Chloride content of dissolver solution from Rocky Flats alloy thirteenth campaign following head end treatment

F-Canyon continues to obtain good chloride removal from Rocky Flats Alloy solution during head end treatment. One single batch of solution from the thirteenth alloy campaign, dissolved earlier this month, has been successfully processed. This was the first campaign to combine Rocky Flats Scrub Alloy (RFSA) with Rocky Flats Anode Heel Alloy (RFAHA) in the same dissolution solution (TA-2-1183). Following dissolution in Tank 6.4D, chloride was precipitated with mercurous ion added as the nitrate. The precipitate, Hg{sub 2}Cl{sub 2}, was concurrently removed with the gelatin floc via centrifugation. For this batch, a set of duplicate samples was initially obtained from Tank 11.2. However, due to repeated acid and density measurements by Laboratories, the volume of sample remaining was insufficient to permit chloride analysis. Samples of the same solution, now transferred to Tank 13.3, were analyzed. During the transfer, a 2% dilution occurred, but this error is not significant due to the larger error in the chloride analysis. For the single batch of RFSA-RFAHA material processed from the thirteenth campaign, the head end product contained 52 ppm ({micro}g/mL) chloride, a DF of 22. Relative standard deviation of the measurement was {+-}6 ppm (n = 4) for a precision of {+-}12%

Chloride content of Rocky Flats scrub alloy eleventh campaign solution following head end treatment

A single batch of dissolver solution from the eleventh Rocky Flats Scrub Alloy (RFSA) campaign has been analyzed for chloride content following head end treatment to reduce its concentration. Scrub alloy buttons were dissolved in Tank 6.4D during May. In subsequent head end processing, chloride was precipitated with mercurous ion added as the nitrate. The precipitate, Hg{sub 2}Cl{sub 2}, was concurrently removed with the gelatin floc via centrifugation. Duplicate samples from Tank 11.2, containing the head end product, produced excellent agreement between their density measurements, acid analyses, and gross alpha activities, indicating them to be truly representative of the tank`s contents. Duplicate aliquots from each of these solutions were analyzed using the turbidimetric chloride method developed in the Separations Technology Laboratory. These resulted in an average chloride value of 41 ppm ({micro}g/mL) chloride for the head end product. Relative standard deviation of the measurement was {+-}4 ppm (n = 4), a precision of {+-}10%. Such a variance is normal at this low chloride level. Since initial chloride values prior to head end averaged 1455 ppm (0.041M), as analyzed by Laboratories Department, a chloride DF of approximately 35 was obtained. Such a reduced chloride level (to less than 100 ppm) in the treated solution will permit further canyon processing with minimal corrosion

Chloride content of Rocky Flats scrub alloy twelfth campaign solution following head end treatment

A single batch of dissolver solution from the twelfth Rocky Flats Scrub Alloy (RFSA) campaign has been analyzed for chloride content following head end treatment to reduce its concentration. Scrub alloy buttons were dissolved in Tank 6.4D during July. In subsequent head end processing, chloride was precipitated with mercurous ion added as the nitrate. The precipitate, Hg{sub 2}Cl{sub 2}, was co-removed with the gelatin floc via centrifugation. Duplicate samples from Tank 11.2, containing the head end product, produced excellent agreement between their density measurements and acid analyses, indicating them to be truly representative of the tank`s contents. Duplicate aliquots from each of these solutions were analyzed using the turbidimetric chloride method developed in the Separations Technology Laboratory. These resulted in an average chloride value of 53 ppm ({micro}g/mL) chloride for the head end product. Relative standard deviation of the measurement was {+-}6 ppm (n = 4), a precision of {+-}11%. Such a variance is normal at this low chloride level. Since initial chloride values prior to head end averaged 1365 ppm (0.0385M), as analyzed by Laboratories Department, a chloride DF of approximately 26 was obtained. Such a reduced chloride level (to less than 100 ppm) in the treated solution will permit further canyon processing with minimal corrosion

Cross Border Business Cycle Impacts on the El Paso Housing Market

There is comparatively little empirical evidence regarding the impacts of cross border business cycle fluctuations on metropolitan housing markets located near international boundaries. This study examines the impacts of economic conditions in Mexico on sales of existing single-family houses in El Paso, Texas. Anecdotal evidence suggests that these impacts are fairly notable. Annual frequency data from the University of Texas at El Paso Border Region Modeling Project are used to test this possibility. Results indicate that solid empirical evidence of such a linkage is elusive.Business Cycles, Border Housing Markets

