The US Department of Energy (DOE) is responsible for designing, obtaining a license for, and constructing a geologic repository for the disposal of commercial high-level radioactive waste. The candidate repository site is currently at Yucca Mountain in Nevada. Part of DOE`s responsibility is to assess compliance with the appropriate environmental regulations, including the Environmental Protection Agency`s containment requirements in 40 CFR Part 191. Sandia National Laboratories (SNL) and Pacific Northwest Laboratories (PNL) have been contracted to aid DOE in the assessment of total systems performance. SNL has been tasked with evaluating and comparing the performance assessment methodologies developed by PNL and SNL, as applied to one conceptual model. In this report, SNL has attempted to reproduce, by way of a benchmark exercise, the results of PNL`s preliminary risk assessment of the proposed repository at Yucca Mountain. In general, the results of the PNL analysis and the SNL benchmark of that analysis agreed quite well, in terms of both ground-water flow and transport of unretarded radionuclides. The largest discrepancy between the analyses was noted for transport of retarded radionuclides, and was the result of different techniques for calculating retardation factors. 27 refs., 28 figs., 17 tabs.
The objective of this work is to develop a general method for remotely sensing the presence of tunneling activities using one or more boreholes and a combination of surface sources. New techniques for tunnel detection and location of tunnels containing no metal and of tunnels containing only a small diameter wire have been experimentally demonstrated. A downhole magnetic dipole and surface loop sources were used as the current sources. The presence of a tunnel causes a subsurface scattering of the field components created by the source. Ratioing of the measured responses enhanced the detection and location capability over that produced by each of the sources individually. 4 refs., 18 figs., 2 tabs.
As part of Sandia National Laboratories` (SNL) pollution prevention program a system is under development to track the movement of hazardous and radioactive materials from procurement, through use, to final disposition. The information provided by this system will improve the flow and enhance the quality of data, avoid duplication of effort, facilitate timely and accurate reporting, better support the information needs of various Environmental, Safety, and Health (ES&H) programs, and allow waste to be minimized more effectively. Such a comprehensive system will incorporate information from other sources and build upon existing databases. The component include the Chemical Information System/Material Safety Data Sheet (CIS/MSDS) system installed by AT&T Bell Laboratories (AT&T-BL) at SNL in Livermore, along with a barcode chemical waste tracking system already in operation at SNL in Albuquerque. Also being developed in Albuquerque are Process Waste Assessments, a radioactive material tracking system, and a radioactive/mixed waste tracking system. A SNL and AT&T-BL joint project is addressing how PWAs will link raw materials to waste streams. With a ``cradle-to-grave`` tracking system, it is possible to assess both financial and environmental life cycle costs. Once in place, this information will improve long-run efficiency and environmental protection, and provide benefits exceeding the initial demands placed upon personnel.
Knowledge of the solubility of gases in pure water and sodium chloride brine is required for the evaluation of gas-liquid behavior associated with numerous processes in the chemical, biological, and geological sciences and in chemical engineering. Modelling of multiphase flow and transport processes used to simulate fluid behavior in geological media requires suitable and accurate gas solubility data, especially when applied to potential nuclear waste repositories such as WIPP. This report contains a critical evaluation of data available in the literature and provides compiled data sets for the solubility of hydrogen, nitrogen, methane, and carbon dioxide gases in pure water and in sodium chloride brine. Mole fraction gas solubilities are presented as functions of temperature and pressure. To evaluate the influence of electrolyte content of the aqueous solution upon the gas solubility, Sechenov coefficients are provided for several concentrated sodium chloride solution. An estimate of the solubility of hydrogen in 5 N sodium chloride brine as a function of pressure exhibits a solubility at 40 MPa that is one fifth the value observed for pure water at the same pressure.
