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 US Department of Energy and the Institute for Ecology of Industrial Area have been working together to develop mutually beneficial, cost-effective environmental remediation technologies such as the demonstration of bioremediation techniques for the clean up of acidic petroleum sludge impacted soils at an oil refinery in southern Poland. After an expedited site characterization, treatability study, and a risk assessment study, a remediation strategy was devised. The waste material was composed primarily of high molecular weight paraffinic and polynuclear aromatic hydrocarbons. A biopile design which employed a combination of passive and active aeration in conjunction with nutrient and surfactant application as used to increase the biodegradation of the contaminants of concern.

This report describes efforts made at the oak Rklge NatiOnrd Laboratory to design high- efficiency-release targets that simultaneously incorporate the short diffusion lengths, high permeabilities, controllable temperatures, and heat-removal properties required for the generation of useful radioactive ion beam (RIB) intensities for nuclear physics and astrophysics research using the isotope separation on-line (ISOL) technique. Short diffusion lengths are achieved either by using thin fibrous target materials or by coating thin layers of selected target material onto low-density carbon fibers such as reticulated-vitreous-carbon fiber (RVCF) or carbon-bonded-carbon fiber (CBCF) to form highly permeable composite target matrices. Computational studies that simulate the generation and removal of primary beam deposited heat from target materials have been conducted to optimize the design of targetheat-sink systems for generating RIBs. The results derived from diffusion release-rate simulation studies for selected targets and thermal analyses of temperature distributions within a prototype targetlheat-sink system subjected to primary ion beam irradiation will be presented in this report.

A multi-sample Cs sputter negative-ion source, equipped with a conical-geometry, W-surface-ionizer has been designed and fabricated that permits sample changes without disruption of on-line accelerator operation. Sample changing is effected by actuating an electro-pneumatic control system located at ground potential that drives an air-motor-driven sample-indexing-system mounted at high voltage; this arrangement avoids complications associated with indexing mechanisms that rely on electronic power-supplies located at high potential. In-beam targets are identified by LED indicator lights derived from a fiber-optic, Gray-code target-position sensor. Aspects of the overall source design and details of the indexing mechanism along with operational parameters, ion optics. intensities, and typical emittances for a variety of negative-ion species will be presented in this report.

New techniques for enhancing the performances of electron cyclotron resonance (ECR) ion sources are being investigated at the Oak Ridge National Laboratory. We have utilized the multiple discrete frequency technique to improve the charge state distributions extracted from conventional magnetic field geometry ECR source by injecting three frequencies into the source. A new flat central magnetic field concept, has been incorporated in the designs of a compact all-permanent-magnet source for high charge-state ion beam generation and a compact electromagnetic source for singly ionized radioactive ion beam generation for use in the Holifield Radioactive Ion Beam Facility (HRIBF) research program. A review of the three frequency injection experiments and descriptions of the design aspects of the "volume-type" ECR ion sources will be given in this report.

Chemically active radioactive species, diffused from RIB target materials, often arrive at the ionization chamber of the source in a variety of molecular forms. Because of the low probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecules with conventional hot-cathode electron-impact ion sources, the species of interest are often distributed in several mass channels in the form of molecular side-band beams and consequently, their intensities are diluted. The sputter negative ion beam generation technique offers an efficient means for simultaneously dissociating and ionizing highly electronegative atomic species present in molecular carriers. We have incorporated these principles in the design and fabrication of a kinetic ejection negative ion source and evaluated its potential for generating {sup 17,18}F{sup {minus}} beams for the Holifield Radioactive Ion Beam Facility astrophysics research program. The source utilizes Cs{sup +} beams to bombard condensable fluorine compounds that emanate from a target material, such as Al{sub 2}O{sub 3}, and are transported to the cooled inner surface of a conical-geometry cathode where they are adsorbed. The energetic Cs{sup +} beams efficiently dissociate these molecules and sputter their constituents. Since the work functions of cesiated surfaces are low, highly electronegative species such as fluorine are efficiently …

By exposing samples to various irradiance levels from a calibrated thermal radiation source, the ignition responses of blackened alpha-cellulose and cotton cloth with and without fire-retardant additives were compared. Samples treated with retardant compounds which showed the most promise were then isothermally pyrolyzed in air for comparisons between the pyrolysis rates. Alpha-cellulose samples containing a mixture of boric acid, borax, and ammonium di-hydrogen phosphate could not be ignited by irradiances up to 4.0 cal cm/sup -2/ s-1 (16.7 W/cm/sup 2/). At higher irradiances the specimens ignited, but flaming lasted only until the flammable gases were depleted. Cotton cloth containing a polymeric retardant with the designation THPC + MM was found to be ignition-resistant to all irradiances below 7.0 cal cm/sup -2/ s/sup -1/ (29.3 W/cm/sup 2/). Comparison of the pyrolysis rates of the retardant-treated alpha-cellulose and the retardant-treated cotton showed that the retardant mechanism is qualitatively the same. Similar ignition-response measurements were also made with specimens exposed to ionizing radiation. It was observed that gamma radiation results in ignition retardance of cellulose, while irradiation by neutrons does not.

