During the summer of 1985, we replaced the WNR T-shaped target/moderator scheme with the LANSCE split-target/flux-trap-moderator design. The intent of this 'LANSCE upgrade' was to increase (to 12) the number of neutron beam lines serviced simultaneously, and to enhance the target area shielding and target system to accept 200 ..mu..A of 800-MeV protons. The four LANSCE moderators consist of three (chilled) water moderators, and a liquid hydrogen (20 K) moderator. The LANSCE target is machinable tungsten.

A single-pass continuous-flow leach test of PNL 76-68 glass beads (7 mm dia) was concluded after 420 days of uninterrupted operation. Variables included in the experimental matrix were flow-rate, leachant composition, and temperature. Analysis was conducted on all leachate samples for /sup 237/Np and /sup 239/Pu as well as a number of nonradioactive elements. Results indicated that flow-rate and leachant systematically affected the leach rate, but only slightly. Temperature effects were significant. Plutonium leach rate was lower at higher temperature suggesting that Pu sorption onto the beads was enhanced at the higher temperature. The range of leach rates for all analyzed elements (except Pu), at both temperature, at all three flow rates, and with all three leachant compositions varied only three orders of magnitude. The range of variables used in this experiment covered those expected in many proposed repository environments. The preliminary interpretation of the results also indicated that matrix dissolution may be the dominant leaching mechanism, at least for Np in bicarbonate leachant. Regardless of the leaching mechanism the importance of this study is that it bounds the effects of repository environments when the ground water is oxidizing and when it doesn't reach the waste form until the waste …

The time variation in the magnetic field of a model Tevatron dipole magnet at constant excitation current has been studied. Variations in symmetry allowed harmonic components over long time ranges show a log t behavior indicative of ''flux creep.'' Both short time range and long time range behavior depend in a detailed way on the excitation history. Similar effects are seen in the remnant fields present in full-scale Tevatron dipoles following current ramping. Both magnitudes and time dependences are observed to depend on details for the ramps, such as ramp rate, flattop duration, and number of ramps. In a few magnets, variations are also seen in symmetry unallowed harmonics. 9 refs., 10 figs.

For heavy-ion fusion energy applications, Mark and Yu have derived hydrodynamic models for numerical simulation of energetic pinched-beams including self-pinches and external-current pinches. These pinched-beams are applicable to beam propagation in fusion chambers and to the US High Temperature Experiment. The closure of the Mark-Yu model is obtained with adiabatic assumptions mathematically analogous to those of Chew, Goldberger, and Low for MHD. Features of this hydrodynamic beam model are compared with a kinetic treatment.

The performance of the Intense Pulsed Neutron Source (IPNS) Accelerator System is reported, including an increase in average beam current to 13.4 microamperes and increased reliability to 93.2%. Brief discussions are given for the performance of the major accelerator subsystems, including the H/sup -/ ion source and preaccelerator, the 50 MeV linac, and the synchrotron and its subsystems. (LEW)

Recently revised estimates of target gain have added additional optimistic inputs to the interface between targets, accelerators and fusion chamber beam transport. But it remains valid that neutralization of the beams in the fusion chamber is useful if ion charge state Z > 1 or if > 1 kA per beamlet is to be propagated. Some engineering and economic considerations favor higher currents.

Methods used to obtain the evaluated prompt fisson neutron spectrum N(E) and the average prompt neutron multiplicity anti ..nu../sub p/ are reviewed. The relative influence of experimental data; interpolated, extrapolated, and fitted experimental data; systematics; and nuclear theory are considered for the cases where (a) abundant experimental data exist, (b) some experimental data exist, and (c) no experimental data exist. The Maxwellian and Watt distributions, and the determination of the parameters of these distributions by data fitting, are described and compared to recent new theoretical work on the calculation of N(E). Similarly, various expressions for anti ..gamma../sub p/ that have been obtained by data fitting and systematics are described and compared to recent new theoretical work. Complications in the evaluation of N(E) and anti ..gamma../sub p/ due to the onset of multiple-chance fission and the interrelationships between N(E), anti ..gamma delta../sub p/ and the multiple-chance fission cross section are discussed using the example of the fission of /sup 235/U. Some statistics and comments are given on the evaluations of N(E) and anti ..gamma../sub p/ contained in ENDF/B-V, and a number of concluding recommendations are made for future evaluation work.

