Transport by groundwater within the Culebra Dolomite, an aquifer above the Waste Isolation Pilot Plant (WIPP), is the most probable mechanism for long-term release of radionuclides to the accessible environment. Radionuclides could be retarded by sorption if the groundwater is exposed to sufficient amounts of fracture-lining clays. In this natural-analog study, distributions of U and trace metals have been examined to constrain the strength of clay/solute interactions within the Culebra. Uranium solid/liquid distribution ratios, calculated from U concentrations of groundwaters and consanguineous fracture-filling clays, range from {approximately}80 to 800 m{ell}/g and imply retardation factors of 60 to 500 using a fracture-flow model. Retardation factors inferred from uranium-series disequilibria and {sup 14}C ages in Culebra groundwaters alone are much lower ({approximately}10), implying that clays may contain a significant unreactive component of U. Such a possibility is corroborated by Rb/Sr ages; these imply long-term stability of the clays,with resetting occurring more than 250 Ma ago. Factor analysis and mass-balance calculations suggest, however, that Mg-rich clays are dissolving in Pleistocene-age groundwaters and/or are converting to Na-rich smectites, and that B and Li are taken up from the water by the clays. Apparently, the solution chemistry reflects gradual equilibration of clays with groundwater, but thus far the bulk of the clays remain structurally intact. Measurements of the distribution of U in the Culebra will be more meaningful if the inert and exchangeable components of the U content of the clays can be quantified. 26 refs., 3 figs., 2 tabs.
The authors present sufficient conditions for the design of strictly positive real (SPR), fixed-order dynamic compensators. The primary motivation for designing SPR compensators is for application to positive real (PR) plants. When an SPR compensator is connected to a PR plant in a negative feedback configuration, the closed loop is guaranteed stable for arbitrary plant variations as long as the plant remains PR. Equations that are a modified form of the optimal projection equations, with the separation principle not holding in either the full- or reduced-order case, are given. A solution to the design equations in shown to exist when the plant is PR (or just stable). Finally, the closed-loop system consisting of a PR plant and an SPR compensator is shown to be S-structured Lyapunov stable.
Computer simulation of low-energy ion-solid processes has greatly broadened in scope in recent years. In particular, realistic descriptions of the ion-solid and solid-solid interactions can now be utilized. The molecular dynamics technique, in which the equations of motion of the interacting atoms are numerically integrated, can now be used to characterize ion-solid interactions in a range of model material systems. Despite practical limitations of this procedure, a number of substantial results have appeared. The available results are examined to investigate the qualitative influence that chemical interactions have on low-energy ion-solid processes. 26 refs., 4 figs.
Good quality, low temperature silicon nitride and oxynitride films were deposited downstream from an electron cyclotron resonance (ECR) plasma source using SiH{sub 4} and N{sub 2} gas mixtures. The Si/N ratio and H content in the deposited films were determined using Rutherford backscattering spectrometry (RBS)and elastic recoil detection (ERD). The H concentration was minimum for films with compositions closest to that of stoichiometric Si{sub 3}N{sub 4}. The optimum conditions for producing a stoichiometric Si{sub 3}N{sub 4}were: a SiH{sub 4}/N{sub 2} flow ratio between 0.1 and 0.2, and an electrically isolated sample far from the ECR source. Infrared absorption spectra showed that as the film composition changed from N rich to Si rich the dominant bonds associated with H changed from N-H to Si-H. The addition of O{sub 2} to the background gas formed an oxynitride with a low H content similar to the stoichiometric Si{sub 3}N{sub 4} 10 refs., 4 figs., 2 tabs.
We have used a Tl-Ca-Ba-Cu-O superconducting flux flow transistor (SFFT) as an active impedance converter between Josephson and FET circuitry. The input of the flux flow device is a control line of low impedance that can be driven by a tunnel junction. The output is the signal across the SFFT which is made of a parallel array of weak links. The output impedance is typically greater than 5 {Omega} with a maximum voltage swing of over 100 mV into a 50 {Omega} system. The switching of an all-Nb junction induced a 90 mV voltage swing at the FET input and over 200 mV at the FET output. The line driver can operate anywhere between 4.2K and 85K with minor changes in speed ({plus minus}5 ps) and output level ({plus minus}10 mV). The switching time measured was about 100 ps and was fixture limited. 13 refs., 5 figs.
