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Near-field mass transfer in geologic disposal systems: A review

Description: A primary purpose of performance assessment of geologic repositories for radioactive waste is to predict the extent to which radioactive species are released from the waste solids and are transported through geologic media to the environment. Reliable quantitative predictions must be made of rates of release of radionuclides from the waste into the rock, transport through the geologic media, cumulative release to the accessible environment, and maximum concentrations in ground water and surface water. Here we review theoretical approaches to making the predictions of near-field release from buried waste solids, which provide the source terms for far-field release. The extent to which approaches and issues depend on the rock media and on regulatory criteria is discussed. 53 refs., 2 figs.
Date: November 1, 1987
Creator: Pigford, T.H. & Chambre, P.L.
Partner: UNT Libraries Government Documents Department

Critical parameters and measurement methods for post closure monitoring: A review of the state of the art and recommendations for further studies

Description: Both NRC and EPA regulations require programs of post closure monitoring to detect substantial and detrimental deviations from expected performance. The unexpected in this case would involve anomalous stress changes that might rupture the canisters or changes in the hydrologic regime that might accelerate corrosion. In the event of leakage brought about by any means transport of radionuclides to the accessible environment could occur through unexpected changes in the hydrologic flow regime caused either by the long term effects of the thermal loading by the waste or by changes in regional stress or hydrology. Studies of performance confirmation have identified six parameters or conditions that should be monitored that are associated with the thermal, mechanical and hydrologic phenomena introduced by the waste heat: temperature, stress, displacement, pore pressure, groundwater velocity and permeability. Since it is the thermal load that continues to increase after decommissioning, and which continues to alter the stress field and the hydrological regime, these same six parameters remain the critical ones in post closure monitoring. At two of the repository sites fractures have been clearly shown to be critical in modelling and performance confirmation; at the tuff site fluid saturation is also a critical parameter and for all the sites estimates of the groundwater velocity through the site are very important. Changes in fracture properties, saturation and fluid flow are thus of continuing importance in post closure monitoring. 14 refs., 19 figs.
Date: May 1, 1987
Creator: Morrison, H.F.; Majer, E.L. & Tsang, C.F.
Partner: UNT Libraries Government Documents Department

Report of the Task Force on Collision Hall Limitations

Description: The Task Force on Collision Hall Limitations met March 23--26, 1987, to obtain a greater understanding of the civil construction requirements for a large scale model SSC detector and to identify limitations, if any, on overall detector scale and individual detector components that may result from civil construction limitations. To this purpose the Task Force studied civil construction techniques and limitations for both deep sites and surface or near surface sites, developed limits and criteria for model detector assembly and servicing, developed a model detector assembly scenario, and estimated an overall schedule from initiation of the design of the experimental hall complex to the completion of the assembly of the model detector. Our conclusions apply only to facilities required to house experiments of the scale of the model detector studied. From our studies it is apparent that the experimental hall complex required for SSC-scale detectors can be constructed under a variety of assumptions regarding the eventual SSC site. There may be significant differences in the schedule and the cost of the experimental hall complex between surface and deep underground locations, with the deep underground, in general, being more expensive and requiring a longer time for construction. The difference in cost and schedule for the experimental facilities for housing the model detector between a surface site and a deep underground site may amount to $25M and two years.
Date: April 1, 1987
Partner: UNT Libraries Government Documents Department

SSC environmental radiation shielding

Description: The environmental radiation shielding requirements of the SSC have been evaluated using currently available computational tools that incorporate the well known processes of energy loss and degradation of high energy particles into Monte Carlo computer codes. These tools permit determination of isodose contours in the matter surrounding a source point and therefore the specification of minimum thicknesses or extents of shielding in order to assure annual dose equivalents less than some specified design amount. For the general public the annual dose equivalent specified in the design is 10 millirem, small compared to the dose from naturally occurring radiation. The types of radiation fall into two classes for the purposes of shielding determinations-hadrons and muons. The sources of radiation at the SSC of concern for the surrounding environment are the interaction regions, the specially designed beam dumps into which the beams are dumped from time to time, and beam clean-up regions where stops remove the beam halo in order to reduce experimental backgrounds. A final, unlikely source of radiation considered is the accidental loss of the full beam at some point around the ring. Conservative choices of a luminosity of 10{sup 34} cm{sup {minus}2}s{sup {minus}1} and a beam current three times design have been made in calculating the required shielding and boundaries of the facility. In addition to determination of minimum distances for the annual dose equivalents, the question of possible radioactivity produced in nearby wells or in municipal water supplies is addressed. The designed shielding distances and beam dumps are such that the induced radioactivity in ground water is safely smaller than the levels permitted by EPA and international agencies.
Date: July 1, 1987
Creator: Jackson, J.D.
Partner: UNT Libraries Government Documents Department