Meager Creek is perhaps the most intensely explored geothermal system occurring in the Cascade and Garibaldi Volcanic Belts. This paper describes the results of new lithologic, petrographic, X-ray, isotopic, and geochemical investigations of core and cuttings from the Meager Creek wells. The data demonstrate that alteration related to the present geothermal system is superimposed on basement rocks which were metamorphosed and intruded by dioritic stocks prior to the onset of volcanism. The geothermal alteration developed mainly after emplacement of hypabyssal dikes associated with Meager Mountain volcanism and is characterized by mineral assemblages consisting primarily of sheet silicates, quartz, carbonate, hematite, iron oxides, pyrite, and minor epidote, potassium feldspar, actinolite and biotite. Permeabilities within the upper portions of the reservoir are low, reflecting filling of the fracture systems by carbonate. Petrographic observations suggest that sealing of the fractures accompanied hydrothermal brecciation and boiling of the fluids.

Thermal 15 was drilled in November, 1983, to a TD of 700 feet. A steam entry encountered at 490 feet was found to communicate with the high-permeability upflow zone of the Thermal Shallow Reservoir. A low-flow-rate, higher-pressure steam entry at 600 feet was not detected while drilling but was indicated during a subsequent spinner survey. The pressure, flowrate, and enthalpy of the five wells completed in the upflow zone, including the Thermal 4 blowout, were monitored and recorded over a four month period before, during and after Thermal 15 was drilled. It was found that the Thermal 4 blowout communicates with the upflow zone of the Thermal Shallow Reservoir, the Thermal 4 flowrate is controlled by the shallow reservoir pressure, and the high permeability of the upflow zone allows such strong interference effects that three of the four commercial production wells will maximize production from this reservoir. A simple model was developed which describes the pressure-production characteristics of the reservoir over the normal range of operating conditions.

The Hawaii Geothermal Project (HGP-A) well, located in the Kilauea volcano east rift zone, was drilled to a depth of 6450 feet in 1976. It is considered to be one of the hot-test producing geothermal wells in the world. This single well provides 52,800 pounds per hour of 371 F and 160 pounds per square inch-absolute (psia) steam to a 3-megawatt power plant, while the separated brine is discharged in percolating ponds. About 50,000 pounds per hour of 368 F and 155 psia brine is discharged. Geothermal energy development has increased steadily in Hawaii since the completion of HGP-A in 1976: (1) a 3 megawatt power plant at HGP-A was completed and has been operating since 1981; (2) Hawaiian Electric Company (HECO) has requested that their next increment in power production be from geothermal steam; (3) three development consortia are actively, or in the process of, drilling geothermal exploration wells on the Big Island; and (4) engineering work on the development of a 400 megawatt undersea cable for energy transmission is continuing, with exploratory discussions being initiated on other alternatives such as hydrogen. The purpose for establishing the Puna Geothermal Research Facility (PGRF) is multifold. PGRF provides a facility in …

In bringing you up to date on DOE's geothermal R and D programs, they are going to emphasize first those elements that may be of special interest to a reservoir engineering audience, because the activities in support of an improved understanding of hydrothermal reservoirs deserve attention. Reservoir definition, brine injection, and reservoir stimulation technologies are major elements of the Hydrothermal Research Program, and in total they account for nearly 50% of the fiscal year (FY) 1985 hydrothermal research budget. These elements fall into the essential R and D category; that is, while some basic technologies have been borrowed from the petroleum industry for geothermal service, they are often ill-suited to geothermal requirements, and cannot be used without significant technological innovations. Into this category fall the current reservoir technology, brine injection, and reservoir stimulation projects that are listed in Table 1. The reservoir technology projects include: (1) development of methods for characterizing and mapping reservoir parameters, processes, and spatial dimensions; (2) development of methods to predict and monitor reservoir changes from fluid extraction; (3) evaluation of existing methods and development of new methods for predicting the location and mapping faults and fractures in geothermal reservoirs; and (4) testing of new analysis …

