The performance of the 1986 three-dimensional numerical model of the Nesjavellir geothermal field for predicting the deliverabilities and pressure decline of the wells during the period 1987 through 1991 is investigated. The model predicted adequately the flow rate and enthalpy transients of most wells, but overpredicted the pressure decline by 3 to 4 bars.

The occasion of this conference, the Sixth International Conference on Accelerator Mass Spectrometry, falls sixteen years after the remarkable triple simultaneous discovery of this powerful isotopic measurement. In the interval since the Fifth Conference in Paris in 1991, new facilities of both large and small size have become fully operational, achieving impressive gains in both measurement throughput and precision. The purpose of this short review is to extrapolate from recent gains and experience and to project the status of the field beyond the coming millennial date. AMS achieved instant application in archaeology and the geosciences and its early growth was stimulated by the excitement caused by the early results. The ability to obtain an accurate radiocarbon date with a sample one thousand times smaller than possible with scintillation or gas counting, the ability to trace {sup 14}CO{sub 2} in sea water with a similar thousand fold shrinkage in sample size, and the wide utility of {sup 10}Be, {sup 26}Al, {sup 36}Cl, and {sup 129}I as tracers and chronometers of erosion, hydrology and paleoclimate were sufficient to drive the partial conversion of existing accelerators and the construction of new dedicated ones. These applications remain the core of the present field and …

An apparatus and method for oxidizing wastes in a two-stage process. The apparatus includes an oxidation device, a gas-liquid contacting column and an electrocell. In the first stage of the process, wastes are heated in the presence of air to partially oxidize the wastes. The heated wastes produce an off-gas stream containing oxidizable materials. In the second stage, the off-gas stream is cooled and flowed through the contacting column, where the off-gas stream is contacted with an aqueous acid stream containing an oxidizing agent having at least two positive valence states. At least a portion of the oxidizable materials are transferred to the acid stream and destroyed by the oxidizing agent. During oxidation, the valence of the oxidizing agent is decreased from its higher state to its lower state. The acid stream is flowed to the electrocell, where an electric current is applied to the stream to restore the oxidizing agent to its higher valence state. The regenerated acid stream is recycled to the contacting column.

Estimates of temperatures, past and present, in geothermal reservoirs can be made by using now standard mineralogical techniques, including fluid inclusion geothermometry, vitrinite reflectance, calc-silicate and clay occurrence, the extent of clay interlayering, and measuring clay crystallinity. Recent studies of clays in 60 drillcores from 6 wells at Wairakei, for example, show an inverse relationship between reservoir temperatures and crystallinities from 90&deg; to 225&deg;C (195 to 435°F) (K&uuml;bler Indices: 1.40 to 0.44 <FONT FACE="Symbol">D</FONT>&deg;2<FONT FACE="Symbol">q</FONT>). Fluid inclusion geothermometry results require careful interpretation but the method need not be calibrated with respect to the reservoir, as do other geothermometric methods.

It presents a systematic methodology to evaluate the reservoir characteristics of Chipilapa- Ahuachapan geothermal field through the highly diluted natural manifestations (springs and domestic wells) in its surroundings. The manifestations are classified in three main groups according to their mechanism of formation: high salinity water (HSW), medium salinity water (MSW), and Sulfated Water (SW). The reservoir temperature at Chipilapa geothermal field is around 220°C which is estimated with application of various chemical geothermometers. The isotopic studies indicate that the heating of local meteoric water with the separated steam of deep reservoir fluids is a dominating process in the formation of springs and domestic wells fluids. The process of formation of primary and secondary vapor explains the isotopic composition of fumaroles.

The adiabatic Born-Oppenheimer potential energy surface approximation is not valid for reaction of a wide variety of energetic materials and organic fuels; coupling between electronic states of reacting species plays a key role in determining the selectivity of the chemical reactions induced. This research program initially studies this coupling in (1) selective C-Br bond fission in 1,3- bromoiodopropane, (2) C-S:S-H bond fission branching in CH[sub 3]SH, and (3) competition between bond fission channels and H[sub 2] elimination in CH[sub 3]NH[sub 2].

