2,559 Matching Results

Search Results

Measurement of instantaneous shut-in pressure in crystalline rock

Description: A method is defined which was found useful, not only for determining the instantaneous shut-in pressure (ISIP) during fracture creation, but also for determining the pressure inside the fracture, near the exit and entrance wellbores, when a circulation of fluid through a fracture is taking place. The basic assumption of the Muskat method is that, after a short transient period, the shut-in pressure approaches an asymptotic value, Pa, in an exponential fashion, i.e., if Pa is subtracted from P at each time, t, and the result is plotted, ln (P-Pa) vs t will be a straight line. Various values of Pa are tried until the best straight line fit is found. Two Muskat analyses are shown. (MHR)
Date: January 1, 1981
Creator: Aamodt, L. & Kuriyagawa, M.
Partner: UNT Libraries Government Documents Department

Important material considerations in INTOR

Description: A number of important material-related problems were identified and analyzed during the Phase-I study for INTOR. The first wall and divertor collector plate are subjected to severe normal and off-normal conditions. A melt layer is predicted to develop in a bare stainless steel wall under plasma disruptions. Graphite tiles will not melt but they introduce other serious uncertainties into the design. The design strategy for the divertor collector plate focused on separating the surface and high heat flux problems and on utilizing a novel mechanical design concept for attaching tungsten tiles to a stainless steel (or copper) heat sink.
Date: January 1, 1981
Creator: Abdou, M.A.; Mattas, R.F. & Smith, D.L.
Partner: UNT Libraries Government Documents Department

Isotope-dilution mass spectrometry in the measurement of plutonium isotope half-lives

Description: Isotope-dilution mass spectrometry has been used at Los Alamos to measure the half-lives of /sup 239/Pu, /sup 240/Pu, and /sup 241/Pu. The latter was determined by measuring the rate of decrease of the /sup 241/Pu//sup 242/Pu ratio in an appropriate isotopic mixture over a period of several years. The half-lives of the two lighter isotopes are too long to be determined in this manner. They were determined by measuring the rate of production of the uranium daughter relative to a known added /sup 233/U spike. Experimental procedures were designed to control sources of error and to permit a detailed statistical treatment which included all known sources of error and accounted for all covariances. The uncertainties, at the 95% confidence level, associated with the measured half-lives were less than 0.4% for /sup 241/Pu and less than 0.2% for /sup 239/Pu and /sup 240/Pu.
Date: January 1, 1981
Creator: Abernathey, R.M. & Marsh, S.F.
Partner: UNT Libraries Government Documents Department

Shear rigidity of spread stearic acid monolayers on water

Description: The effect of Al/sup 3 +/, Fe/sup 3 +/, Ca/sup 2 +/, and Mg/sup 2 +/ ions and of pH on the two-dimensional shear modulus of stearic acid spread on a water substrate was determined. A large shear modulus was displayed by the films when the subphase contained Al/sup 3 +/ and Fe/sup 3 +/ ions at the self buffered pH. With Fe/sup 3 +/ dissolved in the subphase, the film displayed a viscous relaxation when strained but no residual stress was observed. No effect was observed with the Ca/sup 2 +/ or Mg/sup 2 +/. Reducing the pH value in the subphase with the trivalent ions caused the shear modulus to disappear. The observations are interpreted in terms of hydrogen bonding.
Date: January 1, 1981
Creator: Abraham, B.M.; Ketterson, J.B.; Miyano, K. & Kueny, A.
Partner: UNT Libraries Government Documents Department

Stimulated Raman scattering and four-wave mixing: steady-state plane-wave analytic solutions

Description: The equations for plane-wave steady-state propagation of n fields interacting via four wave processes in a Raman medium have been known since at least 1962. Complete analytic solutions have only been found for the process of harmonic generation. However, solutions have been obtained in the gain regime assuming zero pump depletion. Assuming all fields satisfy the phase matching condition, general analytic solutions to these equations have been found. The solutions are complete in that they describe both pump depletion and saturation. Some example problems will be studied.
Date: January 1, 1981
Creator: Ackerhalt, J.R.
Partner: UNT Libraries Government Documents Department