Archimedes is a prototype mechanical assembly system which generates and executes robot assembly programs from a CAD model input. The system addresses the unrealized potential for flexibility in robotic mechanical assembly applications by automating the programming task. Input is a solid model of the finished assembly. Parts relationships and geometric constraints are deduced from the solid model. A rule-based planner generates a generic'' assembly plan that satisfies the geometric constraints, as well as other constraints embodied in the rules. A retargetable plan compiler converts the generic plan into code specific to an application environment. Execution of the compiled plan in a workcell containing an Adept Two robot, a vision system, and other parts handling equipment will be shown on videotape.
This concept brings a condensed source of tritium into close proximity with an inorganic phosphor. That source may thus become the equivalent of many atmospheres of tritium gas pressure. If both phosphor and tritium source material are optically clear, then a lamp's brightness may be made to scale with optical path length. Proof of principle of this concept has been demonstrated and will be described. A theoretical treatment is presented for the results here and for results from aerogel experiments.
Pressurized water reactor pressure vessels operate under US Nuclear Regulatory Commission (NRC) rules and regulatory guides that are intended to maintain a low probability of vessel failure. The NRC has also addressed neutron embrittlement of pressurized water reactor pressure vessels by imposing regulations on plant operation. Plants failing to meet the operating criteria specified by these rules and regulations are required, among other things, to analytically demonstrate fitness for service in order to continue safe operation. The initial flaw size or distribution of initial vessel flaws is a key input to the required vessel integrity analyses. A fracture mechanics sensitivity study was performed to quantify the effect of the assumed flaw distribution on the predicted vessel performance under a specified pressurized thermal shock transient and to determine the critical crack size. Results of the analysis indicate that vessel performance in terms of the estimated probability of failure is very sensitive to the assumed flaw distribution. 20 refs., 3 figs., 2 tabs.
Inorganic zeolites show promise as an alternative to traditional tritium gas tube light sources. Greater proximity of tritium atoms and luminescing centers, as well as greater tritium loading density, have been obtained within the zeolite aluminosilicate matrix. Zeolites are in addition optically clear and radiation stable. The zeolite radioluminescence program is described. Procedures for obtaining light sources are presented and results are discussed. 12 refs., 1 fig.
Solderability of Class II environmentally exposed Ni-Sn plated Cu substrates was evaluated with 60Sn-40Pb solder. Tin thickness were 10, 50, and 150 {mu}in. The 10 {mu}in. plating gave the smallest solder meniscus rise. A general decrease in contact angle, or increase in wettability, was observed with increasing Sn plating. The environmental exposures retarded the wetting rate and increased the time to maximum wetting, particularly with only 10 {mu}in. of Sn. Although the solderability of the 50 and 150 {mu}in. surfaces were not significantly affected by the test conditions, an intermediate plating thickness of 100 {mu}in. is preferred for processing flexibility. 13 refs., 6 figs., 1 tab.
SICADS is a generic command, control and display software package which provides the capability to generate security systems which employ different hardware and system configurations, but which are controlled by the same software. SICADS was designed to avoid the task of developing new software for each site. By reusing software, expenses are reduced and software quality is increased. Tested software can be reused without modifications. Configurations of security systems vary from site to site. In many systems, a seemingly minor change in configuration has required significant software modifications. SICADS has been designed to isolate site specific information into data files so that it can be easily tailored to fit a site's requirements without changing the software. Using SICADS, it is possible to generate systems which distribute processing and control over several computers and consoles. 1 fig.
The ion-hose instability can catastrophically disrupt a classical electron beam propagating in the ion-focussed regime (IFR). Ion hose is driven by a resonant interaction between the smooth electron-betatron and ion-betatron orbits. In a classical beam phase correlations decay secularly in time c(t)/c(t{sub 0}) {approximately} (t{sub 0}/t){sup n} (0 < n {le} 2). In a stochastic electron beam the electron orbits are chaotic. Such a beam can be immune to resonant instabilities because phase correlations decay exponentially fast c(t)/c(0) {approximately} e{sup {minus}ht} thus destroying the coherence of the electron response on the growth time 1/{gamma}{sub g} if h {approximately} {gamma}{sub g}. Using the same principles we can also envision a stochastic damping cell in which electron phase correlations damp exponentially c(z)/c(0) {approximately} e{sup {minus}hz} thus centering and conditioning a beam more effectively than a classical phase-mixing cell in which c(z)/c(z{sub 0}) {approximately} (z{sub 0}/z){sup n}. A triple-Bennett'' IFR system and the analogous triple-wire'' damping cell are analyzed. The K-entrophy is introduced as a figure-of-merit for such stochastic electron beam systems. 16 refs., 7 figs.