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The first stars, forming at redshifts z > 15 in minihalos with M {approx} 10{sup 5-6} M{sub {circle_dot}} may leave behind remnant black holes, which could conceivably have been the 'seeds' for the supermassive black holes observed at z {approx}< 7. We study remnant black hole growth through accretion, including for the first time the radiation emitted due to accretion, with adaptive mesh refinement cosmological radiation-hydrodynamical simulations. The effects of photo-ionization and heating dramatically affect the large-scale inflow, resulting in negligible mass growth. We compare cases with accretion luminosity included and neglected to show that accretion radiation drastically changes the environment within 100 pc of the black hole, increasing gas temperatures by an order of magnitude. Gas densities are reduced and further star formation in the same minihalo is prevented for the two hundred million years we followed. Without radiative feedback included most seed black holes do not gain mass as efficiently as has been hoped for in previous theories, implying that black hole remnants of Pop III stars in minihalos are not likely to be miniquasars. Most importantly, however, our calculations demonstrate that if these black holes are indeed accreting close to the Bondi-Hoyle rate with ten percent radiative …

This article presents a report on the progress made in designing 18 MW water based Beam Dumps for electrons or positrons for an International Linear Collider (ILC). Multi-dimensional technology issues have to be addressed for the successful design of the Beam Dump. They include calculations of power deposition by the high energy electron/positron beam bunch trains, computational fluid dynamic analysis of turbulent water flow, mechanical design, process flow analysis, hydrogen/oxygen recombiners, handling of radioactive 7Be and 3H, design of auxiliary equipment, provisions for accident scenarios, remote window exchanger, radiation shielding, etc. The progress made to date is summarized, the current status, and also the issues still to be addressed.

The role of smoothly varying transverse gain and refraction profiles on x-ray laser intensity and coherence is analyzed by modally expanding the electric field within the paraxial approximation. Comparison with a square transverse profile reveals that smooth-edged profiles lead to: (1) a greatly reduced number of guided modes, (2) the continued cancellation of local intensity from a loosely guided mode by resonant free modes, (3) and the absence of extraneous (or anomalous) free mode resonances. These generic spectral properties should enable a considerable simplification in analyzing and optimizing the coherence properties of laboratory soft x-ray lasers. 6 refs., 3 figs.

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A proof-of-principle electron electric dipole moment (e-EDM)experiment using slow cesium atoms, nulled magnetic fields, and electricfield quantization has been performed. With the ambient magnetic fieldsseen by the atoms reduced to less than 200 pT, an electric field of 6MV/m lifts the degeneracy between states of unequal lbar mF rbar and,along with the low (approximately 3 m/s) velocity, suppresses thesystematic effect from the motional magnetic field. The low velocity andsmall residual magnetic field have made it possible to induce transitionsbetween states and to perform state preparation, analysis, and detectionin regions free of applied static magnetic and electric fields. Thisexperiment demonstrates techniques that may be used to improve the e-EDMlimit by two orders of magnitude, but it is not in itself a sensitivee-EDM search, mostly due to limitations of the laser system.

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A dual-cathode arc plasma source was combined with acomputer-controlled bias amplifier such as to synchronize substrate biaswith the pulsed production of plasma. In this way, bias can be applied ina material-selective way. The principle has been applied to the synthesismetal-doped diamond-like carbon films, where the bias was applied andadjusted when the carbon plasma was condensing, and the substrate was atground when the metal was incorporated. In doing so, excessive sputteringby too-energetic metal ions can be avoided while the sp3/sp2 ratio can beadjusted. It is shown that the resistivity of the film can be tuned bythis species-selective bias. The principle can be extended tomultiple-material plasma sources and complex materials

Proof-of-principle gas-reservoir MnNiMg electrochromic mirror devices have been investigated. In contrast to conventional electrochromic approaches, hydrogen is stored (at low concentration) in the gas volume between glass panes of the insulated glass units (IGUs). The elimination of a solid state ion storage layer simplifies the layer stack, enhances overall transmission, and reduces cost. The cyclic switching properties were demonstrated and system durability improved with the incorporation a thin Zr barrier layer between the MnNiMg layer and the Pd catalyst. Addition of 9 percent silver to the palladium catalyst further improved system durability. About 100 full cycles have been demonstrated before devices slow considerably. Degradation of device performance appears to be related to Pd catalyst mobility, rather than delamination or metal layer oxidation issues originally presumed likely to present significant challenges.

The technical challenge for making two-beam accelerators into realizable power sources for high-energy colliders lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2&A, l-MeV, induction gun for a prototype relativistic klystron two-beam accelerator (RK-TBA). The electron source will be a 8.9 cm diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150-ns flat top (1% energy variation), and a normalized edge emittance of less than 300 pi-mm-n-n. The prototype accelerator will be used to study physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. We have also been studying optimization parameters, such as frequency, for the application of the RK-TBA concept to multi-TeV linear colliders. As an rf power source the RK-TBA scales favorably up to frequencies around 35 GHz. An overview of this work with details of the design and performance of the prototype injector, beam line, and diagnostics will be presented.

