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Two-phase flow visualization and relative permeability measurement in transparent replicas of rough-walled rock fractures

Description: Understanding and quantifying multi-phase flow in fractures is important for mathematical and numerical simulation of geothermal reservoirs, nuclear waste repositories, and petroleum reservoirs. While the cubic law for single-phase flow has been well established for parallel-plate fractures theoretically and experimentally, no reliable measurements of multi-phase flow in fractures have been reported. This work reports the design and fabrication of an apparatus for visualization of two-phase flow and for measurement of gas-liquid relative permeability in realistic rough-walled rock fractures. A transparent replica of a natural rock fracture from a core specimen is fabricated by molding and casting in clear epoxy. Simultaneous flow of gas and liquid with control of capillary pressure at inlet and outlet is achieved with the Hassler ''sandwich'' design: liquid is injected to the fracture through a porous block, while gas is injected directly to the edge of the fracture through channels in the porous block. A similar arrangement maintains capillary separation of the two phases at the outlet. Pressure drops in each phase across the fracture, and capillary pressures at the inlet and outlet, are controlled by means of pumps and needle valves, and are measured by differential and absolute pressure transducers. The clear epoxy cast of the natural fracture preserves the geometry of the fracture and permits visual observation of phase distributions. The fracture aperture distribution can be estimated by filling the fracture with a dyed liquid, and making pointwise measurements of the intensity of transmitted light. A set of two-phase flow experiments has been performed which has proven the viability of the basic experimental design, while also suggesting further improvements in the apparatus. Preliminary measurements are presented for single-phase permeability to liquid, and for relative permeabilities in simultaneous flow of liquid and gas.
Date: January 1, 1991
Creator: Persoff, P.; Pruess, K. & Myer, L.
Partner: UNT Libraries Government Documents Department

Optimizing reinjection strategy at Palinpinon, Philippines based on chloride data

Description: One of the guidelines established for the safe and efficient management of the Palinpinon Geothermal Field is to adopt a production and well utilization strategy such that the rapid rate and magnitude of reinjection fluid returns leading to premature thermal breakthrough would be minimized. To help achieve this goal, sodium fluorescein and radioactive tracer tests have been conducted to determine the rate and extent of communication between the reinjection and producing sectors of the field. The first objective of this paper is to show how the results of these tests, together with information on field geometry and operating conditions were used in algorithms developed in Operations Research to allocate production and reinjection rates among the different Palinpinon wells. Due to operational and economic constraints, such tracer tests were very limited in number and scope. This prevents obtaining information on the explicit interaction between each reinjection well and the producing wells. Hence, the chloride value of the producing well, was tested to determine if use of this parameter would enable identifying fast reinjection paths among different production/reinjection well pairs. The second aim, therefore, of this paper is to show the different methods of using the chloride data of the producing wells and the injection flow rates of the reinjection wells to provide a ranking of the pair of wells and, thereby, optimize the reinjection strategy of the field.
Date: January 1, 1991
Creator: Urbino, Ma. Elena G. & Horne, Roland N.
Partner: UNT Libraries Government Documents Department

Four-Plate Pick-Up Capacitance and Sensitivity Calculations

Description: The goal of calculations presented in this note is to find and maximize the sensitivity of a quadrupole pick-up currently being designed. The calculations are made using the CERN package Poisson. The range of electrode widths under consideration is:.006m < w < .03. Studies indicate that sensitivity is maximized in this range by the smallest width plate if the electronics contributes negligible capacitance. The plate size for which the sensitivity is optimized increases with increasing electronics capacitance. As well, 6cm and 8cm outer shells of both circular and square geometry are considered. An 8cm square quadrupole pickup yields the higher sensitivity.
Date: January 1, 1991
Creator: O'Day, S.
Partner: UNT Libraries Government Documents Department

