502 Matching Results

Search Results

Advanced search parameters have been applied.

Hanford tank waste supernatant cesium removal test plan

Description: This document provides the test plan for the preparation and conduct of a cesium removal test using Hanford DSSF supernatant liquor from tank 241-AW-101 in a bench-scale column. Cesium sorbents to be tested include resorcinol-formaldehyde resin and crystalline silicotitanate.
Date: May 31, 1996
Creator: Hendrickson, D.W., Westinghouse Hanford
Partner: UNT Libraries Government Documents Department

FY99 Status Report on the HSV

Description: 'The HSV in storage in MTF has been monitored during FY99, and its overpressure has been sampled and analyzed. The HSV''s internal pressure continues to rise slowly, and the overpressure still analyzes as 100 percent 3He. The titanium tritide sample that was to be monitored annually and which had developed a leak last year has been repaired and isotherms measured. Unfortunately the sample was showing significant unexpected 3He release, so the isotherm data is corrupted by unknown levels of 3He. This release has disqualified this sample for future use, as it is now seriously divergent from the HSV material. A different sample must be selected for subsequent studies.The unexpected 3He releases of the Ti-3 sample and the possible release in other Ti samples have raised a serious issue. It should be determined why this release is occurring, so that an unexpected release of 3He during HSV unloading can be assessed as unlikely.'
Date: October 15, 1999
Creator: Shanahan, K. L.
Partner: UNT Libraries Government Documents Department

Test procedures and instructions for Hanford tank waste supernatant cesium removal

Description: This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test using Hanford Double-Shell Slurry Feed supernatant liquor from tank 251-AW-101 in a bench-scale column.Cesium sorbents to be tested include resorcinol-formaldehyde resin and crystalline silicotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-022, Hanford Tank Waste Supernatant Cesium Removal Test Plan.
Date: May 31, 1996
Creator: Hendrickson, D.W., Westinghouse Hanford
Partner: UNT Libraries Government Documents Department

Glass formulation development and testing for the vitrification of DWPF HLW sludge coupled with crystalline silicotitanate (CST)

Description: An alternative to the In Tank Precipitation and sodium titanate processes at the Savannah River Site is the removal of cesium, strontium, and plutonium from the tank supernate by ion exchange using crystalline silicotitanate (CST). This inorganic material has been shown to effectively and selectively sorb these elements from supernate. The loaded CST could then be immobilized with High-Level Waste (HLW) sludge during vitrification. Initial efforts on the development of a glass formulation for a coupled waste stream indicate that reasonable loadings of both sludge and CST can be achieved in glass.
Date: September 30, 1997
Creator: Andrews, M.K. & Workman, P.J.
Partner: UNT Libraries Government Documents Department

Radioactive Waste Decontamination Using Selentec Mag*SepSM Particles

Description: A sorbent containing crystalline silicotitanate (CST) tested for cesium removal from simulated Savannah River Site (SRS) soluble high activity waste showed rapid kinetics (1 h contact time) and high distribution coefficients (Kd 4000 mL/g of CST). The sorbent was prepared by Selective Environmental Technologies, Inc., (Selentec) as a MAG*SEP particle containing CST obtained from the Molecular Sieve Department of UOP, LLC, Results of preliminary tests suggest potential applications of the Selentec MAG*SEP particles to radioactive waste decontamination at SRS.
Date: June 1, 1998
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

Final flush of the shielded cells melter

Description: A flush of the Savannah River Technology Center (SRTC) Shielded Cells melter was performed after the completion of a campaign to vitrify loaded crystalline silicotitanate (CST) ion exchange medium. The purpose of the flush was to lower levels of radioisotopes accumulated during the campaign and to lower the level of titanium dioxide present in the glass. This in turn would ready the melter for future campaigns involving the Defense Waste Processing Facility (DWPF).
Date: September 29, 1997
Creator: Marshall, K.M.; Fellinger, T.L. & Harbour, J.R.
Partner: UNT Libraries Government Documents Department

Carboxylic Acid Modified [Ti({mu}-ONep)(Onep){sub 3}]{sub 2} Compounds. Syntheses, Characterizations, X-Ray Structures, and Implications for the Thin Film Densification of TiO{sub 2} from Ti{sub 3}({mu}{sub 3}-O)(O{sub 2}CH){sub 2}(ONep){sub 8}, etc.

