Primary crystallization in high Al-content metallic glasses is driven by nanometer-diameter regions with internal structure similar to fcc Al. Comparison of fluctuation electron microscopy (FEM) data to FEM simulations of fcc Al clusters dispersed in a dense-random packed matrix is used to extract the diameter and volume fraction of the ordered regions in a Al88Y7Fe5 base glass and in glasses with 1 at.% Cu substituted for Y or Al. The size and density of nanocrystals were measured as a function of isothermal annealing time for the same alloys. The volume fraction of crystalline material grows under isothermal annealing, so the phase transformation is not purely grain coarsening, but the crystalline volume fraction is lower than the volume fraction of ordered regions in the as-quenched samples, so not all of the ordered regions act as nuclei. Changes in diameter and volume fraction of the ordered regions with alloying are correlated with changes in the crystallization temperature, nucleation rate, and nanocrystal density. No evidence for phase separation is observed, and FEM simulations from a molecular dynamics quenched structural model of similar composition do not show the features observed in experiment.

offers diverse, complex, and valuable building blocks and products. Second, Consortium researchers developed technologies to enable process intensification, which can reduce equipment needs, energy consumption, and waste generation, thereby cutting bioprocessing capital costs and rendering processes more efficient. Third, the Consortium sought to recover carbon from dilute aqueous streams that are common to bioprocessing; recovering dilute carbon can improve process efficiency and economics. Finally, Consortium researchers designed and developed new materials and catalysts to reduce targeted foulants and poisons in bioprocessing streams that can limit the lifetime of downstream catalysts or fermenting microorganisms. Table 1 lists the technologies that were examined and places them in the context of the Consortium’s capabilities, types of bioprocesses, and critical challenges in bioprocessing separations. Overall, across these projects, we have developed separations technologies for 10 bioprocesses, addressed 9 target compounds in bioprocessing, developed 10 materials, and evaluated 4 processes for cost and sustainability.

Additional technological configurations were pursued, including (1) nanofiltration combined with zeolite dewatering for a near-zero liquid discharge (ZLD) scenario, and (2) polishing discharge from zeolite dewatering using capacitive deionization (CDI) with 90+% salt rejection to produce water with less than 100ppm TDS for more beneficial use. Project results verified that UK CAER’s hybrid approach addressed the complexities of WFGD blowdown with simplified unit operation at relatively low capital investment by demonstrating: (1) an effective in-situ generated solid sorbent material, green-rust (GR), that specifically removes regulated dissolved species in WFGD blowdown, including selenium, arsenic, and nitrates; (2) a low-cost, high flux nanofiltration treatment that removes both monovalent and divalent species at >80% rejection to adequately provide water recycle and extend the life of FGD equipment by mitigating chloride aided pitting corrosion mechanisms; and (3) a solidification and stabilization process using pozzolanic agents that retain regulated species and satisfy the Resource Conservation and Recovery Act (RCRA) leachate requirements. UK CAER proved electrocoagulation with GR to be an intensified solution for effluent limit guidelines (ELG), and based on preliminary techno-economic analysis (TEA), in comparison to DOE’s Case 1 for Biological Wastewater Treatment that had a purchased equipment cost (PEC) of $$\$$$$5.26 million and a Total plant cost (TPC) of $$\$$$$30.0 million, the EC process had a PEC of $$\$$$$2.67 million and the TPC of $$\$$$$17.0 million. While the electricity consumption for Case 1 was 53 kW, it was 110 kW for the EC process due to dissolving iron for a three-stage reaction design. However, electricity consumption for the EC process could be significantly reduced by adopting a counter-current reactor design for at least a 6-stage chemical reaction operation.

diffusivity is larger than the self-diffusion coefficient by ahout a factor of seven. This may result from an increase in diffusivity on annealing, or it may be due to the fact that the U-- C system is far from an ideal solution. (auth)

The accurate interpretation of uranium metal 230 Th/ 234 U and 231 Pa/ 235 U radiochronometry model ages requires an understanding of how uranium parent nuclides and decay progeny ( 230 Th and 231 Pa) behave during uranium metal casting. In order to directly measure the spatial distribution of 230 Th and 231 Pa in uranium metal before and after vacuum induction melting (VIM), Los Alamos National Laboratory identified uranium metal feedstock, characterized the metal feedstock, conducted a controlled casting experiment of an approximately 120 kg uranium metal rod, and characterized the cast metal. This study presents radiochronometry results and quantified 230 Th and 231 Pa VIM separation factors from bulk uranium.

