The authors are developing a networked, multi-user, virtual-reality-based collaborative environment coupled to one or more petaFLOPs computers, enabling the interactive simulation of 10{sup 9} atom systems. The purpose of this work is to explore the requirements for this coupling. Through the design, development, and testing of such systems, they hope to gain knowledge that allows computational scientists to discover and analyze their results more quickly and in a more intuitive manner.

Detailed analysis of a quarter channel was performed using VIPRE and CFX. Results show that VIPRE and CFX agree closely in both cross-sectionally averaged axial temperature and cross-sectionally averaged axial velocity profiles. Detailed temperature distributions in the radial direction over 1mm from the clad surface towards the center of the channel were calculated using CFX, showing significant local variation. This information can be used for example, to determine if this temperature will lead to bubble nucleation. Quarter subassembly calculations were made with both VIPRE and STAR-CD. Comparison between the solutions show that the two codes yield very similar solutions under comparable conditions. However, the STAR-CD CFD calculation provides the analyst with much more detailed flow and temperature distributions than can be predicted by a one-dimensional code such as VIPRE. In addition, a 60 million cell one-eighth reactor core calculation was made using STAR-CD. This analysis showed the importance of accurately predicting the flow and temperature fields in all assemblies simultaneously with modern parallel processing technology, practical turnaround for these types of calculation can be obtained.

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A performance goal-based seismic design philosophy, compatible with DOE`s present natural phenomena hazards mitigation and ``graded approach`` philosophy, has been proposed for high level nuclear waste repository facilities. The rationale, evolution, and the desirable features of this method have been described. Why and how the method should and can be applied to the design of a repository facility are also discussed.

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{Lambda} binding energy data for total baryon number A {le} 208 and for {Lambda} angular momenta {ell}{sub {Lambda}} {le} 3 are analyzed in terms of phenomenological (but generally consistent with meson-exchange) {Lambda}N and {Lambda}NN potentials. The Fermi-Hypernetted-Chain technique is used to calculate the expectation values for the {Lambda} binding to nuclear matter. Accurate effective {Lambda}N and {Lambda}NN potentials are obtained which are folded with the core nucleus nucleon densities to calculate the {Lambda} single particle potential U{sub {Lambda}}(r). We use a dispersive {Lambda}NN potential but also include an explicit {rho} dependence to allow for reduced repulsion in the surface, and the best fits have a large {rho} dependence giving consistency with the variational Monte Carlo calculations for {sub {Lambda}}{sup 5}He. The exchange fraction of the {Lambda}N space-exchange potential is found to be 0.2-0.3 corresponding to m{sub {Lambda}}* {approx_equal} (0.74-0.82)m{sub {Lambda}}. Charge symmetry breaking is found to be significant for heavy hypernuclei with a large neutron excess, with a strength consistent with that obtained from the A = 4 hypernuclei.

High-purity tantalum single crystal cylinders oriented with [011] parallel to the cylinder axis were deformed 10, 20, and 30 percent in compression. The engineering stress-strain curve exhibited an up-turn at strains greater than {approximately}20% while the samples took on an ellipsoidal shape during testing, elongated along the [100] direction with almost no dimensional change along [0{bar 1}1]. Two orthogonal planes were selected for characterization using Orientation Imaging Microscopy (OIM): one plane containing [100] and [011] (longitudinal) and the other in the plane containing [0{bar 1}1] and [011] (transverse). OIM revealed patterns of alternating crystal rotations that develop as a function of strain and exhibit evolving length scales. The spacing and magnitude of these alternating misorientations increases in number density and decreases in spacing with increasing strain. Classical crystal plasticity calculations were performed to simulate the effects of compression deformation with and without the presence of friction. The calculated stress-strain response, local lattice reorientations, and specimen shape are compared with experiment.

We describe an interactive toolkit used to perform comparative analysis of two or more data sets arising from numerical simulations. Several techniques have been incorporated into this toolkit, including (1) successive visualization of individual data sets, (2) data comparison techniques such as computation and visualization of the differences between data sets, and (3) image comparison methods such as scalar field height profiles plotted in a common coordinate system. We describe each technique in detail and show example usage in an industrial application aimed at designing an efficient, low-NOX burner for industrial furnaces. Critical insights are obtained by interactively adjusted color maps, data culling, and data manipulation. New paradigms for scaling small values in the data comparison technique are described. The display device used for this application was the CAVE virtual reality theater, and we describe the user interface to the visualization toolkit and the benefits of immersive 3D visualization for comparative analysis.