Workshop on radiological aspects of SSC operations

Description: Integral to the design of an accelerator facility is the provision of adequate shielding to contain any radiation arising from operation of the facility. Complementary to the questions of environmental shielding are a number of radiation questions related to operation of the completed facility. One obvious need is the specification of systems for monitoring environmental emissions to ensure consistency between the design criteria and the actual levels during operation. Another question is the effect on the components of the machine of the radiation within the environmental shield. These questions were examined at the workshop. This report is a summary of the materials presented at the workshop.
Date: May 1, 1987
Creator: Toohig, T. E.
Partner: UNT Libraries Government Documents Department

DEVELOPMENT TESTING OF THE U.S. COMMON LONG PULSE SOURCE AT 120KV

Description: The U.S. magnetic fusion energy program has developed a single design long pulse neutral beam source for TFTR, MFTF-B, and DIII-D. The arc is a very compact axial magnetic line cusp. The accelerator is an actively cooled tetrode with water cooled grid tubes of shaped molybdenum forming 'slot' beamlets. DIII-D and MFTF-B configurations have an 80 kV accelerator gap, with 12 x 48 cm aperture, and a 10 meter 'module' focus. TFTR modules are unfocused, with a 120 kV gap and 12 x 43 cm mask. The first CLPS was tested in the TFTR configuration, at 120 kV, 2 seconds. Optimum current was 73 Amperes, or 1.76 ppervs (deuterium), with 80% - 85% atomic fraction. Optimum divergence of ions plus neutrals was 0.4' parallel to the slots, and 0.7' perpendicular to the slots ( l / e half angle). The combination of an axial cusp magnetic bucket and slot accelerator apertures gives the CLPS about twice the beam power per unit cross section of other long pulse sources, plus lower divergence in the direction parallel to the slots.
Date: December 1, 1987
Creator: Vella, M. C.; Cooper, W. S. & Pincosy, P. A.
Partner: UNT Libraries Government Documents Department

EVIDENCE FOR COMET STORMS IN METEORITE AGES

Description: Clustering of cosmic-ray exposure ages of H chondritic meteorites occurs at 7 {+-} 3 and 30 {+-} 6 Myr ago. There is independent evidence that comet storms have occurred at the same times, based on the fossil record of family and genus extinctions, impact craters and glass, and geomagnetic reversals. We suggest that H chondrites were formed by the impact of shower comets on asteroids. The duration of the most recent comet shower was {le} 4 Myr, in agreement with storm theory.
Date: October 1, 1987
Creator: Perlmutter, S. & Muller, R.A.
Partner: UNT Libraries Government Documents Department

ZAP AND ITS APPLICATION TO THE OPTIMIZATION OF SYNCHROTRON LIGHT SOURCE PARAMETERS

Description: A new computer code, ZAP, has been written to study the influence of various collective effects on the performance of electron storage rings. In particular, the code can evaluate the equilibrium emittance of a ring including the effects of intrabeam scattering. Examples are presented of utilizing the code to optimize the design of storage rings for the purposes of a third-generation synchrotron radiation source and a high-gain free-electron laser. In addition, the importance of the intrabeam scattering emittance blowup to the issue of low energy injection is discussed. Such considerations will be necessary to optimize the design of compact synchrotrons now being studied for use in x-ray lithography. To verify predictions of the code, comparisons are made with experimental measurements of low energy beam emittance taken from the Aladdin storage ring; reasonable agreement is obtained.
Date: October 1, 1987
Creator: Zisman, M.S.
Partner: UNT Libraries Government Documents Department

On Fluid and Heat Transfer in Deep Zones of Vapor-Dominated Geothermal Reservoirs

