreadsheet-based platform (Microsoft Excel). The REESim circuit simulation package is configured to track the mass and volume flows of components passing through a series of unit operations specified and configured by the user. The mass rates can then be utilized by the user to determine important performance indicators such as product mass yields, concentrate purity levels, element-by-element recoveries, and so forth. The techno-economic analysis showed that the roasting and leaching operations were the most expensive capital items, each contributing approximately 30% to the total capital cost. One notable contributor to the high production costs was the low REE recovery observed in the pilot scale trials. The product basket price was shown to have a strong influence on the economic viability of the scenarios, with the scandium price being the most significant influencer. Operating cost was shown to be extremely sensitive to REE recovery, REE feed grade, and leaching acid consumption. An analysis of ten different scenarios for a 500 t/h commercial operation revealed that three were economically favorable, producing internal rates of return varying from 27.7% to 33.1% and payback periods of 4 to 5 years. The project successfully developed and demonstrated a process to recover REEs from coal and coal byproducts in a pilot-plant operation which consistently produced over 90% grade REO mix from varies types of feedstocks. Commercialization analysis showed that the technology readiness level successfully achieved TRL 6 at the end of the project and demonstrated the need and the potential for scaling the process to further advance the technologies toward the goal of providing a domestic supply of REEs at a commercial scale.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2015

Ion Acceleration by Laser Plasma Interaction from Cryogenic Microjets

Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high-power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. However, this mechanism is not ideal for creating the high-energy proton beams needed for future applications. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for exploring new regimes of ion acceleration. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we achieved a pure proton beam with evidence of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the possibility of transforming our liquid cryogenic jets into droplet streams. This type of target should solve our problems with the jet as it will prevent the flow of exocurrent into the nozzle. It is also highly effective as it is even more mass-limited than standard cryogenic jets. Furthermore, jets break up spontaneously anyway. If we can control the breakup, we can synchronize the droplet emission with the laser pulses. In order to assist the team prepare for an experiment later this year, I familiarized myself with the physics and theory of droplet formation, calculated values for the required parameters, and ordered the required materials for modification of the jet. Future experiments will test these droplet streams and continue towards the goal of ion acceleration using cryogenic targets.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Ion acceleration by laser plasma interaction from liquid cryogenic microjets [Abstract]

Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for this type of interaction, capable of producing the highest proton energies possible with todays laser technologies. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis and investigate new, potentially more efficient mechanisms of ion acceleration, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we acheived a pure proton beam with an indiciation of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the possibility of transforming our liquid cryogenic jets into droplet streams. This type of target should solve our problems with the jet as it will prevent the flow of exocurrent into the nozzle. It is also highly effective as it is even more mass-limited than standard cryogenic jets. Furthermore, jets break up spontaneously anyway. If we can control the breakup, we can synchronize the droplet emission with the laser pulses. In order to assist the team prepare for an experiment later this year, I familiarized myself with the physics and theory of droplet formation, calculated values for the required parameters, and ordered the required materials for modification of the jet. Future experiments will test these droplet streams and continue towards the goal of ion acceleration using cryogenic targets.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Final Technical Report