Solvent problems in first PUREX cycle

In March, 1988, the first PUREX cycle suffered uranium contamination of the solvent, 30% TBP in n-paraffin. Initial indication of maloperation was uranium contamination of the plutonium product stream, 1BP. Uranium in relatively large quantities, 10{sup {minus}3} to 10{sup {minus}4} g/L, was found in the solvent in Tank 14.7. This tank contains first cycle solvent that has been through the solvent washing system and is destined for return back to the cycle. Solvent, contained in Tank 14.7 under normal operating conditions, has <1 {times} 10{sup {minus}4} g U/L following the carbonate-acid-carbonate washing sequence. Work at SRL showed that the interfacial tension of the contaminated solvent, as sampled, was 2.5, indicating that substances, possibly long chain acids, were present that could affect disengaging times for the solvent. Virgin 30% TBP in n-paraffin has a interfacial tension of around 10 or better, for example. Tests conducted by Reif also showed that the contaminated solvent picked up significantly more fission products, Ru{sup 106} and Zr{sup 95}, than did virgin solvent. The contaminated solvent, following contact with alumina, had a greatly improved interfacial tension of 9.5 and exhibited much less pickup of both Ru{sup 106} and Zr{sup 95}. In a H-Area process testing, contact of process solvent with alumina produced improved interfacial tension values and reduced Zr{sup 95} pickup by the 7.5% TBP used there. From these tests, it is concluded that the contaminated solvent resulted from inefficient washing in the solvent washing system for first PUREX cycle. Nominal solvent chemistry should result if the solvent is properly washed in the carbonate-acid-carbonate process cycle. However, attention and study should be given to this solvent system because of the decline of its interfacial tension values. Such deterioration in solvent quality could be a portent of problems to come. Treatment with alumina, as was done with H-Area solvent, may become necessary

Critical thickness and orbital ordering in ultrathin La0.7Sr0.3MnO3 films

Detailed analysis of transport, magnetism and x-ray absorption spectroscopy measurements on ultrathin La0.7Sr0.3MnO3 films with thicknesses from 3 to 70 unit cells resulted in the identification of a lower critical thickness for a non-metallic, non-ferromagnetic layer at the interface with the SrTiO3 (001) substrate of only 3 unit cells (~12 Angstrom). Furthermore, linear dichroism measurements demonstrate the presence of a preferred (x2-y2) in-plane orbital ordering for all layer thicknesses without any orbital reconstruction at the interface. A crucial requirement for the accurate study of these ultrathin films is a controlled growth process, offering the coexistence of layer-by-layer growth and bulk-like magnetic/transport properties.Comment: 22 pages, 6 figures, accepted for publication in Physical Review

Spheromak formation and sustainment studies at the sustained spheromak physics experiment using high-speed imaging and magnetic diagnostics

A high-speed imaging system with shutter speeds as fast as 2 ns and double frame capability has been used to directly image the formation and evolution of the sustained spheromak physics experiment (SSPX) [E. B. Hooper et al., Nucl. Fusion 39, 863 (1999)]. Reproducible plasma features have been identified with this diagnostic and divided into three groups, according to the stage in the discharge at which they occur: (i) breakdown and ejection, (ii) sustainment, and (iii) decay. During the first stage, plasma descends into the flux conserver shortly after breakdown and a transient plasma column is formed. The column then rapidly bends and simultaneously becomes too dim to photograph a few microseconds after formation. It is conjectured here that this rapid bending precedes the transfer of toroidal to poloidal flux. During sustainment, a stable plasma column different from the transient one is observed. It has been possible to measure the column diameter and compare it to CORSICA [A. Tarditi et al., Contrib. Plasma Phys. 36, 132 (1996)], a magnetohydrodynamic equilibrium reconstruction code which showed good agreement with the measurements. Elongation and velocity measurements were made of cathode patterns also seen during this stage, possibly caused by pressure gradients or E×B drifts. The patterns elongate in a toroidal-only direction which depends on the magnetic-field polarity. During the decay stage the column diameter expands as the current ramps down, until it eventually dissolves into filaments. With the use of magnetic probes inserted in the gun region, an X point which moved axially depending on current level and toroidal mode number was observed in all the stages of the SSPX plasma discharge

