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All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Hyperbolic/parabolic development for the GIM-STAR code

Flow fields in supersonic inlet configurations were computed using the eliptic GIM code on the STAR computer. Spillage flow under the lower cowl was calculated to be 33% of the incoming stream. The shock/boundary layer interaction on the upper propulsive surface was computed including separation. All shocks produced by the flow system were captured. Linearized block implicit (LBI) schemes were examined to determine their application to the GIM code. Pure explicit methods have stability limitations and fully implicit schemes are inherently inefficient; however, LBI schemes show promise as an effective compromise. A quasiparabolic version of the GIM code was developed using elastical parabolized Navier-Stokes methods combined with quasitime relaxation. This scheme is referred to as quasiparabolic although it applies equally well to hyperbolic supersonic inviscid flows. Second order windward differences are used in the marching coordinate and either explicit or linear block implicit time relaxation can be incorporated.

Spradley, L. W.↗
NASA NTRS2011

Large-Scale Low-Boom Inlet Test Overview

This presentation provides a high level overview of the Large-Scale Low-Boom Inlet Test and was presented at the Fundamental Aeronautics 2011 Technical Conference. In October 2010 a low-boom supersonic inlet concept with flow control was tested in the 8'x6' supersonic wind tunnel at NASA Glenn Research Center (GRC). The primary objectives of the test were to evaluate the inlet stability and operability of a large-scale low-boom supersonic inlet concept by acquiring performance and flowfield validation data, as well as evaluate simple, passive, bleedless inlet boundary layer control options. During this effort two models were tested: a dual stream inlet intended to model potential flight hardware and a single stream design to study a zero-degree external cowl angle and to permit surface flow visualization of the vortex generator flow control on the internal centerbody surface. The tests were conducted by a team of researchers from NASA GRC, Gulfstream Aerospace Corporation, University of Illinois at Urbana-Champaign, and the University of Virginia

Hirt, Stefanie↗
NASA NTRS1999

Lean Premixed Combustion Stabilized by Low Swirl a Promising Concept for Practical Applications

Since its inception, the low-swirl burner (LSB) has shown to be a useful laboratory apparatus for fundamental studies of premixed turbulent flames. The LSB operates under wide ranges of equivalence ratios, flow rates, and turbulence intensities. Its flame is lifted and detached from the burner and allows easy access for laser diagnostics. The flame brush is axisymmetric and propagates normal to the incident reactants. Therefore, the LSB is well suited for investigating detailed flame structures and empirical coefficients such as flame speed, turbulence transport, and flame generated turbulence. Due to its capability to stabilize ultra-lean premixed turbulent flames (phi approx. = 0.55), the LSB has generated interest from the gas appliance industry for use as an economical low-NO(x) burner. Lean premixed combustion emits low levels of NO(x), due primarily to the low flame temperature. Therefore, it is a very effective NO(x) prevention method without involving selective catalytic reduction (SCR), fuel-air staging, or flue gas recirculation (FGR). En the gas turbine industry, substantial research efforts have already been undertaken and engines with lean premixed combustors are already in use. For commercial and residential applications, premixed pulsed combustors and premixed ceramic matrix burners are commercially available. These lean premixed combustion technologies, however, tend to be elaborate but have relatively limited operational flexibility, and higher capital, operating and maintenance costs. Consequently, these industries are continuing the development of lean premixed combustion technologies as well as exploring new concepts. This paper summarizes the research effects we have undertaken in the past few years to demonstrate the feasibility of applying the low-swirl flame stabilization method for a wide range of heating and power generation systems. The principle of flame stabilization by low-swirl is counter to the conventional high-swirl methods that rely on a recirculation zone to anchor the flame. In LSBS, flow recirculation is not promoted to allow the premixed turbulent flames to propagate freely. A LSB with an air-jet swirler is essentially an open tube with the swirler at its mid section. The small air-jets generate swirling motion only in the annular region and leaving the central core of the flow undisturbed, When this flow exits the burner tube, the angular momentum generates radial mean pressure gradient to diverge the non-swirling reactants stream. Consequently, the mean flow velocity decreases linearly. Propagating against this decelerating flow, the flame self-sustains at the position where the local flow velocity equals the flame speed, S(sub f). The LSB operates with a swirl number, S, between 0.02 to 0.1. This is much lower than the minimum S of 0.6 required for the high-swirl burners. We found that the swirl number needed for flame stabilization varies only slightly with fuel type, flow velocity, turbulent conditions and burner dimensions (i.e. throat diameter and swirl injection angle).

