A three-dimensional thermal analysis has been performed using finite difference techniques to determine the near-field response of a baseline spent fuel repository in a deep geologic salt medium. A baseline design incorporates previous thermal modeling experience and OWI recommendations for areal thermal loading in specifying the waste form properties, package details, and emplacement configuration. The base case in this thermal analysis considers one 10-year old PWR spent fuel assembly emplaced to yield a 36 kw/acre (8.9 w/m/sup 2/) loading. A unit cell model in an infinite array is used to simplify the problem and provide upper-bound temperatures. Boundary conditions are imposed which allow simulations to 1000 years. Variations studied include a comparison of ventilated and unventilated storage room conditions, emplacement packages with and without air gaps surrounding the canister, and room cool-down scenarios with ventilation following an unventilated state for retrieval purposes. At this low power level ventilating the emplacement room has an immediate cooling influence on the canister and effectively maintains the emplacement room floor near the temperature of the ventilating air. The annular gap separating the canister and sleeve causes the peak temperature of the canister surface to rise by 10/sup 0/F (5.6/sup 0/C) over that from a …

The objectives of the Lawrence Livermore National Laboratory (LLNL) Laser Fusion Program are to understand and develop the science and technology required to utilize inertial confinement fusion (ICF) for both military and commercial applications. The results of recent experiments are described. We point out the progress in our laser studies, where we continue to develop and test the concepts, components, and materials for present and future laser systems. While there are many potential commercial applications of ICF, we limit our discussions to electric power production.

We have performed molecular dynamics computer simulation studies of displacement cascades in Cu at low temperature. For 25 keV recoils we observe the splitting of a cascade into subcascades and show that cascades in Cu may lead to the formation of vacancy and interstitial dislocation loops. We discuss a new mechanism of defect production based on the observation of interstitial prismatic dislocation loop punching from cascades at 10 K. We also show that below the subcascade threshold, atomic mixing in the cascade is recoil-energy dependent and obtain a mixing efficiency that scales as the square root of the primary recoil energy. 44 refs., 12 figs.

Doping studies are presented on three materials exhibiting hybridization gaps: Ce{sub 3}Bi{sub 4}Pt{sub 3}, U{sub 3}Sb{sub 4}Pt{sub 3}, and CeRhSb. In the case of trivalent La, Y, or Lu substituting for Ce or U, there is a suppression of the low temperature gap and an increase in the electronic specific heat, {gamma}. In the case of tetravalent Th substitutions for U there is no change in {gamma} and in the case of tetravalent Zr substitution for Ce in CeRhSb, there is an enhanced semiconductor-like behavior in the electrical resistance. These results are discussed in the light of a simple model of hybridization gapped systems. 12 refs., 3 figs.

The Soudan 1 experiment has obtained additional evidence for underground muons associated with the x-ray pulsar Cygnus X-3. We report the preliminary analysis of data recorded during the October 1985 radio outburst of Cygnus X-3, which show a significant excess of muons for a narrow range of Cygnus X-3 phases.

Energy correlations in transitions from the bound state to the three-body continuum of Borromean halo nuclei are considered. A core+n+n three-body cluster model which reproduces experimentally known properties of {sup 6}He and {sup 11}Li has been used to study low-lying resonances and soft modes. The analysis of the correlated responses in {sup 6}He shows that in the case of the narrow three-body 2{sub 1}{sup +} resonance the transition energy correlations are the same as in the intrinsic correlated structure in 3 {yields} 3 scattering. They differ significantly for wide 2{sub 2}{sup +}, 1{sub 1}{sup +} resonances, and also for the soft dipole and monopole modes, where, due to the transition operators, the intertwining of the ground state and the three-body continuum plays a significant role.

