The transportation risk analysis code, RADTRAN 4, computer estimates of incident-free dose consequence and accident dose-risk. The output of the code includes a tabulation of sensitivity of the result to variation of the input parameters for the incident-free analysis. The values are calculated using closed mathematical expressions derived from the constitutive equations, which are linear. However, the equations for accident risk are not linear, in general, and a similar tabulation has not been available. Because of the importance of knowing how accident-risk estimates are affected by uncertainties in the input parameters, a direct investigation was undertaken of the variation in calculated accident dose-risk with changes in individual parameters. A limited, representative group of transportation scenarios was used, initially, to determine which of 23 accident-risk parameters affect the calculated accident dose risk significantly. Many of the parameters were observed to have minimal effect on the output, and others were judged as ``fixed`` either by regulation, convention or standards. The remaining 5 variables were selected for further study through Latin Hypercube Sampling (LHS). LHS yields statistical information from observations (risk calculations) resulting from multiple input-parameter sets compiled from ``random`` sampling of parameter distributions. The LHS method requires fewer observations than classical Monte Carlo methods to yield statistically significant results. This paper presents the preliminary parameter study and LHS application results together with further LHS evaluations of RADTRAN input parameters.
This document contains information about the research and development programs dealing with waste transport at Sandia National Laboratories. This paper discusses topics such as: Why new packaging is needed; analytical methodologies and design codes;evaluation of packaging components; materials characterization; creative packaging concepts; packaging engineering and analysis; testing; and certification support.
In 1993, the mirror facets of one of Sandia`s point-focusing solar collectors, the Test Bed Concentrator {number_sign}2 (TBC-2), were reconditioned. The concentrator`s optical performance was evaluated before and after this operation. This report summarizes and compares the results of these tests. The tests demonstrated that the concentrator`s total power and peak flux were increased while the overall flux distribution in the focal plane remained qualitatively the same.
Computational physicists at Sandia National Laboratories have moved the Eulerian CTH code, and the arbitrary-Lagrangian-Eulerian ALEGRA code to distributed memory parallel computers. CTH is a three-dimensional solid mechanics code used for large-deformation, shock wave analysis. ALEGRA is a three-dimensional arbitrary Lagrangian-Eulerian solid-mechanics code used for coupled large-deformation, shock and structural mechanics problems. This paper discusses our experiences moving the codes to parallel computers, the algorithms we used and our experiences running the codes.
The report presents an evaluation of worldwide research efforts in three specific renewable energy technologies, with a view towards future United States (US) energy security, environmental factors, and industrial competitiveness. The overall energy technology priorities of foreign governments and industry leaders, as well as the motivating factors for these priorities, are identified and evaluated from both technological and policy perspectives. The specific technologies of interest are wind, solar thermal, and solar photovoltaics (PV). These program areas, as well as the overall energy policies of Denmark, France, Germany, Italy, the United Kingdom (UK), Japan, Russia, and the European Community as a whole are described. The present and likely future picture for worldwide technological leadership in these technologies-is portrayed. The report is meant to help in forecasting challenges to US preeminence in the various technology areas, particularly over the next ten years, and to help guide US policy-makers as they try to identify specific actions which would help to retain and/or expand the US leadership position.
Sleefe, G.E.; Engler, B.P.; Drozda, P.M.; Franco, R.J.; Morgan, J.
The Advanced Geophysical Technology Department (6114) and the Telemetry Technology Development Department (2664) have, in conjunction with the Oil Recovery Technology Partnership, developed a Multi-Level Seismic Receiver (MLSR) for use in crosswell seismic surveys. The MLSR was designed and evaluated with the significant support of many industry partners in the oil exploration industry. The unit was designed to record and process superior quality seismic data operating in severe borehole environments, including high temperature (up to 200{degrees}C) and static pressure (10,000 psi). This development has utilized state-of-the-art technology in transducers, data acquisition, and real-time data communication and data processing. The mechanical design of the receiver has been carefully modeled and evaluated to insure excellent signal coupling into the receiver.