In this paper, a design methodology is presented for assessing drift stability for a potential high-level radioactive waste repository. Excavation stability is required during construction, emplacement, retrieval (if required) and closure phases to ensure worker health and safety, and to prevent development of potential pathways for radionuclide migration in the post-closure period. Requirements for the design, site conditions and stresses are considered in the methodology. Methods for evaluating empirical and analytical results in order to estimate ground support requirements are outlined.
Large computational physics codes are increasing in complexity as customers demand improved physics packages and more flexible algorithms and problem specifications. It is not uncommon for a code to exceed one hundred thousand lines of FORTRAN, and some codes are much larger. This poses a considerable challenge for program management. The Computational Physics Research and Development Division at Sandia National Laboratories is aggressively pursuing C++ as the language of choice for new coding efforts. We feel that we cannot meet the stringent customer requirements and delivery schedules we now face with either FORTRAN77 or Fortran-90. 8 refs., 3 tabs.
Cleaning, plating, and painting are chemically intensive processes that involve toxic and potentially carcinogenic materials that pose a significant threat to the environment. EPA/OSHA, the Clean Air Act, and the Montreal Protocol are forcing development of environmentally sound materials and processes. A review is given of the materials and processes that are under investigation that will minimize the environmental impact of these operations. 7 refs.
The Recirculating Linear Accelerator (RLA) is returning to operation with a new relativistic electron beam (REB) injector and a modified accelerating cavity. Upon completion of our pulsed-power test program, we will capture the injected beam on an Ion Focussed Regime (IFR) guiding channel in either a spiral or a closed racetrack drift tube. The relativistic beam will recirculate for four passes through two accelerating cavities, in phase with the ringing cavity voltage, and increase to 8--12 MeV before being extracted. We designed the METGLAS ribbon-wound core, inductively isolated, four-stage injector to produce beam parameters of 4 MeV. 10--20 kA, and 40--55 ns FWHM. The three-line radial cavity is being modified to improve the 1-MV accelerating pulse shape while an advanced cavity design study is in progress. This is a continuation of the Sandia National Laboratory program to develop compact, high-voltage gradient, linear induction accelerators. The RLA concept is based on guiding an injected REB with an IFR channel. This channel is formed from a plasma created with a low energy electron beam inside a beam line containing about 2 {times} 10{sup {minus}4} Torr of argon. The REB is injected onto the IFR channel and is transported down the beamline through a water dielectric accelerating cavity based on the ET-2 design. If the round-tip path of the beam matches the period of the cavity, the REB can be further accelerated by the ringing waveform on every subsequent pass. We have installed the new REB injector because we need a higher amplitude, longer duration., flat-topped pulse shape with a colder beam than that produced by the previous injector. We made extensive use of computer simulations in the form of network solver and electrostatic field stress analysis codes to aid in the design and modifications for the new RLA. The pulsed-power performance of the RLA injector and cavity and the associated driving hardware are discussed.
A major center with emphasis on validation of nondestructive inspection techniques for aging aircraft, the Aging Aircraft NDI Development and Demonstration Center (AANC), has been funded by the FAA at Sandia National Laboratories. The Center has been assigned specific tasks in developing techniques for the nondestructive inspection of static engine parts, assessing inspection reliability (POD experiments), developing test beds for nondestructive inspection validation, maintaining a FAA library of characterized aircraft structural test specimens, and leasing a hangar to house a high flight cycle transport aircraft for use as a full scale test bed. 3 refs.
This paper describes procedure used to produce a test-validated finite element model of a three-stage solid propellant booster system. A series of system-level modal tests were performed for several inert and live propellant configurations. Test-analysis models (TAMs) were used to provide pretest support of the live propellant system tests. Confidence in the model was established by a test-analysis correlation procedure. Optimization techniques were used to determine appropriate model updates. 11 refs., 8 figs., 3 tabs.