In September 2010, RTI and the DOE/NETL signed a cooperative agreement (DE-FE000489) to design, build, and operate a pre-commercial syngas cleaning system that would capture up to 90% of the CO 2 in the syngas slipstream, and demonstrate the ability to reduce syngas contaminants to meet DOE’s specifications for chemical production application. This pre-commercial syngas cleaning system is operated at Tampa Electric Company’s (TEC) 250-MWe integrated gasification combined cycle (IGCC) plant at Polk Power Station (PPS), located near Tampa, Florida. The syngas cleaning system consists of the following units: Warm Gas Desulfurization Process (WDP) - this unit processes a syngas flow equivalent of 50 MWe of power (50 MWe equivalent corresponds to about 2.0 MM scfh of syngas on dry basis) to produce a desulfurized syngas with a total sulfur (H 2 S+COS) concentration ~ 10 ppmv. Water Gas Shift (WGS) Reactor - this unit converts sufficient CO into CO 2 to enable 90% capture of the CO 2 in the syngas slipstream. This reactor uses conventional commercial shift catalyst technologies. Low Temperature Gas Cooling (LTGC) - this unit cools the syngas for the low temperature activated MDEA process and separates any condensed water. Activated MDEA Process (aMDEA) - this unit employs a non-selective separation for the CO 2 and H 2 S present in the raw syngas stream. Because of the selective sulfur removal by the upstream WDP unit, the CO 2 capture target of 90% CO 2 can be achieved with the added benefit that total sulfur concentration in the CO 2 product is < 100 ppmv. An additional advantage of the activated MDEA process is that the non-selective sulfur removal from the treated syngas reduces sulfur in the treated gas to very low sub-ppmv concentrations, which are required for chemical production applications. Testing to date of this pre-commercial syngas cleaning system has shown that the technology has great potential to provide clean syngas from coal and petcoke-based gasification at increased efficiency and at significantly lower capital and operating costs than conventional syngas cleanup technologies. However, before the technology can be deemed ready for scale-up to a full commercial-scale demonstration, additional R&D testing is needed at the site to address the following critical technical risks: WDP sorbent stability and performance; Impact of WDP on downstream cleanup and conversion steps; Metallurgy and refractory; Syngas cleanup performance and controllability; Carbon capture performance and additional syngas cleanup The proposed plan to acquire this additional R&D data involves: Operation of the units to achieve an additional 3,000 hours of operation of the system within the performance period, with a target of achieving 1,000 hours of those hours via continuous operation of the entire integrated pre-commercial demonstration system; Rapid turnaround of repairs and/or modifications required as necessary to return any specific unit to operating status with documentation and lessons learned to support technology maturation, and; Proactive performance of maintenance activities during any unplanned outages and if possible while operating.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Ion Acceleration by Laser Plasma Interaction from Cryogenic Micro Jets - Oral Presentation [Slides]

Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for this type of interaction, capable of producing the highest proton energies possible with today’s laser technologies. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis and investigate new, potentially more efficient mechanisms of ion acceleration, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we achieved a pure proton beam with an indication of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the possibility of transforming our liquid cryogenic jets into droplet streams. This type of target should solve our problems with the jet as it will prevent the flow of exocurrent into the nozzle. It is also highly effective as it is even more mass-limited than standard cryogenic jets. Furthermore, jets break up spontaneously anyway. If we can control the breakup, we can synchronize the droplet emission with the laser pulses. In order to assist the team prepare for an experiment later this year, I familiarized myself with the physics and theory of droplet formation, calculated values for the required parameters, and ordered the required materials for modification of the jet. Future experiments will test these droplet streams and continue towards the goal of ion acceleration using cryogenic targets.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Molecular-Resolution Electron Imaging of Defects and Dynamics at the Ice-Water Interface