This document describes the results of the Workshop on Port Selection Criteria for Shipments of Spent Nuclear Fuel. The workshop was held at the United States Merchant Marine Academy in Kings Point, New York on November 15 and 16, 1993. The workshop panel of maritime experts developed criteria for the US Department of Energy for the evaluation and selection of ports of entry for spent-fuel shipments. While recommending criteria for selecting ports, the workshop panel agreed that any port capable of handling an ocean-going vessel is capable of safely receiving spent nuclear fuel.
A comprehensive three-dimensional numerical investigation of the effect of beat source travel speed on temperatures and resulting thermal stresses was performed for CO{sub 2}-laser welding. The test specimen was a small thermal battery header containing several stress-sensitive glass-to-metal seals surrounding the electrical connections and a temperature sensitive ignitor located under the header near the center. Predictions of the thermal stresses and temperatures in the battery header were made for several travel speeds of the laser. The travel speeds examined ranged from 10mm/sec to 50mm/sec. The results indicate that faster weld speeds result in lower temperatures and stresses for the same size weld. This is because the higher speed welds are more efficient, requiring less energy to produce a given weld. Less energy absorbed by the workpiece results in lower temperatures, which results in lower stresses.
Electrochemically formed porous silicon (PS) was reported in 1991 to exhibit visible photoluminescence. This discovery could lead to the use of integrated silicon-based optoelectronic devices. This LDRD addressed two general goals for optical emission from Si: (1) investigate the mechanisms responsible for light emission, and (2) tailor the microstructure and composition of the Si to obtain photoemission suitable for working devices. PS formation, composition, morphology, and microstructure have been under investigation at Sandia for the past ten years for applications in silicon-on-insulator microelectronics, micromachining, and chemical sensors. The authors used this expertise to form luminescent PS at a variety of wavelengths and have used analytical techniques such as in situ Raman and X-ray reflectivity to investigate the luminescence mechanism and quantify the properties of the porous silicon layer. Further, their experience with ion implantation in Si lead to an investigation into alternate methods of producing Si nanostructures that visibly luminesce.
The present study offers new data and analysis on the transient shock strength and equation-of-state properties of ceramics. Various dynamic data on nine high strength ceramics are provided with wave profile measurements, through velocity interferometry techniques, the principal observable. Compressive failure in the shock wave front, with emphasis on brittle versus ductile mechanisms of deformation, is examined in some detail. Extensive spall strength data are provided and related to the theoretical spall strength, and to energy-based theories of the spall process. Failure waves, as a mechanism of deformation in the transient shock process, are examined. Strength and equation-of-state analysis of shock data on silicon carbide, boron carbide, tungsten carbide, silicon dioxide and aluminum nitride is presented with particular emphasis on phase transition properties for the latter two. Wave profile measurements on selected ceramics are investigated for evidence of rate sensitive elastic precursor decay in the shock front failure process.
Under a cooperative research and development agreement with General Motors Corporation, lead-free solder systems including the flux, metallization, and solder are being developed for high temperature, underhood applications. Six tin-rich solders, five silver-rich metallizations, and four fluxes were screened using an experimental matrix whereby every combination was used to make sessile drops via hot plate or Heller oven processing. The contact angle, sessile drop appearance, and in some instances the microstructure was evaluated to determine combinations that would yield contact angles of less than 30{degrees}, well-formed sessile drops, and fine, uniform microstructures. Four solders, one metallization, and one flux were selected and will be used for further aging and mechanical property studies.