Self-focusing in SF/sub 6/

Description: It is shown by explicit calculation of previously published quasicontinuum model that the molecular susceptibility rapidly approaches zero as higher excited states of the molecule become populated. Hence the overtones of the ..nu../sub 3/-pumped mode are totally responsible for the self focusing effects in SF/sub 6/. The ..nu../sub 3/ ladder contribution to the susceptibility is calculated. The vibrational model is a classical triply degenerate anharmonic oscillator in the Cartesian basis with the anharmonicity parameters chosen to be consistent with the latest spectroscopic analysis of the 3..nu../sub 3/ overtone spectrum. The rotational structure is represented by a distribution of these oscillators where the distribution is chosen to correspond to the spectrum of the ..nu../sub 3/ fundamental. Good agreement is found with the 300/sup 0/ in self-focusing data of Nowak and Ham at CO/sub 2/ P(28), P(20) and P(10) in SF/sub 6/.
Date: January 1, 1981
Creator: Ackerhalt, J.R. & Galbraith, H.W.
Partner: UNT Libraries Government Documents Department

Preparation of higher-actinide burnup and cross section samples. [LMFBR]

Description: A joint research program involving the United States and the United Kingdom was instigated about four years ago for the purpose of studying burnup of higher actinides using in-core irradiation in the fast reactor at Dounreay, Scotland. Simultaneously, determination of cross sections of a wide variety of higher actinide isotopes was proposed. Coincidental neutron flux and energy spectral measurements were to be made using vanadium encapsulated dosimetry materials in the immediate region of the burnup and cross section samples. The higher actinide samples chosen for the burnup study were /sup 241/Am and /sup 244/Cm in the forms of Am/sub 2/O/sub 3/, Cm/sub 2/O/sub 3/, and Am/sub 6/ Cm(RE)/sub 7/O/sub 21/, where (RE) represents a mixture of lanthanide sesquioxides. It is the purpose of this paper to describe technology development and its application in the preparation of the fuel specimens and the cross section specimens that are being used in this cooperative program.
Date: January 1, 1981
Creator: Adair, H.L.; Kobisk, E.H.; Quinby, T.C.; Thomas, D.K. & Dailey, J.M.
Partner: UNT Libraries Government Documents Department

Improved coupling of the conduction and flow equations in TRAC. [PWR]

Description: Recent nuclear-reactor-systems modeling efforts have been directed toward the development of computer codes capable of simulating transients in short computational times. For this reason, a stability enhancing two-stem method (SETS) has been applied to the two-phase flow equations in the Transient Reactor Analysis Code (TRAC) allowing the Courant limit to be violated. Unfortunately, the coupling between the wall conduction equation and the fluid-dynamics equations is performed semi-implicitly, that is, the wall-heat transfer term, is evaluated using old-time heat-transfer coefficients and wall temperatures and new-time coolant temperatures. This coupling may lead to numerical instabilities at large time steps because of large variations in the heat-transfer coefficient in certain regimes of the boiling curve. Consequently, simply using new-time wall temperatures is not sufficient. A technique that also incorporates new-time heat-transfer coefficients must be used.
Date: January 1, 1981
Creator: Addessio, F.L.
Partner: UNT Libraries Government Documents Department

Nonequilibrium flashing model for rapid pressure transients. [PWR]

Description: A detailed, microscopic model for the nonequilibrium flashing of water is coupled to equations describing the bulk liquid state in order to calculate rapid pressure response to an induced liquid strain. The flashing model is predicated on the dynamics of a single bubble growing in an infinite liquid, and it encompasses both the inertia and conduction-limited regimes of bubble growth. The analysis is valid at high temperatures. It is not limited by the assumption of a thin thermal boundary layer for the bubble or by a prescribed boundary layer shape. The analysis can predict arbitrary pressure transients, both decompressive and recompressive. The flashing model involves the solution of a system of ordinary and partial differential equations constituting a classic moving-boundary problem. The solution is obtained numerically by the method of lines and by the use of automatic software.
Date: January 1, 1981
Creator: Aguilar, F. & Thompson, S.
Partner: UNT Libraries Government Documents Department

