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Determination of absolute rate data for the reaction of atomic sodium, Na (3²S(1/2)), with CF₃Cl, CF₂Cl₂, CFCl₃, CF₃Br and SF₆ as a Function of Temperature by Time-resolved Atomic Resonance-absorption Spectroscopy at λ = 589 nm [Na(3²Pᴊ) ← Na(3²S(1/2))

Description: Article on a kinetic study of the reactions of ground-state sodium atoms with the molecules CF₃Cl, CF₂Cl₂, CFCl₃, CF₃Br and SF₆ over the temperature range 644-918 K.
Date: 1985
Creator: Husain, David & Marshall, Paul
Partner: UNT College of Arts and Sciences

Temperature Dependence of the Absolute Third-order Rate Constant for the Reaction between Na + O₂ + N₂ over the Range 571 - 1016 K Studied by Time-resolved Atomic Resonance Absorption Spectroscopy

Description: Article on temperature dependence of the absolute third-order rate constant for the reaction between Na + O₂ + N₂ over the range 571-1016 K studied by time-resolved atomic resonance absorption spectroscopy.
Date: 1985
Creator: Husain, David; Marshall, Paul & Plane, John M. C.
Partner: UNT College of Arts and Sciences

Hydrogeology of the unsaturated zone, Yucca Mountain, Nevada

Description: The unsaturated volcanic tuff beneath Yucca Mountain, Nevada, is being evaluated by the US Department of Energy as a host rock for a potential mined geologic repository for high-level radioactive waste. Assessment of site suitability needs an efficient and focused investigative program. A conceptual hydrogeologic model that simulates the flow of fluids through the unsaturated zone at Yucca Mountain was developed to guide the program and to provide a basis for preliminary assessment of site suitability. The study was made as part of the Nevada Nuclear Waste Storage Investigations Project of the US Department of Energy. Thickness of the unsaturated zone is about 1640 to 2460 feet (500 to 750 meters). Based on physical properties, the rocks in the unsaturated zone are grouped for the purpose of this paper into five informal hydrogeologic units. From top to bottom these units are: Tiva Canyon welded unit, Paintbrush nonwelded unit. Topopah Spring welded unit, Calico Hills nonwelded unit, and Crater Flat unit. Welded units have a mean fracture density of 8 to 40 fractures per unit cubic meter, mean matrix porosities of 12 to 23%, matrix hydraulic conductivities with geometric means ranging from 6.5 x 10{sup -6} to 9.8 x 10{sup -6} foot per day (2 x 10{sup -6} to 3 x 10{sup -6} meter per day), and bulk hydraulic conductivities of 0.33 to 33 feet per day (0.1 to 10 meters per day). The nonwelded units have a mean fracture density of 1 to 3 fractures per unit cubic meter, mean matrix porosities of 31 to 46%, and saturated hydraulic conductivities with geometric means ranging from 2.6 x 10{sup -5} to 2.9 x 10{sup -2} foot per day (8 x 10{sup -6} to 9 x 10{sup -3} meter per day). 15 refs., 4 figs., 1 tab.
Date: December 31, 1985
Creator: Montazer, P. & Wilson, W.E.
Partner: UNT Libraries Government Documents Department

Moisture monitoring in large diameter boreholes

Description: The results of both laboratory and field experiments indicate that the neutron moisture gauge traditionally used in soil physics experiments can be extended for use in large diameter (up to 15 cm) steel-cased boreholes with excellent results. This application will permit existing saturated zone monitoring wells to be used for unsaturated zone monitoring of recharge, redistribution and leak detection from waste disposal facilities. Its applicability to large diameter cased wells also gives the soil physicist and ground-water hydrologist and new set of monitoring points in the unsaturated zone to study recharge and aquifer properties. 6 refs., 6 figs., 2 tabs.
Date: November 19, 1985
Creator: Tyler, S.
Partner: UNT Libraries Government Documents Department

