Search NASA⌕ Search

SEARCH · Search NASA

Results for “Distribution Coefficient”

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

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Impacts of Lanthanide Ion Complexation on the Radiation Robustness of Diglycolamide Extractants

Nuclear power reactors represent a clean and reliable source of baseload energy. However, nuclear reactors produce used nuclear fuel (UNF), which, if not recycled/reprocessed, must be disposed of as high-level radioactive waste, necessitating long-term storage options. UNF contains approximately a third of the periodic table, including the radioactive minor actinides (MA) americium and curium. Removal of these MA from UNF would greatly reduce the radiotoxic burden, volume, and cost of a storage facility or geological repository. Thus, a significant global effort has been devoted to the design of reprocessing strategies for the clean separation of the MA from UNF. As MA separations are difficult, due to the presence of lanthanide elements in UNF and their remarkably similar chemical properties, many extractants have been studied. The diglycolamide (DGA) class of extractants are promising for this separation as they exhibit high distribution coefficients for the MAs, high metal loading capacities, and are robust in highly acidic radiation environments.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2017

Sorption Behavior of Iodide Ions on Calcium Silicate Hydrate Formed under the Condition Saturated with Saline Water - 17069

The sorption behavior of iodide ions on calcium-silicate-hydrate (CSH gel) under the condition saturated with saline water was examined by using a Raman spectroscopy and ICP-AES, without drying process. In the sorption experiments, I-127 is a stable isotope was used as an alternative of I-129. CSH gel was synthesized with mixing CaO, SiO{sub 2}, and NaCl solution. The Ca/Si molar ratios of CSH gel were set to 0.4, 0.8, 1.2 and 1.6, and the concentration of NaCl solution was set to 0.6 M for simulating the condition of saline groundwater. The liquid/solid weight ratios of CSH gel were set to 10, 13, 15, 17, and 20, and the total weight of solid phase was 1.5 g. Furthermore, at the preparation of CSH gel, the substance of iodide ions in each sample was adjusted to 15 μmol. The synthesis procedure for all samples was conducted in a glove bag filled with nitrogen gas. The curing period was 7, 14, 30, and 60 days at a room temperature (298 K) with shaking at 120 strokes/min. The results of the sorption experiments, iodide ions adsorbed on CSH gel regardless of the high concentration of NaCl. The concentration of iodide ions in liquid phase was equal to the initial one under all experimental conditions. Moreover, the distribution coefficients, K{sub d}, were kept constant (K{sub d} = 1 mL/g) after 14 days. In the results of Raman analysis, the structure of CSH gel was scarcely influenced by incorporating iodide ions from the viewpoint of the silicate chain. These results suggest that iodide ions will be incorporated into CSH gel with the hydration water without changing its structure. Such effect of CSH gel formed with leaching cementitious constituents around the repository may retard the migration of radionuclide (I-129) in the natural barrier of the radioactive waste disposal system. (authors)

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

Evaluation and Interpretation of Properties for Saltstone Cores Extracted from an SDU - 17344

Extraction and subsequent analysis of emplaced saltstone samples from a Savannah River Site (SRS) Saltstone Disposal Unit (SDU) were performed in order to realize the following key objectives: (1) to support the use of historical and future laboratory-derived sample data to predict the behavior of field-emplaced samples, and (2) to substantiate the saltstone properties currently assumed in Saltstone Disposal Facility (SDF) transport modeling, i.e., Performance Assessment (PA) and Special Analyses (SA) models. Multiple cores were extracted via a wet core drilling process in April-May 2015 approximately 20 months after the saltstone of interest was processed in the Saltstone Production Facility (SPF) and subsequently emplaced in SDU Cell 2A (SDU2A). The retrieved samples were stored in an inert N{sub 2} environment prior to, and during, the property testing that took place between October 2015 and March 2016. Sample analyses comprised evaluation of physical properties (density, porosity, and moisture content), saturated hydraulic conductivity (K{sub sat}), and determination of distribution coefficients and solubilities for key radionuclides. In general the SDU2A samples indicated comparative properties to laboratory-prepared samples and additionally verified many of the inputs currently assumed in the SDF PA. The principal exception was related to the leaching characteristics of I-129, which demonstrated a lower than anticipated affinity for retention within the saltstone matrix. (authors)

