Analysis Of 2H-Evaporator Scale Pot Bottom Sample [HTF-13-11-28H]

Savannah River Remediation (SRR) is planning to remove a buildup of sodium aluminosilicate scale from the 2H-evaporator pot by loading and soaking the pot with heated 1.5 M nitric acid solution. Sampling and analysis of the scale material from the 2H evaporator has been performed so that the evaporator can be chemically cleaned beginning July of 2013. Historically, since the operation of the Defense Waste Processing Facility (DWPF), silicon in the DWPF recycle stream combines with aluminum in the typical tank farm supernate to form sodium aluminosilicate scale mineral deposits in the 2H-evaporator pot and gravity drain line. The 2H-evaporator scale samples analyzed by Savannah River National Laboratory (SRNL) came from the bottom cone sections of the 2H-evaporator pot. The sample holder from the 2H-evaporator wall was virtually empty and was not included in the analysis. It is worth noting that after the delivery of these 2H-evaporator scale samples to SRNL for the analyses, the plant customer determined that the 2H evaporator could be operated for additional period prior to requiring cleaning. Therefore, there was no need for expedited sample analysis as was presented in the Technical Task Request. However, a second set of 2H evaporator scale samples were expected in May of 2013, which would need expedited sample analysis. X-ray diffraction analysis (XRD) confirmed the bottom cone section sample from the 2H-evaporator pot consisted of nitrated cancrinite, (a crystalline sodium aluminosilicate solid), clarkeite and uranium oxide. There were also mercury compound XRD peaks which could not be matched and further X-ray fluorescence (XRF) analysis of the sample confirmed the existence of elemental mercury or mercuric oxide. On ''as received'' basis, the scale contained an average of 7.09E+00 wt % total uranium (n = 3; st.dev. = 8.31E-01 wt %) with a U-235 enrichment of 5.80E-01 % (n = 3; st.dev. = 3.96E-02 %). The measured U-238 concentration was 7.05E+00 wt % (n=3, st. dev. = 8.25E-01 wt %). Analyses results for Pu-238 and Pu-239, and Pu-241 are 7.06E-05 {+-} 7.63E-06 wt %, 9.45E-04 {+-} 3.52E-05 wt %, and <2.24E-06 wt %, respectively. These results are provided so that SRR can calculate the equivalent uranium-235 concentrations for the NCSA. Because this 2H evaporator pot bottom scale sample contained a significant amount of elemental mercury (11.7 wt % average), it is recommended that analysis for mercury be included in future Technical Task Requests on 2H evaporator sample analysis at SRNL. Results confirm that the uranium contained in the scale remains depleted with respect to natural uranium. SRNL did not calculate an equivalent U-235 enrichment, which takes into account other fissionable isotopes U-233, Pu-239 and Pu-241

Tank 30 and 37 Supernatant Sample Cross-Check and Evaporator Feed Qualification Analysis-2012

This report summarizes the analytical data reported by the F/H and Savannah River National Laboratories for the 2012 cross-check analysis for high level waste supernatant liquid samples from SRS Tanks 30 and 37. The intent of this Tank 30 and 37 sample analyses was to perform cross-checks against routine F/H Laboratory analyses (corrosion and evaporator feed qualification programs) using samples collected at the same time from both tanks as well as split samples from the tanks

Thermoelectric Response of an Interacting Two-Dimensional Electron Gas in Quantizing Magnetic Field