Description: We have presented a preliminary analysis of permeability structure and fluid and heat flow conditions in the deeper horizons of the Larderello geothermal system. Our main observations and findings are: (1) Measurements in deep Larderello wells have indicated formation temperatures near 300 ยบ C at 3000 m depth, and even higher temperatures at greater depth. (2) From an analysis of heat transfer mechanisms we suggest that a transition from vapor-dominated to liquid-dominated conditions must have been present in the natural state of the Larderello geothermal system. No reliable determination of the depth at which this transition occurred has yet been made, but a depth of approximately 2000 m or more appears most likely. (3) From temperature-depth data in two-phase reservoirs it is in principle possible to estimate vertical permeability. (4) For exploited reservoirs such as Larderello, reconstruction of permeability and temperature trends with depth can be made indirectly, using numerical simulation. Our preliminary results indicate that production of high-enthalpy fluids can be explained from two-phase flow effects in a fractured-porous medium. 18 refs., 2 tabs., 7 figs.
Date: January 20, 1987
Creator: Pruess, K.; Celati, R.; Calore, C. & Cappetti, G.
Partner: UNT Libraries Government Documents Department

Analysis of Thermally Induced Permeability Enhancement in Geothermal Injection Wells

Description: Reinjection of spent geothermal brine is a common means of disposing of geothermal effluents and maintaining reservoir pressures. Contrary to the predictions of two-fluid models (two-viscosity) of nonisothermal injection, an increase of injectivity, with continued injection, is often observed. Injectivity enhancement and thermally-affected pressure transients are particularly apparent in short-term injection tests at the Los Azufres Geothermal Field, Mexico. During an injection test, it is not uncommon to observe that after an initial pressure increase, the pressure decreases with time. As this typically occurs far below the pressure at which hydraulic fracturing is expected, some other mechanism for increasing the near-bore permeability must explain the observed behavior. This paper focuses on calculating the magnitude of the near-bore permeability changes observed in several nonisothermal injection tests conducted at the Los Azufres Geothermal Field. In order to evaluate the pressure transient data and calculate the magnitude of the thermally induced permeability changes, a new analytic solution for calculating pressure transients with time-varying sandface flowrates and temperatures has been developed. The effects of temperature-dependent fluid and rock properties, as well as a moving thermal front, are explicitly included in the calculations. Based on this new solution, a technique is developed for calculating the reservoir permeability, skin factor of the well, and near-bore permeability increases. The results of these calculations indicate that the permeability increases by a factor of 5 in the near-bore region during the 2 to 3 hour injection tests. A good correlation between the permeability increase and the sandface injection temperature indicates that the permeability increase is caused by cooling the formation. 9 figs., 9 refs.
Date: January 20, 1987
Creator: Benson, S.M.; Daggett, J.S.; Iglesias, E.; Arellano, V. & Ortiz-Ramirez, J.
Partner: UNT Libraries Government Documents Department

Reservoir Studies of the Seltjarnarnes Geothermal Field, Iceland

Description: The Seltjarnarnes geothermal field in Iceland has been exploited for space heating for the last 16 years. A model of the field has been developed that integrates all available data. The model has been calibrated against the flow rate and pressure decline histories of the wells and the temperature and chemical changes of the produced fluids. This has allowed for the estimation of the permeability and porosity distribution of the system, and the volume of the hot reservoir. Predictions of future reservoir behavior using the model suggest small pressure and temperature changes, but a continuous increase in the salinity of the fluids produced. 10 figs., 23 refs.
Date: January 20, 1987
Creator: Tulinius, H.; Spencer, A.L.; Bodvarsson, G.S.; Kristmannsdottir, H.; Thorsteinsson, T. & Sveinbjornsdottir, A.E.
Partner: UNT Libraries Government Documents Department

Conceptual Model of the Klamath Falls, Oregon Geothermal Area

Description: Over the last 50 years significant amounts of data have been obtained from the Klamath Falls geothermal resource. To date, the complexity of the system has stymied researchers, leading to the development of only very generalized hydrogeologic and geothermal models of the area. Recently, the large quantity of available temperature data have been re-evaluated, revealing new information on subsurface heat flow and locations of faults in the system. These inferences are supported by borehole, geochemical, geophysical, and hydrologic data. Based on re-evaluation of all available data, a detailed conceptual model for the Klamath Falls geothermal resource is proposed. 1 tab., 8 figs., 21 refs.
Date: January 20, 1987
Creator: Prucha, R.H.; Benson, S.M. & Witherspoon, P.A.
Partner: UNT Libraries Government Documents Department

Decline Curve Analysis of Production Data from the Geysers Geothermal Field

Description: Production data for over two hundred wells at The Geysers geothermal field were compiled and analysed. Decline curves for groups of wells with 5, 10, and 40 acre spacing are presented and compared to curves published previously by Budd (1972) and Dykstra (1981). Decline curves for several individual wells and leases are discussed to illustrate the effects of well spacing and location, as well as the heterogeneous nature of the reservoir. 6 figs., 1 tab., 10 refs.
Date: January 20, 1987
Creator: Ripperda, M. & Bodvarsson, G.S.
Partner: UNT Libraries Government Documents Department