Description: No abstract prepared.
Date: August 2, 1999
Creator: Boyle, Timothy J.; Tyner, Ryan P.; Alam, Todd M.; Scott, Brian L.; Ziller, Joseph W. & Potter, B.G. Jr.
Partner: UNT Libraries Government Documents Department

Vitrification of cesium-loaded crystalline silicotitanate (CST) in the shielded cells melter

Description: Through the Tanks Focus Area, the Savannah River Technology Center (SRTC) and the Oak Ridge National Laboratory participated in a joint project in which supernate waste from the Melton Valley Storage Tanks at Oak Ridge was treated by passage through a crystalline silicotitanate (CST) ion exchange column. CST was designed to sorb Cs- 137, Sr-90 and several other radionuclides from highly alkaline solutions containing large quantities of sodium.2 After demonstrating the effectiveness of CST as an ion exchange medium, ORNL shipped some of the loaded sorbent to SRTC where it was mixed with glass formers and processed in a joule-heated melter within the SRTC Shielded Cells. This report details the results of the melter run, along with the preparations that were required to complete the campaign.
Date: September 30, 1997
Creator: Andrews, M. K.; Fellinger, T. L.; Ferrara, D. M.; Harbour, J. R. & Herman, D. T.
Partner: UNT Libraries Government Documents Department

Mixed metal phospho-sulfates for acid catalysis

Description: Mixed metal phospho-sulfates have been prepared and evaluated for use as acid catalysts via 2-methyl-2-pentene isomerization and o-xylene isomerization. Particular members of this class of materials exhibit greater levels of activity than sulfated zirconia as well as lower rates and magnitudes of deactivation. {sup 31}P MAS NMR has been used to examine the role of phosphorus in contributing to the activity and deactivation behavior of these materials, while powder x-ray diffraction, BET surface area, IR, and elemental analysis were used to characterize the bulk catalysts.
Date: December 1, 1997
Creator: Thoma, S.G.; Jackson, N.B.; Nenoff, T.M. & Maxwell, R.S.
Partner: UNT Libraries Government Documents Department

Glass formulation requirements for Hanford coupled operations using crystalline silicotitanates (CST)

Description: The U.S. Department of Energy (DOE) through the Richland Operations Office has requested proposals from the private sector for the treatment of waste from the Hanford Waste Tanks. Phase I of this privatization initiative may include a demonstration for treatment and immobilization of both low activity and high-level waste. If the demonstration includes high-level waste, then the Cs-137 waste stream most likely will be combined with the high-level waste sludge to produce a coupled feed for immobilization (most likely vitrification using a borosilicate glass). It appears that pretreatment will involve the removal of cesium (and perhaps strontium and some transuranic radionuclides) from the supernate using an ion exchange material such as crystalline silicotitanate (CST). The ion exchange sorbent (or the eluted Cs-137) can then be combined with the sludge and vitrified in a coupled operation similar to the DWPF process. Alternatively, the cesium-loaded ion exchange sorbent can be vitrified directly to produce a separate glass waste form. SRTC has been involved in an Office of Science and Technology (EM-50) funded project to determine if Cs-137 loaded CST can be successfully incorporated into glass at significant levels. 1 For a waste form which would include only Cs-137 loaded CST, concentrations up to 60 wt% of CST in glass have been achieved. 2 The glass produced from this demonstration is both processable and durable. This CST-only waste form could be used at Hanford if the cesium-loaded CST is vitrified in a separate melter. For coupled feed operations, the CST would be mixed with high-level radioactive sludge from the Hanford tanks. This report provides the basis and the path forward for SRTC`s efforts at developing a glass frit formulation which will incorporate both Hanford sludge and cesium-loaded CST for a coupled flowsheet. The goal of this work is to demonstrate the feasibility of ...
Date: May 6, 1997
Creator: Andrews, M.K. & Harbour, J.R.
Partner: UNT Libraries Government Documents Department