We present a discussion of the linear thermoelectric response of an interacting electron gas in a quantizing magnetic field. Boundary currents can carry a significant fraction of the net current passing through the system. We derive general expressions for the bulk and boundary components of the number and energy currents. We show that the local current density may be described in terms of ``transport'' and ``internal magnetization'' contributions. The latter carry no net current and are not observable in standard transport experiments. We show that although Onsager relations cannot be applied to the local current, they are valid for the transport currents and hence for the currents observed in standard transport experiments. We relate three of the four thermoelectric response coefficients of a disorder-free interacting two-dimensional electron gas to equilibrium thermodynamic quantities. In particular, we show that the diffusion thermopower is proportional to the entropy per particle, and we compare this result with recent experimental observations.Comment: 18 pages, 2 postscript figures included. Revtex with epsf.tex and multicol.sty. In the revised version, the comparison with experimental observations at $\nu=1/2, 3/2$ is extended to include the possibility of corrections due to weak impurity scattering. The conclusions that we reach regarding the applicability of the composite fermion model at these filling fractions are not affecte

Thermohydrodynamics in Quantum Hall Systems

A theory of thermohydrodynamics in two-dimensional electron systems in quantizing magnetic fields is developed including a nonlinear transport regime. Spatio-temporal variations of the electron temperature and the chemical potential in the local equilibrium are described by the equations of conservation with the number and thermal-energy flux densities. A model of these flux densities due to hopping and drift processes is introduced for a random potential varying slowly compared to both the magnetic length and the phase coherence length. The flux measured in the standard transport experiment is derived and is used to define a transport component of the flux density. The equations of conservation can be written in terms of the transport component only. As an illustration, the theory is applied to the Ettingshausen effect, in which a one-dimensional spatial variation of the electron temperature is produced perpendicular to the current.Comment: 10 pages, 1 figur

Studies of Potential Inhibitors of Sodium Aluminosilicate Scales in High-Level Waste Evaporation

The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing aluminum and silicates has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the tested polymers successfully meets the established criteria for application in the nuclear environment. This paper will describe a summary of the methodology used to prioritize laboratory testing protocols based on potential impacts/risks identified for inhibitor deployment at SRS