Ground reaction curve based upon block theory

Description: Discontinuities in a rock mass can intersect an excavation surface to form discrete blocks (keyblocks) which can be unstable. Once a potentially unstable block is identified, the forces affecting it can be calculated to assess its stability. The normal and shear stresses on each block face before displacement are calculated using elastic theory and are modified in a nonlinear way by discontinuity deformations as the keyblock displaces. The stresses are summed into resultant forces to evaluate block stability. Since the resultant forces change with displacement, successive increments of block movement are examined to see whether the block ultimately becomes stable or fails. Two-dimensional (2D) and three-dimensional (3D) analytic models for the stability of simple pyramidal keyblocks were evaluated. Calculated stability is greater for 3D analyses than for 2D analyses. Calculated keyblock stability increases with larger in situ stress magnitudes, larger lateral stress ratios, and larger shear strengths. Discontinuity stiffness controls blocks displacement more strongly than it does stability itself. Large keyblocks are less stable than small ones, and stability increases as blocks become more slender.
Date: September 1, 1985
Creator: Yow, J.L. Jr. & Goodman, R.E.
Partner: UNT Libraries Government Documents Department

LWR spent fuel characteristics relevant to performance as a wasteform in a potential tuff repository

Description: A testing program has been initiated to determine the probable condition of spent fuel during the post-containment period under NNWSI site specific conditions, and to determine relevant radionuclide release rates for spent fuel. The current testing program is focused on three subject areas: (1) spent fuel leaching/dissolution behavior, (2) spent fuel oxidation, and (3) cladding corrosion. Results are presented. 3 refs.
Date: June 1, 1985
Creator: Wilson, C.N.; Einziger, R.E.; Woodley, R.E. & Oversby, V.M.
Partner: UNT Libraries Government Documents Department

Vacuum drilling of unsaturated tuffs at a potential radioactive-waste repository, Yucca Mountain, Nevada

Description: A vacuum reverse-air circulation drilling method was used to drill two 17-1/2-inch (44.5-centimeter) diameter test holes to depths of 1269 feet (387 meters) and 1887 feet (575 meters) at Yucca Mountain near the Nevada Test Site. The site is being considered by the US Department of Energy for construction of a high-level radioactive-waste repository. One of these two test holes (USW UZ-1) has been equipped with instrumentation to obtain a long-term record of pressure and moisture potential data; the other test hole (USW UZ-6) will be similarly instrumented in the near future. These investigations are being conducted as part of the Nevada Nuclear Waste Storage Investigations Project of the US Department of Energy. The test holes were drilled using a 5-1/2-inch (14-centimeter) by 8-5/8-inch (22-centimeter) dual-string reverse-vacuum assembly. A vacuum, induced at the land surface, removed the drill cuttings through the inner string. Compressed air was injected into the dual-string annulus to cool the bit and to keep the bit and inner string clean. A tracer gas, sulfur hexafluoride (SF{sub 6}), was added to the compressed air for a later determination of atmospheric contamination that might have occurred during the drilling. After reaching the surface, the drill cuttings were routed to a dry separator for sample collection. Then return air and dust from the cuttings were routed to a wet separator where the dust was removed by a water spray, and the remaining air was exhausted through the vacuum unit (blower) to the atmosphere. 6 refs., 4 figs.
Date: December 31, 1985
Creator: Whitfield, M.S.
Partner: UNT Libraries Government Documents Department

Derivation of a waste package source term for NNWSI from the results of laboratory experiments

Description: Results are performed for the dissolution of Turkey Point pressurized water reactor (PWR) spent fuel in J-13 well water at ambient hot cell temperatures. These results are compared with those previously obtained on Turkey Point fuel in deionized water, on H.B. Robinson PWR fuel in J-13 water, and by other workers using various fuels in dilute bicarbonate groundwaters. A model is presented that represents the conditions under which maximum dissolution of spent fuel could occur in a repository sited at Yucca Mountain, Nevada. Using an experimentally determined upper limit of 5 mg/l for uranium solubility in J-13 water, a fractional release rate of 6.4 x 10{sup -8} per year is obtained by assuming that all water entering the repository carries away the maximum amount of uranium. 14 refs., 3 figs., 3 tabs.
Date: September 1, 1985
Creator: Oversby, V. M. & Wilson, C N.
Partner: UNT Libraries Government Documents Department