Extensive study of the Cerro Prieto geothermal field has provided much geologic and thermodynamic data of its structurally-complex, liquid-dominated reservoir. Several of the studies investigated the resource characteristics of fluid and energy flow. An early report by Mercado (1975) showed that the heat source for the part of the reservoir under development, now called Cerro Prieto I (CPI), originated in the eastern part of the field. Subsequent studies confirmed the flow of hot water from the east. A summary of several experimental and numerical studies of fluid and energy transport in the field was given by Lippmann and Bodvarsson (1983). The hydrogeologic model of Halfman et al. (1982) shows hot-water flow from the east divided into a shallow (alpha) aquifer at about 120Om and a deeper (beta) aquifer at about 170Om depth. A cross section along an east-west direction shows a central upflow to the two aquifers and uncertain geology beyond the western border of the field near well M-9. It also shows a fault dividing the line of border wells at M-29 from the inner wells at M-25 to the east. The hydrogeology of the field was described by Sanchez and de la Pena (1981) as an alluvial unit …

A large body of field data from Larderello shows striking temporal correlations between decline of well flow-rate, produced gas/steam ratio, chloride concentration and produced vapor fraction. The latter is inferred from measured concentrations of non-condensible gases in samples of well fluid, using chemical phase equilibrium principles. Observed temporal changes in the vapor fractions can be interpreted in term of a ''multiple source'' model, as suggested by D'Amore and Truesdell (1979). This provides clues to the dynamics of reservoir depletion, and to the evaluation of well productivity and longevity.

The large Thermal Landslide overlies the initial area of geothermal development at The Geysers. The landslide is waterbearing while the underlying Franciscan formation bedrock units are essentially non-waterbearing except where affected by hydrothermal alteration. Perched ground water moving through the landslide is heated prior to discharge as spring flow.

The boundaries of reservoir fluid convection cells are discreet and intricate zones, commonly sealed or reduced in permeabilities, which are often quite readily identifiable in many hydrothermal systems. Cell boundaries in the Geysers Steam Field are more vague; however, they are gradually being revealed by cumulative and extensive wellbore data. A profound example of a type of boundary has been revealed by drilling in one area of the steam field. A proposed model utilizes a sericitic alteration scheme to establish cell self-sealing. Mineralogical, permeability, and temperature properties all coincide so as to allow formation of a boundary model. This reinforces previously held views that the reservoir cell rock and hydrothermal system are greatly out of equilibrium. Such similar phenomena are suggested from drilling experiences in other parts of the steam field. Considerably, more work is required to better define and comprehend the nature and location of reservoir cell boundaries within the Geysers Steam Field.

The Nesjavellir High Temperature Geothermal Field is located in the Northern part of the Hengill Geothermal Area, which has been estimated to be one of the largest geothermal areas in iceland. Drilling started at Nesjavellir some 20 years ago with five wells. In 1982 a renewed exploration phase began and five additional wells have been drilled during the last three years. The pressure distribution within the geothermal system is very inhomogeneous in both horizontal and vertical directions. Variations in temperature are also considerable. The highest pressure and temperature is found in the southwestern part of the investigated area and both pressure and temperature decreases towards northeast. There seem to be four different zones of pressure potential in the system, which require the existence of both horizontal and vertical barriers in the system. Some parts of the geothermal system are in two-phase condition whereas other parts are in single phase liquid condition. The chemical composition of the fluid seem to be relatively uniform and a common origin of the fluid is assumed. The transmissivity of wells is in the range (1,3-3,5) 10{sup -8} m{sup 3}/Pa {center_dot} s whereas the flowing enthalpy ranges from 1200-2100 kJ/kg. The thermal output of wells are …

One of the major concerns of electric utilities in installing geothermal power plants is not only the longevity of the steam supply, but also the potential for changes in thermodynamic properties of the resource that might reduce the conversion efficiency of the design plant equipment. Production was initiated at Los Azufres geothermal field with wellhead generators not only to obtain electric energy at a relatively early date, but also to acquire needed information about the resource so that plans for large central power plants could be finalized. Commercial electric energy production started at Los Azufres during the summer of 1982 with five 5-MWe wellhead turbine-generator units. The wells associated with these units had undergone extensive testing and have since been essentially in constant production. The Los Azufres geothermal reservoir is a complex structural and thermodynamic system, intersected by at least 4 major parallel faults and producing geothermal fluids from almost all water to all steam. The five wellhead generators are associated with wells of about 30%, 60%, and 100% steam fraction. A study to compile existing data on the chemical and reservoir conditions during the first two years of operation has been completed. Data have been compiled on mean values …

The FRACSL flow and transport code is under development as part of an effort to improve reservoir characterization techniques. The present version simulates a two-dimensional, isothermal reservoir composed of a global fracture network imbedded in a porous media. FRACSL simulates the hydraulic response of a reservoir to injection or backflow. The code simulates the movement of injected tracers within the reservoir by adding advective and random dispersive motions of discrete particles. FRACSL has been benchmarked against theoretical flow and transport responses in simple systems. It has been used to simulate a benchscale physical model and to correlate flow and dispersion data from the East Mesa Hydrothermal Injection Test Program. Correlation of East Mesa data has provided an estimate of an anisotropic hydraulic conductivity, a natural drift in the reservoir, and dispersivity.

