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Stress control of seismicity patterns observed during hydraulic fracturing experiments at the Fenton Hill hot dry rock geothermal energy site, New Mexico

Description: Seismicity accompanying hydraulic injections into granitic rock is often diffuse rather than falling along a single plane. This diffuse zone of seismicity cannot be attributed to systematic errors in locations of the events. It has often been asserted that seismicity occurs along preexisting joints in the rock that are favorably aligned with the stress field so that slip can occur along them when effective stress is reduced by increasing pore fluid pressure. A new scheme for determining orientations and locations of planes along which the microearthquakes occurred was recently developed. The basic assumption of the method, called the three point method, is that many of the events fall along well defined planes; these planes are often difficult to identify visually in the data because planes of many orientations are present. The method has been applied to four hydraulic fracturing experiments conducted at Fenton Hill as part of a hot dry rock geothermal energy project. While multiple planes are found for each experiment; one plane is common to all experiments. The ratio of shear to normal stress along planes of all orientations is calculated using a best estimate of the current stress state at Fenton Hill. The plane common to all experiments has the highest ratio of shear to normal stress acting along it, so it is the plane most likely to slip. The other planes found by the three point method all have orientations with respect to current principal stresses that are favorable for slip to occur along preexisting planes of weakness. These results are consistent with the assertion that the rock contains pre-existing joints which slip when the effective stress is reduced by the increased pore fluid pressure accompanying the hydraulic injection. Microearthquakes occur along those planes that are favorably aligned with respect to the current stress field.
Date: April 13, 1987
Creator: Fehler, M.C.
Partner: UNT Libraries Government Documents Department

Personnel neutron dosimetry using CR-39 foils

Description: We are using CR-39 foils for personnel nuetron dosimetry at the Lawrence Livermore National Laboratory. We have developed a three-step electrochemical etching procedure that includes low-frequency electrochemical etching at low frequency and at elevated temperatures. Our first etching step is at 60 Hz, 3000 V for 5 hours in a 60/sup 0/C oven using 6.5 N KOH. The second etching step consists of an additional 23-minute etch at 60/sup 0/C, 2.0 kHz, and 3000 V, which increases the track size and makes them relatively uniform in size. The final step is a 15-minute post etch at 60/sup 0/C, which gives the tracks a smoother appearance. The foils are etched in etch chambers that can etch up to 24 foils. Several of these chambers can be used simultaneously with a single power supply. These chambers are rugged and have been used daily for over a year. 8 refs., 6 figs., 1 tab.
Date: January 13, 1987
Creator: Hankins, D.E.; Homann, S. & Westermark, J.
Partner: UNT Libraries Government Documents Department

Dynamics of heavy ion beams during longitudinal compression

Description: Heavy ion beams with initially uniform line charge density can be compressed longitudinally by an order of magnitude in such a way that the compressed beam has uniform line charge density and velocity-tilt profiles. There are no envelope mismatch oscillations during compression. Although the transverse temperature varies along the beam and also varies with time, no substantial longitudinal and transverse emittance growth has been observed. Scaling laws for beam radius and transport system parameters are given.
Date: March 13, 1987
Creator: Ho, D.D.M.; Bangerter, R.O.; Lee, E.P.; Brandon, S. & Mark, J.W.K.
Partner: UNT Libraries Government Documents Department

Microwave instabilities in Booster and AGS

Description: Microwave instabilities is evaluated for the Booster and AGS for the preparation of the relativistic heavy ion collider. We found that the Booster may require feedback system for the transverse instability at the high intensity proton operation. The coherent instability is not important for the nominal RhIC operational intensity.
Date: March 13, 1987
Creator: Lee, S.Y. & Zhao, X.F.
Partner: UNT Libraries Government Documents Department

Ovecoming matrix organization problems in R and D

Description: This paper describes ORNL's management of its fusion energy program. Guidelines for effective management are given. (JDH)
Date: May 13, 1987
Creator: Morgan, O.B.
Partner: UNT Libraries Government Documents Department

An overview of copper-laser development for isotope separation

Description: We have developed a copper-laser pumped dye-laser system that addresses all of the requirements for atomic vapor laser isotope separation. The requirement for high average power for the laser system has led to the development of copper-laser chains with injection-locked oscillators and multihundred-watt amplifiers. By continuously operating the Laser Demonstration Facility, we gain valuable data for further upgrade and optimization.
Date: March 13, 1987
Creator: Warner, B.E.
Partner: UNT Libraries Government Documents Department