Publications

The Waste Isolation Pilot Plant (WIPP), located in southeastern New Mexico, is a research and development facility to demonstrate safe disposal of defense-generated transuranic waste. Performance assessment comprises scenario development and screening and probability assignment; consequence analysis; sensitivity and uncertainty analysis; and comparison with a standard. This report examines events and processes that might give rise to scenarios for the long-term release of waste from the WIPP and begins to screen and assign probabilities to them. The events and processes retained here will be used to develop scenarios during the WIPP performance assessment; the consequences of scenarios that survive screening will be calculated and compared with the standard. 84 refs., 4 figs., 3 tabs.

Coherent phase transformation occurs under conditions of stress wave loading and there are indications that transformation is dependent on the nonhydrostatic state of stress in the body. Studies under static loading show transformation proceeds at lower confining pressure when combined with shearing stress and similar effects appear to occur under stress-wave loading. Nonlinearities in the stress-strain behavior due to the transformation strain lead to complicated wave propagation, including wave separation and rarefaction shock waves. In the present study a thermodynamic theory of the combined elastic and phase transformtion deformation is developed which incorporates the interrelation of pressure and shear effects. The theory is focused on wave propagation in solids and is compared with earlier experimental work on Oakhall limestone. A thermodynamic Gibbs potential is derived for the material and a phase equilibrium relation identified, which constrains the volume and shape change through the transformation. The theory is extended to account for the effect of microstructural heterogeneities on the transformation process which has been observed experimentally.

This report describes a demonstration of the performance assessment methodology for the Waste Isolation Pilot Plant (WIPP) to be used in assessing compliance with the Environmental Protection Agency. This demonstration incorporates development and screening of potentially disruptive scenarios. A preliminary analysis of the WIPP disposal system's response to human intrusion scenarios produces preliminary complementary cumulative distribution functions (CCDFs) used to assess the compliance of the WIPP with the Containment Requirements of the Standard. The conceptual model of the disposal system consists of geologic, hydrologic, and disposal system subsystems along with the physical and chemical processes associated with these subsystems. Parameter values defining the systems contain uncertainties and modeling approximations of such a disposal system contributes to those uncertainties. The WIPP compliance assessment methodology consists of a system of techniques and computer codes that estimate releases of radionuclides from the disposal system, incorporating analysis of the parameter uncertainties in the estimates. Demonstration CCDFs are presented, but are not yet credible enough to judge the probability of compliance of the WIPP with the EPA Standard. 60 refs., 75 figs., 30 tabs.

The structural response of plasma armature railguns to the electromagnetic load imposed during operation has a significant effect on performance. The railgun support structure must minimize bore deformation; thus stiffness and strength are important design parameters. The step by step evolution of the design toward a structure which will tolerate operation with 500 to 700 kA rail currents is presented. The design effort started with the traditional rail/insulator core structure contained within a V-block which provides a preload. Non-linear dynamic analyses together with model tests were used to assess the effects of changes in geometry, materials, and preload on the railgun structural performance. 39 figs., 5 tabs.

The ignition of reactive powders by a semiconductor bridge (SCB) is analyzed by applying a multiphase flow model based upon the theory of mixtures. The hot plasma produced by the SCB permeates the cold granular explosive, deposits its latent heat upon fusing to the grains, therby heating the explosive granular surfaces to energy states required for self-sustained reaction. This mechanism is predicted to heat the granular explosive in a region local to the SCB to temperatures well above those required for thermal ignition. The analysis demonstates that this mechanism explains the prompt ignition of explosives using SCB's as opposed to the conductively controlled heating of conventional bridgewires. 16 refs., 14 figs., 1 tab.

AEROPLT is an interactive, user-friendly, general purpose plot code for plotting tabular data from multiple files. This DISSPLA-based code is convenient and easy to use while permitting great flexibility for users who want to customize their plots. A series of questions leads the user through the program and permits a return to specific portions of the code for plot refinement. Multidevice capability permits the user to plot on the terminal, write to a file for hardcopy plots, or do both simultaneously. An easily modified Setup File is used to store the terminal and hardcopy type codes, plot and text dimensions, and default plot specifications. Parameters for individual plots are written to a Restart File which can easily be edited to change subsequent plots. Additional capabilities are: color plots; a convenient method (similar to TEX) to implement all DISSPLA fonts, character sets, and math alphabets; superscripts, subscripts, underline, and italicize; and plots of the results of mathematical functions of the input data. 12 figs., 21 tabs.