Geothermal Well Completions in Cerro Prieto

Description: Geothermal well completion criteria have evolved from 1964 to this date. The evolution started with the common techniques used in oil-well completion and gradually changed to accommodate the parameters directly related to the mineralogic characteristics of the geothermal fluids. While acceptable completions can now be achieved, research techniques and data collection should be improved to optimize the procedures.
Date: January 1, 1981
Creator: Aguirre, B. D & Rivera, J. M. C.
Partner: UNT Libraries Government Documents Department

Geothermal Well Maintenance and Repair in Cerro Prieto

Description: When the first well is drilled at a geothermal field, procedures for the cleaning, repair, and control of wells should be established. This aspect will be increasingly important as more wells are drilled. Equipment, tools and techniques need to be improved to achieve economic and safe results. Different systems have been developed and applied in maintenance of wells, in problems of casing incrustations, repairs, plugging, and well control. These systems should be improved, even though they have been reasonably satisfactory to date.
Date: January 1, 1981
Creator: Aguirre, B. D. & Blanco, F. V.
Partner: UNT Libraries Government Documents Department

Geothermal Drilling in Cerro Prieto

Description: To date, 71 geothermal wells have been drilled in Cerro Prieto. The activity has been divided into several stages, and, in each stage, attempts have been made to correct deficiencies that were gradually detected. Some of these problems have been solved; others, such as those pertaining to well casing, cement, and cementing jobs, have persisted. The procedures for well completion--the most important aspect for the success of a well--that were based on conventional oil well criteria have been improved to meet the conditions of the geothermal reservoir. Several technical aspects that have improved should be further optimized, even though the resolutions are considered to be reasonably satisfactory. Particular attention has been given to the development of a high-temperature drilling fluid capable of being used in drilling through lost circulation zones. Conventional oil well drilling techniques have been used except where hole-sloughing is a problem. Sulfonate lignitic mud systems have been used with good results. When temperatures exceed 300 C (572 F), it has been necessary to use an organic polymer to stabilize the mud properties.
Date: January 1, 1981
Creator: Aguirre, B. D. & Garcia, G. S.
Partner: UNT Libraries Government Documents Department

Framework for evaluating the effectiveness of nuclear-safeguards systems. [Aggregated Systems Model (ASM)]

Description: This paper describes an analytical tool for evaluating the effectiveness of safeguards that protect special nuclear material (SNM). The tool quantifies the effectiveness using several measures, including probabilities and expected times to detect and respond to malevolent attempts against the facility. These measures are computed for a spectrum of threats involving outsiders, insiders, collusion, falsification, and deceit. Overall system effectiveness is judged using performance indices aggregated over all threats. These indices can be used by designers and regulators when comparing costs and benefits of various safeguards. The framework is demonstrated with an example in which we assess vulnerabilities of a safeguards system and identify cost-effective design modifications.
Date: October 20, 1981
Creator: Al-Ayat, R.A. & Judd, B.R.
Partner: UNT Libraries Government Documents Department

Mapping of functional activity in brain with /sup 18/F-fluoro-deoxyglucose

Description: A model has been designed based on the assumptions of a steady state for glucose consumption, a first-order equilibration of the free /sup 14/C-DG pool in the tissue with the plasma level, and relative rates of phosphorylation of /sup 14/C-DG and glucose determined by their kinetic constants for hexokinase reaction. Using an operational equation based on this model, the metabolic rates of glucose are calculated in various regions of brain (utilizing brain slices and autoradiography). /sup 14/C is a beta emitter and therefore not suitable for noninvasive imaging in man. With the synthesis of /sup 18/F-2-deoxy-2-fluoro-D-glucose (/sup 18/F-DG) all of the requirements for a suitable radiopharmaceutical for the determination of local cerebral metabolism have been met. This agent behaves very similarly to /sup 14/C-DG and therefore, using the above described model and emission tomography, it has become possible to measure regional cerebral metabolism for the first time in man.
Date: January 1, 1981
Creator: Alavi, A.; Reivich, M.; Greenberg, J. & Wolf, A.
Partner: UNT Libraries Government Documents Department