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

Tin(II)apatite: Synthesis, Characterization, and Challenge with Pertechnetate - 16194

We will report on the synthesis of stannous apatite and the subsequent reductive capacity attained, using a cerium (IV) titration method. Also reported will be the distribution coefficients derived using a Hanford tank supernatant simulant of 7.8 M sodium with chrome (VI) as a contaminant of concern, as a potential non-isotopic oxy-anion and technetium surrogate for reductive capacity determinations. Pertechnetate will be subjected to reduction using hydroxylamine, glucose and threose. The purpose is to take the first step in laboratory analyses to determine the amount of non-pertechnetate species in Hanford tank waste. A proposed sequestration mechanism will be presented as to why the reacted tin(II)apatite does not release technetium once reacted. SEM and EDS spectra will be presented on the crystalline apatite. Areas of incorporation of the tin(II)apatite will be presented for the Hanford tank waste process. (authors)

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

Sorption Behavior of Iodate Ions on Calcium Silicate Hydrate under a High Saline Condition - 18176

The sorption behavior of iodate ions on calcium-silicate hydrate (CSH) gel under high saline condition was examined by monitoring the concentrations of iodate ions and chloride ions using ion chromatography and Raman spectroscopy, without drying process. In the sorption experiments, a stable isotope I-127 was used as an alternative of I-129 which is radioactive one. Each sample was synthesized with mixing CaO powder, SiO{sub 2} as fumed silica and NaCl solution. Ca/Si molar ratios of CSH gel were set to 0.4, 0.8, 1.2 and 1.6 (add 0.2, 0.6, 1.0 and 1.4 only L/S = 20), and the concentration of NaCl solution was set to 0 M or 0.6 M for simulating the condition of fresh or saline groundwater. The liquid/solid (L/S) ratios of CSH gel were set to 10, 15 and 20, and the total weight of solid phase was 1.5 g. At the same time, NaIO{sub 3} solution was added to the sample in order to adjust its concentration to 1.0 mM, 0.67 mM and 0.5 mM for each L/S ratios. The synthesis procedure for all samples was conducted in a glove bag filled with nitrogen gas. The curing period was 7, 14, 30, and 60 days at a room temperature (298 K) with shaking at 120 strokes/min. As a results, the concentration of iodate ions in the liquid phase decreased for all samples under experimental conditions. Besides, the sorption behavior of iodate ions were hardly changed by the concentration of NaCl. That is, iodate ions migrated to solid phase in spite of the high concentration of NaCl. The distribution coefficients, Kd, increased as Ca/Si ratio increased, and hardly depended on NaCl concentration. The results of Raman analysis shows that the structure of CSH gel was almost not changed with or without NaCl from the viewpoint of the silicate chain under this condition. These results suggest that a sorption process except for the electrostatic process such as an ion exchange and a complexation exists between CSH gel and iodate ions. Besides, CSH gel might be able to contribute the retardation for the migration of iodate ions without changing its structure, even if the disposal environment are saturated by a high saline groundwater. (authors)

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

Sorption of Cationic Radionuclides on Chlorite and Sericite formed by the Hydrothermal Alteration - 18180

Chlorite and sericite formed by the hydrothermal alteration of granite distribute predominantly around the geological repository in deep underground. These minerals often cover the surface of a solid phase and fill the fracture of granite considered as the natural barrier to the migration of radionuclides leaching from radioactive waste. Therefore, to assess the practical performance of the natural barrier, it is necessary to clarify the interaction between radionuclides and these minerals. This study examined the sorption of cationic radionuclides by chlorite and sericite through batch experiments, whereby Cs{sup +}, Sr{sup 2+}, and Eu{sup 3+} were used as tracer ions. In these experiments, powder-form chlorite or sericite was mixed with the solutions of the tracer ions to a liquid/solid ratio of 10 ml/g, and the resulting mixture was allowed to incubate for 2-7 days. The concentration of tracer ions was set to 1 mM and that of NaCl to a specific value in the 0-0.6 M range. The solution pH was 3, 5, or 8. As a result, tracer ions were significantly adsorbed by chlorite and sericite, regardless of pH or NaCl concentration, except when NaCl concentration reached the high value of 0.6 M. The distribution coefficient for europium ions at pH 5 was estimated to be 2-7 mL/g in chlorite and 10{sup 3}-10{sup 4} mL/g in sericite. These values significantly exceeded that measured for feldspar (2-4 mL/g), the predominant component of granite before it undergoes any hydrothermal alteration. These results suggest that cationic radionuclides will be immobilized through sorption in chlorite and sericite filling granite fractures, even if these thermal-fluid-formed minerals cover the surface of granite. (authors)