Corrosion performance of metals and alloys in a tuff geochemical environment

Description: Reference and alternate alloy systems have been chosen for use in fabricating waste packages for a potential high-level nuclear waste repository in tuff. The main corrosion concerns have been identified. Testing performed to date indicates that austenitic stainless steels woul perform well as package materials under the expected conditions as well as the less likely extreme conditions so far postulated. Carbon steel appears to be adequate as a material for borehole liners. Copper-based alloys and Zircaloys are also undergoing corrosion testing, the former as alternate package materials, and the latter because of their presence as spent fuel cladding. 17 references, 2 tables.
Date: March 20, 1985
Creator: Van Konynenburg, R.A. & McCright, R.D.
Partner: UNT Libraries Government Documents Department

Borehole-calibration methods used in cased and uncased test holes to determine moisture profiles in the unsaturated zone, Yucca Mountain, Nevada

Description: The use of drilling and coring methods that minimize the disturbance of formation rock and core has permitted field calibration of neutron-moisture tools in relatively large diameter cased and uncased boreholes at Yucca Mountain, Nevada. For 5.5-inch diameter cased holes, there was reasonable agreement between a field calibration in alluvium-colluvium and a laboratory calibration in a chamber containing silica sand. There was little difference between moisture-content profiles obtained in a neutron-access hole with a hand-held neutron-moisture meter and an automated borehole-logging tool using laboratory-generated calibration curves. Field calibrations utilizing linear regression analyses and as many as 119 data pairs show a good correlation between neutron-moisture counts and volumetric water content for sections of uncased 6-inch diameter boreholes in nonwelded and bedded tuff. Regression coefficients ranged from 0.80 to 0.94. There were only small differences between calibration curves in 4.25- and 6-inch uncased sections of boreholes. Results of analyzing field calibration data to determine the effects of formation density on calibration curves were inconclusive. Further experimental and theoretical work is outlined.
Date: December 31, 1985
Creator: Hammermeister, D.P.; Kneiblher, C.R. & Klenke, J.
Partner: UNT Libraries Government Documents Department

{sup 36}Cl measurements of the unsaturated zone flux at Yucca Mountain

Description: Determining the unsaturated zone percolation rate, or flux, is an extremely important site characterization issue for the proposed Yucca Mountain nuclear waste repository. A new technique that measures the {sup 36}Cl content of tuff from the Exploratory Shaft will be used to calculate flux through the unsaturated zone over longer times than could be measured by the more conventional {sup 14}C method. Measurements of the {sup 36}Cl "bomb pulse" in soil samples from Yucca Mountain have been used to confirm that infiltration is not an important recharge mechanism. 5 refs., 3 figs.
Date: December 31, 1985
Creator: Norris, A.E.; Wolfsberg, K. & Gifford, S.K.
Partner: UNT Libraries Government Documents Department

Fractal geometry of two-dimensional fracture networks at Yucca Mountain, southwestern Nevada: proceedings

Description: Fracture traces exposed on three 214- to 260-m{sup 2} pavements in the same Miocene ash-flow tuff at Yucca Mountain, southwestern Nevada, have been mapped at a scale of 1:50. The maps are two-dimensional sections through the three-dimensional network of strata-bound fractures. All fractures with trace lengths greater than 0.20 m were mapped. The distribution of fracture-trace lengths is log-normal. The fractures do not exhibit well-defined sets based on orientation. Since fractal characterization of such complex fracture-trace networks may prove useful for modeling fracture flow and mechanical responses of fractured rock, an analysis of each of the three maps was done to test whether such networks are fractal. These networks proved to be fractal and the fractal dimensions (D) are tightly clustered (1.12, 1.14, 1.16) for three laterally separated pavements, even though visually the fracture networks appear quite different. The fractal analysis also indicates that the network patterns are scale independent over two orders of magnitude for trace lengths ranging from 0.20 to 25 m. 7 refs., 7 figs.
Date: December 31, 1985
Creator: Barton, C.C. & Larsen, E.
Partner: UNT Libraries Government Documents Department

