Publications

MELCOR is a fully integrated, engineering-level computer code being developed at Sandia National Laboratories for the USNRC, that models the entire spectrum of severe accident phenomena in a unified framework for both BWRs and PWRs. As a part of an ongoing assessment, program, MELCOR has been used to model the ACRR in-pile DF-4 Damaged Fuel experiment. DF-4 provided data for early phase melt progression in BWR fuel assemblies, particularly for phenomena associated with eutectic interactions in the BWR control blade and zircaloy oxidation in the canister and cladding. MELCOR provided good agreement with experimental data in the key areas of eutectic material behavior and canister and cladding oxidation. Several shortcomings associated with the MELCOR modeling of BWR geometries were found and corrected. Twenty-five sensitivity studies were performed on COR, HS and CVH parameters. These studies showed that the new MELCOR eutectics model played an important role in predicting control blade behavior. These studies revealed slight time step dependence and no machine dependencies. Comparisons made with the results from four best-estimate codes showed that MELCOR did as well as these codes in matching DF-4 experimental data.

Modern nuclear safety themes depend on excluding unwanted energy from the components required for nuclear detonation. The exclusion region barrier is designed to provide protection from extraneous energy. The barrier must remain unbreached for both normal operations and accident events. Recent advances in computational capabilities permits more accurate modeling of barrier tearing during the extreme mechanical loadings associated with accidents. This report describes a methodology which employs design of experiments strategies coupled with finite element analyses and testing to produce results suitable for inclusion in a guide to design exclusion region barriers. The general approach was to employ finite element analyses to define the effect of materials property and geometric feature parameters on a generic barrier geometry. These parametric studies were based on design of experiments strategies. Four materials properties and six geometric features were included in the parameters. Selected geometries were tested to provide verification of the analyses. Statistical analysis of the results from the finite element analyses identified the important parameters (primarily the material property, true strain-to-failure, along with certain geometric characteristics) which were used to synthesize simplified equations and graphics suitable for inclusion into a guide for designers and safety analysts.

Experiments were done to determine effect of lattice damage on solubility and transport of deuterium (D) in silicon carbide. Beta SiC samples were irradiated with energetic ions to produce lattice damage, and were then soaked in D{sub 2} gas at 1000C. Concentration of D versus depth was then measured by nuclear reaction analysis. Very near the surface (<0.5{mu}m), concentration of D was larger in irradiated than in unirradiated, but beyond 1 {mu}m the D concentrations were similar ({approximately}20{plus_minus}10 atomic ppM), even though the damage extended to 2.2 {mu}m in most of the samples. Results from this study of ion-irradiated SiC together with our previous study of tritium migration in undamaged SiC point to the conclusion that uptake of D from gas into SiC occurs by transport along grain boundaries, whereas uptake of D into lattice damage produced by ion irradiation, and release of energetically implanted D both require permeation of D within grains which is much slower.

This report presents equations and computational algorithms for analyzing reliability of several forms of redundancy in repairable and non-repairable systems. For repairable systems, active, standby, and R of N redundancy with and without repair are treated. For non-repairable systems, active, standby, and R of N redundancy are addressed. These equations can be used to calculate mean time between failures, mean time to repair, and reliability for complex systems involving redundancy.

An eXplosive CHEMical kinetics code, XCHEM, has been developed to solve the reactive diffusion equations associated with thermal ignition of energetic materials. This method-of-lines code uses stiff numerical methods and adaptive meshing to resolve relevant combustion physics. Solution accuracy is maintained between multilayered materials consisting of blends of reactive components and/or inert materials. Phase change and variable properties are included in one-dimensional slab, cylindrical and spherical geometries. Temperature-dependent thermal properties have been incorporated and the modification of thermal conductivities to include decomposition effects are estimated using solid/gas volume fractions determined by species fractions. Gas transport properties, including high pressure corrections, have also been included. Time varying temperature, heat flux, convective and thermal radiation boundary conditions, and layer to layer contact resistances have also been implemented.