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

Containing Tc-99 Using a Multi-sorbing Barrier Material - 18249

Immobilization of Tc-99 is a challenge at on-site waste disposal facilities in the DOE complex because the oxyanion pertechnetate (TcO{sub 4}{sup -}) binds weakly (if at all) to the surface of mineral solids and other conventional barrier materials (distribution coefficient, Kd<2 mL/g). The study described herein evaluated TcO{sub 4}{sup -} uptake from aqueous solutions using a multi-sorbing organo-clay barrier material synthesized from sodium-bentonite (Na-B) exchanged with hexadecyltrimethylammonium (HDTMA). The exchange transformed the negatively charged surface of Na-B to a positively charged surface to bind TcO{sub 4}{sup -}. Batch tests were conducted to evaluate sorption of TcO{sub 4}{sup -} onto the multi-sorbing clay barrier material using ammonium-pertechnetate solutions with activity ranging from 1000 to 2,000,000 pCi/L. Tests were conducted with a solid-to-liquid ratio of 1:100 in 50-mL centrifuge tubes rotated at 30 rpm for 24 hr. Solutions were created by dissolving ammonium-pertechnetate in DI water or synthetic low-level radioactive waste leachate. Solids were separated from the test solution by centrifugation at 4000 rpm for 10 min. A liquid scintillation counter was used to measure the Tc-99 in solution. Isotherms from the batch tests show that the multi-sorbing barrier material is very effective in removing Tc-99, with Kd > 2900 mL/g. Using this high capacity sorbent in engineered barriers may provide a sustainable solution to control release of Tc-99 and other anions of concern from on-site disposal facilities. (authors)

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

Preliminary Study on Sorption Behavior of Iodine on Ca-Al-Si Hydrate - 19310

Sorption behavior of Ca-Al-Si hydrate with iodine sign ion and iodide ion was investigated using ion chromatography and Raman spectroscopy. In the experiment I-127 which is a stable isotope was used instead of I-129 which is a radionuclide. Ca-Al-Si hydrate was synthesized by mixing fumed silica (SiO{sub 2}) calcium oxide (CaO) and aluminum nitrate nonahydrate (Al(NO{sub 3}){sub 3}.9H{sub 2}O) with the solution containing iodine in a polypropylene tube. Two chemical forms of iodine, i.e., iodide ion and iodate ion, were considered in this study. In the samples of Ca-Al-Si hydrate, the Ca/Si molar ratios were adjusted in the range from 0.8 to 1.6, and the Al / Si ratios were in the range from 0.0 to 0.5. The samples liquid / solid (L/S) ratio was 20. In order to adjust the concentration to 0.5 mM for each samples, NaIO{sub 3} solution or NaI solution were added to the sample. NaClO solution was added as an oxidizing agent to maintain the form of iodate ion. The synthesis procedure for all the samples was carried out in a glove bag filled with nitrogen gas. The curing time was 1, 7, 30 days at room temperature (298 K) with shaking at 120 strokes / minute. In the results, although the iodide ion concentration in the liquid phase hardly changed, the liquid phase amount had been reduced to less than the liquid phase amount initially added. This means that iodide ions are incorporated in the solid phase together with the water of hydration. Besides, the concentration of iodate ion remarkably decreased for all samples under experimental conditions. In the Raman analysis, some differences in structure due to incorporation of Al were observed, but the structure of the Ca-Al-Si hydrate hardly changed due to other factors. Based on the sorption distribution coefficients obtained in this study, the Ca-Al-Si hydrate can be expected to have a barrier performance against iodine. (authors)

