Final Report - Glass Formulation Development and Testing for DWPF High AI2O3 HLW Sludges, VSL-10R1670-1, Rev. 0, dated 12/20/10

The principal objective of the work described in this Final Report is to develop and identify glass frit compositions for a specified DWPF high-aluminum based sludge waste stream that maximizes waste loading while maintaining high production rate for the waste composition provided by ORP/SRS. This was accomplished through a combination of crucible-scale, vertical gradient furnace, and confirmation tests on the DM100 melter system. The DM100-BL unit was selected for these tests. The DM100-BL was used for previous tests on HLW glass compositions that were used to support subsequent tests on the HLW Pilot Melter. It was also used to process compositions with waste loadings limited by aluminum, bismuth, and chromium, to investigate the volatility of cesium and technetium during the vitrification of an HLW AZ-102 composition, to process glass formulations at compositional and property extremes, and to investigate crystal settling on a composition that exhibited one percent crystals at 963{degrees}C (i.e., close to the WTP limit). The same melter was selected for the present tests in order to maintain comparisons between the previously collected data. The tests provide information on melter processing characteristics and off-gas data, including formation of secondary phases and partitioning. Specific objectives for the melter tests are as follows: Determine maximum glass production rates without bubbling for a simulated SRS Sludge Batch 19 (SB19). Demonstrate a feed rate equivalent to 1125 kg/m{sup 2}/day glass production using melt pool bubbling. Process a high waste loading glass composition with the simulated SRS SB19 waste and measure the quality of the glass product. Determine the effect of argon as a bubbling gas on waste processing and the glass product including feed processing rate, glass redox, melter emissions, etc.. Determine differences in feed processing and glass characteristics for SRS SB19 waste simulated by the co-precipitated and direct-hydroxide methods. The above tests were proposed based on previous tests for WTP in which there were few differences in the melter processing characteristics, such as processing rate and melter emissions, between precipitated and direct hydroxide simulants, even though there were differences in rheological properties. To the extent this similarity is found also for simulants for SRS HLW, the direct hydroxide methods may offer the potential for faster, simpler, and cheaper simulant production. There was no plan to match the yield stress and particle size of the direct hydroxide simulant to that of the precipitated simulant because that would have increased the preparation cost and complexity and defeated the purpose of the tests. These objectives were addressed by first developing a series of glass frits and then conducting a crucible scale study to determine the waste loading achievable for the waste composition and to select the preferred frit. Waste loadings were increased until the limits of a glass property were exceeded experimentally. Glass properties for evaluation included: viscosity, electrical conductivity, crystallinity (including liquidus temperature and nepheline formation after canister centerline cooling (CCC) heat-treatment), gross glass phase separation, and the 7- day Product Consistency Test (PCT, ASTM-1285) response. Glass property limits were based upon the constraints used for DWPF process control

Chaperone-assisted translocation of a polymer through a nanopore

Using Langevin dynamics simulations, we investigate the dynamics of chaperone-assisted translocation of a flexible polymer through a nanopore. We find that increasing the binding energy $\epsilon$ between the chaperone and the chain and the chaperone concentration $N_c$ can greatly improve the translocation probability. Particularly, with increasing the chaperone concentration a maximum translocation probability is observed for weak binding. For a fixed chaperone concentration, the histogram of translocation time $\tau$ has a transition from long-tailed distribution to Gaussian distribution with increasing $\epsilon$. $\tau$ rapidly decreases and then almost saturates with increasing binding energy for short chain, however, it has a minimum for longer chains at lower chaperone concentration. We also show that $\tau$ has a minimum as a function of the chaperone concentration. For different $\epsilon$, a nonuniversal dependence of $\tau$ on the chain length $N$ is also observed. These results can be interpreted by characteristic entropic effects for flexible polymers induced by either crowding effect from high chaperone concentration or the intersegmental binding for the high binding energy.Comment: 10 pages, to appear in J. Am. Chem. So

Hybridization of Guided Surface Acoustic Modes in Unconsolidated Granular Media by a Resonant Metasurface

We investigate the interaction of guided surface acoustic modes (GSAMs) in unconsolidated granular media with a metasurface, consisting of an array of vertical oscillators. We experimentally observe the hybridization of the lowest-order GSAM at the metasurface resonance, and note the absence of mode delocalization found in homogeneous media. Our numerical studies reveal how the stiffness gradient induced by gravity in granular media causes a down-conversion of all the higher-order GSAMs, which preserves the acoustic energy confinement. We anticipate these findings to have implications in the design of seismic-wave protection devices in stratified soils

