The article evaluates the impacts of physical, chemical and genetic interventions to improve biomass processing singly and in combination. Based on their results and literature studies, some form of non-biological augmentation will likely be necessary for the foreseeable future to achieve high total carbohydrate solubilization (TCS) for most cellulosic feedstocks. The results show that this need not necessarily involve thermochemical processing, and need not necessarily occur prior to biological conversion.

An Achilles heel for the performance of thick-section, cylindrical fiber composite flywheels is the poor interlaminar properties of the material. Methods that have been used to minimize or eliminate radial tensile stresses include prestressing concentric cylinders and mass loading. There can also be significant interlaminar shear stresses at the edges of mass-loaded flywheels and in flywheels for high-power density applications where abrupt braking results in high torque levels. To specify adequate safety factors for thick-section flywheels used in these applications, the failure envelope and fatigue behavior under combined interlaminar stresses are required. Using a hollow cylindrical specimen, which was subjected to combined axial compression and torsion, results for fatigue and failure were generated for several flywheel material systems. Interlaminar compression resulted in significant enhancements to the interlaminar shear strength and results were compared to the predictions of proposed three-dimensional composite failure models. The interlaminar shear fatigue behavior of a carbodepoxy system was also studied and compression was found to greatly enhance fatigue life. The results demonstrate that radial compression stresses can yield improvements in the interlaminar shear strength and fatigue lifetimes of composite flywheel rotors.

Radiation Shield Technologies has developed a lightweight fabric, shown in Fig. 1, with radiation shielding properties for X ray, gamma ray and beta particle emissions in the range of energies relevant to clinical and Homeland Security applications. Detailed measurements were done to measure the shielding properties of this material against the spectra of standard radionuclides and x-ray generators. The mass attenuation coefficients were calculated using LLNL cross section data, a 3-D photon transport code, elemental weight fractions and the measured density of the fabric.

Traditionally, waste management studies for fusion energy have used the Waste Disposal Rating (WDR) to evaluate if radioactive material from irradiated structures could qualify for shallow land burial. However, given the space limitations and the negative public perception of large volumes of waste, there is a growing international motivation to develop a fusion waste management system that maximizes the amount of material that can be cleared or recycled. In this work, we present an updated assessment of the waste management options for the HYLIFE-II inertial fusion energy (IFE) power plant, using the concept of Clearance Index (CI) for radioactive waste disposal. With that purpose, we have performed a detailed neutronics analysis of the HYLIFE-II design, using the TART and ACAB computer codes for neutron transport and activation, respectively. Whereas the traditional version of ACAB only provided the user with the WDR as an index for waste considerations, here we have modified the code to calculate Clearance Indexes using the current International Atomic Energy Agency (IAEA) clearance limits for radiological waste disposal. The results from the analysis are used to perform an assessment of the waste management options for the HYLIFE-II IFE design.

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This paper describes the application of four evolutionary algorithms to the identification of feature subsets for classification problems. Besides a simple GA, the paper considers three estimation of distribution algorithms (EDAs): a compact GA, an extended compact GA, and the Bayesian Optimization Algorithm. The objective is to determine if the EDAs present advantages over the simple GA in terms of accuracy or speed in this problem. The experiments used a Naive Bayes classifier and public-domain and artificial data sets. In contrast with previous studies, we did not find evidence to support or reject the use of EDAs for this problem.

Deformation experiments performed in-situ in the transmission electron microscope have led to an increased understanding of dislocation dynamics. To illustrate the capability of this technique two examples will be presented. In the first example, the processes of work hardening in Mo at room temperature will be presented. These studies have improved our understanding of dislocation mobility, dislocation generation, and dislocation-obstacle interactions. In the second example, the interaction of matrix dislocations with grain boundaries will be described. From such studies predictive criteria for slip transfer through grain boundaries have been developed.

This paper highlights the results of initial investigations conducted to support the development of an integrated treatment process to convert pyrophoric metallic uranium wastes to a non-pyrophoric waste that is acceptable for land disposal. Several dissolution systems were evaluated to determine their suitability to dissolve uranium metal and that yield a final waste form containing uranium specie(s) amenable to precipitation, stabilization, adsorption, or ion exchange. During initial studies, one gram aliquots of uranium metal or the uranium alloy U-2%Mo were treated with 5 to 60 mL of selected reagents. Treatment systems screened included acids, acid mixtures, and bases with and without addition of oxidants. Reagents used included hydrochloric, sulfuric, nitric, and phosphoric acids, sodium hypochlorite, sodium hydroxide and hydrogen peroxide. Complete dissolution of the uranium turnings was achieved with the H{sub 3}PO{sub 4}/HCI system at room temperature within minutes. The sodium hydroxide/hydrogen peroxide, and sodium hypochlorite systems achieved complete dissolution but required elevated temperatures and longer reaction times. A ranking system based on criteria, such as corrosiveness, temperature, dissolution time, off-gas type and amount, and liquid to solid ratio, was designed to determine the treatment systems that should be developed further for a full-scale process. The highest-ranking systems, nitric acid/sulfuric …