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

Subdrain Water Treatment Facility for Reduction of Waste Water Amount at the Fukushima NPS Site - 19318

At the Fukushima Daiichi Nuclear Power Station site, a water treatment facility dedicated to the subdrain and groundwater drain has been constructed by Tokyo Electric Power Company Holdings, Inc. and Hitachi-GE Nuclear Energy, Ltd. The facility consists of three kinds of equipment for collecting, purifying and transferring contaminated water. The purification equipment removes low concentration radionuclides, such as Cs-137 and Sr-90, contained in the pumped groundwater using adsorption vessels filled with Cs-Sr adsorbent. It is important to lower the operational cost of the facility. We have been developing a cost reduction technique to prolong the operating lifetime of the Cs-Sr adsorption vessels by improving the adsorption performance of the Cs-Sr simultaneous adsorbent. Therefore, pH adjustment for the groundwater by using granular MgO as a pH adjustment agent was investigated. The experimental and the simulation results showed that the distribution coefficient Kd with pH adjustment by MgO was evaluated as approximately 1.8 times higher than Kd without pH adjustment and the replacement timing of the Cs-Sr adsorption vessels with pH adjustment was 2 times longer than the timing without pH adjustment. From these results, we decided to include pH adjustment using MgO as the pH adjustment agent in the purification equipment in order to reduce the amount of Cs-Sr simultaneous adsorbent used and the operational cost of the facility. (authors)

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

Transport coefficients in Lorentz plasmas with the power-law kappa-distribution

Transport coefficients in Lorentz plasma with the power-law κ-distribution are studied by means of using the transport equation and macroscopic laws of Lorentz plasma without magnetic field. Expressions of electric conductivity, thermoelectric coefficient, and thermal conductivity for the power-law κ-distribution are accurately derived. It is shown that these transport coefficients are significantly modified by the κ-parameter, and in the limit of the parameter κ→∞ they are reduced to the standard forms for a Maxwellian distribution.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1952

Pressure distribution and aerodynamic coefficients associated with heat addition to supersonic air stream adjacent to two-dimensional supersonic wing

The modifications in the pressure distributions and the aerodynamic coefficients associated with additions of heat to the two-dimensional supersonic in viscid flow field adjacetnt to the lower surface of of a 5-percent-thickness symmetrical circular-arc wing are presented in this report. The pressure distributions are obtained by the use of graphical method which gives the two-dimensional supersonic inviscid flow field obtained with moderate heat addition. The variation is given of the lift-drag ratio and of the aerodynamic coefficients of lift, drag, and moment with free stream Mach number, angle of attack, and parameters defining extent and amount of heat addition. The six graphical solutions used in this study included Mach numbers of 3.0 and 5.0 and angles of attack of 0 degrees and 2 degrees.

Pinkel, I Irving↗
NASA NTRS1991

Measurements of Pressure Distributions and Force Coefficients in a Squeeze Film Damper. Part 2: Partially Sealed Configuration

Experimental results from a partially sealed squeeze film damper (SFD) test rig, executing a circular centered orbit are presented and discussed. A serrated piston ring is installed at the damper exit. This device involves a new sealing concept which produces high damping values while allowing for oil flow to cool the damper. In the partially sealed damper, large cavitation regions are observed in the pressure fields at orbit radii epsilon equals 0.5 and epsilon equals 0.8. The cavitated pressure distributions and the corresponding force coefficients are compared with a cavitated bearing solution. The experimental results show the significance of fluid inertia and vapor cavitation in the operation of squeeze film dampers. Squeeze film Reynolds numbers tested reach up to Re equals 50, spanning the range of contemporary applications.

Jung, S. Y.↗
NASA NTRS1993

Chemical fractionations in group IIIAB iron meteorites - Origin by dendritic crystallization of an asteroidal core

Results of an investigation of the crystallization history of the asteroidal core that produced nearly 200 iron meteorites of group IIIAB are presented. The accuracy of the published distribution of coefficients between solid and liquid metal for seven elements and their dependence on the concentrations of S and P are critically assessed to develop a nonideal fractional crystallization model that reproduces all of the major features of the overall chemical trends in group IIIAB. It is suggested that the apparent distribution coefficient of S was was much higher than its equilibrium value (not greater than 0.01) and that it increased during crystallization. In the present preferred model the apparent distribution coefficient for S increases from 0.6 to 0.8, while the S concentration of the liquid increases from 6 to 13 wt pct. It is inferred that light S-rich liquid accumulates preferentially at the top of the core and in structural traps formed by the advancing solid.

Haack, Henning↗
NASA NTRS1982

Flow distributions and discharge coefficient effects for jet array impingement with initial crossflow

To model the impingement cooled mid-chord region of gas turbine airfoils in cases where an initial crossflow is present, the paper presents experimentally determined flow distributions for jet arrays with ten spanwise rows of holes, which range from uniform to highly nonuniform. The jet flow after impingement is constrained to exit in a single direction along the channel formed by the jet orifice plate and the impingement surface. The streamwise distributions and crossflow velocities are presented for ratios of the initial crossflow rate to the total jet flow rate ranging from zero to unity. For crossflow to jet velocity ratios greater than a value somewhat less than unity, jet orifice discharge coefficients do not remain constant, but decrease significantly, showing a secondary dependence on z/d, where z is the channel height and d is the jet hole diameter.

Florschuetz, L. W.↗
DOE OSTI2013

Electron distribution function and recombination coefficient in ultracold plasma in a magnetic field

The electron distribution function and diffusion coefficient in energy space have been calculated for the first time for a weakly coupled ultracold plasma in a magnetic field in the range of magnetic fields B = 100-50000 G for various temperatures. The dependence of these characteristics on the magnetic field is analyzed and the distribution function is shown to depend on the electron energy shift in a magnetic field. The position of the 'bottleneck' of the distribution function has been found to be shifted toward negative energies with increasing magnetic field. The electron velocity autocorrelators as a function of the magnetic field have been calculated; their behavior suggests that the frequency of collisions between charged particles decreases significantly with increasing magnetic field. The collisional recombination coefficient {alpha}{sub B} has been calculated in the diffusion approximation for a weakly coupled ultracold plasma in a magnetic field. An increase in magnetic field is shown to lead to a decrease in {alpha}{sub B} and this decrease can be several orders of magnitude.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1979

Higher-order skewness and excess coefficients of some probability distributions applicable to optical propagation phenomena

Expressions are derived for higher-order skewness and excess coefficients using central moments and cumulants up to 8th order. These coefficients are then calculated for three probability distributions: (1) Log-normal, (2) Rice-Nakagami, and (3) Gamma distributions. Curves are given to shown the variation of skewness with excess coefficients for these distributions. These curves are independent of the particular distribution parameters. This method is useful for studying fluctuating phenomena, which obey non-Gaussian statistics.

Majumdar, A. K.↗
NASA NTRS2000

Heat Transfer and Pressure Distributions on a Gas Turbine Blade Tip

Heat transfer coefficient and static pressure distributions are experimentally investigated on a gas turbine blade tip in a five-bladed stationary linear cascade. The blade is a 2-dimensional model of a first stage gas turbine rotor blade with a blade tip profile of a GE-E(sup 3) aircraft gas turbine engine rotor blade. The flow condition in the test cascade corresponds to an overall pressure ratio of 1.32 and exit Reynolds number based on axial chord of 1.1 x 10(exp 6). The middle 3-blade has a variable tip gap clearance. All measurements are made at three different tip gap clearances of about 1%, 1.5%, and 2.5% of the blade span. Heat transfer measurements are also made at two different turbulence intensity levels of 6.1 % and 9.7% at the cascade inlet. Static pressure measurements are made in the mid-span and the near-tip regions as well as on the shroud surface, opposite the blade tip surface. Detailed heat transfer coefficient distributions on the plane tip surface are measured using a transient liquid crystal technique. Results show various regions of high and low heat transfer coefficient on the tip surface. Tip clearance has a significant influence on local tip beat transfer coefficient distribution. Heat transfer coefficient also increases about 15-20% along the leakage flow path at higher turbulence intensity level of 9.7% over 6.1 %.

Azad, Gm S.↗