Geology, exploration, and initial developments of significant geothermal areas of the world are summarized in this report which is divided into two parts. Part 1 is a review of the geological and explorational aspects of geothermal energy development; areas of potential development in the Western United States are also discussed. The most favorable geological environment for exploration and development of geothermal steam is characterized by recent normal faulting, volcanism, and high heat flow. Successful exploration for steam consists of coordinated multidisciplinary application of geological, geophysical, and geochemical knowledge and techniques. These are reviewed. California leads in known geothermal reserves and is followed by Nevada, Oregon, and New Mexico. Specific prospective areas in these 11 Western States are described.

Experimental studies designed to fabricate NERVA graphite fuel elements capable of cyclic operations at exit gas temperatures of approximately 4400/degree/R were continued during this report period. Carbon precursor materials, manufacturing parameters, and deposition of carbide films are included in these studies. Accomplishments include the following: three commercial powders were extruded into elements having a desirable coefficient of thermal expansion; molded graphites using low-fired filler carbons and uncured short organic fibers produced graphites having an improved strain-to-failure value; thick-walled tubes of vapor-deposited zirconium carbide were produced, and the chemical composition was determined; vapor-deposited zirconium carbide coatings were applied to fuel-element bores; experimental graphite fuel elements were hot-gas tested; uranium-loaded ion exchange beads survived a heat treatment cycle of 2800/degree/C for three hours. Organic precursor carbon studies were oriented toward modification of the CAI polymers. 2 refs., 66 figs., 23 tabs.

This report documents technical progress at the Santa Barbara Division and the Las Vegas Division. Topics reported on from Santa Barbara include: ecology studies at NTS, passive neutron detection techniques, Henre spectrum modifier, exposure rate conversion studies, delineation of cosmic ray effects, development of isotope contouring techniques, initial radiation studies, detector array response calculations, and arms data analysis compendium. The Las Vegas Division reports on: radiation propagation and free field experiments, Henre, bio-med studies support, IR scanner interpretation techniques, arms support, and pertinent projects relative to DBM programs.

Progress of research in nuclear excitation and reaction mechanisms is reported for the period 1 November 1971 to 31 October 1972. (SDF)

The advent of very high power, high energy pulsed laser systems has stimulated considerable thinking regarding how such systems might be used to engender thermonuclear microexplosions, and, in particular, explosions which may produce more energy than the inputted laser energy or even more energy than that used to pump the laser. Some of the basic physical principles and processes constraining laser-CTR proposals will be discussed, and application of them made to establish basic levels of feasibility of these published types of CTR schemes. It is demonstrated that this class of thermonuclear microexplosions has no potential CTR utility with lasers likely to be available in the next few years.

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This thesis describes the design, selection and scale model test results of a contour design for a convectively-cooled, ground test nozzle extension which originates at an area ratio of 5:1 (termination point of main nozzle).

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Research on nuclear excitations and reaction mechanisms is summarized. A list of publications is included. (JFP)

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