A summary of the problems (encountered as well as anticipated) associated with reinjection of heat-depleted brines and injection of other fluids such as imported brines and gases is presented. Covered are only injection and reinjection problems which are related to the exploitation of liquid-dominated resources by flash-cycle power plants. Suggestions (proven as well as probable) which may offer solutions to many of the identified problems are also covered. In addition, some ideas that should or could be implemented in planning of implementing and/or executing any new geothermal injection operation are described.

The revision of Chapter 18 of NUREG 0800, Human Factors Engineering Standard Review Plan (SRP) will be based on SECY 82-111 and guidance contained in NUREG 0700, NUREG 0801 and NUREG 0835, plus other references. In conducting field reviews of control rooms, the NRC has identified technical issues which can be used to enhance the development of the revised version of NUREG 0800, and to establish priorities among the list of possible Branch Technical Positions (BTP) in NUREG 0800, Rev. 0, Table 18.0-2. This report is a compilation of comments and suggestions from the people who used NUREG 0700 in the Control Room field reviews. This information was used to establish possible BTP topic priorities so that the most important BTPs could be issued first. The comments and suggestions are included for HFEB review in conjunction with the table of priorities.

Microearthquakes, defined as shocks having magnitudes less than 4, are commonly recorded in the vicinity of geothermal manifestations and volcanism. They have been mapped from producing geothermal fields as well as those not yet developed, in such places as Iceland, El Salvador, Japan, Kenya and the US. Microearthquakes have been recorded at several geothermal sites in the Imperial Valley and Coso Hot Springs, California; Kilbourne Hole, New Mexico; Yellowstone National Park, Wyoming; and The Geysers, California, where there is debate over whether or not the seismicity is induced by steam production. Seismicity occurs around active volcanoes, but appears reduced directly over zones of high temperature or magma, where the depth of the brittle fracture zone is shallow, as over Yellowstone caldera. In areas of active hydrothermalism, regional stress is likely to be relieved by low-level seismicity rather than occasional large ruptures, owing to the high temperatures, presence of fluids, and crustal weakening due to alteration and fracturing. Active faulting maintains the permeability of the system, which in its absence, might otherwise seal. on the microscopic scale, pore-fluid pressures rise as a result of heating, resulting in the decrease of effective pressure at the pore-mineral boundary. When this effective pressure becomes …