The technical challenge for making two-beam accelerators into realizable power sources lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2-kA, l-MeV, electron induction prototype injector as a collaborative effort between LBL and LLNL. The electron source will be a 3.5"-diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 120-ns flat top (1% energy variation), and a normalized edge emittance of less than 200 {pi}-mm-mr. Planned diagnostics include an isolated cathode with resistive divider for direct measurement of current emission, resistive-wall and magnetic probe current monitors for measuring beam current and centroid position, capacitive probes for measuring A-K gap voltage, an energy spectrometer, and a pepper-pot emittance diagnostic. Details of the injector, beam line, and diagnostics are presented.

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 …

A study was conducted to assess the ability of phased-array ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of these welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements. For this study, four circumferential welds in 610mm diameter, 36mm thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches range in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through wall to 64% through wall. The welds were examined with two phased-array probes, a 2.0 MHz transmit-receive longitudinal wave array and a 2.0 MHz transmit-receive shear wave array. These examinations showed that both phased-array transducers were able to detect and accurately length-size, but not depth size, all of the notches and …

Palynological results from Julietta Lake currently provide the most direct evidence to support the existence of a glacial refugium for Pinus pumila in mountains of southwestern Beringia. Both percentages and accumulation rates indicate the evergreen shrub survived until at least {approx}19,000 14C yr B.P. in the Upper Kolyma region. Percentage data suggest numbers dwindled into the late glaciation, whereas pollen accumulation rates point towards a more rapid demise shortly after {approx}19,000 14C yr B.P. Pinus pumila did not re-establish in any great numbers until {approx}8100 14C yr B.P., despite the local presence {approx}9800 14C yr B.P. of Larix dahurica, which shares similar summer temperature requirements. The postglacial thermal maximum (in Beringia {approx}11,000-9000 14C yr B.P.) provided Pinus pumila shrubs with equally harsh albeit different conditions for survival than those present during the LGM. Regional records indicate that in this time of maximum warmth Pinus pumila likely sheltered in a second, lower-elevation refugium. Paleoclimatic models and modern ecology suggest that shifts in the nature of seasonal transitions and not only seasonal extremes have played important roles in the history of Pinus pumila over the last {approx}21,000 14C yr B.P.

Staphylothermus marinus is an anaerobic, sulfur-reducing peptide fermenter of the archaeal phylum Crenarchaeota. It is the third heterotrophic, obligate sulfur reducing crenarchaeote to be sequenced and provides an opportunity for comparative analysis of the three genomes. The 1.57 Mbp genome of the hyperthermophilic crenarchaeote Staphylothermus marinus has been completely sequenced. The main energy generating pathways likely involve 2-oxoacid:ferredoxin oxidoreductases and ADP-forming acetyl-CoA synthases. S. marinus possesses several enzymes not present in other crenarchaeotes including a sodium ion-translocating decarboxylase likely to be involved in amino acid degradation. S. marinus lacks sulfur-reducing enzymes present in the other two sulfur-reducing crenarchaeotes that have been sequenced - Thermofilum pendens and Hyperthermus butylicus. Instead it has three operons similar to the mbh and mbx operons of Pyrococcus furiosus, which may play a role in sulfur reduction and/or hydrogen production. The two marine organisms, S. marinus and H. butylicus, possess more sodium-dependent transporters than T. pendens and use symporters for potassium uptake while T. pendens uses an ATP-dependent potassium transporter. T. pendens has adapted to a nutrient-rich environment while H. butylicus is adapted to a nutrient-poor environment, and S. marinus lies between these two extremes. The three heterotrophic sulfur-reducing crenarchaeotes have adapted to their habitats, terrestrial …

Existing theoretical literature suggests that defect-free, pristine carbon nanotubes (CNTs) interact weakly with many gas molecules like H{sub 2}O, CO, NH{sub 3}, H{sub 2}, and so on. The case of NH{sub 3} is particularly intriguing because this is in disagreement with experimentally observed changes in electrical conductance of CNTs upon exposure to these gases. In order to explain such discrepancy, we have carried out Density Functional Theory (DFT) investigations of the role of common atomistic defects in CNT (Stone-Wales, monovacancy, and interstitial) on the chemisorption of NH{sub 3}. Computed binding energies, charge transfer, dissociation barriers, and vibrational modes are compared with existing experimental results on electrical conductance, thermal desorption and infrared spectroscopy.

The effect of the application of a DC current on the annealing of point defects in Ni{sub 3}Ti was investigated by positron annihilation spectroscopy (PAS). An increased rate of point defect annealing is observed under the influence of a current and is attributed to a 24% decrease in the mobility activation energy. The results are interpreted in terms of the electron wind effect and the complex nature of diffusion in ordered intermetallic phases. This work represents the first direct evidence of the role of the current on the mobility of point defects in intermetallic systems.