Search for Ferromagnetism in doped semiconductors in the absence of transition metal ions

In contrast to semiconductors doped with transition metal magnetic elements, which become ferromagnetic at temperatures below ~ 100K, semiconductors doped with non-magnetic ions (e.g. silicon doped with phosphorous) have not shown evidence of ferromagnetism down to millikelvin temperatures. This is despite the fact that for low densities the system is expected to be well modeled by the Hubbard model, which is predicted to have a ferromagnetic ground state at T=0 on 2- or 3-dimensional bipartite lattices in the limit of strong correlation near half-filling. We examine the impurity band formed by hydrogenic centers in semiconductors at low densities, and show that it is described by a generalized Hubbard model which has, in addition to strong electron-electron interaction and disorder, an intrinsic electron-hole asymmetry. With the help of mean field methods as well as exact diagonalization of clusters around half filling, we can establish the existence of a ferromagnetic ground state, at least on the nanoscale, which is more robust than that found in the standard Hubbard model. This ferromagnetism is most clearly seen in a regime inaccessible to bulk systems, but attainable in quantum dots and 2D heterostructures. We present extensive numerical results for small systems that demonstrate the occurrence of high-spin ground states in both periodic and positionally disordered 2D systems. We consider how properties of real doped semiconductors, such as positional disorder and electron-hole asymmetry, affect the ground state spin of small 2D systems. We also discuss the relationship between this work and diluted magnetic semiconductors, such as Ga_(1-x)Mn_(x)As, which though disordered, show ferromagnetism at relatively high temperatures.Comment: 47 page

Household Food Insecurity Is Inversely Associated with Social Capital and Health in Females from Special Supplemental Nutrition Program for Women, Infants, and Children Households in Appalachian Ohio

Food insecurity has been negatively associated with social capital (a measure of perceived social trust and community reciprocity) and health status. Yet, these factors have not been studied extensively among women from households participating in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) or the WIC Farmers’ Market Nutrition Program. A cross-sectional, self-administered, mailed survey was conducted in Athens County, Ohio, to examine the household food security status, social capital, and self-rated health status of women from households receiving WIC benefits alone (n=170) and those from households receiving both WIC and Farmers’ Market Nutrition Program benefits (n=65), as well as the relationship of food security, social capital, and self-rated health status. Household food security and perceived health status were not significantly different between groups; however, high social capital was greater (χ2=8.156, P=0.004) among WIC, compared to WIC/Farmers’ Market Nutrition Program group respondents. Overall, household food insecurity was inversely associated with perceived health status (r=−0.229, P=0.001) and social capital (r=0.337, P\u3c0.001). Enabling networking among clients, leading to client-facilitated programs and projects, and developing programs that strengthen social capital, including community-based mentoring programs and nutrition education programs that are linked to community-based activities, are needed, as is additional research to verify these findings

Metastable liquid lamellar structures in binary and ternary mixtures of Lennard-Jones fluids

We have carried out extensive equilibrium molecular dynamics (MD) simulations to investigate the Liquid-Vapor coexistence in partially miscible binary and ternary mixtures of Lennard-Jones (LJ) fluids. We have studied in detail the time evolution of the density profiles and the interfacial properties in a temperature region of the phase diagram where the condensed phase is demixed. The composition of the mixtures are fixed, 50% for the binary mixture and 33.33% for the ternary mixture. The results of the simulations clearly indicate that in the range of temperatures $78 < T < 102 ^{\rm o}$K, --in the scale of argon-- the system evolves towards a metastable alternated liquid-liquid lamellar state in coexistence with its vapor phase. These states can be achieved if the initial configuration is fully disordered, that is, when the particles of the fluids are randomly placed on the sites of an FCC crystal or the system is completely mixed. As temperature decreases these states become very well defined and more stables in time. We find that below $90 ^{\rm o}$K, the alternated liquid-liquid lamellar state remains alive for 80 ns, in the scale of argon, the longest simulation we have carried out. Nonetheless, we believe that in this temperature region these states will be alive for even much longer times.Comment: 18 Latex-RevTex pages including 12 encapsulated postscript figures. Figures with better resolution available upon request. Accepted for publication in Phys. Rev. E Dec. 1st issu