Sandia National Laboratories is one of the Department of Energy`s primary research and development laboratories. Our essential mission is to support the national interests of the US in defense, energy, and the environment. Managed by Martin Marietta Corporation for DOE, Sandia focuses its resources on problems of national interest that require the integration of science and technology for their solution. We all hope that this period of sweeping alterations in international affairs will result in a successful transition from the Cold War to a period of sustainable global security and prosperity. In the meantime, our nation`s interests are best served by continued commitment to Sandia`s traditional responsibilities. Nonetheless, as momentous developments are reshaping the world, Sandia is also changing from its beginning as a closed operation concentrating on classified defense programs, Sandia has become a more accessible resource that focuses on research and development partnerships with industry and universities as a way to ensure continued success in DOE`s evolving core mission area of nuclear weapons, energy, environment, and the basis sciences. Through these collaborative efforts, Sandia and its partners are also benefiting the economic competitiveness of our nation. Sandia places a special emphasis on working with small businesses as both technology transfer partners and suppliers of goods and services. We are also reaching out the the larger community surrounding Sandia, striving to provide technological solution and accurate information to meet community needs. We believe that the dialogue we are creating will benefit Sandia, the community, and the nation. Our goal is to render `` exceptional service in the national interest`` by returning maximum value on the investment in the labs. As you review this document, look for new ways in which Sandia can contribute to the solution of problems facing our nation.
The US Department of Energy (DOE) is preparing to request the US Environmental Protection Agency to certify compliance with the radioactive waste disposal standards found in 40 CFR Part 191 for the Waste Isolation Pilot Plant (WIPP). The DOE will also need to demonstrate compliance with a number of other State and Federal standards and, in particular, the Land Disposal Restrictions of the Resource Conservation and Recovery Act (RCRA), 40 CFR Part 268. Demonstrating compliance with these regulations requires an assessment of the long-term performance of the WIPP disposal system. Re-evaluation and extension of past scenario development for the WIPP forms an integral part of the ongoing performance assessment (PA) process.
Radiation in participating media is an important transport mechanism in many physical systems. The simulation of complex radiative transfer has not effectively exploited high-performance computing capabilities. In response to this need, a workshop attended by members active in the high-performance computing community, members active in the radiative transfer community, and members from closely related fields was held to identify how high-performance computing can be used effectively to solve the transport equation and advance the state-of-the-art in simulating radiative heat transfer. This workshop was held on March 29-30, 1994 in Albuquerque, New Mexico and was conducted by Sandia National Laboratories. The objectives of this workshop were to provide a vehicle to stimulate interest and new research directions within the two communities to exploit the advantages of high-performance computing for solving complex radiative heat transfer problems that are otherwise intractable.
Perimeter intrusion detection systems are an integral part of most physical security systems. Sandia National Laboratories, under the sponsorship of the U.S. Department of Energy, Office of Safeguards and Security; the U.S. Military Services; and many other U.S. Government Agencies, has over the last 20 years conducted surveys of available perimeter intrusion detection sensors and has tested many of the sensors manufactured in the United States and other countries. An overview of the newer and more advanced technologies employed in these sensors is provided.
Several studies have shown that the surface morphology can be smoother during simultaneous ion bombardment and growth than during growth alone, however, the atomistic mechanism responsible for the smoothing effect has been difficult to determine. We have developed Monte Carlo simulations of growth and defect diffusion to model the interaction between growth atoms and ion-induced defects and to present a simple atomistic mechanism that describes the effects of low-energy ion bombardment during ion-assisted growth of germanium. Measurements of ion-induced point defect production indicate that a large number of defects exist only temporarily on the surface at typical growth temperatures, because the defects have sufficient mobility to recombine and annihilate. We propose that this ion-induced transient defect population plays a significant role in modifying the dynamic surface morphology. The simulations support a surface smoothing mechanism that involves the destabilization of adatom islands by the transient ion-induced defects. The optimum simulated steady-state surface morphology can be achieved with ion-induced defect production rates less than or equal to 10 defects/ion. We find that low-energy ion bombardment during growth effectively lowers the temperature at which step-flow growth can be achieved.
We have characterized the optical properties of heteroepitaxial Si1-xCx and Si0.924-xGe0.076Cx (0≤x≤0.014) alloys grown on Si substrates by solid phase epitaxy using spectroscopic ellipsometry. The measured dielectric function confirms that the samples are of good crystalline quality. We determined the E1 and E2 band gaps by lineshape-fitting the features in the second derivative spectra of the dielectric functions. Also, we discuss the shift of the band gaps with C concentration arising from strain and chemical alloying.
