Countercurrent two-phase flow and “flooding” phenomena in light water reactor systems are being investigated experimentally and analytically to improve reactor safety of current and future reactors. The aspects that will be better clarified are the effects of condensation and tube inclination on flooding in large diameter tubes. The current project aims to improve the level of understanding of flooding mechanisms and to develop an analysis model for more accurate evaluations of flooding in the pressurizer surge line of a Pressurized Water Reactor (PWR). Interest in flooding has recently increased because Countercurrent Flow Limitation (CCFL) in the AP600 pressurizer surge line can affect the vessel refill rate following a small break LOCA and because analysis of hypothetical severe accidents with the current flooding models in reactor safety codes shows that these models represent the largest uncertainty in analysis of steam generator tube creep rupture. During a hypothetical station blackout without auxiliary feedwater recovery, should the hot leg become voided, the pressurizer liquid will drain to the hot leg and flooding may occur in the surge line. The flooding model heavily influences the pressurizer emptying rate and the potential for surge line structural failure due to overheating and creep rupture. The air-water …

We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that the uncertainty on the total charm cross section is difficult to quantify.

Silica aerogel collector tiles have been employed for the collection of particles in low Earth orbit and, more recently, for the capture of cometary particles by NASA's Stardust mission. Reliable, reproducible methods for cutting these and future collector tiles from sample return missions are necessary to maximize the science output from the extremely valuable embedded particles. We present a means of macroscopic subdivision of collector tiles by generating large-scale cuts over several centimeters in silica aerogel with almost no material loss. The cut surfaces are smooth and optically clear allowing visual location of particles for analysis and extraction. This capability is complementary to the smaller-scale cutting capabilities previously described [Westphal (2004), Ishii (2005a, 2005b)] for removing individual impacts and particulate debris in tiny aerogel extractions. Macroscopic cuts enable division and storage or distribution of portions of aerogel tiles for immediate analysis of samples by certain techniques in situ or further extraction of samples suited for other methods of analysis.

We perform linear stability calculations for horizontal fluid bilayers that can undergo a phase transformation, taking into account both buoyancy effects and thermocapillary effects in the presence of a vertical temperature gradient. We compare the familiar case of the stability of two immiscible fluids in a bilayer geometry with the less-studied case that the two fluids represent different phases of a single-component material, e.g., the water-steam system. The two cases differ in their interfacial boundary conditions: the condition that the interface is a material surface is replaced by the continuity of mass flux across the interface, together with an assumption of thermodynamic equilibrium that in the linearized equations represents the Clausius-Clapeyron relation relating the interfacial temperature and pressures. For the two-phase case, we find that the entropy difference between the phases plays a crucial role in determining the stability of the system. For small values of the entropy difference between the phases, the two-phase system can be linearly unstable to either heating from above or below. The instability is due to the Marangoni effect in combination with the effects of buoyancy (for heating from below). For larger values of the entropy difference the two-phase system is unstable only for heating …

Genome features of the Bacillus cereus group genomes (representative strains of Bacillus cereus, Bacillus anthracis and Bacillus thuringiensis sub spp israelensis) were analyzed and compared with the Bacillus subtilis genome. A core set of 1,381 protein families among the four Bacillus genomes, with an additional set of 933 families common to the B. cereus group, was identified. Differences in signal transduction pathways, membrane transporters, cell surface structures, cell wall, and S-layer proteins suggesting differences in their phenotype were identified. The B. cereus group has signal transduction systems including a tyrosine kinase related to two-component system histidine kinases from B. subtilis. A model for regulation of the stress responsive sigma factor sigmaB in the B. cereus group different from the well studied regulation in B. subtilis has been proposed. Despite a high degree of chromosomal synteny among these genomes, significant differences in cell wall and spore coat proteins that contribute to the survival and adaptation in specific hosts has been identified.

Uranium exists in several chemical forms in mining and mill tailings and in nuclear and weapons production wastes. Under appropriate conditions, microorganisms can affect the stability and mobility of U in wastes by altering the chemical speciation, solubility and sorption properties and thus could increase or decrease the concentrations of U in solution and the bioavailability. Dissolution or immobilization of U is brought about by direct enzymatic action or indirect nonenzymatic action of microorganisms. Although the physical, chemical, and geochemical processes affecting dissolution, precipitation, and mobilization of U have been extensively investigated, we have only limited information on the mechanisms of microbial transformations of various chemical forms of U in the presence of electron donors and acceptors.

