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All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Evaluation of a recycling process for printed circuit board by physical separation and heat treatment

Highlights: • The parts mounted on printed circuit board (PCB) were liberated by underwater explosion and mechanical crushing. • The crushed PCB without surface-mounted parts was carbonized under inert atmosphere at 873 K to recover copper. • The multi-layered ceramic capacitors including nickel was carbonized at 873 K to recover nickel by the magnetic separation. • The tantalum powders were recovered from the molded resins by heat treatment at 723 and 823 K in air atmosphere and screening. • Energy and treatment cost of new process increased, however, the environmental burden decreased comparing conventional one. - Abstract: Printed circuit boards (PCBs) from discarded personal computer (PC) and hard disk drive were crushed by explosion in water or mechanical comminution in order to disintegrate the attached parts. More parts were stripped from PCB of PC, composed of epoxy resin; than from PCB of household appliance, composed of phenol resin. In an attempt to raise the copper grade of PCB by removing other components, a carbonization treatment was investigated. The crushed PCB without surface-mounted parts was carbonized under a nitrogen atmosphere at 873–1073 K. After screening, the char was classified by size into oversized pieces, undersized pieces and powder. The copper foil and glass fiber pieces were liberated and collected in undersized fraction. The copper foil was liberated easily from glass fiber by stamping treatment. As one of the mounted parts, the multi-layered ceramic capacitors (MLCCs), which contain nickel, were carbonized at 873 K. The magnetic separation is carried out at a lower magnetic field strength of 0.1 T and then at 0.8 T. In the +0.5 mm size fraction the nickel grade in magnetic product was increased from 0.16% to 6.7% and the nickel recovery is 74%. The other useful mounted parts are tantalum capacitors. The tantalum capacitors were collected from mounted parts. The tantalum-sintered bodies were separated from molded resins by heat treatment at 723–773 K in air atmosphere and screening of 0.5 mm. Silica was removed and 70% of tantalum grade was obtained after more than 823 K heating and separation. Next, the evaluation of Cu recycling in PCB is estimated. Energy consumption of new process increased and the treatment cost becomes 3 times higher comparing the conventional process, while the environmental burden of new process decreased comparing conventional process. The nickel recovery process in fine ground particles increased energy and energy cost comparing those of the conventional process. However, the environmental burden decreased than the conventional one. The process for recovering tantalum used more heat for the treatment and therefore the energy consumption increased by 50%, when comparing with conventional process. However, the market price for tantalum is very large; the profit for tantalum recovery is added. Also the environmental burden decreased by the recycling of tantalum recovery. Therefore, the tantalum recovery is very important step in the PCB recycling. If there is no tantalum, the consumed energy and treatment cost increase in the new process, though the environmental burden decreases.

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

Study of the element abundances in HD 140283: The abundance robustness of the weak r- and main r-process stars

Many works have attempted to investigate the astrophysical origin of the neutron-capture elements in the metal-poor star HD 140283. However, no definite conclusions have been drawn. In this work, using the abundance-decomposed approach, we find that the metal-poor star HD 140283 is a weak r-process star. Although this star is a weak r-process star, its Ba abundance mainly originates from the main r-process. This is the reason that the ratio [Ba/Eu]= −0.58±0.15 for HD 140283 is close to the ratio of the main r-process. Based on the comparison of the abundances in the six-weak r-process stars, we find that their element abundances possess a robust nature. On the other hand, we find that the robust nature of the abundance of the extreme main r-process stars ([r/Fe] ⩾ 1.5) can be extended to the lighter neutron-capture elements. Furthermore, the abundance characteristics of the weak r-process and main r-process are investigated. The abundance robustness of the two category r-process stars could be used as the constraint of the r-process theory and could be used to investigate the astrophysical origins of the elements in the metal-poor stars and population I stars.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Processing liquid organic wastes at the NNL Preston laboratory