Data acquisition and experiment control system for high-data-rate experiments at the National Synchrotron Light Source

Description: A data acquisition and experiment control system for experiments at the Biology Small-Angle X-ray Scattering Station at the National Synchrotron Light Source has been developed based on a multiprocessor, functionally distributed architecture. The system controls an x-ray monochromator and spectrometer and acquires data from any one of three position-sensitive x-ray detectors. The average data rate from the position-sensitive detector is approx. 10/sup 6/ events/sec. Data is stored in a one megaword histogramming memory. The experiments at this Station require that x-ray diffraction patterns be correlated with timed stimuli at the sample. Therefore, depending on which detector is in use, up to 10/sup 3/ time-correlated diffraction patterns may be held in the system memory simultaneously. The operation of the system is functionally distributed over four processors communicating via a multiport memory.
Date: November 1, 1981
Creator: Alberi, J.L. & Stubblefield, F.W.
Partner: UNT Libraries Government Documents Department

Microseismic activity observed during depressurization of an oil storage cavern in rock salt

Description: In November 1978, the Los Alamos National Laboratory installed a triaxial downhole geophone package at the Bryan Mound Strategic Petroleum Reserve, a salt dome near Freeport, Texas. Monitoring was for the purpose of detecting microseismic activity during the depressurization of one of the oil storage caverns. Seismic activity started soon after the start of depressurization, reached a peak 5 days later, and rapidly died off. Nineteen locatable microearthquakes with magnitudes between -1 and -2 were observed during and after depressurization. All but two of these events were located near the side of the oil storage cavern. Because the shear-wave spectra of these events were characterized by well-defined corner frequencies we were able to calculate the radius of the rupture surface, the seismic moment, and the stress drop from the source spectra. Estimates of the source radius vary from 15 to 100 m, stress drops range from 0.3 to 0.01 bar, and seismic moments range from 3 x 10/sup 14/ to 3 x 10/sup 15/ dyne/cm. Important conclusions from this study are that comparatively small changes in the internal pressure of oil storage caverns may be enough to cause failure in the salt near the cavern walls and that downhole microseismic surveys can locate zones near large underground excavations that are undergoing rock failure.
Date: January 1, 1981
Creator: Albright, J. & Pearson, C.
Partner: UNT Libraries Government Documents Department

Characterization of hot dry rock geothermal energy extraction systems

Description: The engineering of heat exchange systems by which geothermal heat can be efficiently extracted from hot impermeable rocks is studied. The system currently under investigation at Fenton Hill, New Mexico consists of a network of large fractures created through the hydraulic pressurization of a well penetrating hot basement rocks and subsequently intersected by a second well drilled to form a flow-thru system. Cool water pumped into the fractures through one well, once heated in the reservoir, returns to the surface through the second well, is cooled, and then recirculated. While much is known about the performance parameters of the fracture network from short-term flow tests, little is understood concerning the spatial dimensions and geometrical relationship of individual fractures comprising the network. Ultimately, the success one has in estimating the long-term performance of such a system where commercialization is an issue, and in engineering future systems with optimal performance, depends on the success in characterizing the flow-thru fracture networks. To date only nonconventional application of oil field logging techniques and acoustic emissions studies have been used in the characterization of the fracture network.
Date: January 1, 1981
Creator: Albright, J.N. & Newton, C.A.
Partner: UNT Libraries Government Documents Department

Review of characteristic methods used to solve the linear transport equation

Description: Characteristic methods used to solve the linear transport equation are reviewed. Characteristic methods are based upon the solution of the transport equation written in the form psi(s) = psi(s/sub 0/)e/sup -sigma/sub T/(s-s/sub 0/)/ + ..integral../sub s/sub 0///sup s/Q(t')e/sup -sigma/sub T/(s-t')/dt', where s is arc length along the characteristic. The methods of solution distinguish themselves in how the characteristics used for computation are selected and how the source term is approximated. Criteria upon which a production method should be based are recommended. 3 figures.
Date: January 1, 1981
Creator: Alcouffe, R.E. & Larsen, E.W.
Partner: UNT Libraries Government Documents Department