Effects of geochemical processes on the transport of contaminants in multicomponent systems: a modeling perspective

Description: An equilibrium geochemical transport model for multicomponent systems, TRANQL, was used to investigate the effects of geochemical processes on the transport of contaminants. TRANQL was used to investigate the sensitivity of cadmium transport to a range of initial condition, pH, complexing ligand concentrations, and concentrations of a simultaneously sorbing solute. Aqueous-phase complexation, dissociation of water, and sorption were the processes considered. First, the transport of an initial pulse of cadmium with a constant concentration of EDTA was examined. Second, the transport of an initial pulse of cadmium with a constant concentration of EDTA was simulated. The effects of variations in EDTA concentrations and pH were investigated. Finally, the transport of an initial pulse of cadmium and cobalt was examined. Results show a significant coupling between the geochemical processes of complexation and sorption and mass-transport. In cases where sorption is considered to be an important controlling reaction the transport of a solute in multicomponent systems is a strong function of the initial concentration and distribution of complexing ligands, pH, equilibrium formation constants, and the concentration of a simultaneously sorbing solute. 5 refs., 8 figs., 3 tabs.
Date: December 31, 1985
Creator: Cederberg, G.A.
Partner: UNT Libraries Government Documents Department

Formation of plutonium(IV) colloid by the alpha-reduction of aqueous solutions of Pu(V) and Pu(VI)

Description: We describe concentration changes caused by chemical and alpha-induced radiolytic reactions in various oxidation state pure solutions of Pu(VI), Pu(V), or Pu(IV) colloid or mixtures of these oxidation states at pH values > 1 for a period of nearly two years. The rates of approach to steady-states and the resulting experimental concentration quotient values were determined in order to find the conditions under which equilibrium in 2PuO{sub 2}{sup +} + PuO{sub 2}{sup 2+} + PuO/sub 2(coll)/ reaction might be attained and to learn about the underlying reactions. Computer calculations were used to compare the data with the results required from proposed reaction schemes.
Date: December 31, 1985
Creator: Hobart, D.E.; Newton, T.W. & Palmer, P.D.
Partner: UNT Libraries Government Documents Department

Measurements of matric and water potentials in unsaturated tuff at Yucca Mountain, Nevada

Description: Two types of instruments were installed in a borehole in order to monitor matric and water potentials of various hydrogeologic units consisting of tuff. The borehole was drilled as part of a study to provide information to the US Department of Energy for their use in evaluating Yucca Mountain, Nevada, for a repository for high-level radioactive waste. Heat-dissipation probes were used to monitor matric potentials and thermocouple psychrometers were used to monitor water potentials. Two major concerns regarding the use of these instruments in deep boreholes are: (1) the effect of length of the lead wires, and (2) the inability to recalibrate the instruments after installation. The length of the lead wire contributes to the source resistance and lead capacitance, which affects the signal settling time. Both instruments tested proved to be insensitive to lead-wire length, except when connected to smaller input-impedance data loggers. Thermocouple wires were more sensitive than heat-dissipation probe wires because of their greater resistance and quality of voltmeters used. Two thermocouple psychrometers were installed at every instrument station for backup and verification of data, because the instruments could not be recalibrated in situ. Multiple scanning rather than single-point scanning of the evaporation curve of a thermocouple psychrometer could give more reliable data, especially in differentiating between very wet and very dry environments. An isolated power supply needs to be used for each heat dissipation probe rather than a single power supply for a group of probes to avoid losing data from all probes when one probe malfunctions. This type of system is particularly desirable if the site is unattended by an operator for as long as a month. 20 refs., 13 figs., 2 tabs.
Date: December 31, 1985
Creator: Thamir, F. & McBride, C.M.
Partner: UNT Libraries Government Documents Department