The effect of resonant magnetic perturbations on heat transport in DIII-D H-mode plasmas has been calculated by combining the TRIP3D field-line tracing code with the E3D two-fluid transport code. Simulations show that the divertor heat flux distribution becomes non-axisymmetric because heat flux is efficiently guided to the divertor along the three-dimensional invariant manifolds of the magnetic field. Calculations demonstrate that heat flux is spread over a wider area of the divertor target, thereby reducing the peak heat flux delivered during steady-state operation. Filtered optical cameras have observed non-axisymmetric particle fluxes at the strike-point and Langmuir probes have observed non-axisymmetric floating potentials. On the other hand, the predicted magnitude of stochastic thermal transport is too large to match the pedestal plasma profiles measured by Thomson scattering and charge exchange recombination spectroscopy. The Braginskii thermal conductivity overestimates the expected heat transport in the pedestal because the mean free path is longer than estimates of the parallel thermal correlation length, and collisionless transport models are probably required for accurate description. However, even the collisionless estimates for electron thermal transport are too large by one to two orders of magnitude. Thus, it is likely that another mechanism such as rotational screening of resonant perturbations …

In most cases, nonlinearities from magnets must be properly included in tracking and analysis to properly compute quantities of interest, in particular chromatic properties and dynamic aperture. One source of nonlinearities in magnets that is often important and cannot be avoided is the nonlinearity arising at the end of a magnet due to the longitudinal variation of the field at the end of the magnet. Part of this effect is independent of the longitudinal of the end. It is lowest order in the body field of the magnet, and is the result of taking a limit as the length over which the field at the end varies approaches zero. This is referred to as a ''hard edge'' end field. This effect has been computed previously to lowest order in the transverse variables. This paper describes a method to compute this effect to arbitrary order in the transverse variables, under certain constraints.

In specifying the magnets for an accelerator, one must be able to determine the aperture required by the beam. In some machines, in particular FFAGs, there is a significant variation in the closed orbit and beta functions over the energy range of the machine. In addition, the closed orbit and beta functions may vary with the longitudinal position in the magnet. It is necessary to determine a magnet aperture which encloses the beam ellipses at all energies and all positions in the magnet. This paper describes a method of determining the smallest circular aperture enclosing an arbitrary number of midplane-centered ellipses.

One of the most important considerations in designing large accelerators is cost. This paper describes a model for estimating accelerator magnet costs, including their dependences on length, radius, and field. The reasoning behind the cost model is explained, and the parameters of the model are chosen so as to correctly give the costs of a few selected magnets. A comparison is made with earlier formulae. Estimates are also given for other costs linearly dependent on length, and for 200 MHz superconducting RF.

A new radioactive shipping packaging for transporting bulk quantities of tritium, the Bulk Tritium Shipping Package (BTSP), has been designed for the Department of Energy (DOE) as a replacement for a package designed in the early 1970s. This paper summarizes significant design features and describes how the design satisfies the regulatory safety requirements of the Code of Federal Regulations and the International Atomic Energy Agency. The BTSP design incorporates many improvements over its predecessor by implementing improved testing, handling, and maintenance capabilities, while improving manufacturability and incorporating new engineered materials. This paper also discusses the results from testing of the BTSP to 10 CFR 71 Normal Conditions of Transport and Hypothetical Accident Condition events. The programmatic need of the Department of Energy (DOE) to ship bulk quantities of tritium has been satisfied since the late 1970s by the UC-609 shipping package. The current Certificate of Conformance for the UC-609, USA/9932/B(U) (DOE), will expire in late 2011. Since the UC-609 was not designed to meet current regulatory requirements, it will not be recertified and thereby necessitates a replacement Type B shipping package for continued DOE tritium shipments in the future. A replacement tritium packaging called the Bulk Tritium Shipping Package (BTSP) …

Low-energy electron microscopy (LEEM) reveals a new mode of graphene growth on Ru(0001) in which Ru atoms from a step edge are injected under a growing graphene sheet. The injected atoms can form under-graphene islands, or incorporate into the topmost Ru layer, thereby increasing its density and forming dislocation networks. Density functional calculations imply that Ru islands nucleated between the graphene layer and the substrate are energetically stable; scanning tunneling microscopy (STM) reveals that dislocation networks exist near step edges.

The concept of self-assembled dendrimers is explored for the creation of discrete nanoparticle assemblies. Hybridization of branched DNA trimers and nanoparticle-DNA conjugates results in the synthesis of nanoparticle trimer and tetramer complexes. Multiple tetramer architectures are investigated, utilizing Au-DNA conjugates with varying secondary structural motifs. Hybridization products are analyzed by gel electrophoresis, and discrete bands are observed corresponding to structures with increasing numbers of hybridization events. Samples extracted from each band are analyzed by transmission electron microscopy, and statistics compiled from micrographs are used to compare assembly characteristics for each architecture. Asymmetric structures are also produced in which both 5 and 10 nm Au particles are assembled on branched scaffolds.