Inorganic materis for anomalous-dispersion phase-matched second harmonic generation: Rubidium titanyl arsenate isomorphs, Rb[Ti{sub 1-2x}Ln{sub x}Nb{sub x}]OAsO{sub 4}

Description: We report the synthesis and optical properties of Rb[Ti{sub 1-2x}Ln{sub x}Nb{sub x}]OAsO{sub 4}. The solid solubility of lanthanide ions in the materials decreases exponentially as the size of the lanthanide ion increases. The materials exhibit absorption spectra characteristic of the particular lanthanide ion in the structure. The spectral regions between absorption peaks are transparent and will allow the transmission of fundamental and second-harmonic radiation. The charge transfer band is red-shifted 0 to 27 nm relative to RbTiOAsO{sub 4} (midpoint 331 nm). Second-harmonic intensities measured at 532 nm decrease exponentially as lanthanide ion concentration increases.
Date: December 31, 1993
Creator: Anderson, M.T.; Phillips, M.L.F. & Stucky, G.D.
Partner: UNT Libraries Government Documents Department

Optical and thermo-optical characterization of KTP and its isomorphs for 1.06 {micro}m pumped OPO`s

Description: The need to protect personnel from inadvertent eye trauma from fielded laser sources dictates that the highest externally accessible fluences produced by these systems be kept below the maximum permissible exposure (MPE) for intra-beam viewing. The large MPE value for a typical Q-switched (10 ns pulsewidth) source is 1 J/cm{sup 2} for wavelengths in the range of 1.5--1.8 microns, while the MPE for a similar pulsewidth Nd:YAG source is 5 {micro}J/cm{sup 2}. This 5 order of magnitude difference in the MPE is one reason for the trend towards shifting the output of near infrared sources used for remote sensing or ranging to the eyesafe wavelength region, even at the expense of overall system efficiency. There are 5 nonlinear optical crystals available with apertures of at least 10 x 10 mm{sup 2} which are also highly transparent in the 1.5 micron region; LiNbO{sub 3}, KNbO{sub 3}, KTP, KTA, and RTA. All 5 crystals are capable of 1,555 nm generation in an orientation with a favorable nonlinear optical coupling. However, KTP, KTA, or RTA are preferred materials, given that the generated signal of the OPO should remain at a fixed wavelength, insensitive to angular or thermal variations. The authors have characterized the phasematching angle, linewidth, thermal conductivity, and d{lambda}/dT for KTP, KTA, and RTA optical parametric oscillators.
Date: February 17, 1996
Creator: Ebbers, C.A. & Velsko, S.P.
Partner: UNT Libraries Government Documents Department

Energy savings through use of an improved reduction-cell cathode. Interim technical report, October 1, 1978-December 31, 1978

Description: This report summarizes the development work during the fifth quarter of the cost sharing contract between the Department of Energy and Kaiser Aluminum and Chemical Corporation. The project purpose is to develop a wettable and drained Hall cell cathode which will reduce the specific energy consumption of commercial cells by 20 to 25%. During this quarter the material characterization work has continued. In the last half of this period the decision was made to restart the 15KA piloe cell for a testing campaign of TiB/sub 2/ parts. The latter were ordered and partial shipments were received at the end of the quarter.
Date: January 1, 1978
Creator: Goodnow, W. H.
Partner: UNT Libraries Government Documents Department