Specification for the Reattachment of the EC North Cryostat Heads

Description: This Engineering Note defines technical requirements and the scope of work for reattachment of the heads of the North EC cryostat This work is to be done in the D-Zero. Assembly Building (DAB) at Fermilab and is expected to begin around May 15, 1991. The task consists primarily of welding four heads onto a 17-foot diameter stainless steel double-wall pressure/varuum vessel. Nominal thicknesses of the welds are all 5/8-inch. Root passes are to be made by TIG welding and the balance by MIG welding. No radiography is required; other NDE per ASME Code, Section VIII, Div. 1. All work is to be done in accordance with the Rules of the National Board of Boiler and Pressure Vessel Inspectors (ANSI/NB-23), and repairs to the inner vessel are to be documented by the R-1 form exeruted by the Contractorts Authorized Inspector. The Contractor will be expected to work two shifts per day, five days per week to support the Fermilab schedule. Details of the cryostat are given on Fermi1ab Drawings 3740.220-ME-222256, Rev. R, 3740.224-ME-273071, and 3740.224-ME-273039. The cryostat was fabricated by Process Engineering, Inc. ofPlaistow, NH in 1989-90. The heads were removed using hand-held air-arc gouging equipment. As a result the welding grooves are not straight and their widths are not uniform, In some places the width may be as wide as 1-inch. For the purposes of quotation, the Contractor should assume a uniform weld groove as shown in Figure 1. The amount of weld metal to be deposited for this geometry is estimated to be 500 lbs. Upon completion, the final contract price will be determined by the following formula: Final Price = Contract Price x (lbs of weld metal deposited/500). Methods of determining the amount ofweld metal deposited will be agreed upon before award of the contract.
Date: March 20, 1991
Creator: Luther, R.
Partner: UNT Libraries Government Documents Department

Specification for the Reattachment of the EC South Cryostat Heads

Description: This Engineering Note defines technical requirements and the scope of work for reattachment of the heads of the South EC cryostat. This work is to be done in the clean room at the D-Zero Assembly Building (DAB) at Fermilab.and is expected to begin around September 15, 1991. The task consists primarily of welding four heads onto a 17-foot diameter stainless steel double-wall pressure/vacuum vessel. Nominal thicknesses of the welds are all 5/8-inch. Root passes are to be made by TIG welding and the balance by MIG welding. No radiography is required; other NDE per ASME Code, Section VIII, Div. 1. All work is to be done in accordance with the Rules of the National Board of Boiler and Pressure Vessel Inspectors (ANSI/NB-23), and repairs to the inner vessel are to be documented by the R-1 form executed by the Contractor's Authorized Inspector. The Contractor will be expected to work two shifts per day, five days per week to support the Fermilab schedule. Details of the cryostat are given on Fermilab Drawings 3740.220-ME-222256, Rev. R, 3740.224-ME-273071, and 3740.224-ME-273039. The cryostat was fabricated by Process Engineering, Inc. of Plaistow, NH in 1989-90. The heads were removed using hand-held air-arc gouging equipment. As a result the welding grooves are not straight and their widths are not uniform. In some places the width maybe as wide as 1-inch. For the purposes of quotation, the Contractor should assume a uniform weld groove as shown in Figure 1. The amount of weld metal to be deposited for this geometry is estimated to be 500 lbs. Upon completion, the final contract price will be determined by the following formula: Final Price = Contract Price x (lbs of weld metal deposited/500). Methods of determining the amount of weld metal deposited will be agreed upon before award of the ...
Date: August 1, 1991
Creator: Luther, R.
Partner: UNT Libraries Government Documents Department

A semi-experimental nodal synthesis method for the on-line reconstruction of three-dimensional neutron flux-shapes and reactivity

Description: The safety and optimal performance of large, commercial, light-water reactors require the knowledge at all time of the neutron-flux distribution in the core. In principle, this information can be obtained by solving the time-dependent neutron diffusion equations. However, this approach is complicated and very expensive. Sufficiently accurate, real-time calculations (time scale of approximately one second) are not yet possible on desktop computers, even with fast-running, nodal kinetics codes. A semi-experimental, nodal synthesis method which avoids the solution of the time-dependent, neutron diffusion equations is described. The essential idea of this method is to approximate instantaneous nodal group-fluxes by a linear combination of K, precomputed, three-dimensional, static expansion-functions. The time-dependent coefficients of the combination are found from the requirement that the reconstructed flux-distribution agree in a least-squares sense with the readings of J ({ge}K) fixed, prompt-responding neutron-detectors. Possible numerical difficulties with the least-squares solution of the ill-conditioned, J-by-K system of equations are brought under complete control by the use of a singular-value-decomposition technique. This procedure amounts to the rearrangement of the original, linear combination of K expansion functions into an equivalent more convenient, linear combination of R ({le}K) orthogonalized modes'' of decreasing magnitude. Exceedingly small modes are zeroed to eliminate any risk of roundoff-error amplification, and to assure consistency with the limited accuracy of the data. Additional modes are zeroed when it is desirable to limit the sensitivity of the results to measurement noise.
Date: December 10, 1991
Creator: Jacqmin, R. P.
Partner: UNT Libraries Government Documents Department

