We have carefully evaluated several processes that might be suitable for uranium recovery from thorium metal, and have chosen two that hold great promise. Both are simple non-aqueous methods that can readily be performed by remote means, and both require only a few simple process steps.

A brief history of the discovery of hypernuclei is given and some recent hypernuclei studies are described. Topics include the study of p-shell hypernuclei, /sup 12/C (K/sup -/, ..pi../sup -/) experiment, and hypernuclear gamma rays. 13 references. (WHK)

Materials preparation techniques are listed. Materials preparation capabilities are discussed for making BeF/sub 2/ glasses and other materials. Materials characterization techniques are listed. (DLC)

Multi-megawatt neutral-beam sources have successfully made the transition from prototype to commercial production, with some operational improvements due to the commercialization. Long pulse source operation results will be available soon.

In this report, the authors describe the development of a chemical equilibrium model for hydrothermal waters based on the semiempirical equations of aqueous electrolyte solutions recently introduced by Pitzer and co-workers. Accurate solubility predictions (usually within 5-10% of experimental results) can be made for ionic strengths 0-20m. Comparison with experimental data indicates that a theory parameterized by binary and ternary data can be used to accurately predict solubilities in much more complex mixtures. Mineral solubilities calculated with this model are compared with those calculated from other currently available models. Whereas the predictions are typically within 5%, the ion pairing models are substantially in error at low ionic strengths. Recent results parameterizing the H{sub 2}S and SiO{sub 2} systems will be presented.

A study was conducted to determine the current requirements for cathodic protection of geothermal wells. Oil well technology was applied in this study. Results of laboratory tests and field tests are presented. Attenuation calculations indicate that the cathodic protection current determined from field tests would protect the specific individual geothermal well.

The applicability of cathodic protection to mitigate corrosion of carbon steel in two different environments containing H{sub 2}S has been investigated using impressed current and sacrificial anode techniques. Results of impressed current tests conducted under potential control shows that the weight loss can be reduced significantly by shifting the potential of the metal 60 to 80 mV cathodic to the open circuit potential. The relationship between the applied current and the potential shift shows that the current requirement does not necessarily increase with the voltage shift, thus implying that the cost of cathodic protection may not increase in proportion to the protection achieved. The feasibility of using zinc as a sacrificial anode in the environment of interest has also been studied.

A consolidated reference of materials for downhole equipment used in geothermal energy exploitation is nearing completion. The reference is a summary of recent developments in the areas of tubular goods materials, highly alloyed metals, high temperature cements, high temperature elastomers, drilling and completion tools, logging tools, and downwell pumps. A brief overview is presented in this paper.

The most important difference between traditional steam systems and those that utilize geothermal fluids is the potential for corrosion of metals. The recently developed sourcebook ''Materials Selection Guidelines for Geothermal Energy Utilization Systems'' is expected to facilitate corrosion engineering decision making and reduce the cost of geothermal systems where new resources are similar to those presented by the corrosivity classification system.

Polymer concrete is a composite material which has strength and durability characteristics greatly superior to those of portland cement concrete and better durability in hot brine than steel. polymer concrete has been successfully tested in brine and steam at temperatures up to 260 C. Exposures were as long as 960 days. Glass filament wound polymer concrete pipe was developed with excellent strength, low weight, and a cost comparable to or less than schedule 40 steel. Connections can be made with slip joints for low pressure applications and flanged joints for high pressure applications.

This paper addresses how designers can take into account, the necessary chemical and materials precautions that other geothermal power plants have learned. Current worldwide geothermal power plant capacity is presented as well as a comparison of steam composition from seven different geothermal resources throughout the world. The similarities of corrosion impacts to areas of the power plants are discussed and include the turbines, gas extraction system, heat rejection system, electrical/electronic systems, and structures. Materials problems and solutions in these corrosion impact areas are identified and discussed. A geothermal power plant design team organization is identified and the efficacy of a new corrosion/materials engineering position is proposed.

The exploitation of geothermal resources often requires that naturally heated subterranean brines be pumped to the surface from depths of up to 6000 feet underground while minimizing heat losses and maintaining sufficient fluid pressure to prevent boiling. To accomplish this requires the use of downhole brine pumps capable of months of uninterrupted operation. Significant problems have occurred with pump lineshaft bearings in the geothermal wells. The objective of this research program was to determine the nature of the problems associated with commonly reported premature failures of downhole lineshaft pump bearings. Using the information gathered, a series of bearing endurance tests was performed on a variety of candidate bearing materials. These tests were accomplished using test rigs specially developed to simulate actual geothermal field conditions and to isolate specific bearing wear problems.