Organic compounds of various kinds have been used in the nuclear industry for numerous duties in uranium chemical, metal and ceramic processing plants. In the course of the various operations undertaken, these organic compounds have become contaminated with uranic material, either accidentally or as an inevitable part of the process. Typically, the chemical/physical form and/or concentration of the uranic content of the organics has prevented disposal. In order to address the issue of contaminated liquid organic wastes, the National Nuclear Laboratory (NNL) has developed a suite of treatments designed to recover uranium and to render the waste suitable for disposal. The developed processes are operated at industrial scale via the NNL Preston Laboratory Residue Processing Plant. The Oil Waste Leaching (OWL) Process is a fully industrialised process used for the treatment of contaminated oils with approximately 200 tonnes of uranium contaminated oil being treated to date. The process was originally developed for the treatment of contaminated tributyl phosphate and odourless kerosene which had been adsorbed onto sawdust. However, over the years, the OWL process has been refined for a range of oils including 'water emulsifiable' cutting oils, lubricating oils, hydraulic oils/fluids and 'Fomblin' (fully fluorinated) oils. Chemically, the OWL process has proved capable of treating solvents as well as oils but the highly volatile/flammable nature of many solvents has required additional precautions compared with those required for oil treatment. These additional precautions led to the development of the Solvent Treatment Advanced Rig (STAR), an installation operated under an inert atmosphere. STAR is a small 'module' (100 dm{sup 3} volume) which allows the treatment of both water miscible and immiscible solvents. This paper discusses the challenges associated with the treatment of liquid organic wastes and the process developments which have allowed a wide range of materials to be successfully treated. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Comparative Assessment of Data-driven Process Models in Health Information Technology

Process mining for conformance analysis consists of comparing a reference process model against a data-driven process model generated via log files from information technology systems. However, in the absence of a complete reference process model, we found no suggested approaches in the literature to address the need for evaluating process conformance among different healthcare facilities to assess standardization of care. Our goal is to find similarities and dissimilarities in data-driven process models among US Veterans Health Administration (VHA) facilities that can be indicative of patient safety issues. Our hypothesis was that the analysis would not produce statistically significant differences in outcome. We present a unique implementation of conformance analysis in process mining that consists of combining process mining, process mapping and statistical metrics. We illustrate our approach by applying it to the analysis of two clinical radiology order process models generated from healthcare data provided by two similar facilities in the VHA. The comparative assessment showed that about 70% of the orders completed successfully and 30% were not completed due to policy and duplications. Our analysis found a good statistical correlation between both facilities, as the Spearman’s correlation coefficient between facilities for the frequency of cases per total hours was 0.87879, for the frequency of cases by state transition was 0.79702 and for the throughput time per state transition was 0.63582. Additional statistical analyses using the Mann-Whitney U test and the root mean square error both produced values that were not significant. The foregoing approach validated our hypothesis by demonstrating a good statistical correlation of data describing the flow of clinical radiology orders absent a credible reference model. Finding good agreement between both facilities was important in confirming that the clinical orders flow in a similar manner, suggesting standardization of care.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Chemical evolution of {sup 244}Pu in the solar vicinity and its implications for the properties of r-process production

Meteoritic abundances of r-process elements are analyzed to deduce the history of chemical enrichment by the r-process, from the beginning of disk formation to the present time in the solar vicinity. Our analysis combines the abundance information from short-lived radioactive nuclei such as {sup 244}Pu with the abundance information from stable r-process nuclei such as Eu. These two types of nuclei can be associated with one r-process event and an accumulation of events until the formation of the solar system, respectively. With the help of the observed local star formation (SF) history, we deduce the chemical evolution of {sup 244}Pu and obtain three main results: (i) the last r-process event occurred 130–140 Myr before the formation of the solar system; (ii) the present-day low {sup 244}Pu abundance as measured in deep-sea reservoirs results from the low recent SF rate compared to ∼4.5−5 Gyr ago; and (iii) there were ∼15 r-process events in the solar vicinity from the formation of the Galaxy to the time of solar system’s formation and ∼30 r-process events to the present time. Then, adopting the hypothesis that a neutron star (NS) merger is the r-process production site, we find that the ejected r-process elements are extensively spread out and mixed with interstellar matter, with a mass of ∼3.5×10{sup 6} M{sub ⊙}, which is about 100 times larger than that for supernova ejecta. In addition, the event frequency of r-process production is estimated to be 1 per ∼1400 core-collapse supernovae, which is identical to the frequency of NS mergers estimated from the analysis of stellar abundances.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Air Pollutant Emissions and Regulatory Implications of Co-Processing Raw Bio-Oil in U.S. Petroleum Refineries