Cheng, R. K.↗
DOE OSTI2014

Wave-wave interactions in solar type III radio bursts

The high time resolution observations from the STEREO/WAVES experiment show that in type III radio bursts, the Langmuir waves often occur as localized magnetic field aligned coherent wave packets with durations of a few ms and with peak intensities well exceeding the strong turbulence thresholds. Some of these wave packets show spectral signatures of beam-resonant Langmuir waves, down- and up-shifted sidebands, and ion sound waves, with frequencies, wave numbers, and tricoherences satisfying the resonance conditions of the oscillating two stream instability (four wave interaction). The spectra of a few of these wave packets also contain peaks at f{sub pe}, 2f{sub pe} and 3 f{sub pe} (f{sub pe} is the electron plasma frequency), with frequencies, wave numbers and bicoherences (computed using the wavelet based bispectral analysis techniques) satisfying the resonance conditions of three wave interactions: (1) excitation of second harmonic electromagnetic waves as a result of coalescence of two oppositely propagating Langmuir waves, and (2) excitation of third harmonic electromagnetic waves as a result of coalescence of Langmuir waves with second harmonic electromagnetic waves. The implication of these findings is that the strong turbulence processes play major roles in beam stabilization as well as conversion of Langmuir waves into escaping radiation in type III radio bursts.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Continual Learning for Production-Level Machine Learning in Particle Accelerators

Particle accelerators operate in complex environments where data distribution can change dynamically, leading to data drifts that significantly challenge Machine Learning (ML) models. These non-stationary conditions often cause ML models to deteriorate in performance, making it difficult to maintain reliable predictions in operation. The primary sources of data drifts are changes in accelerator settings and changes in equipment performance which cannot be measured directly. To bridge this gap between ML development and long-term deployment in operational settings, we identify key areas within particle accelerators where continual learning can help mitigate drift-induced performance degradation. We will provide a practical guide on selecting the appropriate method given resource constraints and desired stability plasticity trade offs. As a concrete example, we will present a real-world use case for anomaly detection to predict errant beams at the Spallation Neutron Source accelerator, where continual learning has been employed to demonstrate stable performance on drifting data streams. We will present practical challenges, lessons learned, and the results from the deployed ML model.

Rajput, Kishansingh [Thomas Jefferson National Acc↗
NASA NTRS1992

Experiments and analysis concerning the use of external burning to reduce aerospace vehicle transonic drag

The external combustion of hydrogen to reduce transonic drag was investigated. A control volume analysis is developed and indicates that the specific impulse performance of external burning is competitive with other forms of airbreathing propulsion and depends on the fuel-air ratio, freestream Mach number, and the severity of the base drag. A method is presented for sizing fuel injectors for a desired fuel-air ratio in the unconfined stream. A two-dimensional Euler analysis is also presented which indicates that the total axial force generated by external burning depends on the total amount of energy input and is independent of the transverse and streamwise distribution of heat addition. Good agreement between the Euler and control volume analysis is demonstrated. Features of the inviscid external burning flowfield are discussed. Most notably, a strong compression forms at the sonic line within the burning stream which may induce separation of the plume and prevent realization of the full performance potential. An experimental program was conducted in a Mach 1.26 free-jet to demonstrate drag reduction on a simple expansion ramp geometry, and verify hydrogen-air stability limits at external burning conditions. Stable combustion appears feasible to Mach number of between 1.4 and 2 depending on the vehicle flight trajectory. Drag reduction is demonstrated on the expansion ramp at Mach 1.26; however, force levels showed little dependence on fuel pressure or altitude in contrast to control volume analysis predictions. Various facility interference mechanisms and scaling issues were studied and are discussed.