CHARACTERIZATION OF URANIUM SOLIDS PRECIPITATED WITH ALUMINOSILICATES

At the Savannah River Site (SRS), the High-Level Waste (HLW) Tank Farms store and process high-level liquid radioactive wastes from the Canyons and recycle water from the Defense Waste Processing Facility. The waste is concentrated using evaporators to minimize the volume of space required for HLW storage. Recently, the 2H Evaporator was shutdown due to the crystallization of sodium aluminosilicate (NAS) solids (such as cancrinite and sodalite) that contained close to 10 weight percent of elementally-enriched uranium (U). Prior to extensive cleaning, the evaporator deposits resided on the evaporator walls and other exposed internal surfaces within the evaporator pot. Our goal is to support the basis for the continued safe operation of SRS evaporators and to gain more information that could be used to help mitigate U accumulation during evaporator operation. To learn more about the interaction between U(VI) and NAS in HLW salt solutions, we performed several fundamental studies to examine the mechanisms of U accumulation with NAS in highly caustic solutions. This larger group of studies focused on the following processes: co-precipitation/structural incorporation, sorption, and precipitation (with or without NAS), which will be reviewed in this presentation. We will present and discuss local atomic structural characterization data about U that has been co-precipitated with NAS solids (such as amorphous zeolite precursor material and sodalite or Na 8 (AlSiO 4 ) 6 ·nH 2 O (s) ) using X-ray absorption fine-structure (XAFS) spectroscopic techniques. Our results indicate that U uptake from solution is greater during the precipitation of sodalite and amorphous zeolite precursor material than during the precipitation of zeolite A. The XAFS data indicate that U exists in several forms, such as U(VI) (uranyl-and uranate-type) oxide and oxyhydroxides (such as clarkeite). Crystalline forms of U(VI)-silicate were not resolved from the XAFS spectra but the presence of Si in the outer coordination shell of U indicate that the U is probably associated with amorphous silica. Mass balance determinations for U in these materials indicate that during formation, the structural incorporation of U within these structures is not a likely mechanism for accumulation. However, uptake of U was greatest during the precipitation of amorphous zeolite precursor material. Additionally, removal of U from solution by surface sorption on the NAS solids (a process which could have occurred after these solids were formed) probably had a minor role with respect to U accumulation in the 2H Evaporator. Processes most likely to largely influence on U accumulation are precipitation as U(VI) (as uranyl/uranate) oxide/oxyhydroxides and formation of an amorphous U-silica material. INTRODUCTION Uranium accumulation during the evaporation of HLW is a potential criticality risk if the incoming waste is enriched in 235 U. Little is known about the interactions between U and NAS in caustic, high Na + HLW salt solutions at room and at elevated temperature. To examine these interactions during NAS formation, we conducted studies that focused on potential mechanisms of U accumulation with NAS in the evaporators and in other process areas at the SRS that may concentrate U in the presence of silicates, Al and NAS. It is intended that the information gained from these studies will help support the basis for the continued safe operation of SRS evaporators and that this fundamental information will be used to help mitigate U accumulation during evaporator operation. Potential Routes of U Accumulation with NAS During the evaporation of caustic Na + -rich solutions, several processes could potentially contribute to the accumulation of U-containing solids. Uptake processes by solids can occur by several mechanisms: structural incorporation, ion exchange (electrostatic or outer-sphere) sorption, specific adsorption and surface precipitation/polymerization. WSRC-MS-2003-00898 3 Ion Exchange in a more restrictive sense as used in this study is an electrostatic process involving the replacement of one readily exchangeable hydrated ion by another similarly exchangeable ion Specific Adsorption (often referred to as Chemisorption or Inner Sphere sorption) involves the formation of predominantly covalent bonds with the surface, but the bonds can have some ionic behavior. These adsorbed metals typically have one or more atoms from the participating surface in the second coordination shell In HLW, U may be concentrated by sorption to the surfaces of the NAS, precipitation within NAS structures and precipitation as U phases. Sorption can be divided into two types of molecular scale processes (outer sphere and specific adsorption) that involve the uptake of atoms near or at a participating sorptive surface. An element such as U could co-precipitate with the NAS and related solids. [For zeolites, the term co-precipitation could be further divided to include uptake into zeolite channels and any isomorphic substitution (i.e., of U for Si or Al) in the zeolite structure Uranium may also interact with silica sols, which have no defined crystal structure because of their amorphous nature. At an atom-or molecular-scale basis, this type of interaction with U may be best be described by structural incorporation in Review of U(VI) Chemistry and Uptake Studies with U(VI) and Zeolites In oxidized systems, dissolved U exists as the highly soluble uranyl [U(VI)O 2 2+ ] species with two axial U=O double bonds at ~1.8 Å. This form of U(VI) can exist in U solids. However, U(VI) can also exist in solids as the less common uranate form, which has at least three single U-O bonds and no short axial double bonds. This form of U(VI) is very small in size (~0.72-0.8 Å) relative to the large uranyl ion group (~3.6 Å). 