Potentially hazardous test activities have historically been a part of Sandia National Labs mission to design, develop, and test new weapons systems. These test activities include high speed air drops for parachute development, sled tests for component and system level studies, multiple stage rocket experiments, and artillery firings of various projectiles. Due to the nature of Sandia's test programs, the risk associated with these activities can never be totally eliminated. However, a consistent set of policies should be available to provide guidance into the level of risk that is acceptable in these areas. This report presents a general set of guidelines for addressing safety issues related to rocket flight operations at Sandia National Laboratories. Even though the majority of this report deals primarily with rocket flight safety, these same principles could be applied to other hazardous test activities. The basic concepts of risk analysis have a wide range of applications into many of Sandia's current operations. 14 refs., 1 tab.

In this report, we examine two global energy consumption scenarios and corresponding nonenergy scenarios to determine how each will contribute to the greenhouse effect and global warming. A steady emissions trend scenario assumes only modest energy conservation and little change in the world's energy consumption patterns and nonenergy emissions. A reduced emissions trend scenario assumes significant conservation, switching from a more carbon-intensive energy source mix to a less intensive mix, and reducing nonenergy emissions. Based on the difference between the two scenarios' results, our conclusions are that it is possible to reduce global warming by over 50% using a combination of conservation and efficiency improvements, increased use of nuclear, geothermal, and solar/renewable energy sources, and reduced nonenergy emissions. 34 refs.

This report summarizes the results and conclusions generated by the US Nuclear Regulatory Commission sponsored Fire Protection Research Program at Sandia National Laboratories. Efforts conducted from the programs inception in 1975 through 1987 are discussed. The individual efforts are discussed within a framework based on specific areas of investigation. Early efforts are presented in the context of investigations of specific regulatory concerns. Later efforts are presented within the context of an integrated investigation of fire safety issues. This integrated approach considers the fire safety issue in terms of (1) source fire characterization, (2) detection and suppression system effectiveness, (3) room effects, (4) equipment response, and (5) room-to-room fire effects. The report provides a complete bibliography of reports and journal articles generated as a result of these efforts with a cross-reference listing of major reports to specific efforts. 98 refs., 23 figs., 20 tabs.

Gas holdup data for oleci acid at 291 K and for 1018 steel at 1823 K has been taken for nitrogen sparging gas. The liquid levels have been measured using a real time x-ray technique. The data have been compared to correlations from the literature to assess the appropriate correlations for use in calculating gas holdup for molten core debris in reactor accident calculations. A suitable correlation has been determined as well as coefficients for use in a drift flux model. The correlation is in the form {alpha} = 0.128 M{sup -0.0207} jg*{sup 0.584} where {alpha} is holdup, M is the Morton Number and jg* is the dimensionless gas flux through the liquid. 19 refs., 9 figs., 9 tabs.

A method to determine the dynamic shape factor of an aerosol from cascade impactor and TSI Aerodynamic Particle Sizer (APS) distribution measurements is presented and demonstrated. The response of the APS to nonspherical, porous particles is derived after the fashion of Wang and John (1987). This method does not require microscopy or chemical analytical techniques and as such is an improvement over previous methods. 37 refs., 13 figs., 1 tab.

The problem of radiative heat transfer through a gray, emitting, absorbing, and scattering medium with uniform optical properties is reduced to one without scattering through two techniques. One uses scaling laws, and the other uses a self-consistent effective gas temperature. The scaling laws are derived via the P1 approximation to the radiative transfer equation and can be applied to multidimensional problems with nonisothermal media. The effective temperature method is presently restricted to isotropic scattering and isothermal media. Both methods are evaluated in the current study as a function of scattering albedo, wall emissivity, and optical thickness for two different geometries, and two sets of wall and gas temperatures. The effects of scattering anisotropy are also assessed for the P1 method.

Unsteady Surface Element (USE) methods are applied to a model of a thermocouple wire attached to a thin disk. Green's functions are used to develop the integral equations for the wire and the disk. The model can be used to evaluate transient and steady state responses for many types of heat flux measurement devices including thin skin calorimeters and circular foil (Gardon) heat flux gages. The model can accommodate either surface or volumetric heating of the disk. The boundary condition at the outer radius of the disk can be either insulated or constant temperature. Effect on the errors of geometrical and thermal factors can be assessed. Examples are given.