THE CHOICE OF THE PROPER REFRACTORY FOR THE CASTING OF HIGHMELTING ELECTROPOSITIVE METALS

Description: As titanium, zirconium, and other of the high melting electropositive metals become more important, the problem of using suitable refractory materials for their casting becomes more important. This paper discusses the method of choosing and testing possible container materials. To make the discussion more specific, titanium is used as an example. As titanium melt at 2000 {+-} 10 K, it is immediately clear that one is restricted to refractory materials melting considerably above 2000 K. This greatly limits the possible materials that might be considered. The possibility of using any pure high melting element can be quickly eliminated as titanium reacts quite vigorously with non-metals such as carbon and due to its high boiling point and therefore high internal pressure, one can predict that it dissolves even the most refractory metals. Examination of phase diagrams confirms that even metals such as tantalum, tungsten, and rhenium would not be able to resist attack by titanium. One is thus limited to high melting compounds such as the oxides, sulfides, nitrides, carbides, silicides, and borides. The first consideration is that, if possible, one would use a compound which is thermodynamically stable in the presence of titanium metal at 2000 K. Titanium should not be able to react with the refractory to form a titanium compound. Thus all compounds less stable than the titanium compound which can exist in equilibrium with titanium metal are excluded.
Date: June 20, 1950
Creator: Brewer, Leo
Partner: UNT Libraries Government Documents Department

Immobilization in ceramic waste forms of the residues from treatment of mixed wastes

Description: The Environmental Restoration and Waste Management Applied Technology Program at LLNL is developing a Mixed Waste Management Facility to demonstrate treatment technologies that provide an alternative to incineration. As part of that program, we are developing final waste forms using ceramic processing methods for the immobilization of the treatment process residues. The ceramic phase assemblages are based on using Synroc D as a starting point and varying the phase assemblage to accommodate the differences in chemistry between the treatment process residues and the defense waste for which Synroc D was developed. Two basic formulations are used, one for low ash residues resulting from treatment of organic materials contaminated with RCRA metals, and one for high ash residues generated from the treatment of plastics and paper products. Treatment process residues are mixed with ceramic precursor materials, dried, calcined, formed into pellets at room temperature, and sintered at 1150 to 1200{degrees}C to produce the final waste form. This paper discusses the chemical composition of the waste streams and waste forms, the phase assemblages that serve as hosts for inorganic waste elements, and the changes in waste form characteristics as a function of variation in process parameters.
Date: November 1, 1993
Creator: Oversby, V. M.; van Konynenburg, R. A.; Glassley, W. E. & Curtis, P. G.
Partner: UNT Libraries Government Documents Department

Dynamic testing and characterization of pre-fractured ceramic

Description: Nearly all of the mechanical behavior studies of armor ceramics, to date, havc involved the characterization and testing of pristine ceramic material. However, balhstic impact causes a strong shock front to propagate rapidly through the ceramic before much penetration can occur. A strong shock wave can result in localized compressive failure and fragmentation of the ceramic before its amplitude is amnuated below the compressive strength of the ceramic. Goals of this effort were to creatc shock-fractured ceramic using test assemblies which maintain the intergranular coupling and high density of the ceramic, characterize the extent and homogeneity of the fragmentation and dilatation of the ceramic, and test the compressive dynamic behavior of the shock-fractured ceramic under conditions of confining pressure. This effort will provide data to support models of the penetration resistance of fractured ceramics including degraded moduli, failure strength-strain, and post-failure characterization of the erosive properties of comminuted ceramic and penetratot materials.
Date: January 1, 1993
Creator: Zurek, A.K. & Hunter, D.A.
Partner: UNT Libraries Government Documents Department

Observation of high field DHVA-effect and induced magnetism in single crystal TiBe/sub 2/

Description: Recently much interest has been given to itinerant magnetism in cubic Laves phase or C15 materials. Primarily this stems from the discussion of the relationship of p-state pairing and ferromagnetism in ZrZn/sub 2/ by Enz and Matthias, and the possibility of triplet superconductivity. The most recent work in this field has focused on the isoelectronic, isostructural material TiBe/sub 2/, and the possibility that this material is metamagnetic. That TiBe/sub 2/ is close to some form of magnetic instability can be infered indirectly from the peaked nature of its density of states near the fermi level, but also from the observation of ferromagnetism in TiBe/sub 2-x/Cu/sub x/, when x is greater than about 0.15. In this paper a single crystal of pure TiBe/sub 2/ is considered in fields larger than 15 Tesla (T) and at a temperature of 1.3/sup 0/K.
Date: January 1, 1981
Creator: van Deursen, A.P.J.; van Ruitenbeek, J.M.; Verhoef, W.A.; de Vroomen, A.R.; Smith, J.L.; de Groot, R.A. et al.
Partner: UNT Libraries Government Documents Department