The high density of aluminum nanocrystals (>1021 m-3) that develop during the primary crystallization in Al-based metallic glasses indicates a high nucleation rate (∼1018 m-3 s-1). Several studies have been advanced to account for the primary crystallization behavior, but none have been developed to completely describe the reaction kinetics. Recently, structural analysis by fluctuation electron microscopy has demonstrated the presence of the Al-like medium range order (MRO) regions as a spatial heterogeneity in as-spun Al88Y7Fe5 metallic glass that is representative for the class of Al-based amorphous alloys that develop Al nanocrystals during primary crystallization. From the structural characterization, an MRO seeded nucleation configuration is established, whereby the Al nanocrystals are catalyzed by the MRO core to decrease the nucleation barrier. The MRO seeded nucleation model and the kinetic data from the delay time (τ) measurement provide a full accounting of the evolution of the Al nanocrystal density (Nv) during the primary crystallization under isothermal annealing treatments. Moreover, the calculated values of the steady state nucleation rates (Jss) predicted by the nucleation model agree with the experimental results. Moreover, the model satisfies constraints on the structural, thermodynamic, and kinetic parameters, such as the critical nucleus size, the interface energy, and the volume-free energy driving force that are essential for a fully self-consistent nucleation kinetics analysis. The nucleation kinetics model can be applied more broadly to materials that are characterized by the presence of spatial heterogeneities.

of the possibility of compliance with standards which would conform to the US Envionmental Protection Agency's (EPA) Interpretative Ruling of December, 1976. Only under a fortuitous set of regulations and events is it likely that compliance will be demonstrated. If the San Francisco Bay Area or if the vicinity of a proposed site is deemed not a non-attainment area for particulates, or if it is and trade-offs can be obtained through very diligent efforts; if ambient CO standards are being met through futher reduction of automotive pollution; and finally if NO/sub x/ offsets can be obtained through retrofitting existing PG and E facilities - a difficult task according to all parties; if all of these conditions prevail, then PG and E might demonstrate compliance. The Committee notes that it is the Staff's opinion that some of these tasks will be extremely difficult if not impossible to accomplish. The Committee recommends that the Commission approve the NOI and allow PG and E to make the decision whether or not to pursue an AFC. But for its own planning purposes, the Commission would be unwise to count on this poject.

High-energy, microfocus x-ray imaging, or x-radiography, is a useful tool for in situ analysis and monitoring of materials processing. Large fields-of-view, spatial and temporal resolutions sufficient for mesoscopic imaging, and high-energy x-rays capable of probing metallic alloy samples make the technique attractive for in situ solidification studies in the laboratory. Here, we demonstrate the usefulness of high-energy, microfocus x-radiography in the laboratory, particularly when paired with complementary techniques. Multimodal, multiscale characterization was performed, including x-radiographic analysis of solidifying Al-Ag and compositional analysis of the same sample after solidification with scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). The dynamics observed through x-radiography during solidification are compared to the compositional results obtained by EDS. The fraction solid measured in radiographs is also used in combination with a calculation of phase diagrams (CalPhaD) Scheil solidification simulation to reconstruct a spatiotemporal microsegregation map. The multimodal, multiscale characterization techniques presented here illustrate a promising pathway toward improved analyses and monitoring of materials processing within a laboratory setting.