Pyrolysis oil, often referred as bio-oil or biocrude, has attracted considerable attention because it has higher energy density and carbon content compared to the raw biomass. Using pyrolysis oil derived from low cost and underutilized biomass to produce renewable hydrocarbon fuels provides a viable link between the agriculture/forestry and (petro-) chemical industry. Co-processing bio-oil with vacuum gas oil (VGO) in petroleum refinery is appealing due to the relatively low capital requirement to retrofit refinery and the compatibility of fuel products with existing infrastructure. In order to implement co-processing, a petroleum refinery would need to consider several process modifications and therefore could be subject to varying levels of air permitting requirements based on bio-oil co-processing ratio, co-processing capacity in existing units, the amount of regulated pollutants expected to be emitted, among other factors. This analysis considers co-processing 5% (by weight) of raw bio-oil with VGO in the fluidized catalytic cracking (FCC) unit(s) in a petroleum refinery. We estimate the potential increase in emissions of regulated air pollutants resulting from the modifications required to implement bio-oil co-processing and evaluate the regulatory and permitting implications for three FCC size categories in the U.S. refineries, which could co-processes raw bio-oil to produce partially renewable transportation fuels. We also assess technically feasible emission control options petroleum refineries could adopt to avoid being subject to major source permitting requirements if the estimated increase in regulated air pollutant emission exceeds the applicable threshold for major modifications. Insights from our analysis can help overcome challenges and risks associated with timely obtaining air permits required to implement bio-oil co-processing in existing refineries. Our analysis also provides needed information for decision makers (e.g., local air quality agencies) to understand the potential air quality implications for retrofitting refineries to co-process bio-oil, particularly in areas with high concentration of petroleum refineries.

09 BIOMASS FUELS↗
DOE OSTI2013

Hanford Low-Activity Waste Processing: Demonstration of the Off-Gas Recycle Flowsheet - 13443

Vitrification of Hanford Low-Activity Waste (LAW) is nominally the thermal conversion and incorporation of sodium salts and radionuclides into borosilicate glass. One key radionuclide present in LAW is technetium-99. Technetium-99 is a low energy, long-lived beta emitting radionuclide present in the waste feed in concentrations on the order of 1-10 ppm. The long half-life combined with a high solubility in groundwater results in technetium-99 having considerable impact on performance modeling (as potential release to the environment) of both the waste glass and associated secondary waste products. The current Hanford Tank Waste Treatment and Immobilization Plant (WTP) process flowsheet calls for the recycle of vitrification process off-gas condensates to maximize the portion of technetium ultimately immobilized in the waste glass. This is required as technetium acts as a semi-volatile specie, i.e. considerable loss of the radionuclide to the process off-gas stream can occur during the vitrification process. To test the process flowsheet assumptions, a prototypic off-gas system with recycle capability was added to a laboratory melter (on the order of 1/200 scale) and testing performed. Key test goals included determination of the process mass balance for technetium, a non-radioactive surrogate (rhenium), and other soluble species (sulfate, halides, etc.) which are concentrated by recycling off-gas condensates. The studies performed are the initial demonstrations of process recycle for this type of liquid-fed melter system. This paper describes the process recycle system, the waste feeds processed, and experimental results. Comparisons between data gathered using process recycle and previous single pass melter testing as well as mathematical modeling simulations are also provided. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Development of a Performance and Processing Property Acceptance Region for Cementitious Low-Level Waste Forms at Savannah River Site - 13174