Diffusion is considered one of the most important retardation mechanisms in fractured media. The diffusion experiments conducted involved solid tuff and groundwater from Yucca Mountain. The uptake of radionuclides by the tuff was studied utilizing containers made of tuff in the form of beakers. The solution containing the radionuclides of interest was placed in the tuff beaker cavity and the uptake of the radionuclides by the tuff was measured as a function of time. Our results indicate that the diffusion coefficient for nonsorbing radionuclides into saturated Yucca Mountain tuff is on the order of 10{sup {minus}6} cm{sup 2}/s. Large anions, such as pertechnetate are excluded from tuff pores and their diffusion coefficients are on the order of 10{sup {minus}7}cm{sup 2}/s. Comparison of the predictions for the uptake of sorbing radionuclides by the tuff with the actual data obtained indicates that conservative transport calculations will result from predicting diffusion using the batch sorption coefficient for the sorbing radionuclide and the diffusion coefficient obtained for tritiated water.

Ukraine operates pressurized water reactors of the Soviet-designed type, VVER. All Ukrainian plants are currently operating with annually renewable permits until they update their safety analysis reports (SARs). After approval of the SARS by the Ukrainian Nuclear Regulatory Authority, the plants will be granted longer-term operating licenses. In September 1995, the Nuclear Regulatory Authority and the Government Nuclear Power Coordinating Committee of Ukraine issued a new contents requirement for the safety analysis reports of VVERs in Ukraine. It contains requirements in three major areas: design basis accident (DBA) analysis, probabilistic risk assessment (PRA), and beyond design-basis accident (BDBA) analysis. The DBA requirements are an expanded version of the older SAR requirements. The last two requirements, on PRA and BDBA, are new. The US Department of Energy (USDOE), through the International Nuclear Safety Program (INSP), has initiated an assistance and technology transfer program to Ukraine to assist their nuclear power stations in developing a Western-type technical basis for the new SARS. USDOE sponsored In-Depth Safety Assessments (ISAs) have been initiated at three pilot nuclear reactor units in Ukraine, South Ukraine Unit 1, Zaporizhzhya Unit 5, and Rivne Unit 1. USDOE/INSP have structured the ISA program in such a way as to …

Heating of the rock mass by the spent fuel in the proposed repository at Yucca Mountain will cause extra amounts of natural radon to diffuse into the fracture system and to migrate faster to the accessible environment. Indeed, free-convection currents due to heating will act to shorten the radon travel times and will cause larger releases than would be possible under undistributed conditions. To estimate the amount of additional radon released due to heating of the Yucca Mountain rock mass, we obtain an expression for the release enhancement factor, E. This factor is defined as the ratio between the total flux of radon at the surface of the mountain before and after closure of the repository assuming the only cause of disturbance to be the heating of the rock mass. With appropriate approximations and using a heat load representative of that expected at Yucca Mountain, the present calculations indicate that the average enhancement factor over the first 10,000 years will be 4.5 as a minimum. These calculations are based on the assumption that barometric pumping does not significantly influence radon release. The latter assumption will need to be substantiated.

Pyrochemical conditioning of spent nuclear fuel for the purpose of final disposal is currently being demonstrated at Argonne National Laboratory (ANL), and ongoing research in this area includes the demonstration of this process on spent oxide fuel. In conjunction with this research a pilot scale of the preprocessing stage is being designed by ANL-W to demonstrate the in situ hot cell capability of the chemical reduction stage. An impurity evaluation was completed for a Li/LiCl salt matrix in the presence of spent LWR uranium oxide fuel. A simple analysis was performed in which the sources of impurities in the salt matrix were only from the cell atmosphere. Only reactions with the lithium were considered. The levels of impurities were shown to be highly sensitive system conditions. A predominance diagram for the Li-O-N system was constructed for the device, and the general oxidation, nitridation and combined reactions were calculated as a function of oxygen and nitrogen partial pressure. These calculations and hotcell atmosphere data were used to determine the total number and type of impurities expected in the salt matrix and the mass rate for the device was determined.

A research program to develop a reaction-rate (RR) data base for stellar explosive hydrogen burning via (p,{gamma}) and (p,{alpha}) reactions involving stable-isotope target elements in the mass range A = 30-50 (phosphorus to titanium) is described. This project includes: (1) a survey of the literature; (2) preparation of written summaries for pertinent contributions; (3) compilation of alpha-numeric information into computer-platform-independent data files; (4) tabulation of reaction resonance parameters (and uncertainties); (5) determination of resonance RRs (and uncertainties) for Maxwellian-distributed reactant energies corresponding to temperatures in the range T{sub 9}=0.01-10 GK (1 GK=10{sup 9} degrees Kelvin); (6) fitting of these calculated RRs with an empirical formula, thereby converting the basic data into a form that is convenient for astrophysical network calculations; (7) examination of deviations between fitted curves and these RRs in the context of the uncertainties. The results of this work are made available to the nuclear astrophysics community through formal laboratory reports and computer files which are distributed to data centers. The procedures used in this work are discussed and some representative examples of products from the activity are given.