An extensive study of the Thermal Shallow Reservoir at The Geysers was performed in 1982 to improve our understanding of the source and flow patterns of steam in the shallow anomaly and how they relate to the Thermal 4 blowout. This project included gathering and analyzing pressure transient, enthalpy, tracer and chemical data and developing a reservoir model that was consistent with this data. Following the pressure transient testing and analysis, a convection-plume with lateral-flow model was proposed. Subsequent analysis of enthalpy, tracer and chemical data corroborated this model. The high flowrate wells--Thermal 4, Thermal 10, Thermal 11 and Magma 1--produce from the high-pressure, high-permeability upflow zone. The source of this upflow is a limited fracture system connecting the shallow anomaly with the underlying main reservoir. The outlying low-pressure, low-permeability wells are supplied by lateral flow of steam from the central area. The pressure gradient from the core to the periphery is caused by condensation in the flanks.

There have been two major high-temperature geothermal field developments in Iceland in the last decade; Krafla in the north-east, and Svartsengi in the south-west. These and other geothermal developments have recently been reported by Palmason et al. The Krafla field will not be discussed here, but details about the field are available in Stefansson and the power plant in Eliasson et al. Several reservoir engineering studies of the Krafla field have been published. The Svartsengi field is one of several fields on the Reykjanes Peninsula in south-west Iceland. About 15 km west of Svartsengi, on the tip of the Peninsula, the Reykjanes field is now under development, primarily for seawater chemicals production. The recently drilled Eldvorp field is located in line between these two fields, about 5 km west of Svartsengi. There are also several fields to the east of Svartsengi, at 15-20 km distance. The Svartsengi, Eldvorp, and Reykjanes fields exist in the same tectonic-volcanic environment, and are surrounded by similar geohydrological conditions, as discussed by Georgsson; see also Gudmundsson et al. and Franzson. Optimum development of these and other fields on the Reykjanes Peninsula, requires an understanding of their depletion behavior with time; that is, how the reservoir …

This paper presents the combined approaches of reservoir geology and engineering to a geothermal field where geological characteristics are highly complex and heterogeneous.Especially,the concrete approaches are discussed for the case of geothermal reservoir performance studies with a developed numerical model, by showing example cases accompanied with reinjection of produced disposal hot water into underground in an object geothermal reservoir. This combined approach will be a great help in solving complicated problems encountered during the development of a geothermal field.

A break in electrical power generation from the Krafla geothermal plant was planned from beginning of May to early September 1984. Early in June most of the production wells were shutin and their pressure recovery monitored. A regular monitoring of the pressure buildup was carried out on a well to well basis until mid-August, when the wells were put back into production except for wells 12 and 16. They were used to monitor the pressure drawdown due to the start of production. This was abruptly brought to an end by a nearby volcanic eruption in early September. The pressure buildup in the two-phase geothermal reservoir at Krafla is described and the first results presented. The results are compared with parameters determined on the completion of the wells and with predictions from numerical simulations of the reservoir. Finally the status of the Krafla geothermal system is discussed with regard to the comparison.

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A published method for calculating excess steam is modified in order to make it applicable to the case of a well producing fluid with a high non-condensable gas content. The method is applied to data from a number of wells from Los Azufres. The results show the expected linear relation between excess steam and the molar fraction of CO{sub 2} in the total discharge. The modified method also provides an estimate for the molar fraction of CO{sub 2} in the liquid phase of the reservoir. It is found that this concentration is relatively homogeneous in the southern section of the field, and seems to be slightly smaller in the deeper zones of the northern section. The calculated values of excess steam agree qualitatively, but not quantitatively, with values of steam quality in the undisturbed reservoir calculated by other authors. The calculation of excess steam tends to overestimate steam quality in cases where steam saturation in the reservoir is low, and has the opposite tendency when the steam quality in the reservoir is high. The first type of deviation is explained in terms of the effects of higher mobility of steam in the two-phase zone induced by pressure drawdown. The second …