1991 annual report to the National Science Foundation

Description: The Geometry Center research program has a number of different aspects, most of which involve longer term commitments, such as, development of research software, teams of individuals visually exploring mathematical structures and sponsoring of workshops. The Center is built on the research programs of its faculty. These programs have flourished and interacted under the Center umbrella. There are many interconnections and commonalities between the fields represented. Here, a summary of the research work of each of the faculty members. Some of the research topics are geometric calculus of variations, group theory, geometric algorithms, and computer graphics.
Date: December 1, 1991
Partner: UNT Libraries Government Documents Department

Laboratory testing of cement grouting of fractures in welded tuff

Description: Fractures in the rock mass surrounding a repository and its shafts, access drifts, emplacement rooms and holes, and exploratory or in-situ testing holes, may provide preferential flowpaths for the flow of groundwater or air, potentially containing radionuclides. Such cracks may have to be sealed. The likelihood that extensive or at least local grouting will be required as part of repository sealing has been noted in numerous publications addressing high level waste repository closing. The objective of this work is to determine the effectiveness of fracture sealing (grouting) in welded tuff. Experimental work includes measurement of intact and fracture permeability under various normal stresses and injection pressures. Grout is injected into the fractures. The effectiveness of grouting is evaluated in terms of grout penetration and permeability reduction, compared prior to and after grouting. Analysis of the results include the effect of normal stress, injection pressure, fracture roughness, grout rheology, grout bonding, and the radial extent of grout penetration. Laboratory experiments have been performed on seventeen tuff cylinders with three types of fractures: (1) tension induced cracks, (2) natural fractures, and (3) sawcuts. Prior to grouting, the hydraulic conductivity of the intact rock and of the fractures is measured under a range of normal stresses. The surface topography of the fracture is mapped, and the results are used to determine aperture distributions across the fractures. 72 refs., 76 figs., 25 tabs.
Date: March 1, 1991
Creator: Sharpe, C. J. & Daemen, J. J.
Partner: UNT Libraries Government Documents Department

The effect of water vapor in the reactor cavity in a MHTGR (Modular High Temperature Gas Cooled Reactor) on the radiation heat transfer

Description: Analyses have been completed to determine the effect of the presence of water vapor in the reactor cavity in a modular high temperature gas cooled reactor on the predicted radiation heat transfer from the vessel wall to the reactor cavity cooling system. The analysis involves the radiation heat transfer between two parallel plates with an absorbing and emitting medium present. Because the absorption in the water vapor is spectrally dependent, the solution is difficult even for simple geometries. A computer code was written to solve the problem using the Monte Carlo method. The code was validated against closed form solutions, and shows excellent agreement. In the analysis of the reactor problem, the results show that the reduction in heat transfer, and the consequent increase in the vessel wall temperature, can be significant. This effect can be cast in terms of a reduction in the wall surface emissivities from 0.8 to 0.59. Because of the insulating effect of the water vapor, increasing the gap distance between the vessel wall and the cooling system will cause the vessel wall temperature to increase further. Care should be taken in the design of the facility to minimize the gap distance and keep temperature increase within allowable limits. 3 refs., 6 figs., 4 tabs.
Date: January 1, 1991
Creator: Cappiello, M.W.
Partner: UNT Libraries Government Documents Department

The effect of realistic antenna geometries on plasma loading predictions

Description: Plasma loading resistances for Ion Cyclotron Resonance Heating (ICRH) antennas are often calculated with sophisticated plasma models and only rudimentary antenna geometries. This paper presents techniques for modifying loading calculations for cavity antennas to account for such realities as return currents in the antenna sidewalls and backplane, the transmission and reflection properties of the Faraday shield, the end effects due to a finite length antenna, the reduction in phase velocity due to strap interaction with the Faraday shield, and the effect of slots in the cavity sidewalls and dividing septa. 4 refs., 4 figs.
Date: January 1, 1991
Creator: Ryan, P.M.; Baity, F.W.; Batchelor, D.B.; Goulding, R.H.; Hoffman, D.J. & Tolliver, J.S.
Partner: UNT Libraries Government Documents Department

Predicting permeability and electrical conductivity of sedimentary rocks from microgeometry

