Article on polycyclic aromatic hydrocarbon solute probes and an unusual solvent-modulated fluorescence emission behavior of 1-methylcoronene and select dimethylcoronenes in nonelectrolyte solvents.

Article on computational studies of the potential energy surface for O(³P) + H₂S and the characterization of transition states and the enthalpy of formation of HSO and HOS.

A two-dimensional time-dependent two-fluid hydrodynamic model has been used to study numerically the effect of interstellar neutrals on the size and structure of the heliosphere. The interstellar neutrals, coupled to the plasma by charge-exchange collisions, lead to a dramatic decrease in the size of the heliosphere -- 30% for the parameters studied. We find that a build up of neutral hydrogen in front of the leading edge of the heliospbere, seen in earlier models, occurs only when the flow in the interstellar medium is supersonic. When the flow is subsonic, no such hydrogen ``wall`` is seen in the simulations, suggesting that the distribution of scattered solar H Ly a light may be quite different for this case. We have also calculated the propagation of an interplanetary shock to the heliopause as a possible trigger for the 1992 Voyager 2--3 kHz radio emission event. We find that the interstellar plasma density, observed emission cut-off frequency, and heliopause location can all b made consistent once the effect of the reduction in the size of the heliosphere by the interaction with the neutrals is included.

The original version of ASCE Standard 4, ``Seismic Analysis of Safety-Related Nuclear Structures`` was published in September 1986. It is ASCE policy to update its standards on a five year interval and the Working Group on Seismic Analysis of Safety Related Nuclear Structures was reconvened to formulate the revisions. The goal in updating the standard is to make sure that it is still relevant and that it incorporates the state of the practice in seismic engineering or, in some cases, where it has been demonstrated that state-of-the-art improvements need to be made to standard practice; new improvements are included. The contents of the new standard cover the same areas as the original version, with some additions. The contents are as follows: Input - response spectra and time histories; modeling of structures; analysis of structures; soil-structure interaction; input for subsystem analysis; special structures - buried pipes and conduits, earth-retaining walls, above-ground vertical tanks, raceways, and base-isolated structures; and an appendix providing seismic probabilistic risk assessment and margin assessment.

Microearthquakes induced by hydraulic fracturing have been studied by many investigators to characterize fracture systems created by the fracturing process and to better understand the locations of energy resources in the earth`s subsurface. The pattern of the locations often contains a great deal of information about the fracture system stimulated during the hydraulic fracturing. Seismic tomography has found applications in many areas for characterizing the subsurface of the earth. It is well known that fractures in rock influence both the P and S velocities of the rock. The influence of the fractures is a function of the geometry of the fractures, the apertures and number of fractures, and the presence of fluids in the fractures. In addition, the temporal evolution of the created fracture system can be inferred from the temporal changes in seismic velocity and the pattern of microearthquake locations. Seismic tomography has been used to infer the spatial location of a fracture system in a reservoir that was created by hydraulic fracturing.

If the strange quark matter hypothesis is true, then a new class of white dwarfs can exist whose nuclear material in their deep interiors can have a density as high as the neutron drip density, a few hundred times the density in maximum-mass white dwarfs and 4 {times} 10{sup 4} the density in dwarfs of typical mass, M {approximately} 0.6M{sub {circle_dot}}. Their masses fall in the approximate range 10{sup {minus}4} to 1M{sub {circle_dot}}. They are stable against acoustical modes of vibration. A strange quark core stabilizes these stars, which otherwise would have central densities that would place them in the unstable region of the sequence between white dwarfs and neutron stars.

Microearthquake activity at the Southeast Geysers, California, geothermal field is monitored with a high-resolution digital seismic network. Hypocenters are spatially clustered in both injection and production areas, but also occur in more diffuse patterns, mostly at depths from 1 to 2.8 km. Hypocenters near the injection well DV-11 exhibit a striking correlation with movement of injectate and injectate-derived steam. Preliminary moment tensor results show promise to provide information on the differing source mechanisms resulting from fluid injection and steam extraction.