The adiabatic Born-Oppenheimer potential energy surface approximation is not valid for reaction of a wide variety of energetic materials and organic fuels; coupling between electronic states of reacting species plays a key role in determining the selectivity of the chemical reactions induced. This research program initially studies this coupling in (1) selective C-Br bond fission in 1,3- bromoiodopropane, (2) C-S:S-H bond fission branching in CH{sub 3}SH, and (3) competition between bond fission channels and H{sub 2} elimination in CH{sub 3}NH{sub 2}.

Two factors which have substantial impact on predicted Mercury emissions are the air flows in the Chemical Process Cell (CPC) and the exit temperature of the Formic Acid Vent Condenser (FAVC). The discovery in the IDMS (Integrated DWPF Melter System) of H{sub 2} generation by noble metal catalyzed formic acid decomposition and the resultant required dilution air flow has increased the expected instantaneous CPC air flow by as much as a factor of four. In addition, IDMS has experienced higher than design (10{degrees}C) FAVC exit temperatures during certain portions of the operating cycle. These temperatures were subsequently attributed to the exothermic reaction of NO to NO{sub 2}. Moreover, evaluation of the DWPF FAVC indicated it was undersized and unless modified or replaced, routine exit temperatures would be in excess of design. Purges required for H{sub 2} flammability control and verification of elevated FAVC exit temperatures due to NO{sub x} reactions have lead to significant changes in CPC operating conditions. Accordingly, mercury emissions estimates have been updated based upon the new operating requirements, IDMS experience, and development of an NO{sub x}/FAVC model which predicts FAVC exit temperatures. Using very conservative assumptions and maximum purge rates, the maximum calculated Hg emissions is …

The Bulalo geothermal field, located in Laguna province, Philippines, supplies 12% of the electricity on the island of Luzon. The first 110 MWe power plant was on line May 1979; current 330 MWe (gross) installed capacity was reached in 1984. Since then, the field has operated at an average plant factor of 76%. The National Power Corporation plans to add 40 MWe base load and 40 MWe standby in 1995. A numerical simulation model for the Bulalo field has been created that matches historic pressure changes, enthalpy and steam flash trends and cumulative steam production. Gravity modeling provided independent verification of mass balances and time rate of change of liquid desaturation in the rock matrix. Gravity modeling, in conjunction with reservoir simulation provides a means of predicting matrix dry out and the time to limiting conditions for sustainable levelized steam deliverability and power generation.

Fully dense, nanocrystalline ceramic articles were prepared by the new nanofabrication process. The process consists of two steps: synthesis of ceramic nanoparticles and fabrication of dense, nanocrystalline ceramic parts. The synthesis step produced 10-nanometer-diameter crystallites, and is capable of being scaled up to kilogram/hour production rates. The fabrication step produced dense parts at significantly reduced sintering temperatures and times -- representing a factor of 10--100 reduction in process energy requirements. The process was demonstrated by producing ultrafine-grained yttria-stabilized ZrO[sub 2], an important material with a variety of energy-related applications (solid electrolytes, oxygen sensors, electrode materials, thermal barrier coatings, etc.). Results from this period clearly illustrate the capabilities of this energy-efficient and directly commercializable process for producing dense, nanocrystalline, multicomponent oxide ceramics.

Fully dense, nanocrystalline ceramic articles were prepared by the new nanofabrication process. The process consists of two steps: synthesis of ceramic nanoparticles and fabrication of dense, nanocrystalline ceramic parts. The synthesis step produced 10-nanometer-diameter crystallites, and is capable of being scaled up to kilogram/hour production rates. The fabrication step produced dense parts at significantly reduced sintering temperatures and times -- representing a factor of 10--100 reduction in process energy requirements. The process was demonstrated by producing ultrafine-grained yttria-stabilized ZrO{sub 2}, an important material with a variety of energy-related applications (solid electrolytes, oxygen sensors, electrode materials, thermal barrier coatings, etc.). Results from this period clearly illustrate the capabilities of this energy-efficient and directly commercializable process for producing dense, nanocrystalline, multicomponent oxide ceramics.

Training new users of complex machines is often an expensive and time-consuming process. This is particularly true for special purpose systems, such as those frequently encountered in DOE applications. This paper presents a computer-based training system intended as a partial solution to this problem. The system extends the basic virtual reality (VR) training paradigm by adding a multimedia component which may be accessed during interaction with the virtual environment: The 3D model used to create the virtual reality is also used as the primary navigation tool through the associated multimedia. This method exploits the natural mapping between a virtual world and the real world that it represents to provide a more intuitive way for the student to interact with all forms of information about the system.