2-or NO 3 -solutions), U(VI) typically has a low affinity for certain solids, like the Fe oxides Use of XAFS Techniques to Characterize Metal Uptake by Surfaces The local environment of metals associated with surfaces can be investigated with analytical techniques such as XAFS spectroscopy. It is an X-ray-based technique that is non-destructive and provides average information on bulk and surface behavior. The XAFS spectroscopic techniques are among the best for providing detailed chemical speciation information in environmental samples-particularly when information from multiple characterization techniques is available. The term XAFS is applicable to both X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectroscopic techniques. XAFS spectra give robust local structural information on coordination number (CN), bonding symmetry, neighbor and near-neighbor atomic distances and bond disorder (as the root mean square deviations of distances about the average values). Additionally, the information gained is atom specific-making it a versatile technique for structural determinations of atom clusters Experimental Objectives The primary objective of this research was to obtain information on speciation of U [added as U(VI)] associated with NAS solids that were synthesized with dissolved U using XAFS. Uranium-XAFS analyses were also conducted on solids that had been washed with solutions of DI water (only) and after washing with DI water and Na 2 CO 3 Washing U-loaded solids with Na 2 CO 3 solutions has been shown to remove sorbed forms of U(VI), in addition to dissolving the readily soluble (i.e., rapidly dissolving) solid phase forms of U(VI) MATERIALS AND EXPERIMENTAL METHODS Sample Preparation The NAS solids (amorphous zeolite, sodalite and zeolite A) were synthesized according to modified methods supplied by A. The difference between the amorphous zeolite and sodalite syntheses was temperature, in that the amorphous zeolite was made at 40 o C and the sodalite was made at 80 o C. Zeolite A was made at 90 o C. After preparation, the solids were washed three times in DI water, filtered with a 0.25 µm nylon filter, and dried in air. The air-dried solids were then washed three times with 0.4 M Na 2 CO 3 , filtered with a 0.25 µm nylon filter, and then air-dried. The air-dried solids were then provided to us for XAFS analyses. Sub-samples of the solids were digested in acid to determine the U concentrations after synthesis (using inductively-coupled argon plasma mass spectrometry) after each of the two washing steps. The results of the sample digests are shown in Additionally, to determine when the U should be added during these NAS syntheses, precipitation timing studies were done with U, Al and caustic salt solutions using the same experimental conditions (such as temperature) as those required for the individual NAS syntheses [ the reference samples as listed in 24]. No Si was added to avoid making NAS for each of these reference U materials. The U added to these solutions underwent precipitation and the unwashed solids were supplied for XAFS analyses. The solids in these &quot;reference&quot; samples may be representative of solids that can form in heated caustic solutions that are low in Si but contain high Al. EXAFS Data Collection and Analyses The XAFS data were collected on beamline X23a2 at the National Synchrotron Light Source (NSLS, Brookhaven National Laboratory, Upton, NY). Uranium-XAFS data were collected at the U L 3 -edge (17,166 eV) on the airdried filtered U-containing NAS solids. The XAFS data were collected in fluorescence mode using an unfocussed X-ray beam and a fixed-exit Si(311) monochromator. Ion chambers were used to collect incident (Io), transmission (It) and reference (Ir) signals. Gas ratios in Io were 100 % Ar. A Lytle detector was used to collect fluorescence X-WM&apos;04 CONFERENCE, FEBRUARY 29-MARCH 4, 2004, TUSCON, AZ. WSRC-MS-2003-00898 6 rays (If). The monochromator energy was maximized using a piezo stack feedback energy stabilization system, with a settling time of 0.3 seconds per change in energy. An X-ray beam size of 2 by 28 mm 2 was used. Energy calibration was done using foils of Pt (L 1 -edge of 13,880 eV), Zr (K-edge, 17,998 eV), and Mo (K-edge, 20,000 eV). In simple terms, chi data (the plot of the wavevector in reciprocal space) show the oscillatory component (with both constructive and destructive interferences) of the atoms in the neighbor environment of the element of interest. The chi data represent part of the photoelectron wave that can be defined by the EXAFS equation Chi of k is the square root of [(2m / • 2 ) * (E -E 0 )]. S 0 2 is the amplitude reduction factor, which is associated with central atom shake-up and shake-off effects. SIGMA 2 or σ 2 is the Debye-Waller Factor or Relative Mean Square Disorder in bond length. &quot;•&quot; is Plank&apos;s constant and R pertains to mean atom position or bond distance (radial distance in Å). &quot;m&quot; is the mass of the photoelectron, E 0 is the EXAFS defined edge energy in electron volts or eV (not equal to edge energy as defined by XANES but is equal to the energy of the photoelectron at k = 0. &quot;F of k&quot; is the backscattering amplitude of the atom. N is the coordination number and δ(K) represents the electronic phase shifts due to atomic potentials. The background contribution to the EXAFS spectra was removed using an algorithm (AUTOBK) developed by RESULTS Background on the XAFS Characterization of Behavior of U on Surface