Description: The determination of hydrologic parameters that characterize fluid flow through rock masses on a large scale (e.g., hydraulic conductivity, capillary pressure, and relative permeability) is crucial to activities such as the planning and control of enhanced oil recovery operations, and the design of nuclear waste repositories. Hydraulic permeability and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. The cross-sectional areas and perimeters of the individual pores are estimated from two-dimensional scanning electron micrographs of rock sections. The hydraulic and electrical conductivities of the individual pores are determined from these geometrical parameters, using Darcy's law and Ohm's law. Account is taken of the fact that the cross-sections are randomly oriented with respect to the channel axes, and for possible variation of cross-sectional area along the length of the pores. The effective medium theory from solid-state physics is then used to determine an effective average conductance of each pore. Finally, the pores are assumed to be arranged on a cubic lattice, which allows the calculation of overall macroscopic values for the permeability and the electrical conductivity. Preliminary results using Berea, Boise, Massilon and Saint-Gilles sandstones show reasonably close agreement between the predicted and measured transport properties. 12 refs., 5 figs., 1 tab.
Date: February 1, 1991
Creator: Schlueter, E.M.; Cook, N.G.W. (Lawrence Berkeley Lab., CA (USA) California Univ., Berkeley, CA (USA). Dept. of Materials Science and Mineral Engineering); Zimmerman, R.W. & Witherspoon, P.A. (Lawrence Berkeley Lab., CA (USA))
Partner: UNT Libraries Government Documents Department

Sensitivity of numerical dispersion modeling to explosive source parameters

Description: The calculation of downwind concentrations from non-traditional sources, such as explosions, provides unique challenges to dispersion models. The US Department of Energy has assigned the Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) the task of estimating the impact of accidental radiological releases to the atmosphere anywhere in the world. Our experience includes responses to over 25 incidents in the past 16 years, and about 150 exercises a year. Examples of responses to explosive accidents include the 1980 Titan 2 missile fuel explosion near Damascus, Arkansas and the hydrogen gas explosion in the 1986 Chernobyl nuclear power plant accident. Based on judgment and experience, we frequently estimate the source geometry and the amount of toxic material aerosolized as well as its particle size distribution. To expedite our real-time response, we developed some automated algorithms and default assumptions about several potential sources. It is useful to know how well these algorithms perform against real-world measurements and how sensitive our dispersion model is to the potential range of input values. In this paper we present the algorithms we use to simulate explosive events, compare these methods with limited field data measurements, and analyze their sensitivity to input parameters. 14 refs., 7 figs., 2 tabs.
Date: February 13, 1991
Creator: Baskett, R.L. (EG and G Energy Measurements, Inc., Pleasanton, CA (USA)) & Cederwall, R.T. (Lawrence Livermore National Lab., CA (USA))
Partner: UNT Libraries Government Documents Department

Texture development in CU-W composites

Description: A model system of polycrystalline Cu containing continuous fibres of W has been deformed in plane strain compression so that the imposed flow occurred perpendicular to the fibre axis. A technique has been developed to grid the sample to examine the detailed distribution of strain around the fibres. In addition, texture measurements have been conducted to compare the behaviour of the composite with that of unreinforced copper of similar grain size. These observations allow the texture components which arise due to the constraints exerted by the fibres to be related to the flow pattern imposed by the fibres. 6 refs., 7 figs.
Date: January 1, 1991
Creator: Poole, W.J.; Embury, J.D. (McMaster Univ., Hamilton, ON (Canada)); Kocks, U.F. (Los Alamos National Lab., NM (USA)) & Bolmaro, R.E. (Rosario Univ. Nacional (Argentina))
Partner: UNT Libraries Government Documents Department

Downflow heat transfer in a heated ribbed vertical annulus with a cosine power profile

Description: Experiments designed to investigate downflow heat transfer in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2c series, which was a follow on series to the ECS-2b series, conducted specifically to provide additional data on the effect of different powers at the same test conditions, for use in evaluation of possible power effects on the aluminum temperature measurements. Electrical powers at 90%, 100%, and 110% of the power required to result in the maximum aluminum temperature at fluid saturation temperature were used at each set of test conditions previously used in the ECS-2b series. The ECS-2b series was conducted in the same test rig as the previous ECS-2b series. Data and experimental description for the ECS-2b series is provided in a previous report. 18 refs., 25 figs., 3 tabs.
Date: October 1, 1991
Creator: Anderson, J.L.; Condie, K.G. & Larson, T.K.
Partner: UNT Libraries Government Documents Department