WASTE LOADING ENHANCEMENTS FOR HANFORD LAW GLASSES VLS-10R1790-1 FINAL REPORT REV 0 12/1/2010

About 50 million gallons of high-level mixed waste is currently stored in underground tanks at The United States Department of Energy's (DOE's) Hanford site in the State of Washington. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) will provide DOE's Office of River Protection (ORP) with a means of treating this waste by vitrification for subsequent disposal. The tank waste will be separated into low- and high-activity waste fractions, which will then be vitrified respectively into Immobilized Low Activity Waste (ILAW) and Immobilized High Level Waste (IHLW) products. The ILAW product will be disposed in an engineered facility on the Hanford site while the IHLW product will likely be directed to a national deep geological disposal facility for high-level nuclear waste. The ILAW and IHLW products must meet a variety of requirements with respect to protection of the environment before they can be accepted for disposal. The Office of River Protection is currently examining options to optimize the Low Activity Waste (LAW) Facility and LAW glass waste form. One option under evaluation is to enhance the waste processing rate of the vitrification plant currently under construction. It is likely that the capacity of the LAW vitrification plant can be increased incrementally by implementation of a variety of low-risk, high-probability changes, either separately or in combination. These changes include: (1) Operating at the higher processing rates demonstrated at the LAW pilot melter; (2) Increasing the glass pool surface area within the existing external melter envelope; (3) Increasing the glass waste loading; and (4) Operating the melter at a slightly higher temperature. The Vitreous State Laboratory (VSL) of The Catholic University of America (CUA) and Energy Solutions, Inc. have evaluated several of these potential incremental improvements for ORP in support of its evaluation of WTP LAW facility optimization. Some of these incremental improvements have been tested at VSL including increasing the waste loading, increasing the processing temperature, and increasing the fraction of the sulfur in the feed that is partitioned to the off-gas (in the event that a decision is made to break the present WTP recycle loop). These approaches successfully demonstrated increases in glass production rates and significant increases in sulfate incorporation at the nominal melter operating temperature of 1150 C and at slightly higher than nominal glass processing temperatures. Subsequent tests demonstrated further enhancement of glass formulations for all of the LAW waste envelopes, thereby reducing the amount of glass to be produced by the WTP for the same amount of waste processed. The next phase of testing determined the applicability of these improvements over the expected range of sodium and sulfur concentrations for Hanford LAW. This approach was subsequently applied to an even wider range of LAW wastes types, including those with high potassium concentration. The feasibility of formulating higher waste loading glasses using SnO{sub 2} and V{sub 2}O{sub 5} in place of Fe{sub 2}O{sub 3} and TiO{sub 2} as glass former additives was also evaluated. The present report provides data from investigation of the effects of magnesium content (up to {approx}10 wt%) on LAW glass properties and from work to identify improved high waste loading glass formulations that meets all processing and product quality requirements for two waste compositions. The scope of testing is detailed in the Test Plan for this work. A glass composition previously developed and tested at VSL for LAW from tank AN-105 (LAWA187) was varied by substituting Mg for other glass former additives such as Ca, B and Si in an attempt to formulate a glass with improved properties, such as higher waste loading and greater sulfur tolerance. The results were used to reformulate another glass (ORPLG9) developed for LAW from tank AP-101 that contains high concentrations of alkalis (Na and K). Glass formulation goals for this waste were to increase the sulfur tolerance of the glass as well as to decrease refractory corrosion. Each of the two final glass compositions was evaluated to determine the maximum amount of sulfur that can be incorporated into the glass through melter testing. The results from these tests together with earlier work for ORP were evaluated to develop recommendations for the work scope necessary to modify and update the WTP LAW glass formulation correlation algorithm

Development and testing of the Minimum Additive Waste Stabilization (MAWS) system for Fernald wastes. Phase 1, Final report

This report presents results of a treatability study for the evaluation of the MAWS process for wastes stored at the Fernald Environmental Management Project (FEMP) site. Wastes included in the study were FEMP Pit 5 sludges, soil-wash fractions, and ion exchange media from a water treatment system supporting a soil washing system. MAWS offers potential for treating a variety of waste streams to produce a more leach resistant waste form at a lower cost than, say, cement stabilization

Final Report - High Level Waste Vitrification System Improvements, VSL-07R1010-1, Rev 0, dated 04/16/07

This report describes work conducted to support the development and testing of new glass formulations that extend beyond those that have been previously investigated for the Hanford Waste Treatment and Immobilization Plant (WTP). The principal objective was to investigate maximization of the incorporation of several waste components that are expected to limit waste loading and, consequently, high level waste (HLW) processing rates and canister count. The work was performed with four waste compositions specified by the Office of River Protection (ORP); these wastes contain high concentrations of bismuth, chromium, aluminum, and aluminum plus sodium. The tests were designed to identify glass formulations that maximize waste loading while meeting all processing and product quality requirements. The work included preparation and characterization of crucible melts in support of subsequent DuraMelter 100 (DM100) tests designed to examine the effects of enhanced glass formulations, increased glass processing temperature, increased crystallinity, and feed solids content on waste processing rate and product quality

Hybridization of Guided Surface Acoustic Modes in Unconsolidated Granular Media by a Resonant Metasurface

We investigate the interaction of guided surface acoustic modes (GSAMs) in unconsolidated granular media with a metasurface, consisting of an array of vertical oscillators. We experimentally observe the hybridization of the lowest-order GSAM at the metasurface resonance, and note the absence of mode delocalization found in homogeneous media. Our numerical studies reveal how the stiffness gradient induced by gravity in granular media causes a down-conversion of all the higher-order GSAMs, which preserves the acoustic energy confinement. We anticipate these findings to have implications in the design of seismic-wave protection devices in stratified soils