The determination of the fully plastic response and pressure limit of high pressure containment structures is of considerable importance in design. The plastic-strain response during and following autofrettage operations, in comparison with the limiting strain condition, is of special interest. This paper presents the results of an analysis method for thick wall, high pressure, cylinders where the effective plastic strain distribution through the thickness is the material response variable of primary interest. The limiting value of this effective plastic strain depends on the level of tensile-stress triaxiality which also varies through the thickness. This strain-to-failure criterion is used to predict the complete pressure versus strain response and the maximum pressure for test cylinders. A simple method of effective-stress versus effective plastic strain is employed. This model is quantified by data taken from uniaxial, tension, true-stress-strain curves and from the fracture zone of the tensile specimen. A sample calculation is included.

The Phase Doppler Particle Analyzer (PDPA) is an LDV-based instrument for simultaneous measurement of single particle size and velocity. A PDPA calibration was performed using well-characterized liquid droplets in the 4 to 80 μm diameter range. Two test liquids were used: oleic acid and kerosone. A standard PDPA instrument and a fiber-optic probe PDPA system were tested. The standard instrument measurements agreed with expected droplet diameters to within the droplet generation accuracy for droplets above 15 μm diameter, and had a measurement accuracy of about 2 μm for smaller droplets.

The linear induction accelerator RADLAC II (Radial Line Accelerator II) is being upgraded to produce a 20-MeV, 40-kA, annular electron beam. Prior to the upgrade, RADLAC II produced a 15-MeV, 15-kA electron beam. Modifications to the pulsed power, injector, and magnetic transport have resulted in a faster-rising flat-topped voltage pulse. A high-quality, 40-kA, 2.0-cm-diameter beam with a low perpendicular thermal velocity has been produced from the injector. The high-quality beam has been accelerated through two accelerating gaps. The final four accelerating stages are being added to RADLAC II, and transport experiments through the full accelerator are beginning. Simulations show that the beam quality will be maintained through the entire accelerator.

Experimental and theoretical work have demonstrated that a proper injector design results in the generation of very-high-brightness beams in a field-immersed foilless diode source which is suitable for use on RADLAC II (a high-current linear induction accelerator for electrons). Time-resolved characterization of the high-brightness immersed diode source was achieved using a time-gated, 2-D X-ray imaging technique. The experiments were performed on the 4-MeV IBEX accelerator and produced currents exceeding 40 kA in a 6-mm-radius, thin annular beam with a measured thermal transverse velocity of 0.1c. For currents of 30 kA, even brighter beams with β2+ = 0.07 were obtained. At lower currents, beams as small as 2 mm in radius were produced with a smaller cathode tip. In all cases, the measured parameters were consistent with 2-D, PIC (particle-in-cell) simulations.

A test method involving simultaneous imposition of temperature cycles and strain on discrete solder joints in a shear orientation is presented. The stress, microstructure, and number of cycles to failure were monitored. Cycles to failure were determined by a continuous electrical detection method. Sodler joints with composition 60Sn-40Pb and 40Sn-40In-20Pb were tested using the method at 20% shear strain. The 60Sn-40Pb alloy had a shorter fatigue lifetime than did 40Sn-40In-20Pb. This is attributed to heterogenous coarsening that concentrates strain in a small area of the 60Sn-40Pb microstructure. In contrast the 40Sn-40In-20Pb microstructure becomes refined. The heterogeneous coarsening also results in cyclic softening in 60Sn-40Pb, which was not observed in 40Sn-40In-20Pb. Failures initiated within the coarsened band in 60Sn-40Pb at Sn-Sn grain boundaries or phase boundaries. In contrast, failures initiated at the surface of 40Sn-40In-20Pb joints and propagated through both phases of the microstructure.

Three different ion beam transport schemes (achromatic lens, wire-guided transport, and Z-discharge channel) for the light ion beam driver for the Laboratory Microfusion Facility (LMF) are examined analytically. For each case the phase space acceptance area is investigated, including the effects of angular momentum. It is shown that, in real diode/transport configurations, there will be some angular momentum (i.e., φ0 ≠ 0) created, e.g., by combinations of diode microdivergence, beam steering errors, foil scattering, and gas scattering. Both the ballistic/lens case and the channel case can accept φ0 = 0 beams if they can be made, and can also tolerate certain amounts of φ0 ≠ 0. On the other hand, the wire case requires φ0 ≠ 0 in a carefully prepared manner. It is concluded that, in regard to angular momentum, the baseline ballistic case is the most accepting transport scheme. The channel transport scheme is less accepting. The wire transport scheme is the least accepting because it requires a tailored nonzero φ0 distribution to be fully accepted.