We advocate a new approach to study models of fermion massesand mixings, namely anarchy proposed in hep-ph/9911341. In this approach,we scan the O(1) coefficients randomly. We argue that this is the correctapproach when the fundamental theory is sufficiently complicated.Assuming there is no physical distinction among three generations ofneutrinos, the probability distributions in MNS mixing angles can bepredicted independent of the choice of the measure. This is because themixing angles are distributed according to the Haar measure of the Liegroups whose elements diagonalize the mass matrices. The near-maximalmixings, as observed in the atmospheric neutrino data and as required inthe LMA solution to the solar neutrino problem, are highly probable. Asmall hierarchy between the Delta m2 for the atmospheric and the solarneutrinos is obtained very easily; the complex seesaw case gives ahierarchy of a factor of 20 as the most probable one, even though thisconclusion is more measure-dependent. U_e3 has to be just below thecurrent limit from the CHOOZ experiment. The CP-violating parameter sindelta is preferred to be maximal. We present a simple SU(5)-likeextension of anarchy to the charged-lepton and quark sectors which workswell phenomenologically.

We calculate line emission from relativistic accretion tori around Kerr black holes and investigate how the line profiles depend on the viewing inclination, spin of the central black hole, parameters describing the shape of the tori, and spatial distribution of line emissivity on the torus surface. We also compare the lines with those from thin accretion disks. Our calculations show that lines from tori and lines from thin disks share several common features. In particular, at low and moderate viewing inclination angles they both have asymmetric double-peaked profiles with a tall, sharp blue peak and a shorter red peak which has an extensive red wing. At high viewing inclination angles they both have very broad, asymmetric lines which can be roughly considered as single-peaked. Torus and disk lines may show very different red and blue line wings, but the differences are due to the models for relativistic tori and disks having differing inner boundary radii. Self-eclipse and lensing play some role in shaping the torus lines, but they are effective only at high inclination angles. If inner and outer radii of an accretion torus are the same as those of an accretion disk, their line profiles show substantial differences only …

We present measurements of the semileptonic decays B{sup -} {yields} D{sup 0}{tau}{sup -}{bar {nu}}{sub {tau}}, B{sup -} {yields} D{sup *0}{tau}{sup -}{bar {nu}}{sub {tau}}, B{sup -} {yields} D{sup +}{tau}{sup -}{bar {nu}}{sub {tau}}, and B{sup -} {yields} D{sup *+}{tau}{sup -}{bar {nu}}{sub {tau}}, which are potentially sensitive to non-Standard Model amplitudes, The data sample comprises 232 x 10{sup 6} {Upsilon}(4s) {yields} B{bar B} decays collected with the BABAR detector. From a combined fit to B{sup -} and {bar B}{sup 0} channels, we obtain the branching fractions {beta}(B {yields} D{sub {tau}}{sup -}{bar {nu}}{sub {tau}}) = (0:86 {+-} 0:24 {+-} 0:11 {+-} 0:06)% and {beta}(B {yields} D*{tau}{sup -}{bar {nu}}{sub {tau}}) = (1:62 {+-} 0:31 {+-} 0:10 {+-} 0:05)% (normalized for the {bar B}{sup 0}), , where the uncertainties are statistical, systematic, and normalization-mode-related.

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because …

The Sloan Digital Sky Survey-II Supernova Survey has identified a large number of new transient sources in a 300 deg2 region along the celestial equator during its first two seasons of a three-season campaign. Multi-band (ugriz) light curves were measured for most of the sources, which include solar system objects, Galactic variable stars, active galactic nuclei, supernovae (SNe), and other astronomical transients. The imaging survey is augmented by an extensive spectroscopic follow-up program to identify SNe, measure their redshifts, and study the physical conditions of the explosions and their environment through spectroscopic diagnostics. During the survey, light curves are rapidly evaluated to provide an initial photometric type of the SNe, and a selected sample of sources are targeted for spectroscopic observations. In the first two seasons, 476 sources were selected for spectroscopic observations, of which 403 were identified as SNe. For the Type Ia SNe, the main driver for the Survey, our photometric typing and targeting efficiency is 90%. Only 6% of the photometric SN Ia candidates were spectroscopically classified as non-SN Ia instead, and the remaining 4% resulted in low signal-to-noise, unclassified spectra. This paper describes the search algorithm and the software, and the real-time processing of the SDSS …