The Saltstone Production and Disposal Facilities (SPF and SDF) at the Savannah River Site (SRS) have been treating decontaminated salt solution, a low-level aqueous waste stream (LLW) since facility commissioning in 1990. In 2012, the Saltstone Facilities implemented a new Performance Assessment (PA) that incorporates an alternate design for the disposal facility to ensure that the performance objectives of DOE Order 435.1 and the National Defense Authorization Act (NDAA) of Fiscal Year 2005 Section 3116 are met. The PA performs long term modeling of the waste form, disposal facility, and disposal site hydrogeology to determine the transport history of radionuclides disposed in the LLW. Saltstone has been successfully used to dispose of LLW in a grout waste form for 15 years. Numerous waste form property assumptions directly impact the fate and transport modeling performed in the PA. The extent of process variability and consequence on performance properties are critical to meeting the assumptions of the PA. The SPF has ensured performance property acceptability by way of implementing control strategies that ensure the process operates within the analyzed limits of variability, but efforts continue to improve the understanding of facility performance in relation to the PA analysis. A similar understanding of the impact of variability on processing parameters is important from the standpoint of the operability of the production facility. The fresh grout slurry properties (particularly slurry rheology and the rate of hydration and structure formation) of the waste form directly impact the pressure and flow rates that can be reliably processed. It is thus equally important to quantify the impact of variability on processing parameters to ensure that the design basis assumptions for the production facility are maintained. Savannah River Remediation (SRR) has been pursuing a process that will ultimately establish a property acceptance region (PAR) to incorporate elements important to both processability and long-term performance properties. This process involves characterization of both emplaced product samples from the disposal facility and laboratory-simulated samples to demonstrate the effectiveness of the lab simulation. With that basis confirmed, a comprehensive variability study using non-radioactive simulants will define the acceptable PAR, or 'operating window' for Saltstone production and disposal. This same process will be used in the future to evaluate new waste streams for disposal or changes to the existing process flowsheet. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Modular Design of Processing and Storage Facilities for Small Volumes of Low and Intermediate Level Radioactive Waste including Disused Sealed Sources - 12372

There are a number of IAEA Member States generating relatively small quantities of radioactive waste and/or disused sealed sources in application of nuclear techniques in medicine, industry and research and in nuclear research centres having small research reactors. At present many of these Member States do not have facilities for processing and storing their radioactive wastes; notably in those countries with small quantities of generated radioactive wastes. In other Member States the existing waste processing and storage facilities (WPSF) are in need of varying degrees of upgrading in order to address new waste streams, incorporate new waste processing technologies, or expand interim storage capacities. The IAEA has developed a modular design approach for a WPSF that is based on a variety of modules for different waste stream treatment and conditioning processes. The modular WPSF design is elaborated in a substantial Design Engineering Package that will be published by IAEA as a technical report. The Design Engineering Package enables users to select the optimum waste processing and storage modules to meet their needs, and to specify the requirements for procurement of individual modules and their integration into a waste processing and storage facility. The Design Engineering Package is planned for publication by the IAEA in 2012 and is presented as: - A Design Engineering Package Summary document. - A supporting CD that contains: - Process module general specifications. - Process module interface specifications. - Design Engineering Package for process modules. - Sample technical specifications for design and construction of modular processing facility. - Design Engineering Package for storage modules. (authors)

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

Facility Improvements and Modifications to Extend the Operational Life of the Modular Caustic-Side Solvent Extraction Process - 16082