An investigation of the chemical and physical properties of pristine, electrochromically damaged, and photochromically damaged KTiOPO{sub 4} (KTP) using surface analytical and optical spectroscopic techniques

Description: A variety of experimental techniques were employed to study the properties of electrochromically (EC) damaged, photochromically (PC) damaged, and pristine KTiOP0{sub 4} (KTP). Additionally, nonlinear optical calculations were performed to complement the experimental work in an effort to elucidate the respective mechanisms operative in producing EC and PC damage to KTP. Several independent experiments indicate that there is Ti deficiency in the EC damaged material, which is due to migration of these ions to the electrode surface. The laser experiments indicate that UV radiation can produce reversible PC damage. UV-producing SFG processes accidentally occurring in SHG cut KTP may lead to macroscopic damage. It must be emphasized that a fundamentally different mechanism is responsible for EC damaged versus PC damaged KTP.
Date: March 1, 1995
Creator: Quagliano, J.R.; Petrin, R.R.; Trujillo, T.C.; Cockroft, N.J.; Paffett, M.T.; Maggiore, C.J. et al.
Partner: UNT Libraries Government Documents Department

Steric and electronic effects of 1,3-disubstituted cyclopentadienyl ligands on metallocene derivatives of Cerium, Titanium, Manganese, and Iron

Description: Sterically demanding 1,3-disubstituted cyclopentadienyl ligands were used to modify the physical properties of the corresponding metallocenes. Sterically demanding ligands provided kinetic stabilization for trivalent cerium compounds. Tris(di-t-butylcyclopentadienyl)cerium was prepared and anion competition between halides and cyclopentadienyl groups which had complicated synthesis of the tris(cyclopentadienyl)compound was qualitatively examined. Bis(di-t-butylcyclopentadienyl)cerium methyl was prepared and its rate of decomposition, by ligand redistribution, to tris(di-t-butylcyclopentadienyl)cerium was shown to be slower than the corresponding rate for less sterically demanding ligands. Asymmetrically substituted ligands provided a symmetry label for examination of chemical exchange processes. Tris[trimethylsilyl(t-butyl)cyclopentadienyl]cerium was prepared and the rate of interconversion between the C1 and C3 isomers was examined. The enthalpy difference between the two distereomers is 7.0 kJ/mol. The sterically demanding cyclopentadienyl ligands ansa-di-t-butylcyclopentadiene (Me2Si[(Me3C)2C5H3]2), ansa-bis(trimethylsilyl)cyclopentadiene (Me2Si[(Me3Si)2C5H3]2) and tetra-t-butylfulvalene and metallocene derivatives of the ligands were prepared and their structures were examined by single crystal X-ray crystallography. The effect that substituents on the cyclopentadienyl ring have on the pi-electron system of the ligand was examined through interaction between ligand and metal orbitals. A series of 1,3-disubstituted manganocenes was prepared and their electronic states were determined by solid-state magnetic susceptibility, electron paramagnetic resonance, X-ray crystallography, and variable temperature UV-vis spectroscopy. Spin-equilibria in [(Me3C)2C5H3]2Mn and [(Me3C)(Me3Si)C5H3]2Mn were examined and indicate an enthalpy difference of 15 kJ/mol between the high-spin and low-spin forms. Cyclopentadienyl groups resistant to intramolecular oxidative addition allowed isolation of compounds susceptible to intramolecular decomposition. A kinetically stable, base-free titanocene was prepared using di-t-butylcyclopentadienyl ligands and the reactivity of the compound toward small molecules was investigated. The titanocene reacts reversibly with hydrogen to form the titanocene dihydride and the equilibrium in solution between titanocene dihydride, and titanocene and hydrogen, was examined.
Date: May 19, 2000
Creator: Sofield, C.D.
Partner: UNT Libraries Government Documents Department