Trefny, Charles J.↗
DOE OSTI2015

Geo-polymer solidification technology approved by Czech / Slovak nuclear authority to immobilise NPP resins and sludge waste - 15555

This paper presents the features and performance record of the geo-polymer solidification technology, SIAL{sup R}, licensed for use by both the Slovakian (UJD SR) and Czech Nuclear (SUJB) regulators. An overview of its performance at Bohunice in Slovakia, where it has been used to successfully treat resins and sludge wasteforms will be provided along with references to other plants where it has been used. More recently, geo-polymers have been noted as an immobilization technology which shows potential for resins produced by treatment of radioactive contaminated water resulting from the clean-up of the Fukushima Daiichi Plant. The Nuclear Power Plant A-1 located in Jaslovske Bohunice was completed in 1972 and operated for 5 years until two accidents in 1976 and 1977. After the second accident in February 1977 (INES level 4) the Nuclear Power Plant was permanently shut down for decommissioning. Fuel assemblies and fuel cladding damaged in the accidents led to significant Sr-90, Cs-137 and transuranic contamination. As a consequence of the long-term corrosion of the barrier's material, highly contaminated sludge accumulated which could not be effectively immobilized using conventional methods such as cementation or bitumen treatment due to adverse physical-chemical properties and high specific activity of the waste (Cs-137). This challenge led to AMEC developing and licensing the geo-polymer, SIAL{sup R}. Today, this geo-polymer is one of the most proven and widely used for on-site solidification of radioactive materials such as sludge, resins, sorbents and organic liquids. There are numerous benefits to using this geo-polymer for waste immobilisation. It can be used at room temperature and can incorporate up to approximately four times as much waste (sludge, resin) as a Portland cement matrix equivalent depending on the waste being treated. In addition, it is characterized by excellent mechanical and physical properties, compared with the earlier generation techniques. This includes higher mechanical strength, lower leachability, low volatility, posing a low fire risk and excellent physical stability in the presence of frost and water (no distortion or cracking). Dedicated facilities to receive and encapsulate waste from different locations can be created but this geo-polymer can also provide efficient and practical on-site treatment of radioactive waste streams. This is achievable because the equipment used to encapsulate waste using SIAL{sup R} is also modular, flexible and versatile. At Bohunice, the facility for encapsulation was designed to occupy existing areas of the plant in close proximity to the tanks where the waste was being stored. This allowed for the removal of the waste using Remote Operated Vehicles (ROVs) and for the waste to be immediately treated on site without the need for transportation saving both time and resource. To achieve this, some of the rooms and areas of the building were assessed and modified to ensure that the waste package flow was suitable whilst ensuring that appropriate safety measures were in place such as adequate shielding to reduce or entirely eliminate dose uptake of workers. To date, SIAL{sup R} has been used to successfully immobilize approximately 500 tons of waste which includes sludge and resin from Bohunice, Slovakia and approximately 250 m{sup 3} of spent ion exchange resins from tanks on site at the Dukovany nuclear plant, Czech Republic. It now has a track record of over 15 years which includes on-going research and development. The International missions WANO and OSART evaluated the SIAL{sup R} matrix technology at NPP Dukovany as an example of good practice. (authors)

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

Engineering Accessible Adsorption Sites in MOFs for CO 2 Capture (Final Report)