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The candidate division Korarchaeota comprises a group of uncultivated microorganisms that, by their small subunit rRNA phylogeny, may have diverged early from the major archaeal phyla Crenarchaeota and Euryarchaeota. Here, we report the initial characterization of a member of the Korarchaeota with the proposed name,"Candidatus Korarchaeum cryptofilum," which exhibits an ultrathin filamentous morphology. To investigate possible ancestral relationships between deep-branching Korarchaeota and other phyla, we used whole-genome shotgun sequencing to construct a complete composite korarchaeal genome from enriched cells. The genome was assembled into a single contig 1.59 Mb in length with a G + C content of 49percent. Of the 1,617 predicted protein-coding genes, 1,382 (85percent) could be assigned to a revised set of archaeal Clusters of Orthologous Groups (COGs). The predicted gene functions suggest that the organism relies on a simple mode of peptide fermentation for carbon and energy and lacks the ability to synthesize de novo purines, CoA, and several other cofactors. Phylogenetic analyses based on conserved single genes and concatenated protein sequences positioned the korarchaeote as a deep archaeal lineage with an apparent affinity to the Crenarchaeota. However, the predicted gene content revealed that several conserved cellular systems, such as cell division, DNA replication, and tRNA …

As part of a program to characterize and baseline selected environmental parameters in the region around the proposed repository at Yucca Mountain, Nevada, ambient radon-222 monitoring was conducted in the rural community of Amargosa Valley, the community closest to the proposed repository site. Passive integrating radon monitors and a continuous radon monitoring instrument were deployed adjacent to the Community Environmental Monitoring Program (CEMP) (http://www.cemp.dri.edu/index.html) station located in the Amargosa Valley Community Center near the library. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated radon measurements as well as verify meteorological data collected by the continuous radon monitoring instrument. Additionally, different types of environmental enclosures that housed the monitors and instrument were used to determine if particular designs influenced the ambient radon measurements.

We present a measurement of the K-shell spectrum of He-like through Be-like praseodymium ions trapped in the Livermore SuperEBIT electron beam ion trap using a bismuth absorber pixel on the XRS/EBIT microcalorimeter. This measurement is the first of its kind where the n=2 to n=1 transitions of the various charge states are spectroscopically resolved. The measured transition energies are compared with theoretical calculations from several atomic codes.

The Department of Energy (DOE) and Tennessee Valley Authority (TVA) entered into an Interagency Agreement to transfer approximately 40 metric tons of highly enriched uranium (HEU) to TVA for conversion to fuel for the Browns Ferry Nuclear Power Plant. Savannah River Site (SRS) inventories included a significant amount of this material, which resulted from processing spent fuel and surplus materials. The HEU is blended with natural uranium (NU) to low enriched uranium (LEU) with a 4.95% 235U isotopic content and shipped as solution to the TVA vendor. The HEU Blend Down Project provided the upgrades needed to achieve the product throughput and purity required and provided loading facilities. The first blending to low enriched uranium (LEU) took place in March 2003 with the initial shipment to the TVA vendor in July 2003. The SRS Shipments have continued on a regular schedule without any major issues for the past 5 years and are due to complete in September 2008. The HEU Blend program is now looking to continue its success by dispositioning an additional approximately 21 MTU of HEU material as part of the SRS Enriched Uranium Disposition Project.

Ionization efficiency studies for high charge state xenon ions using a calibrated gas leak are presented. A 75% enriched {sup 129}Xe gas leak with a gas flow equivalent to 5.11p{mu}A was used in all the measurements. The experiments were performed at the VENUS (Versatile ECR ion source for Nuclear Science) ion source for 18 GHz, 28 GHz and double frequency operation. Overall, total ionization efficiencies close to 100% and ionization efficiencies into a single charge state up to 22% were measured. The influence of the biased disk on the ionization efficiency was studied and the results were somewhat surprising. When the biased disk was removed from the plasma chamber, the ionization efficiency was dramatically reduced for single frequency operation. However, using double frequency heating the ionization efficiencies achieved without the biased disk almost matched the ionization efficiencies achieved with the biased probe. In addition, we have studied the influence of the support gas on the charge state distribution of the xenon ions. Either pure oxygen or a mixture of oxygen and helium were used as support gases. The addition of a small amount of helium can increase the ionization efficiency into a single charge state by narrowing the charge state …