This report presents a five year plan for the laboratory. This plan takes advantage of the technical strengths of the lab and its staff to address issues of concern to the nation on a scope much broader than Sandia`s original mission, while maintaining the general integrity of the laboratory. The plan proposes initiatives in a number of technologies which overlap the needs of its customers and the strengths of its staff. They include: advanced manufacturing technology; electronics; information and computational technology; transportation energy technology and infrastructure; environmental technology; energy research and technology development; biomedical systems engineering; and post-cold war defense imperatives.

This report provides the results and analyses of a detailed survey undertaken in Summer 1993 to address integrated intrusion detection alarm annunciation and entry control system issues. This survey was undertaken as a first attempt toward beginning to answer questions about integrated systems and commercial capabilities to meet or partially meet US Department of Energy (DOE) site needs.

Hanford`s underground storage tanks (USTs) pose one of the most challenging hazardous and radioactive waste problems for the Department of Energy (DOE). Numerous schemes have been proposed for removing the waste from the USTs, but the technology options for doing this are largely unproven. To help assess the options, an Independent Review Group (IRG) was established to conduct a broad review of retrieval systems and the tank waste remediation system. The IRG consisted of the authors of this report. The IRG`s Preliminary Report assessed retrieval systems for underground storage tank wastes at Hanford in 1992. Westinghouse Hanford Company (WHC) concurred with the report`s recommendation that a tool should be developed for evaluating retrieval concepts. The report recommended that this tool include (1) important considerations identified previously by the IRG, (2) a means of documenting important decisions concerning retrieval systems, and (3) a focus on evaluations and assessments for the Tank Waste Remediation System (TWRS) and the Underground Storage Tank-Integrated Demonstration (UST-ID).

This document presents the objectives, accomplishments and activity plan for the Sandia Wind Energy Technology Program. The status of the current program is summarized and the planned FY94 activities are defined. Appendices detailing the cost, performance and schedule associated with these activities are also included. Funding requirements are given for several scenarios in order to reflect the impact of funding variability on program progress.

The Sandia National Laboratories, New Mexico (SNL/NM) Site-Wide Hydrogeologic Characterization (SWHC) project has been implemented as part of the SNL/NM Environmental Restoration (ER) Program to develop the regional hydrogeologic framework and baseline for the approximately 100 mi of Kirtland Air Force Base (KAFB) and adjacent withdrawn public lands upon which SNL/NM has performed research and development activities. Additionally, the SWHC project will investigate and characterize generic hydrogeologic issues associated with the 172 ER sites owned by SNL/NM across its facilities on KAFB. As called for in the Hazardous and Solid Waste Amendments (HSWA) to the Resource Conservation and Recovery Act (RCRA) Part B permit agreement between the U.S. Environmental Protection Agency (EPA) as the permitter and the U.S. Department of Energy (DOE) and SNL/NM as the permittees, an annual report is to be prepared by the SWHC project team. This document serves two primary purposes: (1) to identify and describe the conceptual framework for the hydrogeologic system underlying SNL/NM and (2) to describe characterization activities undertaken in the preceding year that add to our understanding (reduce our uncertainties) regarding the conceptual and quantitative hydrogeologic framework. This SWHC project annual report focuses primarily on purpose 1, providing a summary description of the current {open_quotes}state of knowledge{close_quotes} of the Sandia National Laboratories/Kirtland Air Force Base (SNL/KAFB) hydrogeologic setting.

Small-polarons will only form in covalent crystals whose electronic halfbandwidths are sufficiently narrow, E{sub b} > W. The absence of small polaronic carriers in most covalent crystals presumably indicates that E{sub b} < W in these instances. However, evidence of small polarons is commonly found in disordered materials despite the estimates of E{sub b} and W not being significantly different from those of crystals. This result is ration by stating that disorder has slowed carrier motion enough to permit small-polaron formation. Recently the question of how disorder affects the stability of quasifree carriers with respect to small-polaron formation has been addressed. It is found that only modest energetic disorder is required to induce small-polaron formation. Here I first succinctly describe essential elements of this work. Second, I address the role of disorder on the adiabatic hopping motion of small polarons. Energy bands in most materials in which small-polarons are found are thought to be sufficiently wide (> a phonon energy) that the small-polaronic hopping is ``adiabatic.`` That is, the electronic carriers move between sites sufficienfly rapidly to follow the atomic motions. In this situation the small-polaron jump rates are independent of intersite separations. The magnitudes of the preexponential factors of the measured hopping mobilities typically support this view. Further support for this picture is found from experiments that determine weak dependences of the mobility on hydrostatic pressure.