The nominal 1000-MJ yield of a Laboratory Microfusion Facility (LMF) pellet requires at least a 1.5-m-radius target chamber to contain the blast. A geometry has been identified that uses an annular ion beam with a center plug, has a total transport length of 4 m, and allows no direct line of sight from the target blast to the ion diode. An analytic model for an achromatic, two-lens system that is capable of transporting a 30-MV, 1-MA Li ion beam over this distance has been developed. The system uses both self-Bθ and solenoidal magnetic lenses. The beam microdivergence requirement is minimized by locating the final solenoidal lens at the target chamber wall. In the present work, the analytic model was verified by PIC (particle-in-cell) transport calculations. A realistic coil system has been designed to supply the required 2-T solenoidal fields. Simulations show that a lithium beam can be transported over the 4-m distance with better than 70% energy and power efficiency, delivering roughly 1 MJ/beam to the target if a 6-mrad microdivergence is achieved at the diode.

SAVI (Systematic Analysis of Vulnerability to Intrusion) is a PC-based software package for modeling and analyzing physical protection systems. SAVI implements several features that make it a unique product. First, the user interface for site modeling and data entry is simple and flexible. Second, the SAVI model analyzes all adversary paths to the target location and, if selected, all exit paths from the target location. Third, a reference catalog and database are included that define the protection elements and safeguards components, and give detection and delay performance values for the components. Finally, SAVI's results are output in graphic form and include recommendations for upgrade.

This paper discusses the following topics: theoretical predictions of valence and conduction band offsets in III-V semiconductors; reflectance modulation of a semiconductor superlattice optical mirror; magnetoquantum oscillations of the phonon-drag thermoelectric power in quantum wells; correlation between photoluminescence line shape and device performance of p-channel strained-layer materials; control of threading dislocations in heteroepitaxial structures; improved growth of CdTe on GaAs by patterning; role of structure threading dislocations in relaxation of highly strained single-quantum-well structures; InAlAs growth optimization using reflection mass spectrometry; nonvolatile charge storage in III-V heterostructures; optically triggered thyristor switches; InAsSb strained-layer superlattice infrared detectors with high detectivities; resonant periodic gain surface-emitting semiconductor lasers; performance advantages of strained-quantum-well lasers in AlGaAs/InGaAs; optical integrated circuit for phased-array radar antenna control; and deposition and novel device fabrication from Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub y} thin films.

The FALCON (Fission Activated Laser CONcept) reactor-pumped laser program at Sandia National Laboratories is examining the feasibility of high-power systems pumped directly by the energy from a nuclear reactor. In this concept we use the highly energetic fission fragments from neutron induced fission to excite a large volume laser medium. This technology has the potential to scale to extremely large optical power outputs in a primarily self-powered device. A laser system of this type could also be relatively compact and capable of long run times without refueling.

EPSILON-2 is a general parallel computer architecture that combines the fine grain parallelism of dataflow computing with the sequential efficiency common to von Neumann computing. Instruction level synchronization, single cycle context switches, and RISC-like sequential efficiency are all supported in EPSILON-2. The general parallel computing model of EPSILON-2 is described, followed by a description of the processing element architecture. A sample code is presented in detail, and the progress of the physical implementation discussed. 11 refs., 14 figs.

In the radiation-hardened, optically triggered thyristor development being carried out jointly by Organizations 1141 and 2531, a theoretical model was needed to assist in designing the devices. This model had to accurately predict thyristor performance (e.g., breakover voltage and holding current) for different fabrication and experimental parameters such as doping, layer thickness, temperature, and incident optical intensity. This report describes a mode we are currently developing that is based on treating a p-n-p-n thyristor as coupled p-n-p and n-p-n transistors. This approach has the advantages of providing tractability of the physics that govern thyristor behavior without requiring extensive numerical computations. When benchmarked by a more rigorous (and, consequently, computationally more complicated) treatment, our model should provide accurate and fast screening of a wide range of thyristor configurations. Section 2 describes the general thyristor configuration we wish to investigate. The derivation of the basic equations for our thyristor model is presented in Sections 3. These equations depends on the saturation currents and multiplication factors at each p-n junction, and on the current gains of p-n-p and n-p-n transistors.