Strained layer structures have received a great deal of attention due both to their possible application in electronic devices and their intrinsic interest. The study of strained layer quantum wells grown using lattice mismatched materials has been widely developed for III-V semiconductors. Strained layer quantum wells grown using II-VI materials have not been studied nearly so much as those from III-V, but they are a rapidly growing field of semiconductor research. The wide gap II-VI materials are of interest because they are generally direct gap materials. This makes them attractive for optoelectronic devices. The majority of the work on strained layer structures in the wide gap tellurium based materials has focused in two areas. The first is the inclusion of Mn to produce dilute magnetic semiconductors (DMS) strained layers and superlattices. The other area is CdTe/ZnTe quantum wells and superlattices. Some related work has been done with CdZnTe/ZnTe structures. For the CdZnTe/CdTe very little work has been done and the majority of that used very small amounts of Zn. In this paper we will present the growth and optical characterization of Cd{sub 1-x}Zn{sub x}Te/CdTe strained single quantum wells (SSQW) where the Zn concentration ranges from about 10 to 50%. 10 refs., 3 figs.
Apollo's OmniBack backup system provides a convenient and effective way of storing network backup information on 8mm tape. In addition it has a journaling facility to write extensive log files, recording the backup process in almost any degree of detail desired. The directory structure and file names used are logical and well-defined. Summary files announce the degree of success of the backup as specified in the work file. The system will run unattended under the UNIX cron command, allowing the backup to be performed during the night when user demands on the network are small and most user files are free.
Agencies that are prime contractors to the Department of Energy (DOE) have developed and are currently instituting a quality initiative which applies a QML-like methodology to a complete discrete semiconductor process. Our goal is to demonstrate that improving the quality of this process is a more efficient method than screening to improve the quality of the semiconductor. The QML methodology, MIL-I-38535, is used to achieve this goal for integrated circuits. Our methods, for discrete semiconductor, applies many of the principles found in this specification to provide structured continuous improvement. Improvement in product performance reduces incoming inspection requirements, resulting in reduced cost and product lead time. This paper describes our methodology for this initiative, which consists of a certification, qualification, and monitoring (CQM) program for the complete semiconductor process. This process includes all technical and administrative activities that effect the quality of a device, beginning with circuit design and ending with the installation of the manufactured device into the electronic component assembly. For the initial application, our CQM program is being implemented on a small signal transistor. Four companies are involved in the partnership: Sandia National Laboratories, a design agency and prime contractor to the DOE; Allied-Signal Aerospace Company, Kansas City Division, a production agency and prime contractor to the DOE (for electronic component assembly); Alliance Electronics, a prime contractor and supplier (for procurement and testing); and Motorola Inc., Semiconductor Products Sector, a manufacturer. 2 refs.
A Nuisance Alarm Data System (NADS) was developed to gather long-term background alarm data on exterior intrusion detectors as part of their evaluation. Since nuisance alarms play an important part in the selection of intrusion detectors for use at Department of Energy (DOE) facilities, an economical and reliable way to monitor and record these alarms was needed. NADS consists of an IBM Personal Computer and printer along with other commercial units to communicate with the detectors, to gather weather data and to record video for assessment. Each alarm, its assessment and the weather conditions occurring at alarm time are placed into a database that is used in the evaluation of the detector. The operating software is written in Turbo Pascal for easy maintenance and modification. A portable system, based on the NADS design, has been built and shipped to other DOE locations to do on-site alarm monitoring. This has been valuable for the comparison of different detectors in the on-site environment and for testing new detectors when the appropriate conditions do not exist or cannot be simulated at the Exterior Intrusion Detection Testbed.