The overall goal of this project was to synthesize metal-organic frameworks (MOFs) with improved CO 2 adsorption and selectivity properties for potential application in removing this greenhouse gas from flue gas streams during fossil fuel processing. MOFs are an important class of 2-dimensional (2D) and 3D supramolecular coordination polymer networks that are comprised of organic linkers (ligands) and metal ion-units or clusters. They generally possess very high surface area, porosity, variable thermal stability and tunable chemistry, which make them potentially candidates CO 2 adsorption. The three specific objectives of this project were as follows: 1) To synthesize MOFs with metal ions adsorption sites in more accessible locations within the structures (towards the center of the organic linkers) in order to enhance their CO 2 adsorption characteristics; 2) To investigate the CO 2 adsorption properties of new MOFs containing pyrazine- and other nitrogen containing ligands as possible improved alternatives to known amine-functionalized MOFs; and 3) To investigate the nature of the adsorption sites and mechanism(s) by conducting computational studies on CO 2 adsorption within the MOF structures and compare the results with experimental observations. The main outcomes of this research are as follows. Nitrogen-containing ligands that possesses a diaza-12-crown-4-ether moiety at the center of two phenylcarboxylic acid groups was utilized to synthesize 3D MOFs in which the added transition metal ions (i.e.CO 2 + and Mn2+) were coordinated within the crown moieties. Therefore, the structures had the metal ions in more accessible locations. The new 3D structures, being non-porous however, showed negligible adsorption capacity for CO 2 . The ligand 2,3,5,6,-pyrazinetetracarboxylic acid (PZTC) was successfully used to synthesize four new MOFs, each with one of the following metal ion; Ca2+(1D), Zn2+(2D), Mn2+ (3D) and Gd3+(3D), and with the dimensionality (D) indicated. The Ca-, Zn- and Mn- PZTC-based MOFs had no obvious accessible pores and showed no adsorption capacity for CO 2 . Gd-PZTC structure however, showed promising capacities of 1.0 mmol/g and 0.6 mmol/g at 273K and 298 K respectively. Another nitrogen-containing ligand explored was 2,2’-dinitro- trans-4,4’- stilbenedicarboxylic acid (DNSDC) and in combination with a co-ligand, 2,2’-bipyridine (2,2’-BPY). The combination of DNSDC with CO 2 + and Mn2+ yielded four new thermally stable MOFs that showed significant CO 2 absorption capacities. The experimental CO 2 adsorption capacities varied among the structures, ranging between 1.8 mmol/g at 256 K and 0.8 mmol/g at 298K. The DNSDC-based structures maintained significant stability and capacities over many adsorption cycles at 298K. With 2,2’-diamino- trans-4,4’-stillbene dicarboxylic acid (DASDC) as ligand instead of DNSDC, new 3D MOF structures were also synthesized. The structures however were less stable, and decomposed on activation (exposure to vacuum and or solvents) and therefore showed negligible CO 2 adsorption capacities. The dinitro-stilbene based MOFs showed promising CO 2 adsorption capacities, thermal stabilities and recyclability, and therefore showed potential for application in CO 2 removal from flue gas. The research accomplishments presented herein supports the Department of Energy’s (DOE) Office of Fossil Energy and the National Energy Technology Laboratory (NETL) mission in the area of research that advances the science of coal technologies, specifically carbon capture and storage. The research outcomes can guide rational design/synthesis strategies towards producing advanced materials for CO 2 capture. However, further research is needed in order to develop the materials to meet or exceed capacities and stabilities that are reported for their counterparts.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2019