Charged particle radiography with 800 MeV protons has been used for decades at LANL and developed around the world to study dynamic material properties. Recently, charged particle radiography has been demonstrated with the use of highenergy electrons. Because of the difference in the mass of the electron compared to the mass of the proton, the radiographic processes are substantially different and well suited to the study of fast dynamic processes in relatively thin systems. This presentation will show the layout required for such measurements, along with data collected from this recent demonstration performed with 14 GeV electrons generated at the SLAC National Accelerator Laboratory. The radiographic performance for flash measurements will be presented, along with the limitations of this measurement technique.

Defects are important because they heavily influence material properties (e.g. strength, ductility, elasticity, conductivity, phase transformation temperatures (melting point), corrosion resistance, etc.). At LANL defects in plutonium are being characterized using many different methods (e.g. EXAFS, XRD, microscopy, RUS, DSC, dilatometry, density, etc.) My goal is to introduce a complimentary method of understanding defects in δ-Pu using the mechanical microscope concept. Using well-developed theories of first principles strengthening mechanisms (i.e. how defects influence strength) and carefully designed experiments, mechanical testing can compliment other defect characterization tools.

Microwave-cast material dating from the latest prototype development period and subsequent TRL 7 advancement testing was sent to LANL for additional characterization. The initial characterization described here is considered a supplement to and verification of that performed by Y-12 during the Technology Readiness Assessment process. The carbon chemistry results from Y-12 and LANL regarding early prototype microwave cast test object (CTO) and cylinder castings match within expectations. Only one fully intact as-cast CTO was available for examination in which carbon chemistry does not appear to vary spatially, at least at relatively low carbon levels (hypoeutectic). The large as-cast grain size leads to relatively poor grain size statistics and similar difficulties were encountered during the TRA. Small, isolated gas pores were observed in four of the five metallographic samples in prototype CTO casting PT-01. Finally, the next phase of characterization work, which focuses on corrosion behavior, has started and is described briefly.

Advanced casting modeling has been utilized to more fully explore and explain a case study from U-10Mo triple plate production. The case study involved a configuration difference between two furnaces that lead to systematic casting defects. The differences in thermal profile due to coil displacements has been quantified: the first step in determining a better path forward for casting procedures. Furthermore, it has been found that for this particular case study, this issue would not have been noticed by a furnace operator as the available control information was insensitive to the issue. The simulated data is perhaps most significant in that it would provide a casting SME the required information to adjust heating schedules such that both furnaces could be used successfully, significantly increasing efficiency and throughput. This type of casting modeling can be used in the future to help reduce the number of rejected castings.

High energy electrons have been used to investigate an extension of transmission electron microscopy. This technique, transmission high energy electron microscopy (THEEM), provides two additional capabilities to electron microscopy. First, high energy electrons are more penetrating than low energy electrons, and thus, they are able to image through thicker samples. Second, the accelerating mode of a radio-frequency linear accelerator provides fast exposures, down to 1 ps, which are ideal for flash radiography, making THEEM well suited to study the evolution of fast material processes under dynamic conditions. Initial investigations with static objects and during material processing have been performed to investigate the capabilities of this technique.

An effort to commence conversion of the High Flux Isotope Reactor (HFIR) to a low enriched uranium (LEU) based fuel has been proposed. While recent experience from LEU-10wt%Mo (U-10Mo) monolithic metal fuel production may be leveraged considerably, the significant differences between research fuels requires some degree of strategy reassessment. In that spirit, initial casting trials have been performed at LANL over the last two years in order develop a high quality starting metal ingot.

Process exploration for fuel production for the High Flux Isotope Reactor (HFIR) using cast LEU-10wt.%Mo as an initial processing step has just begun. This project represents the first trials concerned with casting design and quality. The studies carried out over the course of this year and information contained in this report address the initial mold development to be used as a starting point for future operations. In broad terms, the final billet design is that of a solid rolling blank with an irregular octagonal cross section. The work covered here is a comprehensive view of the initial attempts to produce a sound casting. This report covers the efforts to simulate, predict, cast, inspect, and revise the initial mold design.