Control of research oriented software development

Description: The Nuclear Waste Policy Act of 1982 directs the Department of Energy (DOE) to dispose permanently high level radioactive waste and civilian spent nuclear fuel by January 31, 1998. DOE has responded by creating an organizational structure that directs all the activities necessary to carry out the legislative demands. LLNL is conducting research in the earth sciences and is developing some unique computer codes to help establish the feasibility of geologic repositories for nuclear waste. LLNL has several codes under development. This paper examines the administrative and organizational measures that were and still are being undertaken in order to control the development of the two major codes. In the case of one code, the software quality assurance requirements were imposed five years after the code began its development. This required a retroactive application of requirements. The other code is still in the conceptual stages of development and here requirements can be applied as soon as the initial code design begins. Both codes are being developed by scientists, not computer programmers, and both are modeling codes, not data acquisition and reduction codes. Also the projects for which these codes are being developed have slightly different software quality assurance requirements. All these factors contribute unique difficulties in attempts to assure that the development not only results in a reliable prediction, but that whatever the reliability, it can be objectively shown to exist. The paper will examine a software management model. It will also discuss the reasons why it is felt that this particular model would stand a reasonable chance for success. The paper will then describe the way in which the model should be integrated into the existing management configuration and tradition.
Date: December 1, 1985
Creator: Lewis, L.C.; Dronkers, J.J. & Pitsker, B.
Partner: UNT Libraries Government Documents Department

Operational and technical results from the Spent Fuel Test - Climax

Description: The technical feasibility of short-term storage and retrieval of spent nuclear fuel assemblies has recently been demonstrated in a test of deep geologic storage at the US Department of Energy Nevada Test Site (NTS). Handling systems and procedures developed and deployed on this test functioned safely and reliably to emplace eleven intact spent-fuel assemblies and retrieve them three years later. Three exchanges of spent fuel were conducted at regular intervals during the storage period to maintain the proficiency of personnel and the readiness of the handling system. Technical data was collected using nearly 1000 instruments. These data show that the mechanical and thermal properties of granites are compatible with nuclear waste isolation objectives. Measured and calculated temperatures are in excellent agreement, confirming the adequacy of available heat transfer codes. Radiation transport calculations were of high quality, exceeding the accuracy of available long-term dosimetry techniques which were used on the test. We also found good agreement between measured and calculated displacements within the rock mass. 28 references, 4 figures.
Date: January 1, 1985
Creator: Patrick, W.C.
Partner: UNT Libraries Government Documents Department

Material Selection for Defense Waste Processing Facility

Description: Construction has started on a facility to immobilize high-level radioactive waste in borosilicate glass at the Department of Energy's Savannah River Plant. Type 304L stainless steel is generally sufficient for supply tankage and service lines. It is used as the reference material in chemical reprocessing of reactor target and fuel tubes. Type 304L, however, has unacceptable stress corrosion cracking resistance in solutions containing formic acid and chloride. Scouting tests were performed on twelve commercial nickel-based alloys in simulated process solutions containing halides, sulfates, nitrates, mercury and formic acid. Mercuric ions and halides interact in acidic environments to increase pitting and crevice attack. Alloys with combined chromium plus molybdenum contents greater than 30 percent, that also contain greater than 9 percent molybdenum, were most resistant to pitting and crevice corrosion. Based on this testing, Alloy C-276 has been selected as the reference process equipment material, with Inconel 690 and ALLCORR selected for specialty areas.
Date: July 17, 1985
Creator: Bickford, D.F.
Partner: UNT Libraries Government Documents Department