Engineering Accessible Adsorption Sites in MOFs for CO 2 Capture

The overall goal of this project was to synthesize metal-organic frameworks (MOFs) with improved CO 2 adsorption and selectivity properties for potential application in removing this greenhouse gas from flue gas streams during fossil fuel processing. MOFs are an important class of 2-dimensional (2D) and 3D supramolecular coordination polymer networks that are comprised of organic linkers (ligands) and metal ion-units or clusters. They generally possess very high surface area, porosity, variable thermal stability and tunable chemistry, which make them potential candidates for CO 2 adsorption. The three specific objectives of this project were as follows: 1) To synthesize MOFs with metal ion adsorption sites in more accessible locations within the structures (towards the center of the organic linkers) in order to enhance their CO 2 adsorption characteristics; 2) To investigate the CO 2 adsorption properties of new MOFs containing pyrazine- and other nitrogen containing ligands as possible improved alternatives to known amine-functionalized MOFs; and 3) To investigate the nature of the adsorption sites and mechanism(s) by conducting computational studies on CO 2 adsorption within the MOF structures and compare the results with experimental observations. The main outcomes of this research are as follows: Nitrogen-containing ligands that possess a diaza-12-crown-4-ether moiety at the center of two phenylcarboxylic acid groups were utilized to synthesize 3D MOFs in which the added transition metal ions (i.e. Co 2+ and Mn 2+ ) were coordinated within the crown moieties. Therefore, the structures had the metal ions in more accessible locations. The new 3D structures, being non-porous however, showed negligible adsorption capacity for CO 2 . The ligand 2,3,5,6,-pyrazinetetracarboxylic acid (PZTC) was successfully used to synthesize four new MOFs, each with one of the following metal ions; Ca 2+ (1D), Zn 2+ (2D), Mn 2+ (3D) and Gd 3+ (3D), and with the dimensionality (D) indicated. The Ca-, Zn- and Mn- PZTC-based MOFs had no obvious accessible pores and showed no adsorption capacity for CO 2 . Gd-PZTC structure however, showed promising capacities of 1.0 mmol/g and 0.6 mmol/g at 273K and 298 K respectively. Another nitrogen-containing ligand explored was 2,2’-dinitro- trans-4,4’- stilbenedicarboxylic acid (DNSDC) and in combination with a co-ligand, 2,2’-bipyridine (2,2’-BPY). The combination of DNSDC with Co 2+ and Mn 2+ yielded four new thermally stable MOFs that showed significant CO 2 absorption capacities. The experimental CO 2 adsorption capacities varied among the structures, ranging between 1.8 mmol/g at 256 K and 0.8 mmol/g at 298K. The DNSDC-based structures maintained significant stability and capacities over many adsorption cycles at 298K. With 2,2’-diamino- trans-4,4’-stillbene dicarboxylic acid (DASDC) as ligand instead of DNSDC, new 3D MOF structures were also synthesized. The structures, however, were less stable, and decomposed on activation (exposure to vacuum and or solvents) and therefore showed negligible CO 2 adsorption capacities. The dinitro-stilbene based MOFs showed promising CO 2 adsorption capacities, thermal stabilities and recyclability, and therefore showed potential for application in CO 2 removal from flue gas. The research accomplishments presented herein support the Department of Energy’s (DOE) Office of Fossil Energy and the National Energy Technology Laboratory (NETL) mission in the area of research that advances the science of coal technologies, specifically carbon capture and storage. The research outcomes can guide rational design/synthesis strategies towards producing advanced materials for CO 2 capture. However, further research is needed in order to develop the materials to meet or exceed capacities and stabilities that are reported for their counterparts.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRS1973

Effects of reaction control system jet simulation on the stability and control characteristics of a 0.015-scale space shuttle orbiter model in the Ames Research Center 3.5-foot hypersonic wind tunnel

An experimental investigation was performed in the Ames Research Center 3.5-Foot Hypersonic Wind Tunnel to obtain detailed effects which interactions between the RCS jet flow field and the local orbiter flow field have on orbiter hypersonic stability and control characteristics. Six-component force data were obtained through an angle-of-attack range of 15 to 35 deg with 0 deg angle of sideslip. The test was conducted with yaw, pitch and roll jet simulation at a free-stream Mach number of 10.3. These data simulate two SSV reentry flight conditions at Mach numbers of 28.3 and 10.3. Fuselage base pressures and pressures on the nonmetric RCS pods were obtained in addition to the basic force measurements. Model 42-0 was used for these tests.