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High precision uranium isotope measurements of marineclastic sediments are used to measure the transport and storage time ofsediment from source to site of deposition. The approach is demonstratedon fine-grained, late Pleistocene deep-sea sediments from Ocean DrillingProgram Site 984A on the Bjorn Drift in the North Atlantic. The sedimentsare siliciclastic with up to 30 percent carbonate, and dated by sigma 18Oof benthic foraminifera. Nd and Sr isotopes indicate that provenance hasoscillated between a proximal source during the last three interglacialperiods volcanic rocks from Iceland and a distal continental sourceduring glacial periods. An unexpected finding is that the 234U/238Uratios of the silicate portion of the sediment, isolated by leaching withhydrochloric acid, are significantly less than the secular equilibriumvalue and show large and systematic variations that are correlated withglacial cycles and sediment provenance. The 234U depletions are inferredto be due to alpha-recoil loss of234Th, and are used to calculate"comminution ages" of the sediment -- the time elapsed between thegeneration of the small (<_ 50 mu-m) sediment grains in the sourceareas by comminution of bedrock, and the time of deposition on theseafloor. Transport times, the difference between comminution ages anddepositional ages, vary from less than 10 ky to about 300 to 400 ky forthe …

A dual-axis, synchroscan streak camera was used to measure longitudinal bunch profiles in three storage rings at SLAC: the PEP-II low- and high-energy rings, and SPEAR3. At high currents, both PEP rings exhibit a transient synchronous-phase shift along the bunch train due to RF-cavity beam loading. Bunch length and profile asymmetry were measured along the train for a range of beam currents. To avoid the noise inherent in a dual-axis sweep, we accumulated single-axis synchroscan images while applying a 50-ns gate to the microchannel plate. To improve the extinction ratio, an upstream mirror pivoting at 1 kHz was synchronized with the 2kHz MCP gate to deflect light from other bunches off the photocathode. Bunch length was also measured on the HER as a function of beam energy. For SPEAR3 we measured bunch length as a function of single-bunch current for several lattices: achromatic, low-emittance and low momentum compaction. In the first two cases, resistive and reactive impedance components can be extracted from the longitudinal bunch profiles. In the low-alpha configurations, we observed natural bunch lengths approaching the camera resolution, requiring special care to remove instrumental effects, and saw evidence of periodic bursting.

The Sudbury Neutrino Observatory (SNO) used an array of {sup 3}He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active ({nu}{sub x}) {sup 8}B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54{sub -0.31}{sup +0.33}(stat){sub -0.34}{sup +0.36}(syst) x 10{sup 6} cm{sup -2}s{sup -1}, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields {Delta}m{sup 2} = 7.94{sub -0.26}{sup +0.42} x 10{sup -5} eV{sup 2} and {theta} = 33.8{sub -1.3}{sup +1.4} degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.

The equilibrium of an infinitely long, strongly magnetized, non-neutral plasma confined in a Penning-Malmberg trap with an additional mirror coil has been solved analytically [J. Fajans, Phys. Plasmas 10, 1209 (2003)] and shown to exhibit unusual features. Particles not only reflect near the mirror in the low field region, but also may be weakly trapped in part of in the high field region. The plasma satisfies a Boltzmann distribution along field lines; however, the density and the potential vary along field lines. Some other simplifying assumptions were employed in order to analytically characterize the equilibrium; for example the interface region between the low and high field regions was not considered. The earlier results are confirmed in the present study, where two-dimensional particle-in-cell simulations are performed with the Warp code in a more realistic configuration with an arbitrary (but physical) density profile, realistic trap geometry and magnetic field. A range of temperatures and radial plasma sizes are considered. Particle tracking is used to identify populations of trapped and untrapped particles. The present study also shows that it is possible to obtain local equilibria of non-neutral plasmas using a collisionless PIC code, by a scheme that uses the inherent numerical collisionality as …

Recent advances in very-high-energy (VHE) gamma-ray astronomy have opened a new observational window on the physics of pulsars. The high sensitivity of current imaging atmospheric Cherenkov telescopes, and in particular of the H.E.S.S. array, has already led to the discovery of about a dozen VHE-emitting pulsar wind nebulae (PWNe) and PWN candidates. These include the plerions in the composite supernova remnants MSH 15-52, G21.5-0.9, Kes 75, and Vela, two sources in the Kookaburra, and the nebula of PSR B1823-13. This VHE emission is generally interpreted as inverse Compton emission from the relativistic electrons and positrons accelerated by the pulsar and its wind; as such, it can yield a more direct spatial and spectral view of the accelerated particles than can be inferred from observations of their synchrotron emission. The VHE-emitting PWNe detected by the H.E.S.S. telescopes are reviewed and the implications for pulsar physics discussed.