Quasiparticle Hall Transport of d-wave Superconductors in Vortex State

We present a theory of quasiparticle Hall transport in strongly type-II superconductors within their vortex state. We establish the existence of integer quantum spin Hall effect in clean unconventional $d_{x^2-y^2}$ superconductors in the vortex state from a general analysis of the Bogoliubov-de Gennes equation. The spin Hall conductivity $\sigma^s_{xy}$ is shown to be quantized in units of $\frac{\hbar}{8\pi}$. This result does not rest on linearization of the BdG equations around Dirac nodes and therefore includes inter-nodal physics in its entirety. In addition, this result holds for a generic inversion-symmetric lattice of vortices as long as the magnetic field $B$ satisfies $H_{c1} \ll B \ll H_{c2}$. We then derive the Wiedemann-Franz law for the spin and thermal Hall conductivity in the vortex state. In the limit of $T \to 0$, the thermal Hall conductivity satisfies $\kappa_{x y}=\frac{4\pi^2}{3}(\frac{k_B}{\hbar})^2 T \sigma^s_{xy}$. The transitions between different quantized values of $\sigma^s_{xy}$ as well as relation to conventional superconductors are discussed.Comment: 18 pages REVTex, 3 figures, references adde

Broken-Symmetry States in Quantum Hall Superlattices

We argue that broken-symmetry states with either spatially diagonal or spatially off-diagonal order are likely in the quantum Hall regime, for clean multiple quantum well (MQW) systems with small layer separations. We find that for MQW systems, unlike bilayers, charge order tends to be favored over spontaneous interlayer coherence. We estimate the size of the interlayer tunneling amplitude needed to stabilize superlattice Bloch minibands by comparing the variational energies of interlayer-coherent superlattice miniband states with those of states with charge order and states with no broken symmetries. We predict that when coherent miniband ground states are stable, strong interlayer electronic correlations will strongly enhance the growth-direction tunneling conductance and promote the possibility of Bloch oscillations.Comment: 9 pages LaTeX, 4 figures EPS, to be published in PR

Dendritic cell vaccination as postremission treatment to prevent or delay relapse in acute myeloid leukemia

Relapse is a major problem in acute myeloid leukemia (AML) and adversely impacts survival. In this phase II study, we investigated the effect of vaccination with dendritic cells (DCs) electroporated with Wilms’ tumor 1 (WT1) mRNA as post-remission treatment in 30 AML patients at very high risk of relapse. There was a demonstrable anti-leukemic response in 13 patients. Nine patients achieved molecular remission as demonstrated by normalization of WT1 transcript levels, 5 of which are sustained after a median follow-up of 109.4 months. Disease stabilization was achieved in 4 other patients. Five-year overall survival (OS) was higher in responders than in non-responders (53.8% vs. 25.0%; P=0.01). In patients receiving DCs in first complete remission (CR1), there was a vaccine-induced relapse reduction rate of 25% and the 5-year relapse-free survival was higher in responders than in non-responders (50% vs. 7.7%; P65 years who received DCs in CR1, 5-year OS was 69.2% and 30.8% respectively, as compared to 51.7% and 18% in the Swedish Acute Leukemia Registry (SALR). Long-term clinical response was correlated with increased circulating frequencies of poly-epitope WT1-specific CD8+ T-cells. Long-term OS was correlated with interferon-γ+ and tumor necrosis factor-α+ WT1-specific responses in delayed type hypersensitivity-infiltrating CD8+ T-lymphocytes. In conclusion, vaccination of AML patients with WT1 mRNA-electroporated DCs can be an effective strategy to prevent or delay relapse after standard chemotherapy, translating into improved OS rates, which are correlated with the induction of WT1-specific CD8+ T-cell response. This trial was registered at www.clinicaltrials.gov as #NCT00965224