Recent flow testing of the Fenton Hill HDR reservoir has demonstrated that engineered geothermal systems can be shut-in for extended periods of d= with apparently no adverse effects. However, when this particular reservoir at Venton Hill was shut-in for 2 years in a pressurized condition, natural convection within the open-jointed reservoir region appears to have leveled out the preexisting temperature gradient so that the gradient has now approached a condition more typical of liquid-dominated hydrothermal reservoirs which air invariably almost isothermal due to natural convection. As a result of the sudden flow impedance reduction that led to an almost 50% increase in Production flow new the end of the Second Phase of the LTFR in May 1993, we were uncertain as to the state of the reservoir after being shut-in for 2 years. The flow performance observed during the current testing was found to be intermediate between that at-the end of the Second Phase of the LTFT and that following, the subsequent sudden flow increase, implying that whatever caused the sudden reduction in impedance in the first place is probably somehow associated with the cooldown of the reservoir near the injection interval, since temperature recovery at the surfaces of the …

Hot dry rock (HDR) geothermal energy technology is unique in many aspects. HDR resources are much more widely distributed than hydrothermal resources, the production temperatures of fluids extracted from fully-engineered HDR reservoirs can be selected at will, and other important characteristics of HDR reservoirs can be controlled and even deliberately varied over time. Because HDR reservoirs can be rapidly discharged and recharged, a wide variety of operating scenarios can be envisioned that are not normally feasible for hydrothermal systems. Flow testing over the past few years has shown that HDR systems can be operated in a routine, automated manner that should make them rapidly adaptable to industrial applications. An industry-led HDR project now being formulated will lead to the development and operation of a practical facility to produce and market energy from an HDR resource by the turn of the century.

The implementation of Project SAPPHIRE, the top secret mission to the Republic of Kazakhstan to recover weapons grade nuclear materials, consisted of four major elements: (1) the re-packing of fissile material from Kazakh containers into suitable US containers; (2) nondestructive analyses (NDA) to quantify the U-235 content of each container for Nuclear Criticality Safety and compliance purposes; (3) the packaging of the fissile material containers into 6M/2R drums, which are internationally approved for shipping fissile material; and (4) the shipping or transport of the recovered fissile material to the United States. This paper discusses the development and application of a passive neutron counting technique used in the NDA phase of SAPPHIRE operations to analyze uranium/beryllium (U/Be) alloys and compounds for U-235 content.

NREL has completed the initial twisted blade field tests of the ``Unsteady Aerodynamics Experiment.`` This test series continues systematic measurements of unsteady aerodynamic phenomena prevalent in stall-controlled horizontal axis wind turbines (HAWTs). The blade twist distribution optimizes power production at a single angle of attack along the span. Abrupt transitions into and out of stall are created due to rapid changes in inflow. Data from earlier experiments have been analyzed extensively to characterize the steady and unsteady response of untwisted blades. In this report, a characterization and comparison of the baseline aerodynamic performance of the twisted versus non-twisted blade sets will be presented for steady flow conditions.

At the Oak Ridge Y-12 Plant, there are numerous situations in which nuclear criticality safety must be assured and subcriticality demonstrated by some method other than the straightforward use of the double contingency principle. Some cases are cited, and the criticality safety evaluation of contaminated combustible waste collectors is considered in detail. The criticality safety evaluation for combustible collectors is based on applying one very good control to the one controllable parameter. Safety can only be defended when the contingency of excess density is limited to a credible value based on process knowledge. No reasonable single failure is found that will result in a criticality accident. The historically accepted viewpoint is that this meets double contingency, even though there are not two independent controls on the single parameter of interest.