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Improved nuclear analysis, including the treatment of resonance and spatial self-shielding, coupled with an optimization procedure, has resulted in an improved performance estimate for the molten salt blanket. Net U-233 breeding ratio ranges between 0.58 and 0.63, and blanket energy multiplication ranges between 1.8 and 1.9.

A single electrostatic wave in a magnetoplasma causes stochastic ion motion in several physically different situations. Various magnetic fields (uniform, tokamak, and mirror) and various propagation angles with respect to the field have been studied. A brief review of this work shows that all situations can be understood using the concept of overlapping resonances. Analytical calculations of the wave amplitude necessary for stochasticity have been carried out in some cases and compared with computer and laboratory experiments. In the case of an axisymmetric mirror field the calculations predict stochastic motion of ions with energy below a threshold that depends weakly on the wave amplitude and on the scale lengths of the magnetic field. Studies with an azimuthally asymmetric field show that the asymmetry causes substantial changes in the motion of some ions.

A brief parametric survey of the x-ray characteristics of a gold micro-disk irradiated at 3 x 10/sup 14/ watt/cm/sup 2/ by a 1 nsec Nd-glass laser pulse has been provided as an example of a laser generated bright x-ray source. It was shown that a simple phenomenological model of the laser generated x-ray source as a microscopic equilibrium plasma radiating as a blackbody for a finite time determined by its hydrodynamic disassembly and radiation losses, serves to provide an adequate approximation to the x-ray characteristics of such sources. The current state of x-ray microscopy within the LLL laser fusion program was briefly reviewed. Kirpatrick--Baez grazing incidence reflection x-ray microscopes are being used to provide 3 to 5 ..mu..m resolution, broadband images (..delta..E/E approx. 0.3) over a spectral range from .6 keV to 3.5 keV. Zone Plate Coded Imaging is used to provide 5 to 10 ..mu..m resolution, broadband (..delta..E/E approx. 0.5) images over a spectral range from 3 keV to 50 keV. Efficient x-ray lensing elements with anticipated submicron resolution are being developed for narrowband (..delta..E/E approx. 10/sup -2/) imaging applications over a spectral range .1 keV to 8 keV. The x-ray lens design is that of a transmission blazed …

A modified Voitenko compressor generated a Mach-130 air shock in an outlet pipe open to the atmosphere. Fiber optics transmitted luminosity associated with propagation of the air shock to an external display board, which was scanned with a high-speed streaking camera. We describe the computerized microdensitometer scanning technique for converting the film records to pseudo-3D, isodensity, and density profiles. The isodensity contours can be displayed using different colors to facilitate analysis. This technique can achieve resolutions of 1 ns and 2 ..mu..m. We give examples of the pseudo-3D, isodensity, and density profile plots for the experiment. The microdensitometer output was digitized for input to data display programs run on a CDC 7600. These results were used to provide submicrosecond accuracy for shock propagation over a 5 m of the outlet pipes. In addition, we obtained information about gas flow behind the shock front. Other current or possible applications for the technique are measurement of: target implosion in laser fusion, flash x-ray data in hydrodynamic and ballistic experiments, temperature profiles for high energy (> 10/sup 5/ K) gas dynamics, and dynamic events in weapons testing.

We are disIgning a minimum-size Tokamak ignition/Burn Reactor (TIBER II). This design incorporates physics requirements, neutron wall loading and fluence parameters that will make it compatible with a nuclear testing mission. Reactor relevant physics will be tested by using current drive and steady-state operation. Although the design accommodates several current drive options, including neutral beams, the base case uses a combination of lower hybrid and electron-cyclotron radio frequency power. Minimum neutron shielding, compact structures, high magnet-current densities, and remotely maintainable vacuum seals, all contribute to the compact size.