This report discusses development on the technology used to assess the safety of irradiation-embrittled nuclear reactor pressure vessels containing flaws. Fracture mechanics tests on reactor pressure vessel steel have shown that local brittle zones do not significantly degrade the material fracture toughness, constraint relaxation at the crack tip of shallow surface flaws results in increased fracture toughness, and biaxial loading reduces but does not eliminate the shallow-flaw fracture toughness elevation. Experimental irradiation investigations have shown that the irradiation-induced shift in Charpy V-notch versus temperature behavior may not be adequate to conservatively assess fracture toughness shifts due to embrittlement and the wide global variations of initial chemistry and fracture properties of a nominally uniform material within a pressure vessel may confound accurate integrity assessments that require baseline properties.

The convention for field emission cathode (FEC) synthesis involves coating with a very-high tolerance in thickness uniformity using a planetary substrate fixture and a large source-to-substrate separation. New criteria for a deposition process must facilitate a reduction in the operating voltage by increasing the density of emitters through a reduction of cathode size and spacing. The objective of scaling the substrate size from small (less than 30 cm{sup 2}) to large (greater than 500 cm{sup 2}) areas further compounds manufacturing requirements to a point beyond that easily obtained by modifications to the convention for FEC deposition. A new patented approach to design, assemble, and operate a coating system enables FEC deposition over large areas through process control of source divergence coupled to incremental substrate positioning.

The continued operation of existing US Department of Energy (DOE) nuclear facilities and laboratories requires a safety reassessment based on current criteria and guidelines. This also includes evaluations for the effects of Natural Phenomena Hazards (NPH), for which these facilities may not have been designed. The NPH evaluations follow the requirements of DOE Order 5480.28, Natural Phenomena Hazards Mitigation (1993) which establishes NPH Performance Categories (PCs) for DOE facilities and associated target probabilistic performance goals. These goals are expressed as the mean annual probability of exceedance of acceptable behavior for structures, systems and components (SSCs) subjected to NPH effects. The assignment of an NPH Performance Category is based on the overall hazard categorization (low, moderate, high) of a facility and on the function of an SSC under evaluation (DOE-STD-1021, 1992). Detailed guidance for the NPH analysis and evaluation criteria are also provided (DOE-STD-1020, 1994). These analyses can be very resource intensive, and may not be necessary for the evaluation of all SSCs in existing facilities, in particular for low hazard category facilities. An approach relying heavily on screening inspections, engineering judgment and use of NPH experience data (S. J. Eder et al., 1993), can minimize the analytical effort, give reasonable …

Electromotive force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made on the YBa{sub 2}Cu{sub 3}O{sub x}, GdBa{sub 2}Cu{sub 3}O{sub x}, NdBa{sub 2}Cu{sub 3}O{sub x} and bismuth cuprate systems in the temperature range {approximately}400-750 C by means of an oxygen titration technique with an yttria-stabilized zirconia electrolyte. The shapes of the 400 C isotherms as a function of oxygen stoichiometry for the Gd and Nd cuprate systems suggest the presence of miscibility gaps at values of x that are higher than those in the YBa{sub 2}Cu{sub 3}O{sub x} system. For a given oxygen stoichiometry, oxygen partial pressures above GdBa{sub 2}Cu{sub 3}O{sub x} and NdBa{sub 2}Cu{sub 3}O{sub x} are higher (above x=6.5) than that for the promising YBa{sub 2}Cu{sub 3}O{sub x} system. A thermodynamic assessment and intercomparison of our partial pressure measurements with the results of related measurements will be presented.