Dziubala, T. J.↗
NASA NTRS1981

Weighted-mean scheme for solving incompressible viscous flow

The problem of how a boundary layer responds to the motion of a convexed vortex on a porous wall was investigated. The wall velocity is approximately given by Darcy's law. The vorticity-stream function approach was adopted for solving Navier-Stokes equations of two dimensional incompressible viscous flows. The weighted-mean scheme was used for constructing finite difference approximations of spatial derivatives. Several test problems were solved and numerical results demonstrate clearly the accuracy, stability, and efficiency of the scheme. The weighted mean scheme then can be applied to the vortical flow problem.

Huynh, Q. Q.↗
NASA NTRS1982

Computer program for calculating full potential transonic, quasi-three-dimensional flow through a rotating turbomachinery blade row

A fast, reliable computer code is described for calculating the flow field about a cascade of arbitrary two dimensional airfoils. The method approximates the three dimensional flow in a turbomachinery blade row by correcting for stream tube convergence and radius change in the throughflow direction. A fully conservative solution of the full potential equation is combined with the finite volume technique on a body-fitted periodic mesh, with an artificial density imposed in the transonic region to insure stability and the capture of shock waves. The instructions required to set up and use the code are included. The name of the code is QSONIC. A numerical example is also given to illustrate the output of the program.

Farrell, C. A.↗
NASA NTRS1995

Boundary layer transition studies

A small-scale wind tunnel previously used for turbulent boundary layer experiments was modified for two sets of boundary layer transition studies. The first study concerns a laminar separation/turbulent reattachment. The pressure gradient and unit Reynolds number are the same as the fully turbulent flow of Spalart and Watmuff. Without the trip wire, a laminar layer asymptotes to a Falkner & Skan similarity solution in the FPG. Application of the APG causes the layer to separate and a highly turbulent and approximately 2D mean flow reattachment occurs downstream. In an effort to gain some physical insight into the flow processes a small impulsive disturbance was introduced at the C(sub p) minimum. The facility is totally automated and phase-averaged data are measured on a point-by-point basis using unprecedently large grids. The evolution of the disturbance has been tracked all the way into the reattachment region and beyond into the fully turbulent boundary layer. At first, the amplitude decays exponentially with streamwise distance in the APG region, where the layer remains attached, i.e. the layer is viscously stable. After separation, the rate of decay slows, and a point of minimum amplitude is reached where the contours of the wave packet exhibit dispersive characteristics. From this point, exponential growth of the amplitude of the disturbance is observed in the detached shear layer, i.e. the dominant instability mechanism is inviscid. A group of large-scale 3D vortex loops emerges in the vicinity of the reattachment. Remarkably, the second loop retains its identify far downstream in the turbulent boundary layer. The results provide a level of detail usually associated with CFD. Substantial modifications were made to the facility for the second study concerning disturbances generated by Suction Holes for laminar flow Control (LFC). The test section incorporates suction through interchangeable porous test surfaces. Detailed studies have been made using isolated holes in the impervious test plate that used to establish the Blasius base flow. The suction is perturbed harmonically and data are averaged on the basis of the phase of the disturbance, for conditions corresponding to strong suction and without suction. The technique was enhanced by using up to nine multiple probes to reduce the experimental run-time. In both cases, 3D contour surfaces in the vicinity of the hole show highly 3D TS waves which fan out in the spanwise direction forming bow-shaped waves downstream. The case without suction has proved useful for evaluating calculation methods. With suction, the perturbations on the centerline are much stronger and decay less rapidly, while the TS waves in the far field are similar to the case without suction. Downstream, the contour surfaces of the TS waves develop spanwise irregularities which eventually form into clumps. The spanwise clumping is evidence of a secondary instability that could be associated with suction vortices. Designers of porous surfaces use Goldsmith's Criterion to minimize cross-stream interactions. It is shown that partial TS wave cancellation is possible, depending on the hole spacing, disturbance frequency and free-stream velocity. New high-performance Constant Temperature Hot-Wire Anemometers were designed and built, based on a linear system theory analysis that can be extended to arbitrary order. The motivation was to achieve the highest possible frequency reponse while ensuring overall system stability. The performance is equal to or superior to commercially available instruments at about 10% of the cost. Details, such as fabrication drawings and a parts list, have been published to enable the instrument to be construced by others.