We are conducting research into the direct electrochemical conversion of reactive carbons into electricity--with experimental evidence of total efficiencies exceeding 80% of the heat of combustion of carbon. Together with technologies for extraction of reactive carbons from broad based fossil fuels, direct carbon conversion addresses the objectives of DOE's ''21st Century Fuel Cell'' with exceptionally high efficiency (>70% based on standard heat of reaction, {Delta}H{sub std}), as well as broader objectives of managing CO{sub 2} emissions. We are exploring the reactivity of a wide range of carbons derived from diverse sources, including pyrolyzed hydrocarbons, petroleum cokes, purified coals and biochars, and relating their electrochemical reactivity to nano/microstructural characteristics.

Successful development of Heavy Ion Fusion (HIF) will require scientific and technology advances in areas of targets, drivers and chambers. Design work on heavy ion targets indicates that high gain (60-130) may be possible with a -3-6 MJ driver depending on the ability to focus the beams to small spot sizes. Significant improvements have been made on key components of heavy ion drivers, including sources, injectors, insulators and ferromagnetic materials for long-pulse induction accelerator cells, solid-state pulsers, and superconducting quadrupole magnets. The leading chamber concept for HIF is the thick-liquid-wall HYLEE-II design, which uses an array of flibe jets to protect chamber structures from x-ray, debris, and neutron damage. Significant progress has been made in demonstrating the ability to create and control the types of flow needed to form the protective liquid blanket. Progress has also been made on neutron shielding for the final focus magnet arrays with predicted lifetimes now exceeding the life of the power plant. Safety analyses have been completed for the HYLEE-II design using state-of-the-art codes. Work also continues on target fabrication and injection for HE. A target injector experiment capable of > 5 Hz operation has been designed and construction will start in 2002. Methods …

As environmental restoration activities progress at the DOE`s Fernald site, and across the country, large volumes of radioactive scrap metal (RSM) are being generated. Despite the existence of ``free-release`` guidelines from DOE. The strategy of onsite decontamination and release of RSM for unrestricted use has been generally overlooked in recent years. A pilot project was completed at Fernald in which 120 tons of RSM were decontaminated onsite and released for unrestricted use. This paper compares that strategy to more traditional DOE RSM management practices. Many options exist for managing RSM. DOE orders dictate that contractors demonstrate flexibility in utilizing a combination of techniques to optimize the benefits of waste management activates. The FERMCO Recycling Department led an effort to provide their customer with an economical alternative to the traditional approach of burying contaminated metal as LLW, based on established DOE free-release guidelines.

The present calculations are applicable to any beam geometry with cylindrical symmetry, including the converging beam geometry (large entrance port with radius > or approx. = 10 cm), as well as the pencil-shaped beam (small porthole with radius approx. mm). The small porthole is clearly advantageous from the reactor vessel design point of view. While the physics of the latter mode of propagation may be more complex, analyses up to this point have not revealed any detrimental instability effects that will inhibit propagation. In fact, the large perpendicular velocity v/sub perpendicular/ that the pinched mode can accommodate provides a mechanism for the quenching of filamentary instability. Furthermore, this mode of propagation can withstand more ion scattering and is not subject to the upper bound on pressure (p < 10 torr) which is imposed on the converging beam mode.

Detailed spectral and temporal measurements of the output radiation from Xe flashlamps are reported together with their use in predicting the pumping efficiency of Nd-doped laser glass. We have made absolute spectral-intensity measurements for 0.5, 1.5, and 4.2-cm-bore flashlamps for input powers ranging from 5 to 90 kW/cm/sup 2/ and pulselengths of 600 ..mu..s. Under quasi-stationary conditions these flashlamps emit essentially identical spectra when excited at equal input power per unit-area of the bore. This behavior is characteristic of an optically-thick radiator although it is not completely clear why flashlamps should behave this way. A simple model is also described which accounts for the transient response of flashlamps by characterizing the output spectra and radiation efficiencies in terms of the radiant output power rather than the electrical input power. 23 refs., 16 figs.

