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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.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS

Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Cesium Ion Exchange Loading Kinetics Testing with SRF Resin

Ion exchange using the Spherical Resorcinol-Formaldehyde (SRF) resin has been selected by the U.S. Department of Energy’s Office of River Protection for use in the Pretreatment Facility of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in an at-tank deployment for removing 137Cs. Recent proposed changes to the WTP ion exchange process baseline indicate that loading may include a broader range of sodium molarities (2 to 8 M) due to caustic leaching and higher temperatures (50°C) to alleviate post-filtration precipitation issues prior to reaching the ion exchange columns. Therefore, it is important to understand the behavior of SRF resin performance under the conditions expected with the new equipment and process changes. This research examined the impact of linear load velocity (4, 6, 8 cm/min), initial sodium concentration (2, 5, 8 M), initial sodium-to-cesium ratio (1.4E+05, 2.1E+05, 2.8E+05 mol/mol), initial sodium-to-hydroxide ratio (2.0, 3.0, 4.0 mol/mol), and resin degradation during extended solution flow using elevated temperature (45°, 50°, 55°, 60°, 65°, 75°C). Testing was performed using a~2mL column packed with SRF resin with feed flowing through it in an up-flow pattern. Samples were taken at set intervals and the data analyzed to help understand the impact of these conditions on the SRF resin performance. It was found that the loading kinetics were not significantly impacted by the sodium concentration over the range tested. However, the loading kinetics were impacted by the linear load velocity. These results indicated that at the test temperature, the adsorption of cesium is strongly dependent on mass transfer through the film and not significantly impacted by interparticle diffusion. Testing for extended times at elevated temperatures showed that the resin does degrade and loading capacity is reduced at and above 45°C. Above 60°C the resin appears to not load at all.

Ion exchange↗
DOE OSTI2013

Using Process Knowledge to Manage Disposal Classification of Ion-Exchange Resin - 13566

It has been previously shown by EPRI [1] that Class B and C resins represent a small portion by volume of the overall generation of radioactively contaminated resins. In fact, if all of the resins were taken together the overall classification would meet Class A disposal requirements. Lowering the classification of the ion exchange resins as they are presented for disposal provides a path for minimizing the amount of waste stored. Currently there are commercial options for blending wastes from various generators for Class A disposal in development. The NRC may have by this time introduced changes and clarifications to the Branch Technical Position (BTP) on Concentration Averaging and Encapsulation [2] that may ultimately add more flexibility to what can be done at the plant level. The BTP has always maintained that mixtures of resins that are combined for ALARA purposes or operational efficiency can be classified on the basis of the mixture. This is a point often misinterpreted and misapplied. This paper will address options that can be exercised by the generator that can limit B and C waste generation by more rigorous tracking of generation and taking advantage of the normal mix of wastes. This can be achieved through the monitoring of reactor coolant chemistry data and coupled with our knowledge of radionuclide production mechanisms. This knowledge can be used to determine the overall accumulation of activity in ion-exchange resins and provides a 'real-time' waste classification determination of the resin and thereby provide a mechanism to reduce the production of waste that exceeds class A limits. It should be noted that this alternative approach, although rarely used in a nuclear power plant setting, is acknowledged in the original BTP on classification [3] as a viable option for determining radionuclide inventories for classification of waste. Also included is a discussion of an examination performed at the Byron plant to estimate radionuclide content in the final waste stream from upstream sampling of reactor coolant and fuel pool water. (authors)