The introduction of rapid prototyping machines into the marketplace promises to revolutionize the process of producing prototype parts with production-like quality. In the age of concurrent engineering and agile manufacturing, it is necessary to exploit applicable new technologies as soon as they become available. The driving force behind integrating these evolutionary processes into the design and manufacture of prototype parts is the need to reduce lead times and fabrication costs, improve efficiency, and increase flexibility without sacrificing quality. Sandia utilizes Stereolithography (SL) and Selective Laser Sintering (SLS) capabilities to support internal design and manufacturing efforts. SL is used in the design iteration process to produce proof-of-concept models, hands-on models for design reviews, fit-check models, visual aids for manufacturing, and functional parts in assemblies. SLS is used to produce wax patterns for the lost wax process of investment casting in support of an internal Sandia National Laboratories program called FASTCAST which integrates experimental and computational technologies into the investment casting process. This presentation will provide a brief overview of the SL and SLS processes and address our experiences with these technologies from the standpoints of application, accuracy, surface finish, and feature definition. Also presented will be several examples of prototype parts manufactured by the Stereolithography and Selective Laser Sintering rapid prototyping machines.

Technical advances in lead-acid battery design have created new opportunities for battery systems in telecommunications, computer backup power and vehicle propulsion power. Now the lead-acid battery has the opportunity to become a major element in the mix of technologies used by electric utilities for several power quality and energy and resource management functions within the network. Since their introduction into industrial applications, Valve Regulated Lead-Acid (VRLA) batteries have received widespread acceptance and use in critical telecommunications and computer installations, and have developed over 10 years of reliable operational history. As further enhancements in performance, reliability and manufacturing processes are made, these VRLA batteries are expanding the role of battery-based energy storage systems within utility companies portfolios. This paper discusses the rationale and process of designing, optimizing and testing VRLA batteries for specific utility application requirements.

This paper describes an approach to developing a business plan which also serves as a quality plan and quality manual. It is organized following the major categories of the Malcolm Baldrige National Quality Award. It has been applied to the Measurement Standards Program Operations at Sandia National Laboratories.

Sandia National Laboratories (SNL) is engaged actively in research to improve the ability to accurately predict the response of engineered systems to thermal and structural abnormal environments. Abnormal environments that will be addressed in this paper include: fire, impact, and puncture by probes and fragments, as well as a combination of all of the above. Historically, SNL has demonstrated the survivability of engineered systems to abnormal environments using a balanced approach between numerical simulation and testing. It is necessary to determine the response of engineered systems in two cases: (1) to satisfy regulatory specifications, and (2) to enable quantification of a probabilistic risk assessment (PRA). In a regulatory case, numerical simulation of system response is generally used to guide the system design such that the system will respond satisfactorily to the specified regulatory abnormal environment. Testing is conducted at the regulatory abnormal environment to ensure compliance.

A wide variety of space-based system components have been qualified for use through neutron irradiation testing performed at the Sandia Pulsed Reactor (SPR) Facility. The SPR Facility is the operating location for two fast burst reactors, SPR II and SPR III, which have been used to induce neutron and gamma damage in electronic components and other materials for customers in the Department of Energy, Department of Defense, NASA,, and the private sector. In addition to the pulse mode of operation, during which peak fluxes of up to lel9 n/cm{sup 2}{minus}s are achieved, the steady state mode allows for the long term irradiation of components and systems in a fast neutron environment at a flux of up to 5e11 n/cm{sup 2}{minus}s. The SPR reactors are operated in a 9.2 meter diameter exposure cell, or Kiva, suitable for the irradiation of large test articles external to the reactors. Currently, a new upgraded version of SPR Ill (SPR IIIM) is in fabrication; a unique feature of SPR IIIM is its 19 cm (usable diameter) central irradiation cavity, the largest of any US fast burst reactor. An improved cooling system permits continuous operation at power levels in excess of 20 kW{sub t}. The SPR Facility is also the operating site for a critical assembly which was used to characterize prototypic fuels in arrays appropriate for the Space Nuclear Thermal Propulsion Program. Work continues on use of the facility to design, build, and operate critical assemblies for a diverse customer base.