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The time of peak fusion reactivity with respect to the impingement of laser light on an ICF capsule is known as Bang Time (BT). This is an essential parameter in the understanding of ICF implosions. Traditionally, BT has been determined through temporal measurements of 14 MeV fusion neutrons. Because the neutron energy spectrum is Doppler broadened, the detector must be positioned close to target-chamber center in order to minimize the neutron temporal spreading which can compromise such a measurement. Fusion gammas, on the other hand, are not subject to temporal spreading, making proximity of the detector to the source a lesser concern. However, the low branching ratio for DT fusion reactions producing gammas ({approx}1e-4) presents detector sensitivity challenges.

We study the e+e- --> Lambda anti-Lambda gamma, Lambda anti-Sigma0 gamma, Sigma0 anti-Sigma0 gamma processes using 230 fb-1 of integrated luminosity collected by the BaBar detector at e+e- center-of-mass energy of 10.58 GeV. From the analysis of the baryon-antibaryon mass spectra the cross sections for e+e- --> Lambda anti-Lambda, Lambda anti-Sigma0, Sigma0 anti-Sigma0 are measured in the dibaryon mass range from threshold up to 3 GeV/c{sup 2}. The ratio of electric and magnetic form factors, |G{sub E}/G{sub M}|, is measured for e+e- --> Lambda anti-Lambda, and limits on the relative phase between Lambda form factors are obtained. We also measure the J/psi --> Lambda anti-Lambda, Sigma0 anti-Sigma0 and psi(2S) --> Lambda anti-Lambda branching fractions.

The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5 degrees wide centered on the celestial equator in the Southern Galactic Cap that has been imaged numerous times in earlier years, enabling construction of a deep reference image for discovery of new objects. Supernova imaging observations are being acquired between 1 September and 30 November of 2005-7. During the first two seasons, each region was imaged on average every five nights. Spectroscopic follow-up observations to determine supernova type and redshift are carried out on a large number of telescopes. In its first two three-month seasons, the survey has discovered and measured light curves for 327 spectroscopically confirmed SNe Ia, 30 probable SNe Ia, 14 confirmed SNe Ib/c, 32 confirmed SNe II, plus a large number of photometrically identified SNe Ia, 94 of which have host-galaxy spectra taken so far. This paper provides an overview of the project and briefly describes the observations completed during the first two seasons of operation.

In a coordinated effort, the Department of Transportation (DOT) and Nuclear Regulatory Commission (NRC) proposed the elimination of the Specification Packaging from 49 CFR 173.[1] In accordance with the Federal Register, issued on October 1, 2004, new fabrication of Specification Packages would no longer be authorized. In accordance with the NRC final rulemaking published January 26, 2004, Specification Packagings are mandated by law to be removed from service no later than October 1, 2008. This coordinated effort and resulting rulemaking initiated a planned phase out of Specification Type B and Type A fissile (F) material transportation packages within the Department of Energy (DOE) and its subcontractors. One of the Specification Packages affected by this regulatory change is the UN1A2 Specification Package, per DOT 49 CFR 173.417(a)(6). To maintain continuing shipments of DOE materials currently transported in UN1A2 Specification Package after the existing authorization expires, a replacement Type A(F) material packaging design is under development by the Savannah River National Laboratory. This paper presents a summary of the prototype design effort and testing of the new Type A(F) Package development for the DOE. This paper discusses the progress made in the development of a Type A Fissile Packaging to replace the …

The National Compact Stellarator Experiment (NCSX) was a collaborative effort between ORNL and PPPL. PPPL provided the assembly techniques with guidance from ORNL to meet design criteria. The individual vacuum vessel segments, modular coils, trim coils, and toroidal field coils components were delivered to the Field Period Assembly (FPA) crew who then would complete the component assemblies and then assemble the final three field period assemblies, each consisting of two sets of three modular coils assembled over a 120o vacuum vessel segment with the trim coils and toroidal field coils providing the outer layer. The requirements for positioning the modular coils were found to be most demanding. The assembly tolerances required for accurate positioning of the field coil windings in order to generate sufficiently accurate magnetic fields strained state of the art techniques in metrology and alignment and required constant monitoring of assembly steps with laser trackers, measurement arms, and photogrammetry. The FPA activities were being performed concurrently while engineering challenges were being resolved. For example, it was determined that high friction electrically isolated shims were needed between the modular coil interface joints and low distortion welding was required in the nose region of those joints. This took months of …