The Department of Energy (DOE) is investigating the use of ductile cast iron (DCI) as a candidate material for radioactive material transportation cask construction. The investigation will include materials testing and full-scale cask testing. The major effort will focus on materials qualification and cask evaluation of the 9 meter and puncture drop test events. The test plan shall include a series of drop tests, and several core bars will be removed from the casting wall for material properties testing. Of particular interest is the evaluation of the material microstructure and fracture toughness parameters. Test instrumentation, used to define cask deceleration loads and strain during the drop tests, will be strategically placed in areas of the greatest structural interest. Part of the testing will include placement of an induced flaw. At the conclusion of the cask drop tests, the induced flaw(s) will be sectioned from the cask body for metallurgical examination. All test results will be documented in the safety analysis report for packaging for submission to the US Nuclear Regulatory Commission (NRC). The goal of this program is a certificate of compliance for DCI from the NRC to transport high-level radioactive materials. The acceptance of DCI within the USA cask design community will offer an alternative to present-day materials for cask construction, and its entry has the potential of providing significant cost-savings.
Accommodation of lattice mismatch is investigated for the case of large ({epsilon} > 0.02) mismatch. The conventional Matthews- Blakeslee mechanism for creation of misfit dislocations is found to be inadequate for the case of large lattice relaxation owing to interactions amongst the misfit dislocations at the interface. In particular, the regime where the separation D between misfit dislocations is much less than the strained layer thickness h is considered here. The energetics of insertion of dense misfit dislocation networks is examined. According to St Venant's Principle, the existence of a new length scale, D, serves as a cutoff for the stress fields of the dislocation network. This observation has several consequences, including the prevention of relaxation by repulsive interaction amongst threading dislocation segments and the melting'' of moderately relaxed heterointerfaces at conventional semiconductor growth temperatures. A number of experimental observations may be explained via these models.
Infrared reflectance and transmittance measurements between 500 and 1800 cm{sup {minus}1} were obtained on boron carbides with between 10 and 20 atomic percent carbon. Measurements on both boron and carbon isotopically enriched samples indicate that all prominent modes involve boron motion, and that all but a mode near 950 cm{sup {minus}1} involve carbon motion. Since the spectrum remains qualitatively unaltered as a function of carbon concentration, its prominent features must have a common structural origin. 5 refs., 4 figs., 2 tabs.
The thermal neutron absorption cross sections of geologic materials are of first-order importance to the interpretation of pulsed neutron porosity logs and of second-order importance to the interpretation of steady-state porosity logs using dual detectors. Even in the latter case, uncertainties in log response can be excessive whenever formations are encountered that possess absorption properties appreciably greater than the limestones used in most tool calibrations. These effects are of importance to logging operations directed at geothermal applications where formation vary from igneous to sedimentary and which may contain solution-deposited minerals with very large cross-section values. Most measurements of cross-section values for geologic materials have been made for hydrocarbon production applications. Hence, the specimen materials are sedimentary and clean in the sense that they are not altered by geothermal fluids. This investigation was undertaken to measure cross-section values from a sequence of igneous materials obtained from a single hole drilled in an active hydrothermal system. 3 refs., 1 fig.
An automatic optical track identification/counting system has been developed for counting the total number of fission tracks on a fused quartz solid state track recorder. The system is capable of analyzing up to twenty recorders a day with an operator input of less than two hours. The uncertainty introduced by the counting system is about one percent. 6 refs., 2 figs.
Niemer, K.A.; Gilligan, J.G.; Croessmann, C.D.; England, A.C.
A new runaway electron suppression paddle was designed with the PTA code package to reduce the runaway electron population in the Advanced Toroidal Facility (ATF), Oak Ridge National Laboratory. The PTA code package is a unique application of PATRAN, the Integrated TIGER Series, and ABAQUS for modeling high energy electron impact on magnetic fusion components and materials. By its nature, ATF is susceptible to runaway electron formation and confinement resulting in the production of a high level of hard x-rays near the machine. Four previous stainless steel paddles proved effective in reducing the runaway electron population; however, electrons above 15 MeV have still been observed. Melting and bending were observed in each of the previous paddles, reducing their effectiveness. Scoping experiments are under way to further characterize the runaway electrons in ATF. Data from these experiments will provide insight into runaway electron damage mechanisms. Proposals for the insertion of a new paddle in ATF are being considered. These analyses add to the knowledge of runaway electron damage and will aid in the design of future components to withstand runaway electron discharges in all magnetic fusion devices, including tokamaks. 8 refs., 3 figs., 1 tab.