The durability of each of 16 different cements was evaluated by both room temperature compressive strength and water permeability measurements, following various periods of treatment of the cements in flowing geothermal fluid of the Cerro Prieto field of Mexico. Some of these cements were selected through a Department of Energy program to develop improved cements for geothermal well completion while the others were contributed by several other institutions interested in the tests. Two types of specimens of the cements were used in the tests: (a) 50 mm cubes which were precured 1 da in molds under water in an autoclave at 200 C and 20 MPa and (b) cement slurries which were prepared and cast in sandstone cups at the field. Federal de Electricidad a set of both types of specimens was installed in baskets which were placed 700 m downhole a well at 214 C, and an identical set of specimens was installed in special aboveground vessels near the wellhead. Following periods of 1 da. 3 mo, 6 mo. and 12 mo, specimens were withdrawn from the geothermal treatment and divided evenly between the Instituto de Investigaciones Electricas and the National Bureau of Standards for property measurements. This paper …

For the last two decades the rubber division of BJ-Hughes, has been in the forefront of rubber technology as applied to products for the oil-well drilling industry. We welcomed the opportunities presented when we were selected to participate in the GEM program and extend our appreciation to L'Garde Inc., Department of Energy and Radian Corporation. Our first efforts, approximately 15 months ago were to duplicate the four compounds recommended by L'Garde and verify our ability to obtain equal physical properties. After some minor problems in obtaining exact duplication of the chemicals. we did succeed in matching the properties obtained by L'Garde. Aflas, a copolymer of teflon and propylene manufactured in Japan by Asahi Glass and represented by Xenox. Inc., is the basis elastomer for GEM formulation 291. Advantages of Aflas are high temperature resistance up to 550 F. (Short term), resistance to H{sub 2}S and amine environment, acids, basis, many solvents and hydrocarbons. It also has excellent resistance to steam and will not hydrolize when exposed to high temperature and high pressure steam. It has excellent physical properties including long term compression-set resistance at high temperature. We have submitted two products manufactured from GEM 297 to customers for evaluation. One …

A technology transfer was made from L'Garde to Precision Rubber Products for the fabrication of L'Garde geothermal seal compound Y267. Precision Rubber reports their experience as fabricators and gives field reports from three of their customers. Most of the experience has been very successful.

The authors must have accurate knowledge of the geothermal fluid chemistry at operating temperature if they are to optimize operation, prevent corrosion, increase equipment service life and maximize profit and use. Available electrochemical sensors do not survive at the temperatures encountered in geothermal fluids; and new developments in this area are required. In order to fill this gap in technology, the Pacific Northwest Laboratory (PNL) is developing chemical control and monitoring instruments for measuring in situ characteristics of geothermal fluids. Progress in the development of electrochemical sensors to measure pH, carbonate and sulfide-sulfur is discussed.

High performance elastomers were developed for hostile geothermal environments which clearly advance the state-of-the-art. The Y267 EPDM compound is eminently successful and has accumulated broad laboratory and field test experience. Over 15 separate tests are reviewed with about 95% performed independently by other organizations. The tests include a broad spectrum of environments with temperatures in excess of 320 C (608 F), differential pressures up to 138 MPa (20,000 psi) and in fluids including brine, oils, isobutane, and others.

In response to the need for tapping national energy resources, an improved high temperature sealing material has been developed through the sponsorship of the Department of Energy. Parker Seal was selected as one of the technology transferees from L'Garde Inc. and has optimized this transferred technology for further improved performance capabilities and acceptable plant processing. This paper summarizes Parker Seal's testing and evaluation efforts on L'Garde's Y267 transferred technology for a new geothermal and stream service material. This new product, Parker's E962-85 is described in this paper.

The results of an investigation conducted to determine the corrosion characteristics of a number of alloys in a high saline environment are discussed. The ferritic stainless steels and several copper/nickel alloys exhibited good corrosion resistance in these high saline geothermal environments.

This document describes the changes that have been made to the EMIS Program and its associated Data Bases. Derivation of PWR and BWR availability data is also discussed. (DLC)

The Magma Binary Cycle Plant at the East Mesa KGRA is the first geothermal generating plant of its kind in the US. In cooperation with the Magma Electric Company, the Pacific Northwest Laboratory conducted a DOE sponsored program at the plant to document the chemistry and materials performance during the first two years of operation. This paper describes the methods used, the instruments and the results.

Geothermal brines at 600 F which contain metallic salts, H{sub 2}S, and hydrocarbons quickly degrade conventional hydrocarbon elastomers, and hydrolyse crosslinks. Carbon-carbon and carbon-fluorine bonds are expected to be superior, but no such elastomer is now commercially available. We have prepared crosslinked, perfluorocarbon elastomers by radiation crosslinking VDFHFP and TFEP (alternating) copolymers in film and sheet form, and then converting C-H bonds to C-F bonds with elemental Fluorine gas. EPLM elastomers became brittle on fluorination. The best products exceeded 100 days survival at 300 C in simulated geothermal brine. Tensile, elongation, solvent swelling, and TCA methods were used to study the products.

An extensive compatibility test program was conducted starting with 34 compounds and six 190 C fluids. Both immersion tests and simulation tests were conducted for time periods ranging from 46 hours to over six months. Deficiencies in both types of tests were determined. Immersion tests, while useful for reducing the number of candidate compounds, can easily lead to incorrect conclusions. it is essential that simulation tests be conducted before a final elastomer is selected for use in a critical design.

A specific polymer concrete formulation was applied as a steel pipe liner in response to a need for durable, economical materials for use in contact with high temperature geothermal brine. Compressive strengths of up to 165.8 MPa and splitting tensile strengths of 23.5 MPa were measured at ambient temperature. Compressive strengths of 24 MPa and splitting tensile strengths of 2.5 MPa were measured at about 150 C. Cost of piping a geothermal plant with PC and PC-lined steel pipe is calculated to be $1.21 million, which compares favorably with a similar plant piped with alloy steel piping at a cost of $1.33 million. Life-cycle cost analysis indicates that the cost of PC-lined steel pipe would be 82% of that of carbon steel pipe over a 20-year plant operating life.