Final Report - Melt Rate Enhancement for High Aluminum HLW Glass Formulation, VSL-08R1360-1, Rev. 0, dated 12/19/08

The principal objective of the work reported here was to develop and identify HLW glass compositions that maximize waste processing rates for the aluminum limted waste composition specified by ORP while maintaining high waste loadings and acceptable glass properties. This was accomplished through a combination of crucible-scale tests, confirmation tests on the DM100 melter system, and demonstration at pilot scale (DM1200). The DM100-BL unit was selected for these tests since it was used previously with the HLW waste streams evaluated in this study, was used for tests on HLW glass compositions to support subsequent tests on the HLW Pilot Melter, conduct tests to determine the effect of various glass properties (viscosity and conductivity) and oxide concentrations on glass production rates with HLW feed streams, and to assess the volatility of cesium and technetium during the vitrification of an HLW AZ-102 composition. The same melter was selected for the present tests in order to maintain comparisons between the previously collected data. These tests provide information on melter processing characteristics and off-gas data, including formation of secondary phases and partitioning. Once DM100 tests were completed, one of the compositions was selected for further testing on the DM1200; the DM1200 system has been used for processing a variety of simulated Hanford waste streams. Tests on the larger melter provide processing data at one third of the scale of the actual WTP HLW melter and, therefore, provide a more accurate and reliable assessment of production rates and potential processing issues. The work focused on maximizing waste processing rates for high aluminum HLW compositions. In view of the diversity of forms of aluminum in the Hanford tanks, tests were also conducted on the DM100 to determine the effect of changes in the form of aluminum on feed properties and production rate. In addition, the work evaluated the effect on production rate of modest increases in melter operating temperature. Glass composition development was based on one of the HLW waste compositions specified by ORP that has a high concentration of aluminum. Small-scale tests were used to provide an initial screening of various glass formulations with respect to melt rates; more definitive screening was provided by the subsequent DM100 tests. Glass properties evaluated included: viscosity, electrical conductivity, crystallinity, gross glass phase separation and the 7- day Product Consistency Test (ASTM-1285). Glass property limits were based upon the reference properties for the WTP HLW melter. However, the WTP crystallinity limit (< 1 vol% at 950oC) was relaxed slightly as a waste loading constraint for the crucible melts

Recovery of the herbaceous layer in the young silver birch and black alder stands that developed spontaneously after a forest fire

The studies, which were conducted in southern Poland, focused on the recovery of the herb layer in 17-year-old post-fire silver birch and black alder forests. Although both types of stands, which are of the same age, developed spontaneously, the alder stands occupied damper sites (with thicker A horizons that survived the fire) than those in the birch forests. We surveyed the migration rates of 44 woodland species, primarily ancient woodland indicators, into both forests and the potential differences in these rates depending on their moisture regime and the community type represented by unburned forests, which were treated as the source of the woodland species pool. Additionally, the role of local depressions with high humidity that were covered by post-fire alder woods in the colonization process, as well as species survivorship and recolonisation, were estimated. Woodland species showed diverse migration paces among the sites; most of them migrated faster on more fertile sites with a higher humidity. Small patches of post-fire alder woods contributed to the recolonisation process since many woodland species in the herb layer survived the fire due to its high humidity, which inhibited the intensity of the forest fire. The recovery of woodland species in post-fire woods is the combined effect of regeneration, which relies on autochthonic propagules, and secondary succession, which is based on allochthonic propagules. Local depressions, which provide refuges for fire-sensitive, dispersal-limited species, contribute to their survivorship and thus to the successive recovery of herbaceous layers after a fire

Soil seed bank of the invasive Robinia pseudoacacia in planted Pinus nigra stands

Pinus nigra and Robinia pseudoacacia are exotic trees used for afforestation in Hungary. Pinus nigra was non-invasive, however R. pseudoacacia escaped from cultivation and invaded several vegetation types including pine plantations. It has recently been planned to cut P. nigra plantations and replace them by native tree stands, especially in nature reserves. The scattered presence of R. pseudoacacia specimens in pine stands might place constraints on planned tree replacement because of their vegetative resprouting and recolonization from an established seed bank. The aim of this study was to investigate the soil seed bank under the canopy of solitary R. pseudoacacia specimens found in P. nigra plantations. Altogether 250 soil samples were collected from the 0–6 and 6–12 cm soil layers under solitary Robinia trees of varying ages (with basal areas between 62.4 and 1089.3 cm2). Seeds were separated by sieving then scarified and germinated. Seed bank density ranged between 640 and 2285 seedsm–2 with an average distribution of 82.7% and 17.3% in the upper and lower soil layer, respectively. Total density of the seed bank and also the seed bank ratio of the lower soil layer increased with tree age. The accumulated seed bank of R. pseudoacacia should be considered in the careful planning of tree replacement operations in Pinus nigra stands