Water crystallization into hexagonal ice (type I h ) is one of the most critical processes relevant to the Earth’s environment and human activities. However, despite recent breakthroughs in imaging non-equilibrium condensed ice structures, the ice-water interface has never been imaged at a molecular resolution. This is primarily due to the low stability of the hydrogen bonds in ice under high-resolution microscopy conditions and a lack of methods to prepare compatible samples. Here, this presentation describes the first molecular-resolution imaging of ice crystallized from liquid water and the ice-water interface using high-resolution transmission electron microscopy (HRTEM). By encapsulating deionized (DI) water between two amorphous carbon (a-C) TEM grids and subsequently freezing it with liquid N 2 on a cryo sample stage, we generated two types of ice: non-equilibrium, condensed ice from the atmosphere and encapsulated ice from the DI water (Fig. 1A). Condensed ice usually shows irregular, spherulitic shapes (Fig. 1B). Selected area electron diffraction (SAED) shows that they are a mixture of cubic and hexagonal crystals (Fig. 1C). On the contrary, encapsulated ice forms thin films that contain large-area single-crystalline regions of hexagonal ice oriented along the [0001] zone axis (Fig. 1D). Differential electron energy-loss spectroscopy (EELS) confirmed the high purity of the encapsulated ice free from organic contaminations that are common in other encapsulation methods for HRTEM such as graphene liquid cells. These single-crystalline areas are robust under the electron beam up to ~100 e/Å 2 s. Aberration-corrected HRTEM imaging in these areas achieved a line resolution of ~1.3 Å (Fig. 1E and F). This platform allows us to study near-equilibrium ice structures and dynamics at an unprecedented spatial resolution (Fig. 2). For example, we discovered subdomain-rich regions near the defective crystal edges despite the structure appearing single-crystalline according to diffraction criteria. These subdomains connect via low-angle grain boundaries with flat energy landscapes as a function of tilt angles (according to simulations), showing the high tolerance of ice to defect structures. When we tuned the sample temperature and electron flux rate, we observed radiolysis-controlled bubble generation and dissolution in ice single crystals near a steady state of bubble dynamics. Furthermore, rich beam-induced melting and recrystallization dynamics were observed at the ice-water interface with lattice resolution. These data represent the first observation of the ice-water phase transformation at the sub-nanometer level. In summary, the methods developed in this work enabled molecular-resolution observations of ice and the ice-water interface and shed light on the microstructures and phase transformation pathways. Finer control on the temperature, electron irradiation profile, and imaging detector could eventually lead to real-time observation of ice nucleation in water and address long-standing questions in the nucleation pathways.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2017

Site Environmental Report for 2016

Lawrence Berkeley National Laboratory (LBNL, Berkeley Lab) is a multi-program scientific facility operated by the University of California (UC) for the U.S. Department of Energy (DOE). Berkeley Lab’s research is focused on the physical, biological, environmental, and computational sciences with the objective of delivering scientific knowledge and discoveries pertinent to DOE’s mission. This annual report describes environmental protection activities and potential impacts resulting from LBNL operations conducted in 2016. The format and content of this report satisfy the requirements of both DOE Order 231.1B Admin Chg 1, Environment, Safety, and Health Reporting, and the operating contract between UC and DOE (DOE Contract No. DE-AC02-05CH11231, also known as Contract 31). Activities are planned and conducted with full regard to protecting employees, the public, and the environment, as well as complying with all applicable environmental, safety, and health laws and regulations. Berkeley Lab implements an Environmental Management System (EMS) to oversee these compliance activities and improve overall environmental performance while maintaining operational capability and sustaining its overall mission. The effectiveness of the EMS and environmental programs is reviewed annually as part of the operating contract’s performance evaluation process. For fiscal year (FY) 2016, which began October 1, 2015, and ended September 30, 2016, the EMS was given a performance rating of A minus for its management of environmental activities (on a scale from A plus as the highest grade to F as the lowest). The measurement and rating system was developed jointly by Berkeley Lab, UC, and DOE. The FY 2016 rating was based on how Berkeley Lab met the objective in DOE’s FY 2017 Performance Evaluation and Measurement Plan (Appendix B in Contract 31, Section J) of providing an efficient and effective EMS. To support this rating, Berkeley Lab prepared a list of projects completed during the performance period that achieved reduced environmental impacts. The EMS was also graded through the federal Office of Management and Budget’s EMS Annual Report Data, in which elements of the International Organization for Standardization (ISO) 14001 standard are rated and the degree of integration between the EMS and Berkeley Lab’s sustainable practices is measured. Overall scores fall into one of three categories: green (highest), yellow (middle), or red (lowest). For FY 2016, Berkeley Lab received a score of green, as described in more detail in Chapter 2. An overview of environmental protection and restoration programs is provided (Chapter 3), including information about compliance activities, operating permits, and regulatory agency inspections that occurred during 2016. Six minor violations issued during these inspections are discussed, one of which was rescinded in 2017. This report also includes information on environmental monitoring performed in 2016 (Chapter 4). The results of these monitoring activities confirmed that groundwater cleanup actions continue to show improving conditions, and all emissions and discharges from LBNL operations were within environmental compliance release limits with the exception of some stormwater discharges. While most stormwater discharges measured throughout the LBNL site fall within acceptable levels established by the state's stormwater permit, iron and aluminum exceeded permitted levels. Berkeley Lab is aggressively implementing controls to reduce iron and aluminum discharge levels. The controls include construction of asphaltic berms to restrain and filter runoff to storm drains, and installation of filtration units in storm drain basins to absorb metal contaminants. The radiological dose assessments (Chapter 5) performed in 2016 concluded that the maximum dose to a hypothetical resident from Berkeley Lab’s airborne radionuclide releases was approximately 0.12% of the DOE and U.S. Environmental Protection Agency annual limit of 10 millirem per year (mrem/year); the dose from all radiation sources at Berkeley Lab was approximately 0.1% of the average natural background radiation dose of 310 mrem/yr in the United States, and about 0.4% of the DOE annual limit of 100 mrem/yr from all sources.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Decommissioning and Environmental Cleanup of a Small Arms Training Facility - 13225