The present political and environmental climate may slow the inevitable direct utilization of nuclear power in space. In the meantime, there is another approach for using nuclear energy for space power. That approach is to let nuclear energy generate a laser beam in a ground-based nuclear reactor-pumped laser (RPL), and then beam the optical energy into space. Potential space applications for a ground-based RPL include (1) illuminating geosynchronous communication satellites in the earth`s shadow to extend their lives, (2) beaming power to orbital transfer vehicles, (3) providing power (from earth) to a lunar base during the long lunar night, and (4) removing space debris. FALCON is a high-power, steady-state, nuclear reactor-pumped laser (RPL) concept that is being developed by the Department of Energy with Sandia National Laboratories as the lead laboratory. The FALCON program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at wavelengths of 0.585, 0.703, 0.725, 1.271, 1.733, 1.792, 2.032, 2.63, 2.65, and 3.37 {mu}m with intrinsic efficiency as high as 2.5%. Frequency-doubling the 1.733{minus}{mu}m line would yield a good match for photovoltaic arrays at 0.867 {mu}m. Preliminary designs of an RPL suitable for power beaming have been completed. The MWclass laser is fairly simple in construction, self-powered, closed-cycle (no exhaust gases), and modular. This paper describes the FALCON program accomplishments and power-beaming applications.

The production, suspension and transport of fluorocarbon particulates in rf discharges have been studied using in situ laser light scattering and ex situ chemical analysis. The time evolution of the spatial distribution of suspended particles was obtained by 2-D imaging of the scattered light. The chemistry of the discharge was varied by the use of a range of pure fluorocarbon gases and mixtures with argon, oxygen and hydrogen-containing molecules. The addition of hydrogen to a fluorocarbon discharge increases the rate of formation of particles although these powders are found by FTIR to contain negligible hydrogen. Particle formation rates correlate with polymer deposition rates and are independent of apparatus history. It is proposed that this is a clear example of gas-phase rather than surface processes leading to particle nucleation and growth.

The government electronics community faces the exciting challenge of entering into new of types of partnerships with the commercial electronics industry. Past interactions have been based primarily on the needs of government. Future interactions will be based more on the needs of industry, particularly its need to be competitive in commercial products. The most successful groups will be those most adept at forming this new type of ``win-win`` partner. Fortunately, both government and industry want to make these new partnerships successful. The government is driven by the necessity of establishing a common government/commercial manufacturing base and the desire to support US competitiveness. Industry is driven by the need to partner with government to remain competitive. Unfortunately, there are no detailed guides available to help government electronics groups and their sponsors in the Administration and Congress cross this uncharted terrain. The purpose of this paper is to share some ``lessons learned`` from the experiences of a government electronics group that has been active in establishing these new types of partnerships with industry. It is our hope that by sharing these lessons we will make it easier for other government groups to work with the commercial industry.

The author proposes using the collective Thomson scattering lineshape from ion acoustic waves to measure the spatial structure of local heat transport parameters and collisionality. Ion acoustic peak height asymmetry is used in conjunction with a recently developed model describing the effects of collisional and Landau damping contributions on the low-frequency electron density fluctuation spectrum to extract the relative electron drift. The local heat flux q{sub e} (proportional to drift) and the electron thermal conductivity {kappa}{sub e}{minus}q{sub e}/{gradient}T{sub e} would be inferred from experimentally determined temperature gradients {gradient}T{sub e}. Damping of the entropy wave component at zero mode frequency is shown to be an estimate of the ion thermal conductivity {kappa}{sub i}, and its visibility is a direct measure of the ion-ion mean free path {lambda}{sub ii}.

