The Ninth Underground Coal Gasification Symposium was held August 7 to 10, 1983 at the Indian Lakes Resort and Conference Center in Bloomingdale, Illinois. Over one-hundred attendees from industry, academia, National Laboratories, State Government, and the US Government participated in the exchange of ideas, results and future research plans. Representatives from six countries including France, Belgium, United Kingdom, The Netherlands, West Germany, and Brazil also participated by presenting papers. Fifty papers were presented and discussed in four formal sessions and two informal poster sessions. The presentations described current and future field testing plans, interpretation of field test data, environmental research, laboratory studies, modeling, and economics. All papers were processed for inclusion in the Energy Data Base.

The attendance at the Workshop was similar to last year's with 123 registered participants of which 22 represented 8 foreign countries. A record number of technical papers (about 60) were submitted for presentation at the Workshop. The Program Committee, therefore, decided to have several parallel sessions to accommodate most of the papers. This format proved unpopular and will not be repeated. Many of the participants felt that the Workshop lost some of its unique qualities by having parallel sessions. The Workshop has always been held near the middle of December during examination week at Stanford. This timing was reviewed in an open discussion at the Workshop. The Program Committee subsequently decided to move the Workshop to January. The Tenth Workshop will be held on January 22-24, 1985. The theme of the Workshop this year was ''field developments worldwide''. The Program Committee addressed this theme by encouraging participants to submit field development papers, and by inviting several international authorities to give presentations at the Workshop. Field developments in at least twelve countries were reported: China, El Salvador, France, Greece, Iceland, Italy, Japan, Kenya, Mexico, New Zealand, the Philippines, and the United States. There were 58 technical presentations at the Workshop, of …

A tracer test was carried out in a geothermal doublet system to study the injection behavior of a developed reservoir known to be fractured. The doublet produces about 320 gpm of 160 F water that is used for space heating and then injected; the wells are spaced 250 ft apart. Tracer breakthrough was observed in 2 hours and 45 minutes in the production well, indicating fracture flow. However, the tracer concentrations were low and indicated porous media flow; the tracers mixed with a reservoir volume much larger than a fracture.

We present an analytic theory of Richtmyer-Meshkov instabilities in an arbitrary number N of stratified fluids subjected to a shock. Following our earlier work on Rayleigh-Taylor instabilities, the theory assumes incompressible flow in which a shock is treated an impulsive acceleration, g = ..delta.. v delta(tau/sub s), ..delta..v being the jump velocity induced in the system by a shock at time tau/sub s/. We discuss the special cases N = 2 and N = 3, and illustrate both Rayleigh-Taylor and Richtmyer-Meshkov instabilities by examples patterned after inertial confinement fusion implosions.

The meeting consisted of the following six sessions: (1) plenary session I; (2) disposal technology; (3) characteristics and treatment of low-level waste; (4) environmental aspects and performance prediction; (5) overall summary sessions; and (6) plenary session II. Fifty two papers of the papers presented were processed for inclusion in the Energy Data Base. (ATT)