US DOE performed a (CERCLA) non-time critical removal (NTCR) action at the Small Arms Training Area (SATA) Site Evaluation Area (SEA) located at the Savannah River Site (SRS), in Aiken, South Carolina. From 1951 to May 2010, the SATA was used as a small weapons practice and qualifying firing range. The SATA consisted of 870.1 ha (2,150 ac) of woodlands and open field, of which approximately 2.9 ha (7.3 ac) were used as a firing range. The SATA facility was comprised of three small arms ranges (one static and two interactive), storage buildings for supplies, a weapons cleaning building, and a control building. Additionally, a 113- m (370-ft) long earthen berm was used as a target backstop during live-fire exercises. The berm soils accumulated a large amount of spent lead bullets in the berm face during the facilities 59- years of operation. The accumulation of lead was such that soil concentrations exceeded the U.S. Environmental Protection Agency (USEPA) residential and industrial worker regional screening levels (RSLs). The RSL threshold values are based on standardized exposure scenarios that estimate contaminant concentrations in soil that the USEPA considers protective of humans over a lifetime. For the SATA facility, lead was present in soil at concentrations that exceed both the current residential (400 mg/kg) and industrial (800 mg/kg) RSLs. In addition, the concentration of lead in the soil exceeded the Toxicity Characteristic Leaching Procedure (TCLP) (40 Code of Federal Regulations [CFR] 261.24) regulatory limit. The TCLP analysis simulates landfill conditions and is designed to determine the mobility of contaminants in waste. In addition, a principal threat source material (PTSM) evaluation, human health risk assessment (HHRA), and contaminant migration (CM) analysis were conducted to evaluate soil contamination at the SATA SEA. This evaluation determined that there were no contaminants present that constitute PTSM and the CM analysis revealed that no constituents posed a migration risk to groundwater. The NTCR action involved removal of approximately 12,092 m{sup 3} (15,816 yd{sup 3}) of spent bullets and lead-impacted soil and off-site disposal. The removal action included soils from the berm area, a fill area that received scraped soils from the berm, and soil from a drainage ditch located on the edge of the berm area. Also included in the removal action was a mixture of soil, concrete, and asphalt from the other three range areas. Under this action, 11,796 m{sup 3} (15,429 yd{sup 3}) of hazardous waste and impacted soil were removed from the SATA and transported to a permitted hazardous waste disposal facility (Lone Mountain Facility in Oklahoma) and 296 m{sup 3} (387 yd{sup 3}) of nonhazardous waste (primarily concrete debris) were removed and transported to a local solid waste landfill for disposal. During the excavation process, the extent was continuously assessed through the use of a hand-held, field-portable X-ray fluorescence unit with results verified using confirmation sampling with certified laboratory analysis. Following the completion of the excavation and confirmation sampling, final contouring, grading, and establishment of vegetative cover was performed to stabilize the affected areas. The NTCR action began on August 17, 2010, and mechanical completion was achieved on April 27, 2011. The selected removal action met the removal action objectives (RAOs), is protective of human health and the environment both in the short- and long-term, was successful in removing potential ecological risks, and is protective of surface water and groundwater. Furthermore, the selected NTCR action met residential cleanup goals and resulted in the release of the SEA from restricted use contributing to the overall footprint reduction at SRS. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Artificial Soiling Replication of Field Losses on Commercial Photovoltaic Modules