Mass Estinctions Caused by Large Bolide Impacts

Description: In this talk, I will describe the wealth of evidence that has forced my colleagues and me to conclude that the great mass extinctions, 65 million years ago, were caused by a large bolide impact on the earth. Bolide is a new word to most people, and it means any piece of solar system debris, such as a meteorite, asteroid, or comet nucleus. As I will show, the bolide responsible for the extinction of most of the then existing species, including the dinosaurs, was about 10 kilometers in diameter.
Date: January 1, 1987
Creator: Lavarez, Luis W.
Partner: UNT Libraries Government Documents Department

Measurement of the Intensity of the Cosmic Background Radiation at3.7 GHz

Description: We measured the temperature of the cosmic background radiation (CBR) at a frequency of 3.7 GHz (8.1 cm wavelength), using a total power, direct RF-gain receiver. The results give a brightness temperature, T{sub CBR}, of 2.58 {+-} 0.13 K (68% C.L.). Details of the instrument and of the experimental procedure are given. This measurement is part of a larger experiment to measure the spectrum of the Cosmic Background Radiation between 0.6 and 90 GHz (50 and 0.33 cm wavelength).
Date: April 1, 1987
Creator: De Amici, G.; Smoot, G.F.; Aymon, J.; Bersanelli, M.; Kogut, A.; Levine, S.M. et al.
Partner: UNT Libraries Government Documents Department

An Analysis of Recent Measurements of the Temperature of theCosmic Microwave Background Radiation

Description: This paper presents an analysis of the results of recent temperature measurements of the cosmic microwave background radiation (CMBR). The observations for wavelengths longer than 0.1 cm are well fit by a blackbody spectrum at 2.74 {+-} 0.02 K; however, including the new data of Matsumoto et al. (1987) the result is no longer consistent with a Planckian spectrum. The data are described by a Thomson-distortion parameter u = 0.021 {+-} 0.002 and temperature 2.823 {+-} 0.010 K at the 68% confidence level. Fitting the low-frequency data to a Bose-Einstein spectral distortion yields a 95% confidence level upper limit of 1.4 x 10{sup -2} on the chemical potential {mu}{sub 0}. These limits on spectral distortions place restrictions on a number of potentially interesting sources of energy release to the CMBR, including the hot intergalactic medium proposed as the source of the X-ray background.
Date: July 1, 1987
Creator: Smoot, G.; Levin, S.M.; Witebsky, C.; De Amici, G. & Rephaeli, Y.
Partner: UNT Libraries Government Documents Department

Long-Wavelength Measurements of the Cosmic Microwave BackgroundRadiation Spectrum

Description: We have measured the temperature of the cosmic microwave background radiation at wavelengths of 0.33, 3.0, 8.2 and 21.3 cm. These measurements represent a continuation of the work reported by Smoot et al. (1985). The new results have a weighted average of 2.70 {+-} 0.05 K and are consistent with past measurements. They limit the possible distortion of the cosmic microwave background radiation spectrum to less than 6%. The results of all measurements to date are consistent with a Planckian spectrum with temperature 2.74 {+-} 0.02 K spanning a wavelength range of 0.1 to 21 cm.
Date: February 1, 1987
Creator: Smoot, G.F.; Bensadoun, M.; Bersanelli, M.; pDe Amici, G.; Kogut,A.; Levine, S. et al.
Partner: UNT Libraries Government Documents Department

A Large L-Band Rectangular Corrugated Horn

Description: This paper describes a lightweight, corrugated-horn antenna, constructed from sheet metal. Over a 1.3-1.7 GHz operating band, its half-power beam width is approximately 20{sup o} in the E-plane and varies from 17{sup o} to 13{sup o} in the H-plane. Quarter-wave choke slots at the aperture help to reduce the E-plane sidelobes below -55 dB at angles greater than 90{sup o}, while the H-plane sidelobes lie in that range both with and without choke slots. Return loss throughout the operating band is -25 dB or below. Critical dimensions are provided, together with useful guidelines for designing similar antennas.
Date: January 1, 1987
Creator: Witebsky, C.; Smoot, G.F.; Levin, S. & Bensadoun, M.
Partner: UNT Libraries Government Documents Department