Inferring phylogenetic trees is a fundamental problem in computational-biology. We present a new objective criterion, the phylogenetic number, for evaluating evolutionary trees for species defined by biomolecular sequences or other qualitative characters. The phylogenetic number of a tree T is the maximum number of times that any given character state arises in T. By contrast, the classical parsimonycriterion measures the total number of times that different character states arise in T. We consider the following related problems: finding the tree with minimum phylogenetic number, and computing the phylogenetic number of a given topology in which only the leaves are labeled by species. When the number of states is bounded (as is the case for biomolecular sequence characters), we can solve the second problem in polynomial time. We can also compute a fixed-topology 2-phylogeny (when one exists) for an arbitrary number of states. This algorithm can be used to further distinguish trees that are equal under parsimony. We also consider a number of other related problems.
The NASA Standard Detonator (NSD) is employed in support of a number of current applications, including the Space Shuttle. This effort was directed towards providing test results to characterize the output of this device for its use in a safe and arm device. As part of the investigation, flash X-ray was used to provide stop-motion photographs of the flying metal plate that is created by initiation of the detonator. This provided researchers with a better understanding of the shape and character of the high- velocity disk as it propagated across the gap between the detonator and next assembly. The second portion of the study used a velocity interferometer to evaluate the acceleration and velocity histories of the flying plate, providing a quantified assessment of the detonator’s ability to initiate the explosive in the next explosive.
For many years, explosive components have used hotwires to convert an electrical stimulus into the thermal energy required to initiate the device. A Semi-conductor Bridge (SCB) performs the same function, but with the advantage of requiring approximately 1/10 the input energy of a comparable hotwire, while retaining excellent no-fire characteristics. The SCB also demonstrates faster function times due to its inherently-lower thermal mass. This paper discusses the development and production of two SCB-based devices, the MC4491 Initiator and the MC4492 Actuator. The initiator is designed to shock initiate a linear shaped charge by accelerating a thin metal plate across a small gap. The actuator functions several different components, sewing as either an actuator by producing a rapidly expanding gas to activate piston mechanisms or as an ignitor by providing hot particles for initiating pyrotechnic mixtures. Details are provided on the construction of both devices, methods of assembly, and performance characteristics (function time, flyer velocity, pressure in a closed bomb, heat content, and no-fire and all-fire levels).
Proceedings of the IEEE International Symposium on Assembly and Task Planning
Hwang, Yong K.
We present a motion planner for multiple moving objects in two dimensions. The search for collision-free paths is performed in the composite configuration space of all the moving objects to guarantee a solution, and the efficiency of our planner is demonstrated with examples. Our motion planner can be characterized with a hierarchical, multi-resolution search of the configuration space along with a generate-and-test paradigm for solution paths. Because of the high dimensionality of the composite configuration space, our planner is most useful for cases with a small number of moving objects. Some of the potential applications are navigation of several mobile robots, and planning part motions for a multi-handed assembly operation.
Proceedings of the IEEE International Symposium on Assembly and Task Planning
Hwang, Yong K.
There have been numerous research efforts in the field of motion planning, resulting in many theoretical and practical results. We review the current status of existing motion planning algorithms, evaluate their completenesses and efficiencies on modern computers, and suggest fruitful future research directions.
The semiconductor bridge, SCB, developed by Sandia National Laboratories is a maturing technology now being used in several applications by Sandia customers. Most applications arose because of a need at the system level to provide explosive assemblies that were light weight, small volume, low cost and required small quantities of electrical energy to function — for the purposes of this paper we define an explosive assembly to mean the combination of the firing set and an explosive component. As a result, and because conventional firing systems could not meet the stringent size, weight and energy requirements of our customers, we designed and are investigating SCB applications that range from devices for Sandia applications to igniters for fireworks. We present in this paper an overview of SCB technology with specific examples of the systems designed for our customers to meet modern requirements that sophisticated explosive systems must satisfy in today’s market environments.