Structure, Adhesion, and Stability of Metal/Oxide and Oxide/Oxide Interfaces

Description: Studies of structural, electronic, and chemical properties of metal/oxide and oxide/oxide interfaces were performed on well-defined interfaces that created by depositing ultra-thin potassium and aluminum films and their oxides onto single crystal TiO[sub 2] and NiO surfaces. Work focused on determining the structure, growth mechanisms, and morphologies of metal and oxide films as they are deposited an single crystal oxide surfaces using RHEED and atomic force microscopy probing electronic structure, bonding and chemical interactions at the interfaces using x-ray and uv photoelectron spectroscopies (XPS, UPS) and Auger electron spectroscopy (AES), and understanding factors affecting stability and reactivity of the interface regions including the role of defects and impurities. Results indicate that kinetic effects have an important influence on interface structure and composition, and they also show that defects in the oxide substrate induce new electronic states at the interface which play a major role in cation-anion bonding and interface interactions. The results establish a link between electronic and chemical bonding properties and the interface structure and morphology, which is required to successfully manipulate the interfacial properties of advanced ceramic materials.
Date: November 1, 1992
Creator: Lad, R. J.
Partner: UNT Libraries Government Documents Department

Structural study of high temperature metal-rich titanium sulfide phases

Description: Ti/sub 2/S and Ti/sub 8/S/sub 3/ have been prepared by high temperature annealing techniques. The crystal structures of these two phases have been determined from single crystal x-ray diffraction data. Both structures were refined using a full-matrix least-squares treatment of positional parameters and isotropic temperature factor coefficients. Ti/sub 2/S crystallizes with orthorhombic symmetry, space group Pnnm, having unit cell dimensions a = 11.367A, b= 14.060A, and c = 3.326A. Ti/sub 2/S is isostructural with Ta/sub 2/P. Ti/sub 8/S/sub 3/ crystallizes with monoclinic symmetry, space group C2/m, a = 32.69A, b = 3.327A, c = 19.35A, ..beta.. = 139.9/sup 0/ (b - unique). Ti/sub 2/S and Ti/sub 8/S/sub 3/ have structural features similar to the features of a large number of metal-rich transition-metal chalcogenides and pnictides. These various structure types have been characterized in terms of nonmetal trigonal prismatic coordination polyhedra, eight different metal partial coordination polyhedra, a short (approximately equal to 3.4A) crystallographic axis, two unique layers of atoms containing both metal and nonmetal atom positions, and mirror planes coincident with the two layers of atom positions. The existence of a variety of structures with these structural features has led to their consideration as a unique structural class. The structural similarities and differences between the structure types of this class have been discussed in detail. Comparison of different structure types emphasized the importance of the metal bonding contribution in understanding the structural features and suggested limitations on qualitative bonding models used to understand the structural-chemical principles underlying structure stability.
Date: January 1, 1979
Creator: Owens, J.P.
Partner: UNT Libraries Government Documents Department

Time-resolved picosecond reflectivity study of laser-excited layered compounds

Description: We have employed the pump-and-probe technique to perform picosecond time resolved measurements of the reflectivity changes in two archetypal layered compounds, 1T-TiS/sub 2/ and 1T-TiSe/sub 2/ probed at 1.064 ..mu..m after pumping by 20 ps, 0.532 ..mu..m laser pulses. At the threshold fluence, approx.40 mJ/cm/sup 2/, the reflectivity drops sharply, marking the occurrence of a phase transformation on the surface of the sample. Above threshold, the reflectivity reaches a value as low as approx.0.1 at high fluences, strongly suggesting that, like in graphite, the high temperature phase is not metallic.
Date: January 1, 1986
Creator: Huang, C.Y.; Malvezzi, A.M.; Bloembergen, N. & DiSalvo, F.J. Jr.
Partner: UNT Libraries Government Documents Department