Savannah River Remediation, LLC (SRR) is working to remove, stabilize, and dispose of approximately 36.7 million gallons (138.9 million liters) of liquid radioactive waste currently stored in 43 underground waste tanks, and ultimately close waste tanks. In 2008, as an interim salt treatment system to remove cesium from high level waste salt solutions prior to the Salt Waste Processing Facility start up, the Modular Caustic-Side Solvent Extraction Unit (MCU) initiated the removal of cesium from liquid radioactive salt waste prior to disposal. The MCU was designed and built for an expected three-year operational life and five-year design life. The first MCU cold runs began in June 2007 and hot startup was completed in April 2008. MCU remains in hot operation to this day, aiding in multiple, high-level tank closures. In an effort to continue liquid waste disposition at the Savannah River Site (SRS), equipment upgrades and operational improvements have been made to extend the life of the MCU beyond the original three years. Several pieces of fixed equipment have been converted into removable equipment which reduces the downtime associated with equipment change-outs and thereby reduces the dose to workers and processing impacts. Multiple pumps and filters have been upgraded to more robust designs. Process monitoring and controls have been upgraded to improve process performance. Redundant centrifugal contactor vibration equipment has been installed on each contactor in order to better assess the reliability, processing performance, and lifetime of the contactors. A new Solvent Hold Tank (SHT) Sampler has been installed to minimize the organic cross-contamination within the sampler, dose to workers, and sample analysis time. To increase processing availability and aid in visually obtained data, camera port has been added to the Salt Solution Feed Tank (SSFT). In order to decrease the overall background dose to the workers, the Process Vessel Ventilation (PVV) duct work now has the capability to be flushed to remove contamination. The caustic wash addition system has been modified to be a once-through system to improve equipment reliability, decrease downtime, and decrease dose to workers. In addition, the solvent that MCU utilizes to extract Cesium out of salt waste has been upgraded to Next Generation Solvent (NGS) which is based on MaxCalix extractant instead of a BobCalix extractant. Further, these upgrades and improvements have allowed MCU to be able to process at higher flow rates (up to 8.5 GPM) and with increased throughput (as high as 1.3 million gallons in FY13 and 5.3 million gallons since hot operations initiated) that have allowed SRR to continue the disposition of nuclear salt waste. The continued operation of MCU ensures more curies are stabilized into a glass matrix at SRS's Defense Waste Processing Facility (DWPF) and less curies are retained within South Carolina at SRS's Saltstone Disposal Facility (SDF). Unique challenges associated with modifying and improving a demonstration plant that is in hot operations and was designed to be temporary with a limited plant footprint have been successfully overcome. Further, creative strategies for removing old equipment have been utilized given the limited decontamination agents available for use that will not interfere with the organic solvent. This paper presents and discusses the deployment of these upgrades and operational improvements to MCU in order to allow continued, increased salt waste processing beyond the initial design life. (authors)

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

Filtration Improvements in Support of Increased Salt Waste Processing Throughput at the Savannah River Site - 16173

Crossflow Filtration is currently used at the U.S. Department of Energy (DOE) Savannah River Site (SRS) for the removal of actinides, strontium and sludge solids from the high-level salt waste stored in underground tanks. At SRS, crossflow filtration is deployed in the Actinide Removal Process (ARP). Salt waste is transferred from an underground waste tank to one of two strike tanks where it is struck with Monosodium Titanate (MST), which adsorbs uranium, plutonium and strontium. The MST laden salt waste is then transferred to the ARP filtration facility, which contains the crossflow filter. The filtrate, which is called Clarified Salt Solution (CSS), is sent to a downstream facility for cesium removal, while the MST and sludge solids are concentrated at the filtration facility and eventually sent to the Defense Waste Processing Facility (DWPF) for vitrification. ARP and the downstream cesium removal facility, the Modular Caustic Side Solvent Extraction Unit (MCU), were both developed as an interim salt waste processing technology and as smaller scale radioactive demonstration plants for the Salt Waste Processing Facility (SWPF), which is currently under construction. Since the beginning of ARP in 2008, there have been challenges with achieving desired filtration rates through the crossflow filter system. Historically the crossflow filter system has been the flow limiter in salt waste processing and many changes have been made and are planned to achieve desired throughput, especially as MCU increases its processing capacity. Some of these changes include the design of a new crossflow filter, the implementation of a new process chemistry flowsheet and several operational changes. The modifications to the ARP crossflow filter have helped contribute to periods of record throughput in salt waste processing in FY 2015. This paper will discuss the technical challenges and system limitations of retrofitting an older facility as well as past, present and future modifications to the ARP filtration process in order to achieve salt waste processing goals at SRS. (authors)

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

Process Control Approach to Implement High Waste Loading Glass Formulations for Hanford Low Activity Waste Vitrification - 18435