Sandia National Laboratories (SNL) is actively engaged in research to characterize abnormal environments, and to improve our capability to accurately predict the response of engineered systems to thermal and structural events. Abnormal environments, such as impact and fire, are complex and highly nonlinear phenomena which are difficult to model by computer simulation. Validation of computer results with full scale, high fidelity test data is required. The number of possible abnormal environments and the range of initial conditions are very large. Because full-scale tests are very costly, only a minimal number have been conducted. Scale model tests are often performed to span the range of abnormal environments and initial conditions unobtainable by full-scale testing. This paper will discuss testing capabilities at SNL, issues associated with thermal and structural scaling, and issues associated with extrapolating scale model data to full-scale system response. Situated a few minutes from Albuquerque, New Mexico, are the unique test facilities of Sandia National Laboratories. The testing complex is comprised of over 40 facilities which occupy over 40 square miles. Many of the facilities have been designed and built by SNL to simulate complex problems encountered in engineering analysis and design. The facilities can provide response measurements, under closely controlled conditions, to both verify mathematical models of engineered systems and satisfy design specifications.

Over the past 40 years, Sandia National Laboratories (SNL) has been actively engaged in research to improve the ability to accurately predict the response of engineered systems to abnormal thermal and structural environments. These engineered systems contain very hazardous materials. Assessing the degree of safety/risk afforded the public and environment by these engineered systems, therefore, is of upmost importance. The ability to accurately predict the response of these systems to accidents (to abnormal environments) is required to assess the degree of safety. Before the effect of the abnormal environment on these systems can be determined, it is necessary to ascertain the nature of the environment. Ascertaining the nature of the environment, in turn, requires the ability to physically characterize and numerically simulate the abnormal environment. Historically, SNL has demonstrated the level of safety provided by these engineered systems by either of two approaches: (1) a purely regulatory approach, or (2) by a Probabilistic Risk Assessment (PRA). This paper will address the latter of the two approaches.

We have found that aluminum alloys exhibit unusual passivity when exposed to alkaline Li-salt solutions. Observed passivity is due to the formation of a polycrystalline Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O film on the aluminum surface. This film is persistent in aggressive environments and provides a significant degree of corrosion protection. On this basis, we have developed a simple non-electrolytic method of forming corrosion resistant coatings in alkaline Li-salt solution. This process is procedurally similar to traditional conversion coating methods, offers desirable properties, and has a low toxic hazard. In this paper, coating methods, coating characterization, and coating properties are presented. Results from parallel test performed with a commercial chromate conversion coatings are presented for comparison.

This report discusses fourteen tests which were conducted to investigate the perforation of thin unreinforced concrete slabs. The 4340-steel projectile used in the test series is 50.8 mm in diameter, 355.6 mm in length, has a mass of 2.34 kg. and an ogive nose with caliber radius head of 3. The slabs, contained within steel culverts, are 1.52 m in diameter and consist of concrete with a nominal unconfined compressive strength of 38.2 MPa and maxima aggregate size of 9.5 mm. Slab thicknesses are 284.4, 254.0, 215.9 and 127.0 mm. Tests were conducted at impact velocities of about 313 m/s on all slab thicknesses and about 379 and 471 m/s on the 254.0-mm-thick slab. All tests were conducted at normal incidence to the slab. All tests were conducted at normal incidence to the slab. Information obtained from the tests used to determine the loading (deceleration) on the projectile during the perforation process, the velocity-displacement of the projectile as it perforated the slab, and the projectile position as damage occurred on the backface of the slab. The test projectile behaved essentially as a rigid body for all of the tests.

Sandia`s gas sensor program encompasses three separate electronic platforms: Acoustic Wave Devices, Fiber Optic Sensors and sensors based on silicon microelectronic devices. A review of most of these activities was presented recently in a article in Science under the title ``Chemical Microsensors.`` The focus of the program has been on understanding and developing the chemical sensor coatings that are necessary for using these electronic platforms as effective chemical sensors.