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

Pyrolysis of Radioactive Spent Resins in the PRIME Installation - 20190

Montair and Belgoprocess developed the pilot PRIME (Pyrolysis Resins In Mobile Electric) Installation for treatment of spent resins in one single reactor without pre-treatment and without intermixing of other waste, allowing for easy traceability and isotopic characterization of the end product. Both low level waste (LLW, < 2 mSv/h) and medium level waste (MLW, > 2 mSv/h) can be treated in the installation. The PRIME pilot installation is designed to treat 2 batches of 100 liter of saturated ion exchange resins over a period of 24 hours. A dosing unit with screw feeder is used for the dosing of the saturated ion exchange resins to the pyrolysis reactor. This completely new developed innovative pyrolysis reactor contains a special design mechanical stirrer and can operate at a temperature of up to 600 deg. C under inert conditions. As a result, the organic molecules will decompose at an accelerated rate until only the mineralized material remains. The lower temperature and the absence of oxygen also prevent the breakdown of ion exchange resins into (powdery) ash, which is a considerable advantage during further handling. Gases that are released during drying and pyrolysis are treated in an also newly developed thermal oxidizer, which uses an innovative, electrically heated design instead of a traditional natural gas- or fuel oil secondary combustion chamber design. After passing through the thermal oxidizer, the gases are cooled down to saturation temperature and treated in the wet scrubbing system. An extraction fan keeps the system under negative pressure to prevent the possibility of any off-gas leakage out of the system. A series of tests were performed successfully with wet cationic resins, anionic resins and a mixture of both. The results of these tests are described in the presentation. For intellectual property protection, the system and process of pyrolysis of organic waste and the system of thermal oxidation of pyrolysis gases described in this paper are patent pending. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Separation of dilute plutonium(IV) from nitric acid solutions via Reillex HPQ anion exchange resin

Anion exchange is a common method for the separation of plutonium (Pu) in aqueous systems, providing high recovery and decontamination from impurities. Reillex HPQ anion exchange resin has been used around the Department of Energy complex in this application for decades but has typically been used for Pu feed concentrations greater than 1 g/L. It is desirable to recover Pu at more dilute concentrations from a dissolved used fuel or target element, for example. In this work, the performance of Reillex HPQ anion exchange resin was characterized with feed solutions of ca. 0.24 g/L Pu. A significant reduction in the performance of the resin was realized with this dilute concentration relative to a feed solution of 2.35 g/L Pu with similar feed flow rates and the same resin column, likely due to the increased driving force for mass transfer with a higher feed concentration. The maximum capacity of Reillex HPQ resin for Pu can be improved by reducing the flow rate and increasing the feed Pu concentration. Furthermore, the breakthrough point of Pu can be improved in the same manner and by increasing the resin bed height. Diffusion of Pu into the resin was illustrated to be the rate limiting step.

Plutonium separations↗
DOE OSTI2025

Utilization of traceable standards to validate plutonium isotopic purification and separation of plutonium progeny using AG MP-1M resin for nuclear forensic investigations

Radio-chronometric studies on plutonium (Pu) materials require independent measurement of the Pu (parent) content and isotopic distribution as well as concentration and isotopic distribution of the plutonium isotopic decay products. We performed a series of experiments to demonstrate the consistency of separations using the Lewatit MP 800 macroporous anion exchange resin and the AG MP-1M resin with traceable Pu isotopic certified reference material (CRM) standards 136, 137, 138, and 126-A. Two different mesh-sizes of the AG MP-1M resin were tested and the 50–100 mesh size resin was found to work more efficiently for the separation task. Both Lewatit and AG MP-1M resins were found to perform satisfactorily for quantitatively extracting the americium (Am) and uranium (U) progeny as well as gallium (Ga) present as a tracer in the Pu material. Both resins were effective in removing isobaric interferences from the Pu fraction used in isotopic measurements by thermal ionization mass spectrometry (TIMS). To address the co-elution of uranium and gallium, Alizarin red S (ARS) was used as a colorimetric dye to determine the behavior of UO 2 2+ and Ga 3+ on AG MP-1M resin with various acidic solutions as eluents using UV–vis spectra. Poor resolution of these peaks complicated quantitative analysis by UV–vis spectroscopy, but these results were informative in planning automated separation experiments by HPLC. LA-UR-24-28919.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Mark-18A Loading Capacity and Dilute Acid Rinse of DGA Resin