In support of pacific Northwest Laboratory`s (PNL) preliminary total system performance assessment of the proposed high-level nuclear-waste repository at Yucca Mountain, transport of carbon-14 (C{sup 14}) in the unsaturated zone was numerically modeled with the Multiphase Subsurface Transport Simulator (MSTS). Total system performance assessments are being conducted to estimate potential cumulative releases and doses from radionuclides being transported through different pathways to the accessible environment from the proposed waste repository. Transport of radionuclides in the gaseous and liquid phases are pathways through which some of the inventory in the proposed repository could reach the accessible environment. Carbon-14 transport in the unsaturated zone at Yucca Mountain was estimated with MSTS by considering two-phase diffusion, advection, phase petitioning, and radioactive decay.Transport results were based on a two-dimensional physical and hydrogeological system that represented an east-west cross section through Yucca Mountain. Carbon-14 source rates from failed repository waste canisters were estimated from the source term modeling subtasks associated with PNL`s total system performance assessment of the proposed Yucca Mountain repository. Simulation results included estimates of liquid, gas, heat, and C{sup 14} transport within the unsaturated zone at Yucca Mountain. Predictions of C{sup 14} distributions surrounding the proposed nuclear waste repository within Yucca Mountain …

Results are presented detailing the status of tests of perturbative QCD in hard parton-parton collisions generated by high energy collisions of protons and antiprotons at the Fermilab Collider. Recent data fro the CDF and DO experiments are compared to Next-to-Leading Order QCD calculations in hadronic jet production, prompt photon production, jet production in events with W bosons, and b-quark production.

At Los Alamos National Laboratory we are developing a new imaging sensor which combines high spatial and high temporal resolution over a large area format, while maintaining single-photon counting sensitivity and substaining a high count rate. The detector is called a microchannel plate with crossed delay line readout, or MCP/CDL. This detector is ideally suited to the observation of weak transient events, such as stellar flares from red dwarf flare stars in our Galaxy. At present we are initiating an experiment with the MCP/CDL detector which will utilize a 30-cm aperture f/7 telescope to characterize U-band, B-band, and U-band emission from such low- luminosity flare stars, and to search for weak optical transients associated with other astrophysical sources.

We present progress in experiments for high efficiency Ne-like and Ni-like ion x-ray lasers using the transient collisional excitation scheme. Experimental results have been obtained on the COMET 15 TW table-top laser system at the Lawrence Livermore National Laboratory (LLNL). The plasma formation, ionization and collisional excitation of the x-ray laser have been optimized using two sequential laser pulses of 600 ps and 1 ps duration with an optional pre-pulse. We have observed high gains up to 55 cm{sup {minus}1} in Ne-like and Ni-like ion schemes for various atomic numbers. We report strong output for the 4d - 4p line in lower Z Ni-like ion sequence for Mo to Y, lasing from {approximately}190 {angstrom} to 240 {angstrom}, by pumping with less than 5 J energy on target.

We describe recent, energetics performance results on the engineering preamplifier module (PAM) prototype located in the front end of the 1.8MJ National Ignition Facility (NIF) laser system. Three vertically mounted subsystem located in the PAM provide laser gain as well as spatial beam shaping. The first subsystem in the PAM prototype is a diode pumped, Nd:glass, linear, TEM{sub 00}, 4.5m long regenerative amplifier cavity. With a single diode pumped head, we amplify a 1nJ, mode matched, temporally shaped ({approx} 20ns) seed pulse by a factor of approximately 10{sup 7} to 20mJ. The second subsystem in the PAM is the beam shaping module, which magnifies the gaussian output beam of the regenerative amplifier to provide a 30mm x 30mm square beam that is spatially shaped in two dimensions to pre-compensate for radial gain profiles in the main amplifiers. The final subsystem in the PAM is the 4-pass amplifier which relay images the 1mJ output of the beam shaper through four gain passes in a {phi}5cm x 48cm flashlamp pumped rod amplifier, amplifying the energy to 175. The system gain of the PAM is 10{sup 10}. Each PAM provides 35 of injected energy to four separate main amplifier chains which in turn …

A computational fluid dynamics (CFD) computer code, ICRKFLO, has been developed for flow simulation of fluid catalytic cracking (FCC) riser reactors, which convert crude oil into gasoline and other valuable products. The FCC flow, especially in the entry region, is a three-phase reacting flow including hot catalyst particles, inert lift gas, and feed oil droplets. The impact of the hydrodynamics processes of heat transfer, droplet evaporation, and mixing on the chemical kinetics or riser performance can be significant. ICRKFLO was used to evaluate the impact of these processes on the performance of an advanced FCC unit. The code solves for major flow properties of all three phases in an FCC riser, with models governing the transport of catalyst particles and feed oil droplet, the vaporization of the feed oil droplets, the cracking of the oil vapor, and the formation and deposition of coke on particles. First, the code was validated against available test data of a pilot-scale FCC unit. Then, flow calculations for the FCC unit were performed. Computational results indicate that the heat transfer and droplet vaporization processes have a significant impact on the performance of a pilot-scale FCC unit. The impact is expected to be even greater on …