Watmuff, Jonathan H.↗
NASA NTRS2004

Development and Characterization of a Low-Pressure Calibration System for Hypersonic Wind Tunnels

Minimization of uncertainty is essential for accurate ESP measurements at very low free-stream static pressures found in hypersonic wind tunnels. Statistical characterization of environmental error sources requires a well defined and controlled calibration method. A calibration system has been constructed and environmental control software developed to control experimentation to eliminate human induced error sources. The initial stability study of the calibration system shows a high degree of measurement accuracy and precision in temperature and pressure control. Control manometer drift and reference pressure instabilities induce uncertainty into the repeatability of voltage responses measured from the PSI System 8400 between calibrations. Methods of improving repeatability are possible through software programming and further experimentation.

Green, Del L.↗
NASA NTRS1978

Nonlinear stability of solar type 3 radio bursts. 2: Application to observations near 1 AU

A set of rate equations including strong turbulence effects and anomalous resitivity are solved using parmeters which model several solar type 3 bursts. Exciter distributions observed at 1 AU are excitation of the linear bump-in-tail instability, amplifying Langmuir waves above the threshold for the oscillating two stream instability (OTSI). The OTSI, and the attendant anomalous resistivity produce a rapid spectral transfer of Langmuir waves to short wavelengths, out of resonance with the electron exciter. Further energy loss of the beam is thus precluded. The various parameters needed to model the bursts are extrapolated inside 1 AU with similar results. Again, the OTSI is excited and decouples the electron beam from the Langmuir radiation. Reabsorption of the Langmuir waves by the beam is shown to be unimportant in all cases, even at 0.1 AU. The theory provides a natural explanation for the observed realationship between radio flux, and the electron flux.

Goldstein, M. L.↗
DOE OSTI2018

Application of SIAL{sup R} Solidification Technology for Processing of Problematic Waste Streams - 18267