Here, this study demonstrates the capabilities of an indoor artificial soiling approach developed to closely replicate the natural, cyclic soil accumulation processes in the field-dust suspension, deposition, and sedimentation/cementation-for a subtropical climate. In this work, a near-field environment is replicated in an artificial soiling cubic chamber through controlled regulation of humidity, temperature, dust type, and dust concentration, based on site-specific historical climate data. Two different models (MA and MB) of full-size commercial photovoltaic modules from a single manufacturer, installed side by side in the mid-Atlantic United States, were retrieved and subjected to artificial soiling experiments and various characterization measurements, including short-circuit current, colorimetry, reflectance, X-ray fluorescence, laser diffraction, and optical microscopy. Both in the field and in our improved field-representative artificial soiling tests, the MA model experienced roughly twice the soiling loss as the MB model. To closely replicate the field soiling losses for a site-specific climate, it is critical to include: 1) The use of field-collected dust with identical dust chemistry and particle distribution instead of standardized ISO 12103 Arizona Road dusts, 2) the use of only a small amount of field-collected dust inside the chamber during the deposition process (e.g., 0.15 g), and 3) the preconditioning of the surface coating for the partial/full dose of UV stress as experienced in the field during sunlight exposure and the abrasion as experienced in the field during regular module cleaning activities, if/as needed. The field-representative artificial soiling method developed here could potentially be adopted for rank ordering of various antisoiling coatings developed by researchers and industry stakeholders.

14 SOLAR ENERGY↗
DOE OSTI2018

Site Environmental Report for 2017

Lawrence Berkeley National Laboratory (LBNL, Berkeley Lab) is a multi-program scientific facility operated by the University of California (UC) for the U.S. Department of Energy (DOE). Berkeley Lab’s research is focused on the physical, biological, environmental, and computational sciences with the objective of delivering scientific knowledge and discoveries pertinent to DOE’s mission. This annual report describes environmental protection activities and potential impacts resulting from LBNL operations conducted in 2017. The format and content of this report satisfy the requirements of both DOE Order 231.1B, Administrative Change 1 (Environment, Safety, and Health Reporting) and the operating contract between UC and DOE (DOE Contract No. DE-AC02-05CH11231, also known as Contract 31). Activities are planned and conducted with full regard to protecting employees, the public, and the environment, as well as complying with all applicable environmental, safety, and health laws and regulations. Berkeley Lab implements an Environmental Management System (EMS) to oversee these compliance activities and continually improve overall environmental performance while maintaining operational capability and sustaining its overall mission. The effectiveness of the EMS and environmental programs is reviewed annually as part of the performance evaluation process of Contract 31. For fiscal year (FY) 2017, which began October 1, 2016, and ended September 30, 2017, the EMS was given a performance rating of B plus for its management of environmental activities (on a scale from A plus as the highest grade to F as the lowest). The measurement and rating system was developed jointly by Berkeley Lab, UC, and DOE. The FY 2017 rating was based on how Berkeley Lab met the objective in DOE’s FY 2017 Performance Evaluation and Measurement Plan (Appendix B in Contract 31, Section J) of providing an efficient and effective EMS. Six significant accomplishments, which ranged from effective teaming on projects and with regulatory agencies to improved program assessment approaches, were factors in the rating. The EMS was also graded through the federal Office of Management and Budget’s annual EMS performance metrics, in which a reporting scorecard rates elements of the International Organization for Standardization (ISO) 14001 standard and the degree of integration between the EMS and Berkeley Lab’s sustainable practices. Overall scores fall into one of three categories: green (highest), yellow (middle), or red (lowest). For FY 2017, Berkeley Lab received a score of green, as described in more detail in Chapter 2. An overview of environmental protection and restoration programs is provided, including information about compliance activities, operating permits, and regulatory agency inspections that occurred during 2017. Thirteen minor violations issued during City of Berkeley inspections of above and underground storage tanks, treatment units, and hazardous waste storage areas are discussed in this chapter. This report also includes information on environmental monitoring performed in 2017. The results of these monitoring activities confirmed that groundwater cleanup actions continue to show improving conditions, and all emissions and discharges from LBNL operations were within environmental compliance release limits, with the exception of some stormwater discharges. Most stormwater discharges measured throughout the LBNL site fall within acceptable levels established by the state’s stormwater permit; however, iron and aluminum exceeded Numeric Action Levels. To reduce iron and aluminum discharge levels, Berkeley Lab is aggressively implementing controls such as construction of asphaltic berms and check dams to restrain and filter runoff to storm drains, and installation of filtration units in storm drain basins to collect sediment and absorb metal contaminants. The radiological dose assessments performed in 2017 concluded that the maximum potential dose to a hypothetical resident from Berkeley Lab’s airborne radionuclide releases was approximately 0.1% of the DOE and U.S. Environmental Protection Agency annual limit of 10 millirem per year (mrem/yr); the potential dose from all radiation sources at Berkeley Lab was approximately 0.06% of the average natural background radiation dose of 310 mrem/yr in the United States, and about 0.2% of the DOE annual limit of 100 mrem/yr from all sources.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Bisphenol A degradation by manganese oxides at circumneutral pH: Quantitative evaluation of dissolved Mn(III) species with pyrophosphate