Savannah River National Laboratory is developing a separations flowsheet for the recovery of valuable elements from irradiated 242 Pu targets. The primary impetus for this effort is to recover the rich amount of 244 Pu contained in the targets, however, the targets also contain other valuable isotopes such as heavy Cm and 241,243 Am. DGA Resin, developed by Eichrom Technologies Inc., was selected to recover these materials from the 7 – 9 M HNO 3 matrix raffinate of the anion exchange process used to separate Pu. The resin has a high affinity for trivalent actinides and rare earth elements (REEs) in moderate to strong nitric acid. After loading the resin, the extracted materials (including Cm and Am) are to be recovered as oxides in a two-step process by thermally drying and reducing the mass and volume of the resin in the process column followed by calcination of the resultant residue. It is desirable to reduce the amount of residual HNO 3 in the resin bed prior to these furnace operations, but the reduced acid concentration is known to lower the distribution coefficients of the components of interest to the extractant. The purpose of this study was to validate the loading capacity of the resin and determine losses to be expected from rinsing the loaded resin with dilute HNO 3 .

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Simultaneous Thermal Analysis of Anion and Cation Exchange Resins

The decomposition reactions of one anion exchange resin (Bio-Rad AG MP-1) and one cerium-loaded cation exchange resin (DOWEX 50W-X8), both in nitrate form, were analyzed using simultaneous thermal analysis methods. Thermogravimetric analysis, dynamic scanning calorimetry, and evolved gas analysis were deployed in combination to probe the temperature profiles, reaction enthalpies, and off-gases from these resins under process-relevant temperature ranges. Analysis indicates that both resins undergo three clear phases during heating. The first is a dehydration step with prominent off-gassing of water, the second is a decomposition step with evolution of several gaseous species, and lastly is a combustion step with a large release of CO 2 . The temperature at which combustion ends varies slightly between AG MP-1 and DOWEX 50W: combustion completed at ~690°C and ~810°C, respectively. For the DOWEX cation resin, the combustion reaction showed greater sensitivity to the availability of oxygen under the test conditions. Both resins displayed broad exotherms during the combustion step of the decomposition, but the DOWEX cation resin demonstrated a 4.5 times higher specific enthalpy than that of the AG MP-1.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Phenoxy resins containing pendent ethynyl groups

As part of an effort on tougher/solvent resistant matrix resins for composites, research was directed towards exploring methods to improve the solvent resistance of linear amorphous thermoplastics. Ethyl reactive groups were placed on the ends of oligomers and pendent along the polymer chain and subsequently thermally reacted to provide crosslinking and thus improvement in solvent resistance. This concept is extended to another thermoplastic, a phenoxy resin. A commercially available phenoxy resin (PKHH) was systematically modified by reaction of the pendent hydroxyl groups on the phenoxy resin with various amounts of 4-ethynylbenzoyl chloride. As the pendent ethynyl group content in the phenoxy resin increased, the cured resin exhibited a higher glass transition temperature, better solvent resistance and less flexibility. The solvent resistance was further improved by correcting a low molecular weight diethynyl compound, 2,2-bis(4-ethynylbenzoyloxy-4'-phenyl)propane, with a phenoxy resin containing pendent ethynyl groups.

Hergenrother, P. M.↗
NASA NTRS1983

Technique for removing resin from a molded object

Resin is removed from a molded object in such a way that no cracks or expansion occurs in the casting. The resin is first mixed with a ceramics powder or metal powder. This mixture is then molded and the resin is removed by heat. The molded object is then placed into a container which is sealed and large enough to allow the gas from the resin to be controlled by heat from the resin. The gas pressure at the surface of the object is increased by the gas pressure generated from the resin and the resin removed. The increase in gas pressure from the surface of the molded object is 1.5 atm to 3 atm at 350 C to 400 C.

Hemmi, I.↗
NASA NTRS1986

Cobalt Ions Improve the Strength of Epoxy Resins

Technique developed for improving mechanical strength of epoxy resins by adding cobalt ions in form of tris(acetylacetonato)cobalt (III) complex. Solid cast disks prepared from cobalt ion-containing epoxy resins tested for flexural strength and stiffness. Incorporation of cobalt ions into epoxies increased flexural strength of resins by 10 to 95 percent. Suitable resins for this technique include any liquid or solid TGMDA resins. Improved epoxy formulation proves useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft.