Soldering is often referred to as a mature technology whose fundamentals were established long ago. Yet a multitude of soldering problems persist, not the least of which are related to the wetting and spreading of solder. The Buff-Goodrich approach to thermodynamics of capillarity is utilized in a review of basic wetting principles. These thermodynamics allow a very compact formulation of capillary phenomena which is used to calculate various meniscus shapes and wetting forces. These shapes and forces lend themselves to experimental techniques, such as the sessile drop and the Wilhelmy plate, for measuring useful surface and interfacial energies. The familiar equations of Young, Wilhelmy, and Neumann are all derived with this approach. The force-energy duality of surface energy is discussed and the force method is developed and used to derive the Herring relations for anisotropic surfaces. The importance of contact angle hysteresis which results from surface roughness and chemical inhomogeneity is presented and Young's equation is modified to reflect these ever present effects. Finally, an analysis of wetting with simultaneous metallurigical reaction is given and used to discuss solder wetting phenomena. 60 refs., 13 figs.
Titanium dioxide (TiO{sub 2}) is a known photocatalyst for solar detoxification of water containing organic contaminants including PCB's and dioxins. Unfortunately, the UV light used by the photocatalyst only comprises about 4% of the strong spectrum. Metalloporphyrins strongly absorb in the visible and near infrared region. Using visible light, we have investigated Ni(II) uroporphyrin (NiUroP), Sn(IV)Cl{sub 2} uroporphyrin (SnUroP) and Sn(IV)Cl{sub 2} tetrakis(p-carboxyphenyl) porphyrin (SnTCPP) as possible enhancers of destruction of a model organic compound, salicylic acid (SA), by means of photosensitization of colloidal TiO{sub 2} particles. All three porphyrins are found to adsorb reversibly onto the colloidal TiO{sub 2} upon variation of pH. Adsorption of porphyrins results in the increased colloidal stability of fine TiO{sub 2} particles in the pH range 5--8. While NiUroP on TiO{sub 2} does not show any enhancement of photodestruction, the adsorption of SnUroP increases the destruction rate compared to that of the bare TiO{sub 2} surface. The effect of ambient oxygen on the observed photolability of the Sn porphyrins and enhancement of photodestruction of SA was also investigated. SnTCPP does not photodecompose upon illumination either in the presence or absence of TiO{sub 2}, but neither does it bind to the photocatalyst at pH 6. At pH 4.5 it adsorbs onto TiO{sub 2} but it also photodecompose at this pH. We are attempting to stabilize the adsorbed porphyrins by adding suitable peripheral substituents onto the porphyrin macrocycle. 27 refs., 6 figs.
We have designed and tested a system for applying a ramped vertical magnetic field for turning the electron beam in the IFR Recirculating Linear Accelerator. The field is highly uniform over two Gaussian beam radii, and can be adjusted for a large radial gradient for increased energy bandwidth. The system includes shielding of the current-carrying rods to protect the pulser from REB induced fields and to reduce the effect of REB images on the beam transport to negligible levels. The system has been tested on the IBEX accelerator with > 95% peak current transport and > 90% charge transport through a 90{degree} turn. 2 refs., 6 figs.
The cleaning efficiency of five alternative solvents for chlorofluorocarbons (CFCs) and chlorohydrocarbons (CHCs) used in the manufacture of certain electronic components was studied. These solvents were evaluated in the first phase of a two-phase program to remove various manufacturing contaminants such as oils, greases, mold release, and body oils. Results have shown that EXXATE 1000 and EC-7 were able to effectively remove these contaminants from copper board substrates. 4 refs., 5 figs., 1 tab.
Eight Gulf Coast salt domes have emerged as candidate sites for possible expansion of the Strategic Petroleum Reserve (SPR) to one billion barrels. Two existing SPR sites, Big Hill, TX, and Weeks Island, LA, are among the eight that are being considered. To achieve the billion barrel capacity, some 25 new leached caverns would be constructed, and would probably be established in two separate sites in Louisiana and Texas because of distribution requirements. Geotechnical factors involved in siting studies have centered first and foremost on cavern integrity and environmental acceptability, once logistical suitability is realized. Other factors have involved subsidence and flooding potential, loss of coastal marshlands, seismicity, brine injection well utility, and co-use by multiple operators. 5 refs., 11 figs., 2 tabs.