Adsorption is potentially an important consideration when calculating reserves at The Geysers. Our investigations of the mineralogical relationships in core samples have shown matrix pore spaces to be largely associated with fractures. Dissolution of calcite from hydrothermal veins increases porosity in the graywacke reservoir. The high relative surface area of secondary alteration phases could promote adsorption. In order to quantify porosity distribution and surface area, Scanning Electron Microscope (SEM) images were analyzed using software developed for the interpretation of satellite imagery, This software classifies the images as either crystal or pore and then accumulates data on pore size, total porosity and surface area of the mineral-pore interface. Review of literature shows that data on thickness of adsorbed water layer does not exist for many of the mineral phases of interest in The Geysers. We have assumed thicknesses of 10, 100, and 5300 Angstroms for the adsorbed layer and calculated the relative proportions of adsorbed water. These calculations show 0.005%, 0.05%, and 2.5% of total water would be adsorbed using the above thicknesses.

A general empirical correlation for estimating the intrinsic dissolution rate of quartz in pure water from 25” to 625°C was presented. Data obtained from five different apparatus in this study correlated favorably to rate measurements reported by seven other research groups using both nominal and BET-determined surface area bases. More than eleven orders of magnitude of variation of dissolution rate occur over a 600°C temperature change exhibiting Arrhenius-like behavior with a global activation energy of about 97 kJ/mol SiO₂. Discrepancies in low temperature (25°C) measurements were resolved by waiting sufficiently long to permit annealing processes to produce a “steady-state” dissolving surface.

Using thermodynamic gas equilibria to calculate temperature and steam fraction in the reservoir, three main physical phenomena due to exploitation of Palinpinon field are identified. 1) Pressure drawdown producing a local increase in the computed steam fraction, with the fluid maintaining high temperature values (close to 300°C). Strong decline in flow rate is observed. 2) Irreversible steam losses from the original high temperature liquid phase during its ascent through fractures in upper zones of the reservoir. Steam is generally lost at temperatures (e.g. 240°C) lower then those of the original aquifer. 3) Dilution and cooling effects due to reinjection fluid returns. These are function of the local geostructural conditions linking through fractures the injectors and production wells. The computed fraction of the recovered reinjected brine can in some case exceed 80% of the total produced fluid. At the same time the computed gas equilibration temperatures can decline from 280-300°C to as low as 215-220°C. Comparing these values with the well bottom measured temperatures, the proposed methodology based on gas chemistry gives more reliable temperature estimate than water chemistry based geothermometers for fluids with high fractions of injected brine.

This description of work (DOW) details the field activities associated with assessing the vertical extent of groundwater contamination in the uppermost unconfined and confined aquifers beneath the southeastern portion of the 200 West area. The document serves as the test plan for those performing the work. It should be used in conjunction with the Remedial Investigation/Feasibility Study Work Plan for the 200-UP-1 Groundwater Operable Unit, Hanford Site, Richland, Washington (200-UP-1 Operable Unit Workplan) (DOE/RL 1991) for general investigation strategy and with specific procedures. Work scope for the vertical profiling activity is defined in sections 4.2 and 5.1.3 of the 200-UP-1 Operable Unit Workplan. The work is one portion of a proposed Limited Field Investigation (LFI) data collection program.

A detailed three-dimensional numerical model has been developed for the low-temperature hydrothermal system at Botn in Central North Iceland. It is based on a conceptual reservoir model which has evolved during two decades of geothermal research in the area and on the 10 year production history of the system. The model consists of (1) A powerful recharge system at depth, (2) a shallow production reservoir and (3) a cold ground-water system at the surface. About 10 million tons of hot water have been extracted from the production reservoir since late 1981. The presence of the powerful recharge system results in a very slow long-term pressure decline. Flow of water in the production reservoir appears to be controlled by a highly permeable, vertical fracture-zone confined by low-permeability rocks. Cold ground-water flows down into the fracture-zone during production causing some cooling of the extracted water.