Acceptable glass formulations for vitrification of Hanford low activity waste (LAW) at The Hanford Tank Waste Treatment and Immobilization Plant (WTP) must meet a variety of product quality, processability, and waste loading requirements. The glass formulation development work underpinning the WTP baseline LAW glasses was captured in a vitrification process control approach developed by the Vitreous State Laboratory (VSL) and Atkins Energy Federal EPC, Inc. that permits the calculation of the glass formulation required for each particular batch of LAW delivered to the LAW vitrification facility. Since that time, we have developed a wide range of glass formulations that achieve considerably higher waste loadings and which therefore are more economically attractive in terms of reduced amounts of glass produced and decreased time for treatment. That work was done in support of the Department of Energy's Office of River Protection program that is examining options to optimize the LAW facility and LAW glass waste form. Implementation of these high waste loading formulations at the WTP requires the development of a new LAW vitrification process control algorithm, which is the subject of this paper. Waste loadings in LAW glasses are typically limited by either the alkali loading for LAW with low sulfate content or the SO{sub 3} loading for LAW with high sulfate content. In the former case, waste loadings are limited by refractory corrosion and glass corrosion on the vapor hydration test (VHT) and product consistency test (PCT), all of which tend to increase with higher alkali concentrations. In the latter case, waste loadings are limited by the formation of a molten sulfate phase in the melter, which has deleterious effects. The LAW vitrification process control strategy must mitigate these effects while optimizing waste loadings. Given the composition of any LAW stream, the new LAW vitrification process control algorithm permits the calculation of a suitable high waste loading glass composition and the required glass forming additives such that all processing, waste loading, and product quality requirements are met. This algorithm was developed from data for a large number of glasses that were formulated, and characterized with respect to a variety of properties affecting processability and product quality; many of these formulations were also subjected to melter testing to verify acceptable processing characteristics, processing rates, and the absence of secondary sulfate phase formation. This paper describes the development of the present algorithm, comparisons to the present lower waste loading baseline WTP process control approach, and plans for further development and testing. (authors)

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

Implementation of Increased Salt and Decreased Sludge Volumes in the Defense Waste Processing Facility - 19597

The Savannah River Site (SRS) Liquid Waste System (LWS) safely stores and treats high-level radioactive waste. The LWS consists of 51 waste storage tanks (eight of which are operationally closed and filled with grout), waste evaporators, treatment facilities, and solidification facilities such as the Defense Waste Processing Facility (DWPF) and Saltstone Production Facility (SPF). The disposition of high-level waste (HLW) into a glass waste form poured into canisters at the DWPF began in 1996. DWPF processed a sludge only flowsheet until 2008 when the Actinide Removal Process (ARP) and Modular Caustic Side Solvent Extraction Unit (MCU) began treating the salt waste from the underground liquid storage tanks by striking with monosodium titanate (MST) to remove actinides, when necessary to meet downstream acceptance criteria, and removing the MST and entrained sludge solids (SS) by filtration before using an organic solvent to strip the cesium from the salt, creating two new concentrated HLW streams. This change caused the DWPF to begin processing under both a sludge-only and a coupled operations flowsheet where salt streams would only be added when available. This strategy allows for continuous glass canister production at DWPF. Recently, DWPF completed a 10-month melter replacement in December 2017 and the Concentrate, Storage, and Transfer Facility (CSTF) has completed repairs to the 3H Evaporator system. These facility outages have caused delays in preparing the next batch of sludge feed for DWPF. Concurrent with these facility outages, the Salt Waste Processing Facility (SWPF) has been undergoing system testing and commissioning, working toward startup. SWPF is designed to process salt waste in the same manner as ARP/MCU, but with much higher throughput volumes produced per unit time. In order to process the SWPF salt streams efficiently, DWPF will implement a coupled operation only flowsheet. Based on the facility outages mentioned above, efforts have been made to identify strategies to minimize sludge volumes and maximize salt volumes in the DWPF until the next sludge batch is ready for processing in DWPF. Savannah River Remediation (SRR) recently performed an evaluation that examines the effects of reducing the volume of sludge and maximizing the addition of the cesium-rich concentrated salt solution in each Sludge Receipt and Adjustment Tank (SRAT) batch in order to extend the existing sludge batch as long as possible until the next sludge batch is ready. These effects include a reduction of weight percent solids in the DWPF processing vessels, an increase in cycle time, a new canister heat generation value that remains within regulatory limits, and higher gamma source that remains within bulk facility gamma shielding. Balancing the above parameters resulted in a small reduction of sludge volume per SRAT batch under SWPF operation and maximizing the salt volumes for both ARP/MCU and SWPF operation. This slight reduction in sludge volume and increase in salt volumes allows SRR to mitigate some of the schedule impact incurred by the facility outages. This strategy was evaluated for both ARP/MCU and SWPF operation. This strategy has been successfully implemented under ARP/MCU operation using small step changes in the current process. This paper provides an overview of the evaluation performed for DWPF with ARP/MCU and DWPF with SWPF operations. (authors)