Industrial development has led to the release of numerous hazardous materials into the environment posing a potential threat to surrounding waters. Environmental analysis of sites contaminated by several chemicals calls for continuous monitoring of multiple analytes. Monitoring can be achieved by using imaging bundles (300--400 {micro}m in diameter), containing several thousand individual optical fibers for the fabrication of sensors. Multiple sensor sites are created at the distal end of the fiber by immobilizing different analyte-specific fluorescent dyes. By coupling these imaging fibers to a charge coupled device (CCD), one has the ability to spatially and spectrally discriminate the multiple sensing sites simultaneously and hence monitor analyte concentrations.

Field measurements and modeling have shown the potential for using a Hot Dry Rock (HDR) geothermal reservoir for electric load following: either with Power-Peaking from a base-load operating condition, or for Pumped Storage of off-peak electric energy with a very significant thermal augmentation of the stored mechanical energy during periods of power production. For the base-load with power- peaking mode of operation, and HDR reservoir appears capable of producing over twice its nominal power output for short -- 2 to 4 hour -- periods of time. In this mode of operation, the reservoir normally would be produced under a high-backpressure condition with the HDR reservoir region near the production well highly inflated. Upon demand, the production backpressure would be sharply reduced, surging the production flow. The analytical tool used in these investigations has been the transient finite element model of the an HDR reservoir called GEOCRACK, which is being developed by Professor Dan Swenson and his students at Kansas State University. This discrete-element representation of a jointed rock mass has recently been validated for transient operations using the set of cyclic reservoir operating data obtained at the end of the LTFT.

Neural networks are powerful and elegant computational tools that can be used in the analysis of geophysical signals. At Lawrence Livermore National Laboratory, we have developed neural networks to solve problems in seismic discrimination, event classification, and seismic and hydrodynamic yield estimation. Other researchers have used neural networks for seismic phase identification. We are currently developing neural networks to estimate depths of seismic events using regional seismograms. In this paper different types of network architecture and representation techniques are discussed. We address the important problem of designing neural networks with good generalization capabilities. Examples of neural networks for treaty verification applications are also described.

Hot dry rock (HDR) is the most abundant geothermal resource, and is found almost everywhere at depth. The technology to extract energy from HDR for practical use has been under development at the Los Alamos National Laboratory for more than twenty years. During the 1970`s, the possibility of mining the heat from HDR by circulating water through an engineered geothermal reservoir was first demonstrated on a small scale. Between 1980 and 1986 a larger, deeper, and hotter HDR reservoir was constructed. This large reservoir was subsequently mated to a permanent surface plant. A number of flow tests of this large HDR reservoir were conducted between 1991 and 1995. The results of these tests have indicated that it should be practical to operate an HDR heat mining facility to produce power on a sustained basis. An industry-led, government cost-shared project to produce and market energy generated from HDR is currently being put in place. That project should help demonstrate that HDR reservoirs can be operated to provide energy for long periods of time at rates sufficient to be commercially viable. In the longer run, additional applications of HDR technology such as water and waste treatment, and steam generation for oil field …

Wind energy is a commercially available renewable energy source, with state-of-the-art wind plants producing electricity at about $0.05 per kWh. However, even at that production cost, wind-generated electricity is not yet fully cost-competitive with coal- or natural-gas-produced electricity for the bulk electricity market. The wind is a proven energy source; it is not resource-limited in the US, and there are no insolvable technical constraints. This paper describes current and historical technology, characterizes existing trends, and describes the research and development required to reduce the cost of wind-generated electricity to full competitiveness with fossil-fuel-generated electricity for the bulk electricity market. Potential markets are described.

The high-energy particles in the galactic cosmic rays, (GCR) can produce nuclides deep in any object exposed to them. These cosmic-ray-produced (cosmogenic) nuclides have been extensively studied during the last four decades, mainly in meteorites and lunar samples (e.g., 1,2). In extraterrestrial matter, several approaches have been used to determine the production systematics of these cosmogenic nuclides. Production rates of most cosmogenic nuclides in the Earth axe much lower, especially those nuclides made ``in situ`` in the Earth`s surface. Many of these @trial cosmogenic nuclides are only now being measured because of improved techniques, such as accelerator mass spectrometry (AMS). There have been very few determinations of the production rates of nuclides made in the Earth by cosmic rays. The work being done for terrestrial cosmogenic nuclides is following the approaches used for, studying the production of extraterrestrial nuclides.