Although trivalent manganese (Mn(III)) species have been recognized as crucial intermediates in the degradation of organic contaminants by Mn oxides, quantitative research on their specific roles remains scarce. Here, our study investigated the degradation processes of an organic pollutant, Bisphenol A (BPA), by dissolved Mn(III) and Mn(III)-bearing oxides, and elucidated the differences of the underlying mechanisms and reaction pathways between several Mn oxides and dissolved Mn(III). Our results indicated that BPA degradation rates with Mn(III)-bearing oxides alone follow the order: δ-MnO 2 >> γ-MnOOH > Mn 3 O 4 . Adding pyrophosphate (PP) significantly enhanced BPA degradation by promoting the formation of Mn(III)-PP complexes and exposing more reactive sites, achieved through destabilizing the crystal structure and mitigating of Mn(II) readsorption, particularly in γ-MnOOH and Mn 3 O 4 . Our kinetic model revealed that heterogeneous degradation by Mn oxides is the predominant reaction pathway, accounting for 61.4 %, 87.8 %, and 73.8 % of the total degraded BPA for δ-MnO 2 , γ-MnOOH, and Mn 3 O 4 , respectively, even in the presence of significant amount of dissolved Mn(III) intermediates due to high PP concentrations. These results offer mechanistic details on BPA degradation by Mn oxides and the influence of ligand concentration, providing helpful insights for optimizing degradation strategies of organic pollutants.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Adaptation of Commercially Available Robots for Conditioning and Packaging ILW at Sellafield - 18282

The Legacy Ponds and Silos at Sellafield site contain some of the most hazardous Intermediate Level Waste (ILW) in the UK. As part of a multi-billion pound decommissioning programme, this waste will be retrieved and transported across the site for conditioning and packaging in the Box Encapsulation Plant (BEP). Current plans are to commence plant active commissioning in 2022, which will represent a major milestone in the UK nuclear decommissioning programme. Within the plant, skips of waste will be transferred from the shielded transport package into standard 3 cubic metre ILW containers. Waste from the Pile Fuel Storage Pond and First Generation Magnox Storage Pond will be immobilised in cementitious grout before being transferred to an adjacent store. Waste from the Magnox Swarf Storage Silo will not be immobilised in grout, but will be packaged, providing multi-barrier containment. During the concept design, the project team selected commercially available robots as the most viable technology for carrying out the numerous dexterous and repetitive tasks involved in characterising, conditioning and packaging the waste within the shielded 'hot' cells. Significant technical challenges had to be overcome during the design to adapt a commercially available robot for use within a high radiation / high contamination environment, where human access is not safe even for short periods of time. These challenges included: - Designing robot assemblies that could be retrofitted into the existing cell structure that was constructed as part of an earlier project but never completed; - Designing robot assemblies that could be recovered to their 'transport' position without requiring manual intervention; - Designing robot assemblies that could be remotely removed and replaced with new ones if they failed part way through the plant operational life; - Designing through-wall service and power connections that allow maintenance and recovery; - Designing control systems and human-machine interfaces that enable both manual and automated operation of the robot, whilst avoiding collisions with the in-cell cranes and other in cell furniture; - Assessing the radiation tolerance of all items. Bespoke computer simulations and full-scale development trials have been carried out, using non-active test materials, in order to demonstrate the Technology Readiness Level (TRL) required by Sellafield Limited (SL) at each stage of the project [1]. The results of these trials have been recorded in both video and written form so that they can form part of the project's Knowledge Management database. Detailed designs and specifications for the robot assemblies have been updated to incorporate the recommendations from the development trials. Procurement and manufacture of robot assemblies has already commenced to deliver two waste handling robots, two waste container lidding / swabbing robots and associated critical spares. (authors)

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

Bi-Modal Model for Neutron Emissions from PuO{sub 2} and MOX Holdup

The measurement of uranium and plutonium holdup in plants during process activity and for decommissioning is important for nuclear safeguards and material control. The amount of plutonium and uranium holdup in glove-boxes, pipes, ducts, and other containers has been measured for several decades using both neutron and gamma-ray techniques. For the larger containers such as hot cells and glove-boxes that contain processing equipment, the gamma-ray techniques are limited by self-shielding in the sample as well as gamma absorption in the equipment and associated shielding. The neutron emission is more penetrating and has been used extensively to measure the holdup for the large facilities such as the MOX processing and fabrication facilities in Japan and Europe. In some case the totals neutron emission rates are used to determine the holdup mass and in other cases the coincidence rates are used such as at the PFPF MOX fabrication plant in Japan. The neutron emission from plutonium and MOX has 3 primary source terms: 1) Spontaneous fission (SF) from the plutonium isotopes, 2) The (α,n) reactions from the plutonium alpha particle emission reacting with the oxygen and other impurities, and 3) Neutron multiplication (M) in the plutonium and uranium as a result of neutrons created by the first two sources. The spontaneous fission yield per gram is independent of thickness, whereas, the above sources 2) and 3) are very dependent on the thickness of the deposit. As the effective thickness of the deposit becomes thin relative to the alpha particle range, the (α,n) reactions and neutrons from multiplication (M) approach zero. In any glove-box, there will always be two primary modes of holdup accumulation, namely direct powder contact and non-contact by air dispersal. These regimes correspond to surfaces in the glove-box that have come into direct contact with the process MOX powder versus surface areas that have not had direct contact with the powder. The air dispersal of PuO{sub 2} particles has been studied for several decades by health physicists, because the primary health hazard of plutonium is breathing the airborne particles. The air dispersal mechanism results from the smaller particles in the top layer of powder that are lifted into the air by the electrostatic charge buildup from the alpha decay process, and the air convection carries the particles to new more distant locations. If there is open plutonium powder in a glove-box, the surfaces at more distant locations will become contaminated over time. The range of an alpha particle in a solid or powder is a function of the particle energy, the material density, and the atomic number A of the material. The average energy of a plutonium alpha particle is ∼5.2 MeV and the range in air is ∼37 mm. The range in other materials can be estimated via the Bragg-Kleenman equation. For plutonium, A is 94, and the typical density for a single particle is ∼11.5 g/cm{sup 3}, but for a powder, the density would be less because of the air packing fraction. The significance of the small diameter is that the range of the alpha particle is ∼50 μm for powder density 2.5 and significantly less for a single particle with density 11.5, so the thin deposit of separate small particles will have a greatly reduced (α,n) yield. The average alpha transit length to the surface in the isolated MOX particle would be < 2.5 μm; whereas, the range of the alpha particle is much longer. Thus, most of the alpha particles would escape from the MOX particle and be absorbed by the walls and air. The air dispersal particles will have access to a large surface area that includes the walls, whereas, the powder contact surface area will be orders of magnitude smaller. Thus, the vast majority of the glove-box surface area does not produce the full (α,n) reaction neutron yield, even from the O{sub 2} in the PuO{sub 2} as well as any impurity contamination such as H{sub 2}O. To obtain a more quantitative estimate of the neutron (α,n) yields as a function of holdup deposit thickness, we have used MCNPX calculations to estimate the absorption of alpha particles in PuO{sub 2} holdup deposits. The powder thickness was varied from 0.1 μm to 5000 μm and the alpha particle escape probability was calculated. As would be expected, as the thickness approaches zero, the escape probability approaches 1.0, and as the thickness gets much greater than the alpha particle range (∼50 μm), the escape probability becomes small. Typically, the neutron holdup calibration measurement are performed using sealed containers of thick MOX that has all 3 sources of neutrons [SF, (α,n), and M], and no significant impurities. Thus, the calibration counting rates need to include corrections for M and (α,n) yields that are different for the holdup compared with the calibration samples. If totals neutron counting is used for the holdup measurements, the variability of the (α,n) term needs to be considered.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Preparation and testing of corrosion and spallation-resistant coatings