SIAL{sup R} is a proven, safe, cost-effective and licensed waste solidification technology that has been used successfully for 20 years in Slovakia and the Czech Republic for processing of various problematic radioactive waste streams. This abstract presents and summarises the most interesting performance records of the SIAL{sup R} geopolymer solidification technology, the applied mobile devices as well as the characteristics of final products. Radioactive waste solidification into matrix SIAL{sup R} is based on polycondensation of inorganic aluminosilicate components with chemical composition similar to average cement. The main components of matrix SIAL{sup R} are natural inorganic raw materials containing SiO{sub 2}, Al{sub 2}O{sub 3}, CaO, MgO, Na{sub 2}O, K{sub 2}O, Fe{sub 2}O{sub 3}, and TiO{sub 2}. The treatment/solidification process is modified for individual radioactive streams with different compositions. To determine the most appropriate composition, the SIAL{sup R} application technology is laboratory tested on real samples of each individual waste stream identified for solidification. Then an appropriate mixture of aluminosilicate composition and other inorganic compounds is defined for a given solidification application. When determining the most appropriate mixture, other requirements are taken into consideration: maximum dose rate on the drum with solidified product, mass, volume, alpha radionuclide content in the final product, need for a waste's dewatering before solidification, dry matter content in the solidification product as well as other specific waste acceptance criteria (i.e., compressive strength, leachability, diffusion coefficients, radiation stability, biodegradability of matrix, distribution and partition coefficients, influence of frost and water presence to the product stability including long term physical stability in water, dustiness, flammability, time dependence of compression strength and water reduction, product homogeneity and also radiolytic G-value for hydrogen release, GH{sub 2}). The Amec Foster Wheeler baseline approach to implementing the SIAL{sup R} waste treatment process is structured on three steps - waste characterization, waste retrieval and pre-treatment and at last the solidification of pre-treated waste itself. The equipment used for the solidification process is relatively small, lightweight and designed for the specific application on site, directly 'in situ' or local to the tanks storing the sludge's/resins/other waste streams. This mitigates the problems normally experienced by transferring sticky, tight waste through long pipes. The equipment is normally 'tailor-made' to take into account the real space conditions and other existing facility requirements. At Bohunice and Dukovany sites, the facilities for encapsulation were designed to occupy existing areas of the plants in close proximity to the tanks where the waste was being stored. This allowed for the removal of the waste using Remote Operated Vehicles and for the waste to be immediately treated on site without the need for transportation thus saving both, time and resource. To date, SIAL{sup R} has been used successfully to immobilize approximately 2 x 10{sup 6} kg of waste which includes sludge, resin, crystalline borates and contaminated organic waste from Bohunice and Mochovce, Slovakia and approximately 300 m{sup 3} of spent ion exchange resins and sludge from tanks on site at the Dukovany NPP (Nuclear Power Plant) in the Czech Republic. The technology now has a track record of over 20 years which includes on-going research and development. The International missions WANO (the World Association of Nuclear Operators) and OSART (the Operational Safety Review Team) evaluated the SIAL{sup R} matrix technology at Dukovany NPP as an example of good practice. (authors)

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

Molecular Level Understanding of How Oxygen and Carbon Monoxide Improve NOx Storage in Palladium/SSZ-13 Passive NOx Adsorbers: The Role of NO+ and Pd(II)(CO)(NO) Species

Addition of molecular oxygen to NO-containing stream improves NOx storage of the Pd/H-SSZ-13. Model Pd/SSZ-13 with high dispersion of Pd ions (0.1 and 1 wt% Pd) was synthesized. The material was characterized with FTIR and cryo-STEM. Adsorption of NO leads to the formation of Pd(II)-NO and Pd(I)-NO complexes as well as NO+ species that replace residual H+ (extra framework) sites. These nitrosyl species are characterized by notable thermal stability, with resistance to decomposition under high vacuum at 200 ºC. Addition of O2 to NO slightly increases the amount of Pd(II)-NO complex with ?NO at ~1865 cm-1 whereas the low frequency ?NO band at 1805 cm-1, assigned to Pd(I)-NO, decreases in intensity. Simultaneously, polydentate nitrate species appear in small amounts, contributing to the high temperature NOx release stage during a PNA cycle. The concentration of NO+ (characterized by the broad IR band centered at 2170 cm-1), in the presence of O2, increases in intensity profoundly and contributes to the increased capacity of Pd/SSZ-13 to store NOx and release it at temperatures >140 ºC. In the presence of H2O/O2, Pd/SSZ-13 does not perform satisfactorily as PNA, but the addition of CO to the stream improves the PNA storage capacity and shifts the NOx release peak temperature to >320 ºC where SCR catalysts are the most effective. With the aid of FTIR spectroscopy, we reveal the selective formation of a mixed carbonyl-nitrosyl complex Pd(II)(NO)(CO) in the presence of CO. Due to shielding of the Pd(II) ion from excess water and selective formation of stable coordinately saturated Pd(NO)(CO) complexes, the PNA performance is improved by CO. Therefore, we demonstrate that beside NO species adsorbed on Pd, nitrosyl ions (NO+) in extra framework positions of chabazite are important for PNA storage. Furthermore, the important role of CO in promoting PNA performance is elucidated, thus highlighting the utility of the combined spectroscopic approach (in addition to materials performance testing) to derive structure/PNA performance relationships and identify new avenues to improve the PNA performance.

Khivantsev, Konstantin↗