A new type of dual-porosity model is being developed to simulate two-phase flow processes in fractured geothermal reservoirs. At this time it is assumed that the liquid phase in the matrix blocks remains immobile. By utilizing the effective compressibility of a two-phase water/steam mixture in a porous rock, flow within the matrix blocks can be modeled by a single diffusion equation. This equation in turn is replaced by a nonlinear ordinary differential equation that utilizes the mean pressure and mean saturation in the matrix blocks to calculate the rate of fluid flow between the matrix blocks and fractures. This equation has been incorporated into the numerical simulator TOUGH to serve as a source/sink term for computational gridblocks that represent the fracture system. The new method has been compared with solutions obtained using fully-discretized matrix blocks, on a problem involving a three-dimensional vapor-dominated reservoir containing an injection and a production well, and has been found to be quite accurate.

In examining methods for enhancing the biomethanation of TxL, several experiments were conducted to study the mechanisms of lowering the pH during biomethanation of Texas lignite (TxL) at higher solids loadings. Results indicated that: Treatment of TxL with different pH solutions did not influence the biomethanation process; The decrease in methane production at higher solids loadings still needs further investigations; Anaerobic conditions containing deoxygenated nitrogen:carbon dioxide provide better methanation of TxL; The most promising combination between the isolates from Mic-1 and Mic-4 was found to be combination D (KS14RMK8-1458); The KS14RMK8 shows the highest accumulation of acetate in the cell-free culture broth from this consortium.

Reported here is the progress on the Development of Biological Coal Gasification for DOE contract No. DE-AC21-90MC27226 MOD A006. Task 1, NEPA Compliance and Updated Test Plan has been completed. Progress toward Task 2, Enhanced Methane Production, is reported in the areas of bacterial strain improvement, addition of co-substrates, and low cost nutrient amendment. Conclusions reached as a result of this work are presented. Plans for future work are briefly outlined.

Single crystal silicon has been the material of choice for x-ray monochromators for the past several decades. However, the need for suitable monochromators to handle the high heat load of the next generation synchrotron x-ray beams on the one hand and the rapid and on-going advances in synthetic diamond technology on the other make a compelling case for the consideration of a diamond monochromator system. In this paper, we consider various aspects, advantages and disadvantages, and promises and pitfalls of such a system and evaluate the comparative performance of a diamond monochromator subjected to the high heat load of the most powerful x-ray beam that will become available in the next few years. The results of experiments performed to evaluate the diffraction properties of a currently available synthetic single crystal diamond are also presented. Fabrication of a diamond-based monochromator is within present technical means.

This is the seventeenth edition of the Directory of Energy Data Collection forms, an authoritative listing of selected public use forms currently used as basic energy information gathering tools by the Department of Energy (DOE). Originally entitled EIA Data Collection forms, this directory provides an overview of DOE`s energy information collection programs for decisionmakers in Government and industry.

Small scale crucible studies were performed by Schumacher to examine the effects of formate and nitrate on glass redox at high copper levels. The results of the crucible studies were used to determine the regions where copper precipitates in the glass. However, durability tests were not performed on the glass samples. Studies were performed in the 774 Research Melter using a simulated feed from the Purex 4 Campaign in the Integrated DWPF Melter System (IDMS). Three runs were performed with this simulated feed. The first used the feed as it was received to determine a baseline. The results from the second and third campaigns were compared to the baseline. The second run increased the copper concentration. The third increased the copper and formate concentrations. The purpose of these experiments was to investigate melter performance and glass durability using a feed with increased copper concentration. The Purex 4 feed did not contain the target amounts of sludge and Precipitate Hydrolysis Aqueous (PHA). Less than 20% of the feed slurry consisted of simulated sludge, making it a low waste-loading feed. The use of this feed with significantly more copper added than anticipated in the DWPF, showed no indication of copper precipitating in …

The SRTC has formally transmitted a recommendation to DWPF to replace copper formate with copper nitrate as the catalyst form during precipitate hydrolysis [1]. The SRTC was subsequently requested to formally document the technical bases for the recommendation. A memorandum was issued on August 23, 1993 detailing the activities (and responsible individuals) necessary to address the impact of this change in catalyst form on process compatibility, safety, processibility environmental impact and product glass quality [2]. One of the activities identified was the preparation of a material balance in which copper nitrate is substituted for copper formate and the identification of key comparisons between this material balance and the current Batch 1 sludge -- Late Wash material balance [3].