Analysis of colloid transport

Description: The population balance methodology is described and applied to the transport and capture of polydispersed colloids in packed columns. The transient model includes particle growth, capture, convective transport, and dispersion. We also follow the dynamic accumulation of captured colloids on the solids. The multidimensional parabolic partial differential equation was solved by a recently enhanced method of characteristics technique. This computational technique minimized numerical dispersion and is computationally very fast. The FORTRAN 77 code ran on a VAX-780 in less than a minute and also runs on an IBM-AT using the Professional FORTRAN compiler. The code was extensively tested against various simplified cases and against analytical models. The packed column experiments by Saltelli et al. were re-analyzed incorporating the experimentally reported size distribution of the colloid feed material. Colloid capture was modeled using a linear size dependent filtration function. The effects of a colloid size dependent filtration factor and various initial colloid size distributions on colloid migration and capture were investigated. Also, we followed the changing colloid size distribution as a function of position in the column. Some simple arguments are made to assess the likelihood of colloid migration at a potential NTS Yucca Mountain waste disposal site. 10 refs., 3 figs., 1 tab.
Date: December 31, 1985
Creator: Travis, B.J. & Nuttall, H.E.
Partner: UNT Libraries Government Documents Department

Analysis of gaseous-phase stable and radioactive isotopes in the unsaturated zone, Yucca Mountain, Nevada

Description: The Nevada Nuclear Waste Storage Investigations Project of the US Department of Energy provides that agency with data for evaluating volcanic tuff beneath Yucca Mountain, Nevada, to determine its suitability for a potential repository of high-level radioactive waste. Thickness of the unsaturated zone, which consists of fractured, welded and nonwelded tuff, is about 1640 to 2460 feet (500 to 750 meters). One question to be resolved is an estimate of minimum ground-water traveltime from the disturbed zone of the potentail repository to the accessible environment. Another issue is the potential for diffusive or convective gaseous transport of radionuclides from an underground facility in the unsaturated zone to the accessible environment. Gas samples were collected at intervals to a depth of 1200 feet from the unsaturated zone at Yucca Mountain, Nevada. Samples were analyzed for major atmospheric gases; carbon dioxide in the samples was analyzed for carbon-14 activity and for {delta}2!{sup 3}C; water vapor in the samples was analyzed for deuterium and oxygen-18. These data could provide insight into the nature of unsaturated zone transport processes. 15 refs., 4 figs., 4 tabs.
Date: December 31, 1985
Creator: Yang, I.C.; Haas, H.H.; Weeks, E.P. & Thorstenson, D.C.
Partner: UNT Libraries Government Documents Department

Treatment of uncertainties in the geologic disposal of radioactive waste

Description: Uncertainty in the analysis of geologic waste disposal is generally considered to have three primary components: (1) computer code/model uncertainty, (2) model parameter uncertainty, and (3) scenario uncertainty. Computer code/model uncertainty arises from problems associated with determination of appropriate parameters for use in model construction, mathematical formulatin of models, and numerical techniques used in conjunction with the mathematical formulation of models. Model parameter uncertainty arises from problems associated with selection of appropriate values for model input, data interpretation and possible misuse of data, and variation of data. Scenario uncertainty arises from problems associated with the "completeness` of scenarios, the definition of parameters which describe scenarios, and the rate or probability of scenario occurrence. The preceding sources of uncertainty are discussed below.
Date: December 31, 1985
Creator: Cranwell, R.M.
Partner: UNT Libraries Government Documents Department

Topography, stresses, and stability at Yucca Mountain, Nevada

Description: Plane-strain solutions are used to analyze the influence of topography on the state of stress at Yucca Mountain, Nye County, Nevada. The results are in good agreement with the measured stress components obtained in drill holes by the hydraulic-fracturing technique, particularly those measured directly beneath the crest of the ridge, and indicate that these stresses are gravitationally induced. A separate analysis takes advantage of the fact that a well-developed set of vertical faults and fractures, subparallel to the ridge trend, imparts a vertical transverse isotropy to the rock and that, as a consequence of gravitational loading, unequal horizontal stresses are induced in directions perpendicular and parallel to the anisotropy.
Date: December 31, 1985
Creator: Swolfs, H.S. & Savage, W.Z.
Partner: UNT Libraries Government Documents Department