Energy efficiency improvements in domestic refrigerator/freezers, are directly influenced by the overall thermal performance of the cabinet and doors. An advanced system for reducing heat gain is Gas-Filled Panel thermal insulation technology. Gas-Filled Panels contain a low-conductivity, inert gas at atmospheric pressure and employ a reflective baffle to suppress radiation and convection within the gas. This paper presents energy use test results for a 1993 model 500 liter top mount refrigerator/freezer operated with its original doors and with a series of alternative prototype doors. Gas-Filled Panel technology was used in two types of prototype refrigerator/freezer doors. In one design, panels were used in composite with foam in standard metal door pans; this design yielded no measurable energy savings. In the other design, special polymer door pans were fitted with panels that fill nearly all of the available insulation volume; this design yielded a 6.5% increase in energy efficiency for the entire refrigerator/freezer. The EPA Refrigerator Analysis computer program has been used to predict the change in daily energy consumption with the alternative doors. The computer model also projects a 25% energy efficiency improvement for a refrigerator/freezer that would use Gas-Filled Panel insulation throughout the cabinet as well as the doors.

Lawrence Livermore National Laboratory, as a super-user, supercomputer, and super-application site, is anticipating the future bandwidth and protocol requirements necessary to connect to other such sites as well as to connect to remote-sited control centers and experiments. In this paper the authors discuss their vision of the future of Wide Area Networking, describe the plans for a wavelength division multiplexed link connecting Livermore with the University of California at Berkeley and describe plans for a transparent, {approx} 10 Gb/s ring around San Francisco Bay.

An experimental program has been designed to examine the chemical durability of glass compositions derived from the vitrification of simulated wastewater treatment sludges. These sludges represent the majority of low-level mixed wastes currently in need of treatment by the US DOE. The major oxides in these model glasses included SiO{sub 2}, Al{sub 2}O{sub 3}, B{sub 2}O{sub 3}, Na{sub 2}O, CaO and Fe{sub 2}O{sub 3}. In addition, three minor oxides, BaO, NiO, and PbO, were added as hazardous metals. The major oxides were each varied at two levels resulting in 32 experimental glasses. The chemical durability was measured by the 7-Day Product Consistency Test (PCT). The normalized sodium release rates (NRR{sub Na}) of these glasses ranged from 0.01 to 4.99 g/m{sup 2}. The molar ratio of the glass-former to glass-modifier (F/M) was found to have the greatest effect on PCT durability. Glass-formers included SiO{sub 2}, Al{sub 2}O{sub 3}, and B{sub 2}O{sub 3}, while Na{sub 2}O, CaO, BaO, NiO, and PbO were glass-modifiers. As this ratio increased from 0.75 to 2.0, NRR{sub Na} was found to decrease between one and two orders of magnitude. Another important effect on NRR{sub Na} was the Na{sub 2}O/CaO ratio. As this ratio increased from 0.5 to …

Good illumination uniformity at the mask and wafer planes, and high wafer thoroughput in the EUVL front-end test bed facility at LLNL require graded period multilayer (ML) coatings on several of the optics. The ML deposition was accomplished using a newly developed deposition technique which avoids the use of {open_quotes}uniformity masks{close_quotes} to define the spatial dependence of the ML period variation. The capabilities of the process in providing the specified ML coatings are discussed for both EUVL condenser and imaging systems.

Tight-binding molecular dynamics (TBMD) simulations are performed (i) to evaluate the formation and binding energies of point defects and defect clusters, (ii) to compute the diffusivity of self-interstitial and vacancy in crystalline silicon, and (iii) to characterize the diffusion path and mechanism at the atomistic level. In addition, the interaction between individual defects and their clustering is investigated.

Mo/Si multilayers, were removed from superpolished zerodur and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates.