Waste management has reached paramount importance in recent years. The successful management of radioactive waste is a key ingredient in the successful operation of any nuclear facility. This paper discusses the options available for on-site storage of low-level radioactive waste and those options that have been selected by the Department of Energy facilities operated by Martin Marietta Energy Systems, Inc. in Oak Ridge, Tennessee. The focus of the paper is on quality assurance (QA) features of waste management activities such as accountability and retrievability of waste materials and waste packages, retrievability of data, waste containment, safety and environmental monitoring. Technical performance and careful documentation of that performance are goals which can be achieved only through the cooperation of numerous individuals from waste generating and waste managing organizations, engineering, QA, and environmental management.

Pyrotechnic ignition has been studied in the past by making a limited number of discrete temperature-time observations during ignition. Present-day infrared scanning techniques make it possible to record thermal profiles, during ignition, with high spacial and temporal resolution. Data thus obtained can be used with existing theory to characterize pyrotechnic materials and to develop more precise kinetic models of the ignition process. Ignition has been studied theoretically and experimentally using various thermal methods. It has been shown that the whole process can, ideally, be divided into two stages. In the first stage, the sample pellet behaves like an inert body heated by an external heat source. The second stage is governed by the chemical reaction in the heated volume produced during the first stage. High speed thermographic recording of the temperature distribution in the test sample during laser ignition makes it possible to calculate the heat content at any instant. Thus, one can actually observe laser heating and the onset of self-sustained combustion in the pellet.

A fusion breeder holds the promise of a new capability - ''dialable'' reserve capacity at little additional cost - that offers stockpile planners a new way to deal with today's uncertainties in forecasting long range needs. Though still in the research stage, fusion can be developed in time to meet future military requirements. Much of the necessary technology will be developed by the ongoing magnetic fusion energy program. However, a specific program to develop the nuclear technology required for materials production is needed if fusion is to become a viable option for a new production complex around the turn of the century.

While formerly studied in terms of ancient Franciscan stratigraphy, The Geysers Steam Field now offers new views and interpretations on the deeper structure and importance of the lithocap, main metagraywacke, and felsic intrusive basement units with respect to the huge fractured reservoir. The Big Sulphur Creek enhanced tectonic disruption area provides the best situation for shallow felsite injection, shallow reservoir top, metasomatism transformation, and profound fracture permeability. Steam cells commonly extend to great depths and laterally drop off sharply, with relatively flat lateral continuance in some resource areas. Injectate ponding may offer a third fluid interface for reservoir steam reserves. A possible boiled down residuum of complex evaporates and hematite has been viewed in one area of the field where the reservoir (proper) bottom was encountered. Such a deposit may exist along all reservoir cell(s) bottoms, where in numerous cases the reservoir proper has been seen to pass into a somewhat mysterious ultra-superheated reservoir.

Abstract: For equal flows of hot water wells, the electric power which can be generated increases with feed water temperature. However, high temperature wells discharge greater flows than that of lower temperature wells of similar permeability, with the result of enhanced power potential. In fact, where fluids are exploited utilizing two-stage flash, these factors combine to give a power potential which is proportional to the cube of the feed water temperature in degrees celsius. Hence a feed of 315 C would generate twice the power of that of water at 250 C for wells of good permeability and where the reservoir exists under conditions of boiling point with depth. Higher temperature water (exceeding 300 C) has, however, a commensurate higher tendency to mineral deposition in reinjection water lines and this disposes design to single-stage flash with slightly reduced power, compared with the two-stage alternative.

Presently, there are few methods available for analyzing pressure transient data from two-phase reservoirs. Methods published in the oil and gas literature (Earlougher, 1977) have been adapted for analyzing data from geothermal reservoirs, assuming a uniform initial steam saturation. However, it is well known that two-phase conditions often prevail only in parts of the reservoir, primarily in the top portion, and that vapor saturations are not uniform. Thus, there is a need to examine the pressure behavior during well tests considering more realistic conditions. Two-phase effects are important in pressure transient analysis because the mobility of two-phase mixtures can differ significantly from that of single-phase fluids. Also, the compressibility of two-phase mixtures is orders of magnitude higher than for single-phase liquid and vapor (Grant and Sorey, 1979). In this paper we perform scoping calculations on the effects of two-phase zones on well pressure transients. Three different cases are considered (Figure 1). The first is that of a fully two-phase system (e.g. Krafla, Iceland; Stefansson, 1981). This problem has been studied by various authors, including Moench and Atkinson (1977, 1978), Grant (1978), Garg (1978, 1980), Grant and Sorey (1979), and Aydelotte (1980). Some of the complexities of this type of system …

This paper presents results from a flowing pressure-temperature-spinner log run in a well drilled by GEO Operator Corporation (GEOOC) at The Geysers. Analysis and interpretation of the log data are also presented. The data indicated superheated steam with a temperature of 600 F (316 C) and an enthalpy of 1316 BTU/lbm (725 cal/gm) entered the wellbore below 8000 feet (2438 meters). This temperature and enthalpy is much higher than most Geysers steam wells which produce steam at or below 475 F (246 C) and 1240 BTU/lbm (683 CALIgm). The high temperature and enthalpy are even more puzzling since static pressure and temperature measurements conducted with Kuster type instruments six months later, indicate a ''normal'' vapor-dominated system existing at 475 F (246 C) and 500 psia (35 Kg/cm{sup 2}). Conceptual reservoir models which can explain these unusual thermodynamic conditions are presented.

After nearly 30 years of power generation, parts of the present production area at Wairakei are near the end of their economic life due to local cooling. To the west of the present production area there remains a large volume of high temperature resource whose deep liquid temperatures have not changed from those measured during the 1960's. Power generation can be maintained for many more years by producing from this high temperature resource.

An experimental study of two-phase concurrent flow of steam and water conducted (Verma et al., 1985) and a set of relative permeability curves was obtained. These curves were compared with semi-empirical results (Brooks and Corey, 1964) and experimental results obtained by other investigators (Johnson et al., 1959, and Osoba et al., 1951) for two-phase, two-component flow (oil/gas; gas/water; gas/oil). It was found that while the wetting phase relative permeabilities were in good agreement, the relative permeability for the steam phase was considerably higher than the relative permeabilities of the non-wetting phase (oil in oil/water and non-condensing gas in gas/oil or gas/water) in two-component systems (Figs. 1 and 2). This enhancement of steam relative permeability is attributed to phase transformation effects at the pore level in flow channels. There are two separate mechanisms by which phase transformation affected relative permeability CUTVBS (1) phase transformation in converging-diverging flow channels with hydrophilic walls can cause an enhancement of steam phase relative permeability; and (2) phase transformation along the interface of a stagnant phase and the phase flowing around it controls the irreducible phase saturation of the stagnant phase (Verma, 1986). A pore level model was considered to study the first mechanism. In this …

Research into the stimulation of hot dry rock (HDR) systems in crystalline rock has been underway in Cornwall, England for several years. Two deviated wells were drilled to a depth of 2100 m in 1981 with an interwell separation of 300 m. These wells were connected by massive hydraulic injections using water, but the interconnection was insufficient to permit long term circulation without excessive water losses. In 1985 a third well was drilled to a depth of 2600 m in a direction chosen from the analysis of the reservoir behavior during the previous circulation. A massive stimulation (200 l/s, 75 bbl/min) of gel was used to connect the wells and circulation was re-established in August 1985. Reservoir models have been developed from hydraulic analyses, thermal behavior, microseismic mapping, tracer dispersion and chemical modeling. The system behaves like an interconnected network of flow paths with a few dominant routes acting as flow conduits. The storage is associated with pressure dependent joint compliance, but it is isolated from the dominant flow paths. No unique physical model has yet been derived but the various techniques have been used to establish constraints on the geometry and nature of the heat transfer regions. The experiments …

Tracers can be used to monitor the movement of groundwaters and geothermal fluids and they can be used as a reference to quantify changes in fluid chemistry as a result of injection. Despite their potential importance to the geothermal operator, very few tracers are presently available and of those that are, little is known about their stability or behavior at the elevated temperatures that typify resources capable of electric power generation. During the past two years the University of Utah Research Institute has been involved in tracer research and testing, largely through the DOE Injection Research Program. The purpose of this paper is to summarize the results of these laboratory and field investigations.

A three-dimensional model of the Cerro Prieto geothermal field, Mexico, is under development. It is based on an updated version of LBL's hydrogeologic model of the field. It takes into account major faults and their effects on fluid and heat flow in the system. First, the field under natural state conditions is modeled. The results of this model match reasonably well observed pressure and temperature distributions. Then, a preliminary simulation of the early exploitation of the field is performed. The results show that the fluid in Cerro Prieto under natural state conditions moves primarily from east to west, rising along a major normal fault (Fault H). Horizontal fluid and heat flow occurs in a shallower region in the western part of the field due to the presence of permeable intergranular layers. Estimates of permeabilities in major aquifers are obtained, and the strength of the heat source feeding the hydrothermal system is determined.

A pressure transient analysis method is presented for interpreting breakthrough time between two constant rate wells. The wells are modeled as two line source wells in an infinite reservoir. The first well injects at a constant rate and the second well produces at a constant rate. We studied the effects of transient pressure conditions on breakthrough time. The first arrival of injected fluid at the production well may be significantly longer under transient condition than under steady state condition. A correlation of the deviation of the breakthrough time for transient pressure conditions from the steady state condition is presented.

The Nesjavellir geothermal system in southern Iceland is very complex from both a thermal and hydrologic point of view. There are large pressure and temperature gradients in the wellfield and zones with drastically different pressure potentials. Thus, natural fluid flow is substantial in the system and flow patterns are complex. We have developed a two-dimensional natural state model for the Nesjavellir system that matches reasonably well the observed pressure and temperature distributions. The match with field data has allowed determination of the energy recharge to the system and the permeability distribution. Fluids recharge the system at rate of 0.02 kg/s/m with an enthalpy of 1460 kJ/kg. The permeability in the main reservoir is estimated to be in the range of 1.5 to 2.0 md, which agrees well with injection test results from individual wells. Permeabilities in shallower reservoirs are about an order of magnitude higher. Most of the main reservoir is under twephase conditions, as are shallow aquifers in the southern part of the field. The model results also suggest that the low temperatures in the shallow part of the northern region of the field may be due to the young age of the system; i.e., the system is gradually …

Increased confidence in the predictive power of two-phase correlations is a vital part of wellbore deliverability and deposition studies for geothermal wells. Previously, the Orkiszewski (1967) set of correlations has been recommended by many investigators to analyze geothermal wellbore performance. In this study, we use measured flowing pressure profile data from ten geothermal wells around the world, covering a wide range of flowrate, fluid enthalpy, wellhead pressure and well depth. We compare measured and calculated pressure profiles using the Orkiszewski (1967) correlations.

A three dimensional fracture system synthesis and flow simulation has been developed to correlate drawdown characteristics measured in a geothermal well and to provide the basis for an analysis of tracer tests. A new dual permeability approach was developed which incorporates simulations at two levels to better represent a discrete fracture system within computer limitations. The first incorporates a discrete simulation of the largest fractures in the system plus distributed or representative element simulation of the smaller fractures. the second determines the representative element properties by discrete simulation of the smaller fractures. The fracture system was synthesized from acoustic televiewer data on the orientation and separation of three distinct fracture sets, together with additional data from the literature. Lognormal and exponential distributions of fracture spacing and radius were studied with the exponential distribution providing more reasonable results. Hydraulic apertures were estimated as a function of distance from the model boundary to a constant head boundary. Mean values of 6.7, 101 and 46 {micro}m were chosen as the most representative values for the three fracture sets. Recommendations are given for the additional fracture characterization needed to reduce the uncertainties in the model.

The concern about possible decline in Whakarewarewa spring activity led to the creation of the rotorua Monitoring Program and the rotorua Task Force. Both will shortly issue their final reports (Ministry of Energy 1985a,b). Under the Monitoring Program a considerable database was collected about aquifer, well and spring behavior. From this it has been concluded that exploitation has had the following effects: (1) geothermal aquifer pressures have fallen by up to 0.5 bar; geothermal aquifer pressures beneath Whakarewarewa have fallen by about 0.2 bar; and (3) geothermal flow from Whakarewarewa has been reduced by about half. The effects on the springs could be reduced by reducing withdrawal particularly near Whaka, reinjection (including the use of downhole heat exchangers), or a combination of these.

In this paper we present some basic concepts of two-phase flow and review the Orkiszewski (1967) correlations which have been suggested by various investigators to perform well for geothermal wellbore flow situations. We also present a flow regime map based on the transition criteria used by Orkiszewski (1967) and show that most geothermal wells flow under slug flow regime. We have rearranged bubble- to slug-flow transition criterion used by Orkiszewski (1967) to show that the transition depends on the dimensionless pipe diameter number in addition to dimensionless liquid and gas velocity numbers. Our aim is also to identify what research may lead to improvements in two-phase pressure drop calculations for geothermal wellbore flow.

Numerical simulation is used to define the rather special conditions under which large-scale vapor-dominated zones can evolve. Given an adequate supply of heat, a vapor-dominated zone can evolve within low-permeability barriers without changes in rock properties or boundary conditions. However, the evolution of the system is accelerated in cases involving an initially high fluid throughflow rate that decreases with time. Near-steady-state pressures within the vapor-dominated zone are shown to vary with depth to the caprock.

Downhole instruments based on a thermal perturbation principle are being developed to measure heat flow in permeable formations where convective transport of heat is important. To make heat flow measurements in these regions, the ground water velocity vector must be determined. A downhole probe has been designed to measure the local ground water velocity vector. The probe is a cylindrical heat source operated at a constant heat flux. In a convecting environment, surface temperatures on the probe are perturbed from those values of a purely conductive environment. With the aid of analytical and numerical models, these temperature differences can be related to the local velocity vector.

A wireline and mud logging program has been conducted in conjunction with redrilling operations in well EE-3 at the Fenton Hill Hot Dry Rock (HDR) site near Valles Caldera, New Mexico. The trajectory for the new bore, EE-3A, penetrated a fractured zone stimulated from adjacent well EE-2 and thereby established hydraulic communication. To test and stimulate selected zones in EE-3A inflatable open hole packers designed for high temperature service were used. Proper identification and selection of packer seats was crucial to the success of the project. The logging program successfully identified five competent packer seats in six attempts. Wireline temperature, caliper, sonic televiewer and natural gamma ray logs were used in conjunction with mud logs, drill cuttings and drilling parameter data to locate fractures, out-of-gage hole, temperature anomalies and mineralized zones which were avoided in selection of the packer seats.

Because the costs of drilling, completing, and testing a well can be extremely high, it is important to develop better tools and methods for locating high permeability zones prior to drilling, and to develop better tools and methods for identifying and characterizing major fracture zones during the drilling and well testing stages. At the recommendation of the LBL Industry Review Panel on Geothermal Reservoir Technology, we organized and convened a one-day workshop this past July to discuss various aspects of DOE's current and planned activities in fracture detection, to review the geothermal industry's near-term and long-term research needs, to determine the priority of those needs, to disseminate to industry the status of research in progress, and to discuss the possibility of future joint research between industry and DOE. In this paper we present a brief overview of the workshop from the perspective of those who participated in it and provided us with written comments to a questionnaire that was distributed.

Data collected on several occasions between 1983 and 1985 as part of a hydrologic monitoring program by the U.S. Geological Survey permit preliminary estimation of the natural variability in the discharge characteristics of hydrothermal features in Lassen Volcanic National Park and the Lassen KGRA in northern California. The total rate of discharge of high-chloride hot springs along Mill Creek and Canyon Creek in the Lassen KGRA has averaged 20.9 {+-} 1.7 L/s, based on seven measurements of the flux of chloride in these streams. Measured chloride flux does not appear to increase with streamflow during the spring-summer snowmelt period, as observed at Yellowstone and Long Valley Caldera. The corresponding fluxes of arsenic in Mill Creek and Canyon Creek decrease within distances of about 2 km downstream from the hot springs by approximately 30%, most likely due to chemical absorption on streambed sediments. Within Lassen Volcanic National Park, measurements of sulfate flux in streams draining steam-heated thermal features at Sulphur Works and Bumpass Hell have averaged 7.5 {+-} 1.0 and 4.0 {+-} 1.5 g/s, respectively. Calculated rates of steam upflow containing, dissolved H{sub 2}S to supply these sulfate fluxes are 1.8 kg/s at Sulphur Works and 1.0 kg/s at Bumpass Hell.

Los Alamos National Laboratory has conducted a number of pumping and flow-through tests at the Hot Dry rock (HDR) test site at Fenton Hill, New Mexico. These tests consisted of injecting fresh water at controlled rates up to 12 BPM (32 {ell}/s) and surface pressures up to 7,000 psi (48 MPa) into the HDR formation at depths from 10,000-13,180 feet (3050-4000 m). The formation is a naturally fractured granite at temperatures of about 250 C. The matrix porosity is < 1%and permeability is on the order of 1 nD (10 m{sup 2}). Hence most of the injected fluid is believed to move through fractures. there has been no evidence of fracture breakdown phenomena, and hence it is believed that pre-existing joints in the formation are opened by fluid injection. Water losses during pumping are significant, most likely resulting from flow into secondary fractures intersecting the main fluid conducting paths. The pressure-time response observed in these tests can be interpreted in terms of non-isothermal, fracture-dominated flow. As the fluid pressure increases from small values to those comparable to fracturing pressures, the formation response changes from linear fracture flow to the highly nonlinear situation where fracture lift off occurs. A numerical heat …