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

Novel Foaming Solutions for High Level Waste (HLW) Processing - 20195

Foaming occurs during treatment of high level waste (HLW) at Savannah River Site's Defense Waste Processing Facility (DWPF) in the Chemical Process Cell (CPC) due to high gas generation from process steam and chemical offgas products [1]. The presence of amphiphilic particles in the waste slurry stabilizes the foam [2], [3]. Efficient processing of HLW requires foam control, as foam-overs lead to lower productivity and potential radioactive contamination of condensate streams. DWPF currently employs Siovation Antifoam 747, a surfactant produced by Momentive Performance Materials, as an antifoaming agent during waste treatment. Despite its ability to control foam generation, processing issues have arisen from its use [4]. During DWPF chemical processing, a chemical antifoam agent must be effective at temperatures up to 103 deg. C between pH 3-13. Antifoam 747 is effective at pH 7 but degrades as pH deviates [5]. Antifoam 747 is 90% by weight Momentive{sup TM} L77 and 10% by weight Momentive{sup TM} Y-17580. These ingredients are trisiloxane products, which are especially vulnerable to attack in acidic and caustic environments. Since Antifoam 747 readily degrades, periodic addition is required. Several processing concerns related to Antifoam 747 have affected DWPF operation. Its overuse warranted concern of potential flammable melter offgas under upset conditions due to the generation of carbon dioxide and hydrogen. As a result, a Potential Inadequacy in the Safety Analysis (PISA) was declared [6]. Antifoam contribution has been included in the melter offgas flammability strategy and the quantity of antifoam is monitored to ensure limits are not exceeded. Testing at Savannah River National Laboratory (SRNL) determined that propanal, tri-methylsilanol, and hexamethyldisiloxane are generated as Antifoam 747 degrades, leading to a second PISA [7]. The formation of these byproducts poses additional flammability risks. Furthermore, the methyl and ethyl groups of these compounds may be responsible for the formation of the methyl and ethyl mercury discovered in DWPF [8], [9]. The formation of organomercury has specifically been called out by DOE as a need for increased research. The effectiveness of non-chemical methods for foam control and the efficiency of alternative antifoam agents were evaluated as part of an effort to improve HLW treatment operations at DWPF and to reduce, or eliminate, the flammability hazards associated with Antifoam 747 currently in use. Foaming of high-level waste (HLW) slurries is an issue at the Defense Waste Processing Facility (DWPF) Chemical Process Cell (CPC) which is currently mitigated with a chemical antifoam agent. The effectiveness of non-chemical methods for foam control and the efficiency of alternative antifoams were examined to improve HLW treatment at DWPF and to eliminate the flammability hazards associated with Siovation Antifoam 747 currently in use. Non-chemical foam control methods were deemed unviable for chemical processing at DWPF, as the spray/mist technique requires too much water and space limitations make installation and implementation of headspace agitators unfeasible. The use of ultrasonic energy thickened and further stabilized the foam. Two suitable alternative defoaming agents, Momentive{sup TM} Y- 17112 and Evonik Surfynol{sup R} MD-20, were identified. Both defoamers control foam over a pH range of 4- 13 at boiling, with no flammable degradation products, and only minimal quantities (100-200 mg/kg) are required under glycolic acid conditions. In order to validate the effectiveness of these defoaming agents, SRNL recommends irradiation testing and laboratory scale SRAT/SME experiments with actual radioactive waste. (authors)