Stoakley, D. M.↗
NASA NTRS1983

Development of new and improved polymer matrix resin systems, phase 1

Vinystilbazole (vinylstryrylpyridine) and vinylpolystyrulpyridine were prepared for the purpose of modifying bismaleimide composite resins. Cure studies of resins systems were investigated by differential scanning calorimetry. The vinylstyrylpyridine-modified bismaleimide composite resins were found to have lower cure and gel temperatures, and shorter cure times than the corresponding unmodified composite resins. The resin systems were reinforced with commercially avialable satin-weave carbon cloth. Prepregs were fabricated by solvent or hot melt techniques. Thermal stability, flammability, moisture absorption, and mechanical properties of the composites (such as flexural strength, modulus, tensile and short beam shear strength) were determined. Composite laminates showed substantial improvements in both processability and mechanical properties compared to he bismaleimide control systems. The vinylstyrylpyridine modified bismaleimide resins can be used as advanced matrix resins for graphite secondary structures where ease of processing, fireworthiness, and high temperature stability are required for aerospace applications.

Hsu, M. S.↗
NASA NTRS1984

Phosphorus-containing imide resins - Modification by elastomers

The syntheses and general features of addition-type maleimide resins based on bis(m-aminophenyl)phosphine oxide and tris(m-aminophenyl)phosphine oxide have been reported previously. These resins have been used to fabricate graphite cloth laminates having excellent flame resistance. These composites did not burn even in pure oxygen. However, these resins were somewhat brittle. This paper reports the modification of these phosphorus-containing resins by an amine-terminated butadiene-acrylonitrile copolymer (ATBN) and a perfluoroalkylene diaromatic amine elastomer (3F). An approximately two-fold increase in short beam shear strength and flexural strength was observed at 7 percent ATBN concentration. The tensile, flexural, and shear strengths were reduced when 18 percent ATBN was used. Anaerobic char yields of the resins at 800 C and the limiting oxygen indexes of the laminates decreased with increasing ATBN concentration. The perfluorodiamine (3F) was used with both imide resins at 6.4 percent concentration. The shear strength was doubled in the case of the bisimide with no loss of flammability characteristics. The modified trisimide laminate also had improved properties over the unmodified one. The dynamic mechanical analysis of a four-ply laminate indicated a glass transition temperature above 300 C. Scanning electron micrographs of the ATBN modified imide resins were also recorded.

Varma, I. K.↗
NASA NTRS1985

Differences in interfacial bond strengths of graphite fiber-epoxy resin composites

The effect of epoxy-size and degree of cure on the interfacial bonding of an epoxy-amine-graphite fiber composite system is examined. The role of the fiber-resin interface in determining the overall mechanical properties of composites is poorly understood. A good interfacial adhesive bond is required to achieve maximum stress transfer to the fibers in composites, but at the same time some form of energy absorbing interfacial interaction is needed to achieve high fracture toughening. The incompatibility of these two processes makes it important to understand the nature and basic factors involved at the fiber-resin interface as stress is applied. The mechanical properties including interlaminar shear values for graphite fiber-resin composites are low compared to glass and boron-resin composites. These differences have been attributed to poor fiber-matrix adhesion. Graphite fibers are commonly subjected to post-treatments including application of organic sizing in order to improve their compatibility with the resin matrix and to protect the fiber tow from damage during processing and lay-up. In such processes, sized graphite fiber tow is impregnated with epoxy resin and then layed-up i nto the appropriate configuration. Following an extended ambient temperature cure, the graphite-resin composite structure is cured at elevated temperature using a programmed temperature sequence to cure and then cool the product.