Estimation of the risks of accidental radioactive releases is necessary in assessing the safety of any nuclear waste management system. The case of a radioactive waste form enclosed in a barrier system is considered. Two test calculations were carried out. (DLC)

A test facility is described which detects small opaque inclusions in large transparent components by using a commercial laser which delivers high energy pulses to the test sample at moderate frequency in a small diameter beam. The sample is automatically scanned such that each point in the volume is irradiated with ten pulses at twice the inclusion damage threshold - an amount sufficient to cause visible damage at inclusion sites. This approach permits detection of opaque inclusions in the parts per trillion and lower concentration range. The specifics of the device design and its performance are discussed in the context of automatic inclusion inspection and mapping in large laser optics.

Disk amplifier design for inertial fusion lasers has evolved with changing fusion-driver requirements from a primary emphasis on gain to a primary emphasis on efficiency. In this paper we compare Shiva and Nova amplifiers to a developmental amplifier (SSA) and show greater than a two-fold improvement in efficiency over past designs under all operating conditions. Experiments to optimize the efficiency of the SSA show that preionization of the flashlamps produces significant benefits and that the packing fraction of lamps is more important than the flashlamp reflector shape. They also show that the optimized flashlamp pulselength and reflector geometry depend on the desired stored energy in the laser medium. We have demonstrated a 7% storage efficiency at a stored fluence per disk of 0.5 J/cm/sup 2/ (stored energy density of 0.06 J/cm/sup 3/) and 4% at 2.0 J/cm/sup 2/ (0.25 J/cm/sup 3/). Comparison of SSA measurements with storage-efficiency calculations show that our flashlamp model accurately predicts the single-pass pumping of disk amplifiers. 24 refs., 22 figs.

The breeder reactor industry throughout the world has grown impressively over the last two decades. Despite the uncertainties in some national programs, breeder reactor technology is well established on a global scale. Given the magnitude of this technological undertaking, there has been surprisingly little emphasis on general breeder reactor education - either at the university or laboratory level. Many universities assume the topic too specialized for including appropriate courses in their curriculum - thus leaving students entering the breeder reactor industry to learn almost exclusively from on-the-job experience. The evaluation of four course presentations utilizing visual aids is presented.

This paper presents one-dimensional particle-fluid hybrid simulations in which the strongly collisional components of the plasma (e.g., ions and thermal electrons with nu/sub cf/..delta..t > 1) are treated as fluids and the weakly collisional components (e.g., energetic electrons with nu/sub cp/..delta..t << 1) are treated as particles. Here nu/sub cf/ denotes the fluid ion and electron collision frequencies, nu/sub cp/ is the energetic particle collision frequency and ..delta..t is the time step. Collisions between particle and fluid components are treated by a Monte-Carlo method and mass transfers between the particle and fluid electron components are governed by collision frequency thresholds. The field is computed implicitly to allow time steps with ..omega../sub p/ ..delta..t > 1 (..omega../sub p/: plasma frequency).

This article discusses the development of a high-strength molded fiber material using pulp fibers, which coudl be a good substitute for plastic and solid wood materials.

This article evaluates the phase-specific electrochemical and friction characteristics of a Zr-based mtallic glass composite, which comprised roughly of 40% by volume crystalline dendrites in an amorphous matrix.

BS>From surface effects in controlled thermonuclear fusion devices and reactors Meeting; Argonne, Illinois, USA (10 Jan 1974). The physics of plasma confinement using the magnetic mirror principle is discussed, and the unique features of the mirror reactor approach to fusion are discussed and compared to the toroidal confinement approach. (auth)

From surface effects in controlled thermonuclear fusion devices and reactors meeting; Argonne, Illinois, USA (10 Jan 1974). There are two major electrostatic direct energy converter concepts whlch will be discussed from the point of view of the surfaces. One is the Venetian blind concept and the other is the periodic electrostatic focusing concept. They are both of the direct collector type. Fluxes of D/sup +/, T/sup +/, He/sup ++/, electrons, and x-rays are given. Design consideration due to thermionic emission, secondary electron emission, and radiation cooling are discussed. A detailed discussion is devoted to breakdown physics, the voltages and electric field strengths that can be employed, and how surface deterioration may affect voltage holding due to He/sup ++/ bombardment blistering. (auth)

This article reanalyzes experimental solubility data reported in the recent paper "Solubility and solution thermodynamics of cetilistat in water and (acetone, isopropyl alcohol, acetonitrile) binary solvent mixtures" in the Journal of Molecular Liquids.

This article discusses the study of two interfaces– {112}β1/{1100}Mg and {111}β1/{1120}Mg– that are commensurate with β1/hcp-Mg orientation relationship via first principles calculations.