Avoiding water hammer/fluid transients in nuclear piping systems by controlled filling

Description: A variety of geometries and operating procedures that lead to steam bubble collapse induced water hammers have been explored experimentally. Construction guidelines that will eliminate the problem at the design stage have been proposed and methods for predicting the pressure signatures proposed.
Date: January 1, 1991
Partner: UNT Libraries Government Documents Department

Whispering-gallery mirrors for short-wavelength laser cavities: Shapes and tolerances

Description: The whispering-gallery mirrors desired for use in short-wavelength laser cavities are seen to be highly aspheric and very different from the shapes encountered in conventional optics. Fabrication tolerance are established by examining the effects of various surface imperfections. The mirrors are found to be relatively insensitive to figures errors. The requirements on surface finish are shown to be fairly strict, though less severe than with normal-incidence optics.
Date: January 1, 1991
Creator: Braud, J.P.
Partner: UNT Libraries Government Documents Department

A semi-experimental nodal synthesis method for the on-line reconstruction of three-dimensional neutron flux-shapes and reactivity. Final report

Description: The safety and optimal performance of large, commercial, light-water reactors require the knowledge at all time of the neutron-flux distribution in the core. In principle, this information can be obtained by solving the time-dependent neutron diffusion equations. However, this approach is complicated and very expensive. Sufficiently accurate, real-time calculations (time scale of approximately one second) are not yet possible on desktop computers, even with fast-running, nodal kinetics codes. A semi-experimental, nodal synthesis method which avoids the solution of the time-dependent, neutron diffusion equations is described. The essential idea of this method is to approximate instantaneous nodal group-fluxes by a linear combination of K, precomputed, three-dimensional, static expansion-functions. The time-dependent coefficients of the combination are found from the requirement that the reconstructed flux-distribution agree in a least-squares sense with the readings of J ({ge}K) fixed, prompt-responding neutron-detectors. Possible numerical difficulties with the least-squares solution of the ill-conditioned, J-by-K system of equations are brought under complete control by the use of a singular-value-decomposition technique. This procedure amounts to the rearrangement of the original, linear combination of K expansion functions into an equivalent more convenient, linear combination of R ({le}K) orthogonalized ``modes`` of decreasing magnitude. Exceedingly small modes are zeroed to eliminate any risk of roundoff-error amplification, and to assure consistency with the limited accuracy of the data. Additional modes are zeroed when it is desirable to limit the sensitivity of the results to measurement noise.
Date: December 10, 1991
Creator: Jacqmin, R. P.
Partner: UNT Libraries Government Documents Department

Avoiding water hammer/fluid transients in nuclear piping systems by controlled filling. Final report

Description: A variety of geometries and operating procedures that lead to steam bubble collapse induced water hammers have been explored experimentally. Construction guidelines that will eliminate the problem at the design stage have been proposed and methods for predicting the pressure signatures proposed.
Date: December 31, 1991
Partner: UNT Libraries Government Documents Department

Seismic decoupling of an explosion centered in a granite chimney rubble -- scaled experiment results. Final report

Description: This report describes the small scale evaluation of the feasibility of significant decoupling by siting an explosion in granite rubble. The chimney characteristics scaled to laboratory dimensions were those of the PILE DRIVER event. The scaled charges were of 1 KT and 8KT in the PILE DRIVER chimney. The measure of the effect was the velocity field history in the granite outside the chimney volume with the chimney rubble and with no rubble. A number of chimney sizes and shapes were studied. The explosion process was modeled via two-din=mensional, finite-difference methods used for prediction of velocity histories at the Nevada Test Site. The result was that both the spectral shape and the magnitude of the transmitted shock wave were drastically altered. The chimney geometry was as important as the rubble characteristics.
Date: December 1, 1991
Creator: Keller, C.; Miller, S.; Florence, A.; Fogle, M. & Kilb, D.
Partner: UNT Libraries Government Documents Department

Whispering-gallery mirrors for short-wavelength laser cavities: Shapes and tolerances

Description: The whispering-gallery mirrors desired for use in short-wavelength laser cavities are seen to be highly aspheric and very different from the shapes encountered in conventional optics. Fabrication tolerance are established by examining the effects of various surface imperfections. The mirrors are found to be relatively insensitive to figures errors. The requirements on surface finish are shown to be fairly strict, though less severe than with normal-incidence optics.
Date: December 31, 1991
Creator: Braud, J. P.
Partner: UNT Libraries Government Documents Department