Needles, H. L.↗
NASA NTRS1992

Structure-to-property relationships in addition cured polymers. 4: Correlations between thermo-oxidative weight losses of norbornenyl cured polyimide resins and their composites

Relationships are identified between the thermo-oxidative stability (TOS) at 316 C of a wide variety of PMR (polymerization of monomeric reactants) addition cured polyimide resins and their corresponding graphite fiber composites. Weight loss results at 316 C confirmed the expected relationship of increasing aliphatic endcap content with decreasing TOS. Moreover, the resin TOS study also showed an unexpected linear correlation of decreasing weight loss to increasing ratio of benzylic diamine to aliphatic endcap in the range of the stoichiometries studied. Only after long term 316 C aging does the dianhydride used with the benzylic diamines become an additional factor in influencing the amount of PMR resin and composite weight losses. Also, the benzylic systems consistently showed much lower resin and composite weight losses at 316 C than the corresponding nonbenzylic norbornenyl resins and composites, except when the nonbenzylic diamine monomer does not contain a connecting group. Instead, this diamine resulted in a 316 C resin and composite weight loss that was only competitive with benzylic type diamines. Results show excellent correlation between TOS of all graphite fiber PMR composites and resins.

Alston, William B.↗
NASA NTRS1991

Infiltration/cure modeling of resin transfer molded composite materials using advanced fiber architectures

A model was developed which can be used to simulate infiltration and cure of textile composites by resin transfer molding. Fabric preforms were resin infiltrated and cured using model generated optimized one-step infiltration/cure protocols. Frequency dependent electromagnetic sensing (FDEMS) was used to monitor in situ resin infiltration and cure during processing. FDEMS measurements of infiltration time, resin viscosity, and resin degree of cure agreed well with values predicted by the simulation model. Textile composites fabricated using a one-step infiltration/cure procedure were uniformly resin impregnated and void free. Fiber volume fraction measurements by the resin digestion method compared well with values predicted using the model.

Loos, Alfred C.↗
NASA NTRS1993

Advanced resin systems and 3D textile preforms for low cost composite structures

Advanced resin systems and 3D textile preforms are being evaluated at Lockheed Aeronautical Systems Company (LASC) under NASA's Advanced Composites Technology (ACT) Program. This work is aimed towards the development of low-cost, damage-tolerant composite fuselage structures. Resin systems for resin transfer molding and powder epoxy towpreg materials are being evaluated for processability, performance and cost. Three developmental epoxy resin systems for resin transfer molding (RTM) and three resin systems for powder towpregging are being investigated. Various 3D textile preform architectures using advanced weaving and braiding processes are also being evaluated. Trials are being conducted with powdered towpreg, in 2D weaving and 3D braiding processes for their textile processability and their potential for fabrication in 'net shape' fuselage structures. The progress in advanced resin screening and textile preform development is reviewed here.

Shukla, J. G.↗
NASA NTRS2003

High Temperature Transfer Molding Resins: Status of PETI-298 and PETI-330

Two phenylethynyl terminated oligomers designated PETI-298 and PETI-330 were developed at the NASA Langley Research Center and have emerged as leading candidates for composite applications requiring high temperature performance (i.e. greater than or equal to 288 C for 1000 hours) combined with the ability to be readily processed into composites without the use of an autoclave or complex/lengthy cure or post-cure cycle. These high performance/high temperature composites are potentially useful on advanced aerospace vehicles in structural applications and as aircraft engine components such as inlet frames and compressor vanes. The number designation (i.e. 298, 330) refers to the glass transition temperature in degrees Celsius as determined on neat resin cured for 1 hour at 371 C. The resins are processable by non-autoclave techniques such as resin transfer molding (RTM), vacuum assisted RTM (VARTM) and resin infusion (RI). Both resins exhibit low complex melt viscosities (0.1-10 poise) at 280 C and are stable for greater than or equal to 2 hours at this temperature. Typically, the resins are melted, de-gassed and infused or injected at 280 C and subsequently cured at 371 C for 1-2 hours. Virtually no volatiles are evolved during the cure process. The resin synthesis is straightforward and has been scaled-up to 25 kg batches. The chemistry of PETI-298 and PETI-330 and the RTM AS-4 and T-650 carbon fabric laminate properties, and those of BMI-5270 for comparison, are presented.

Connell, John W.↗