The goal of this project was to take a recently developed method of bonding oxide dispersion-strengthened (ODS) FeCrAl plating to nickel superalloys closer to commercial use in syngas-fired turbines. The project was designed to better understand and develop the bonding process and to determine if plating APMT®, a specific highly oxidation-resistant ODS FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The superalloys investigated for protection were CM247LC and Rene® 80, both alumina scale-forming alloys. The method for bonding the APMT plate to the superalloys is called evaporative metal bonding, which involves placing a thin foil of zinc between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the zinc melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The zinc then diffuses through the alloys and evaporates from their surfaces, creating a bond between the APMT and the superalloy that is stronger than the APMT itself. Testing showed that the diffusivity of zinc in both APMT and CM247LC is quite similar at 700°C but 15 times higher in the APMT at 1214°C. Coefficients of thermal expansion were determined for each of the alloys as a function of temperature. This information was entered into a finite-element model using ANSYS, which was used to design a clamping jig for pressing the APMT to the superalloys at the bonding temperature. Scanning electron microscopy analyses of representative joints showed that no zinc remained in the alloys after bonding Unfortunately, the analyses also showed some small pieces of broken aluminum oxide scale near the bond lines, indicating that its scale was not sufficiently removed during prebonding cleaning. Samples from each of the bonded blocks were sent to Siemens for its standard oxidation, spallation, and corrosion testing, which was scheduled for completion in the spring of 2016. However, because of commercial demands, the tests were not completed by the time of this report except some initial spallation tests at 1150°C. In those tests, several of the APMT plates separated from the CM247LC, likely because of the remaining aluminum oxide scale on the surface of the CM247LC. This implies that surface preparation may need to include machining to remove the oxide scale before bonding rather than just sandblasting. In previous tensile testing at 950°C, the breaks in the tensile samples always occurred in the APMT and not at the joints. Gasifier sampling was completed to determine what types of trace contaminants may occur in cleaned and combusted syngas and that could lead to corrosion or deposition in turbines firing coal syngas. The sampling was done from a pressurized fluidized-bed gasifier and a pressurized entrained-flow gasifier. The particles captured on a filter from syngas were typically 0.2 to 0.5 μm in diameter, whereas those captured from the combusted syngas were slightly larger and more spherical. X-ray photoelectron spectroscopy done at Oak Ridge National Laboratory showed that the particles do not contain any metals and have an atomic composition almost identical to that of the polycarbonate filter. This indicates that the particles are primarily soot-based and not formed from volatilization of metals in the gasifiers.

20 FOSSIL-FUELED POWER PLANTS↗