Hertel, E.S.; Chhabildas, L.C.; Yarrington, L.; Hill, S.A.
A series of numerical simulations has been performed using the multi-dimensional hydrodynamics code CTH to computationally determine a ballistic limit for a Whipple bumper shield. The ballistic limit is generally characterized as a critical diameter such that particle diameters greater than the ballistic limit will generate debris clouds that will penetrate the rear wall and particle diameters less than the ballistic limit will not. The particular shield design used for these analyses is defined as a 1.27 mm bumper, a 102 mm void space, and a 3.18 mm rear wall. Since debris shape is expected to be a contributing factor in the impact phenomena, two different shapes are considered for the numerical simulations. The particle shapes considered were flat plates of constant 1 mm thickness and varying diameters and spheres of varying diameters. The critical diameter (ballistic limit) was determined over the velocity range 4 km/s to 15 km/s for both geometries. 13 refs., 2 figs.
In response to a request from the US Government, Sandia National Laboratories has developed an instrumentation system to monitor the conditions along an underwater, rotating drive shaft. It was desired to study the structural integrity and signal acquisition capabilities of the Shaft Instrumentation System (SIS) in an environment which closely simulates the actual deployment conditions. In this manner, the SIS response to ill-defined conditions, such as flow field turbulence or temperature fluctuations, could be determined. An Underwater Spin Facility was developed in order to verify the operation of the instrumentation and telemetric data acquisition system in a combined environment of external pressure, transient axial loads and centrifugal force. The main components of the Underwater Spin Facility are a large, five foot diameter pressure vessel, a dynamically sealed shaft, a drive train assembly and a shaker table interface which is used to apply the axial loads. This paper presents a detailed description of the design of the Underwater Spin Facility. It also discusses the SIS certification test program in order to demonstrate the successful performance of the Underwater Spin Facility. 8 refs., 10 figs.
There are three aspects to an environmentally safe battery. The first deals with the manufacturing process, the second with the use of environmentally friendly materials, and the third with the disposal and/or recycling of spent units. In this paper, several ongoing programs at Sandia National Laboratories that relate to the environmentally conscious manufacturing of batteries, are discussed. The solvent substitution/elimination program is a two-pronged effort, aimed at identifying new solvents which are compatible with the environment, while at the same time developing dry process cleaning technology. The joining program is evaluating new solvents for flux removal as well as the development of fluxless soldering processes. In the area of welding, new cleaning processes are under study. Chemical microsensors are under development that are capable of identifying and quantifying single chemical species. These sensors have been used to monitor and improve processes using toxic/hazardous solvents. 1 ref., 1 fig.
Phased-array antenna systems are well known for rapid beam steering and their ability to bring high power to the target. Such systems are also quite complex and heavy, which have limited their usefulness. The issues of weight, size, power use, and complexity have been addressed through a system named COMPASS (Coherent Optical Monolithic Phased Array Steering System). All phased-array antenna systems need: (1) small size; (2) low power use; (3) high-speed beam steering; and (4) digitally-controlled phase shifting. COMPASS meets these basic requirements, and provides some very desirable additional features. These are: (1) phase control separate from the transmit/receive module; (2) simple expansion to large arrays; (3) fiber optic interconnect for reduced sensitivity to EMI; (4) an intrinsically radiation-hard GaAs chip; and (5) optical power provided by a commercially available continuous wave (CW) laser. 4 refs., 8 figs.