System tuning often occurs in response to observed changes in key performance indicators. But, how do we determine if a change is significant Our indicators are random variables. They display a natural'' variation. This presentation reviews techniques that may provide a great deal of assistance in determining the significance of a change -- and more importantly -- when and what to tune. The techniques were developed by Dr. William Shewhart at Bell Labs and refined by internationally known quality specialist W. Edwards Deming. Although founded on statistical theory, the techniques are easy to use, require no formal statistical training, and may help you
The US Department of Energy National Photovoltaics Program considers the photovoltaic (PV) concentrator technology as a viable entity, likely to penetrate the utility market in the foreseeable future. To achieve this, it has launched the National Photovoltaic Concentrator Initiative under the management of Sandia National Laboratories. The objective of this program is to encourage PV concentrator system design and manufacture, with a view to bringing the energy cost to $0.12/kWh in the next four years and to $0.06/kWh by the year 2000. To achieve these goals, the systems have to perform reliably for 20 to 30 years. This necessitates a stringent quality assurance/quality control (QA/QC) program in all phases of PV concentrator design, production, and installation. In order to assist the PV industry in this effort a project was initiated to provide a generic QA/QC guide, capable of being adapted by any PV concentrator industry to prepare its individual QA/QC plan. The draft plan of the guide was prepared and circulated to various government laboratories and industries involved in PV concentrator work. Their input is now being incorporated into a final document, which will serve as an industry standard. 1 ref., 1 fig.
The design-basis, defense-related, transuranic (TRU) waste to be emplaced in the Waste Isolation Pilot Plant (WIPP) could, if sufficient H{sub 2}O and nutrients were present, produce as much as 1,500 moles of gas per drum of waste. Gas production could pressurize the repository to 150 atm (lithostatic pressure) and perhaps higher. Anoxic corrosion of Fe and Fe-base alloys and microbial degradation of cellulosics are the processes of greatest concern, but radiolysis of brine could also be important. The proposed backfill additives CaCO{sub 3}, CaO, CuSO{sub 4}, KOH, and NaOH may remove or prevent the production of some of the expected gases. Because of the heterogeneous nature of design-basis waste, the Eh and pH of any brine present in WIPP disposal rooms could vary significantly over short distances after reacting with the waste. The WIPP Project is investigating the consequences of gas production and considering engineered alternatives, including reprocessing the waste, to reduce gas production rates or potentials. Reprocessing would also reduce the range of Eh and pH expected for the repository. 12 refs.
More than 20 years ago, a philosophy was developed for the design and analysis of hardware systems to ensure that they would perform in a predictably safe manner, even in severe abnormal environments. This philosophy has been scrutinized and tested during the intervening years, and has proved successful in practice. A requirement guiding the development of the philosophy was that the resulting design must be simple enough to be amenable to analysis. The inherent simplicity is a safety attribute, because complex analyses, such as those represented by fault trees containing hundreds of branches, are extremely susceptible to error. There are many examples where such errors led analysts to believe systems were safe when they were not, with disastrous consequences. The purpose of this workshop problem is to determine whether the principles developed to ensure hardware safety are applicable in any way to safety-critical software systems. It is possible that hardware associations with software will need to be considered, but whether or not this is true is left as an aspect of the investigation. In order to put the ground rules in perspective, it will be necessary to establish some framework.
We present here the SMILE modification of the RADLAC II accelerator which enabled us to produce high quality 12--14 MV, 100 kA beams. It consists of replacing the 40-kA 4-MV beam injector, magnetic vacuum transport and accelerating gaps by a long cathode shank which adds up the voltages of the 8 pulse forming lines. The beam now is produced at the end of the accelerator and is free of all the possible instabilities associated with accelerating gaps and magnetic vacuum transport. Annular beams with {beta}{perpendicular} {le} 0.1 and radius r{sub b} {le} 2 cm are routinely obtained and extracted from a small magnetically immersed foilless electron diode. Results of the experimental evaluation are presented and compared with design parameters and numerical simulation predictions. 6 refs., 7 figs., 1 tab.