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

ProCAFD: Computer-aided Tool for Sustainable Process Synthesis, Intensification and Hybrid solutions

Process industry is always in quest for innovative designs which are both efficient, safe and sustainable. The feasible search space of all unit operations that can be combined to generate process flowsheet alternatives for a given synthesis problem can be large and difficult to manually navigate in order to determine the best processing route. Therefore, it is helpful to utilize computer-aided methods and tools to enumerate, analyze and determine within the design space, the more sustainable processes. In this study, an integrated computer-aided method and corresponding software-tool that’s capable of generating and searching the entire design space for more sustainable process options is presented. In this work a comprehensive analysis method consisting of economic, life cycle, sustainability and process safety indicators is used to identify process bottlenecks on the selected alternative which are translated to design targets. Matching of these design targets minimizes/eliminates the process hot-spots and, thereby generating non-trade-off innovative process designs.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Effect of tube processing methods on microstructure, mechanical properties and irradiation response of 14YWT nanostructured ferritic alloys

In this research, innovative thermal spray deposition (Process I) and conventional hot extrusion processing (Process II) methods have been used to produce thin walled tubing (~0.5 mm wall thickness) out of 14YWT, a nanostructured ferritic alloy. The effects of processing methods on the microstructure, mechanical properties and irradiation response have been investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and, micro- and nano-hardness techniques. It has been found that these two processes have a significant effect on the microstructure and mechanical properties of the as-fabricated 14YWT tubes. Even though both processing methods yield the formation of various size Y-Ti-O particles, the conventional hot extrusion method results in a microstructure with smaller, homogenously distributed nano-oxides (NOs, Y-Ti-O particles < 5 nm) with higher density. Therefore, Process II tubes exhibit twice the hardness of Process I tubes. It has also been found that these two tremendously different initial microstructures strongly affect irradiation response in these tubes under extremely high dose ion irradiations up to 1100 peak dpa at 450 °C. The finer, denser and homogenously distributed NOs in the Process II tube result in a reduction in swelling by two orders of magnitude. On the other hand, inhomogeneity of the initial microstructure in the Process I tube leads to large variations in both swelling and irradiation induced hardening. Moreover, hardening mechanisms before and after irradiation were measured and compared with detailed calculations. In conclusion, this study clearly indicates the crucial effect of initial microstructure on radiation response of 14YWT alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching

Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na{sub 2}CO{sub 3}, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na{sub 2}CO{sub 3}, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4 M HCl, 100 °C and pulp density of 20 g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. - Highlights: • Simplest process for treatment of GaN an LED industry waste developed. • The process developed recovers gallium from waste LED waste dust. • Thermal analysis and phase properties of GaN to Ga{sub 2}O{sub 3} and GaN to NaGaO{sub 2} revealed. • Solid-state chemistry involved in this process reported. • Quantitative leaching of the GaN was achieved.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Current challenges and potential directions towards precision microscale additive manufacturing – Part III: Energy induced deposition and hybrid electrochemical processes

The Part III of the four-part series of articles discusses the challenges and opportunities in microscale additive manufacturing processes, specifically focusing on energy-induced deposition and electrochemical processes. Compared to the direct ink write (DIW) and laser-based processes, the energy-induced deposition methods can fabricate high-resolution, high aspect ratio and complex parts, while the hybrid electrochemical process can be used to fabricate complex parts using a wide range of conductive and photoactive materials. However, the volumetric throughput of these processes is lower than their DIW and laser-based counterparts. The processes that have been explored in this process are Focused-ion Beam Induced Deposition (FIBID), Laser Chemical Vapor Deposition (LCVD), Menicus-confined Electrodeposition (MCED) and Laser-Enabled Electrochemical Printing (LECP). The range of processable materials, feature-size resolution, geometry and volumetric throughput are used as factors to evaluate the current state-of-the-art for these processes. Finally, novel approaches have been proposed in the article to address these challenges associated with microscale AM processes.

42 ENGINEERING↗