Geological and geophysical signatures of the Jemez lineament: a reactivated Precambrian structure

Description: The Jemez lineament (N52/sup 0/E) is one of several northeast-trending lineaments that traverse the southwestern United States. It is defined by a 500-km-long alignment of late Cenozoic volcanic fields extending southwest from at least the Jemez Mountains in the north-central New Mexico to the San Carlos-Peridot volcanic field in east-central Arizona. Geochronologic data from Precambrian basement rocks indicate that the lineament is approximately coincident with a boundary between Precambrian crustal provinces. Characteristics of the lineament are high heat flow (>104.5 mW/m/sup 2/), an attenuated seismic velocity zone from 25 to 140 km depth, and an upwarp of the crustal electrical conductor inferred from magnetotelluric studies. The high electrical conductivity is probably caused by the presence of interstitial magma in the rocks of the mid-to-upper crust. The average electical strike within the Precambrian basement is N60/sup 0/E, supporting a relationship between the Precambrian structural grain and the Jemez lineament. The geological and geophysical data suggest that the lineament is a structural zone that extends deep into the lithosphere and that its location was controlled by an ancient zone of weakness in the Precambrian basement. Ages of late Cenozoic volcanic rocks along the lineament show no systematic geographic progression, thus indicating that a mantle plume was not responsible for the alignment of the volcanic fields.Most of the faults, dikes, and cinder cone alignments along the lineament trend approximately N25/sup 0/E and N5/sup 0/W. These trends may represent Riedel shears formed by left-lateral transcurrent movement along the structure. Less common trends of cinder cone alignments and dikes are approximately N65/sup 0/W and N85/sup 0/W. The diversity in orientation indicates that the magnitudes of the two horizontal principal stresses within the lineament have been approximately equal for at least the last 5 m.y.
Date: January 1, 1981
Creator: Aldrich, M.J. Jr.; Ander, M.E. & Laughlin, A.W.
Partner: UNT Libraries Government Documents Department

Development of multiampere negative ion sources

Description: The Neutral Beam Development Group at BNL is developing H-/D- surface plasma sources as part of a high energy neutral beam injector. Uncooled Penning and magnetron sources have operated at a maximum beam current of 1 A (10 ms pulses, Mk III) and a maximum pulse length of 200 ms (0.3 A, Mk IV). A magnetron source with focusing grooves on the cathode and an asymmetric anode-cathode geometry operates at a power efficiency of 8 kW/A and a 6% gas efficiency. As the next step, a water cooled magnetron, designed to give a steady state beam of 1 to 2 A, has been constructed. Experiments are in progress to test a modification of the magnetron which may significantly improve its performance. By injecting a sheet of plasma, produced by a highly gas efficient hollow cathode discharge, into a magnetron type anode-cathode geometry, we anticipate a reduction of the source operating pressure by at least three orders of magnitude. Initial experiments have given indications of H/sup -/ production. The next plasma injection experiment is designed to give a steady state beam of approx. = 1 A.
Date: January 1, 1981
Creator: Alessi, J.; Hershcovitch, A.; Prelec, K. & Sluyters, T.
Partner: UNT Libraries Government Documents Department

Negative ion beam formation, transport and acceleration

Description: The BNL Neutral Beam Development Group is working on the development of negative ion based neutral beam systems, using high current density surface plasma sources of the magnetron and hollow cathode discharge (HCD) type. With the magnetron source, the plan is to transport a 2A D/sup -/ beam through a bending magnet before acceleration to 200 keV. In experiments with a pulsed magnetron, 0.4A of H/sup -/ was transported through a 90/sup 0/, n = 1, bending magnet with 80% transmission. With the lower operating pressure in the HCD source, close coupled acceleration will be applied. The MEQALAC, RFQ, and a dc accelerating scheme with periodic quadrupole focusing are considered for reaching higher energies. A preliminary experiment was performed with quadrupole beam transport and a 3.8 mA beam was transported through a series of twelve quadrupoles, with 3 mm apertures and a total length of 7.2 cm.
Date: January 1, 1981
Creator: Alessi, J.G.
Partner: UNT Libraries Government Documents Department