Titanium alloys offer desirable properties that make them attractive candidates for tribological applications. Their surface-related properties, however, such as coefficient of friction and wear rate, are less than optimum and must be improved by surface modification. To increase the tribological properties of Ti-6Al-4V, a high temperature ion implantation method, employing a high current density beam (e.g., 500 {mu}A/cm{sup 2}) of nitrogen (N) ions is being developed, where surface temperatures greater than 1000{degrees}C can be obtained. A systematic study was performed with N implantation at temperatures from 400{degrees} to >1000{degrees}C, and to a range of doses from 0.1--1.0{times}10{sup 18} N{sub 2}{sup +}--N{sup +}/cm{sup 2}. Microstructure characterization by Rutherford Backscattering Spectroscopy (RBS) and Glancing Incidence X-ray Diffraction (GID) was performed to determine N distribution and compound formation. RBS analysis showed enhanced N penetrations (i.e., greater than 0.3 {mu}m) for the 800{degrees} and 1000{degrees}C implantations, with the deepest penetration (about 3.5 atomic percent N remaining at 0.75 {mu}m) for the 1000{degrees}C treatment. GID indicated TiN and Ti{sub 2}N concentrations were the greatest for the 800{degrees}C implantation treatment. 11 refs., 4 figs.
The debonding rates of H-passivated P and As in silicon have been observed to be very sensitive to the concentration of majority and minority charge carriers. A theoretical study of the stable and metastable configurations of the {l brace}P,H{r brace} and {l brace}As,H{r brace} pairs in the 0 and +1 charge states has been carried out at the near-ab-initio Hartree-Fock level. These calculations show that the lowest-energy configuration in the 0 charge state is the highest-energy configuration in the +1 charge state and vice-versa. This bistability of donor-hydrogen pairs implies that H cannot remain in place upon change of charge state, whether 0 {r arrow} +1 or +1 {r arrow} 0. Quantitative differences between the P and the As cases are qualitatively consistent with the observed differences in the temperature dependence of the debonding rates of {l brace}P,H{r brace} and {l brace}As,H{r brace}. 14 refs., 1 fig.
The usefulness of neutron radiography as a nondestructive engineering tool is heavily dependent on how a neutron reaches the image plane. Neutron interactions such as scattering and absorption, within a neutron radiography facility or a test part, affect the contrast of the resulting image generated by the process. It is important that the radiographer has a general understanding of how neutrons interact with matter to produce a quality image utilizing a neutron beam. 4 refs.
The distribution of copper aluminum thin films is examined with respect to how the copper can influence electromigration behavior. Al-Cu thin films annealed in the single phase region, to just below the solvus {theta}-phase Al{sub 2}Cu precipitates at the aluminum grain boundaries. The grain boundaries between precipitates are depleted in copper. Al-Cu thin films heat treated at lower temperatures, within the two phase region, also have {theta}-phase precipitates at the grain boundaries but the aluminum grain boundaries continuously become enriched in copper, perhaps due to the formation of a thin coating of {theta}-phase at the grain boundary. Here, it is proposed that electromigration behavior of aluminum is improved by adding copper because the {theta}-phase precipitates may hinder aluminum diffusion along the grain boundaries. It was also found that resistivity of Al-Cu thin films decrease during accelerated electromigration testing prior to failure. Pure Al films did not exhibit this behavior. The decrease is resistivity is attributed to the redistribution of copper from the aluminum grain matrix to the {theta}-phase precipitates growing at the grain boundaries thereby reducing the number of defects in the microstructure. 34 refs., 12 figs.
The large deformation elastic response of a plane woven Kevlar fabric is investigated analytically and experimentally. The analysis assumes the undeformed geometry to be a sequence of interlaced arcs of circles which reverse at each yarn midpoint, ad each yarn is modeled as an extensible elastical subject to certain compatibility conditions. Deflection-force relations for the fabric are determined in terms of the initial weave geometry and the elastic properties of the individual yarns. The theoretical results agree well with the results of experiments performed on a fabric woven from 400 denier Kevlar yarns under conditions of uniaxial loading in both warp and fill directions. 13 refs., 4 figs.