A diode employing a thermionic cathode has produced 80 A beams at 200 kV for at least 6 {mu}s. Moreover, the diode operates at rates as high as 1 Hz. EGUN simulations of the experimental geometry agree with the experiments. Finally, simulation of a proposed diode geometry predicts a 1 kA, 500 kV beam.
An algorithm is presented or rendering scalar field data which reduces rendering times by as much as two orders of magnitude over traditional full resolution image. Less than full resolution sampling of the scalar field is performed using a fast ray tracing method. The sampling grid points are output as a set of screen based gouraud shaded polygons which are rendered in hardware by a graphics workstation. A gradient based variable resolution algorithm is presented which further improves rendering speed. Several examples are presented. 16 refs., 8 figs., 2 tabs.
Efficient conversion of radioactive decay to electrical power has been the goal of a number of past research efforts. One of these was the Elgin-Kidde nuclear battery. In this concept promethium-147 was used as a beta source which was then mixed with a phosphor to produce a radioluminescent (RL) source of light. The light source was coupled to silicon photovoltaic converters to create electricity. This photoelectric approach is being revisited using tritium based solid state compounds and advanced gas concepts to produce RL light sources being disclosed at this conference. Efficient conversion of the RL light energy to electrical energy imposes certain requirements on the semiconductor converter. These requirements will be discussed. Projections of power source electrical and physical characteristics will be presented based on reasonable design parameter assumptions. The words Power Supply'' usually evoke a vision of a rotating machine or chemical battery. However, today's technology is making increasing use of photonics, where information and even power can be moved through optical fibers. Brighter volumetric RL light sources open a whole new range of photonics-based applications, while solid state tritiated compounds provide the foundation for improved mechanical adaptability and safety. 4 refs., 6 figs., 1 tab.
We describe the development of the first all-organic, opitcally clear, radioluminescent (RL) light. Although gas-phase RL lights have been known for many years, a number of advantages accrue to solid state devices. These include greater ruggedness and ease of brightness scale-up. In our systems, tritium is covalently bound to an organic getter, which is dissolved in an organic monomer, along with appropriate scintillating dyes. The entire system cures by monomer polymerization due to the radiation field, resulting in a clear, glowing solid plastic block. We outline here the design considerations employed in producing these materials. 12 refs., 1 fig.
The initial reactions that occur during liquefaction can have significant impacts on process yields and downstream process conditions. Reactions that result in compounds with low molecular weights and decreased boiling points are beneficial, whereas retrogressive reactions, which yield higher molecular weight compounds that are refractory to further processing, give lower yields of desired products. The objectives of this research are to determine the process conditions that give rise to retrogressive reactions during preconversion processing and to identify methods for minimizing the occurrence of these reactions. Initial studies have been performed using dibenzyl ether as a compound to model ether linkages in coal. Results show that retrogressive reactions can occur at temperatures as low as 180{degree}C. The presence of a good hydrogenation catalyst and a hydrogen donor was found to minimize retrogressive reactions, whereas the presence of mineral matter, primarily clay minerals, and ZnCl{sub 2}, enhanced the reactions. 8 refs., 3 figs.
Under the sponsorship of the United States Nuclear Regulatory Commission (NRC), Sandia National Laboratories is conducting several research programs with the common goal of developing a complete methodology for the prediction of the ultimate pressure capacity, at elevated temperatures, of light water reactor (LWR) containment systems. These programs are collectively known as the Containment Integrity Programs. This paper will provide a brief overview of these programs. As a part of the Containment Integrity Programs, a series of scale model containment test have been conducted at Sandia including a 1:8-scale steel model and a 1:6 scale reinforced concrete model. The model were pneumatically pressurized up to point of functional failure; that is, the point at which the containment was no longer effective in preventing significant leakage past its pressure boundary. Also, a 1:10-scale prestressed concrete model has been hydrostatically tested in the United Kingdom under a cooperative agreement with the NRC and others. Because the containment pressure boundary consists of numerous mechanical and electrical penetrations, several independent test programs of typical penetrations have also been performed to determine their leakage behavior when subjected to severe accident conditions. Completed containment penetration research programs include testing of typical compression seals and gaskets, inflatable seals, a personal air lock and electrical penetration assemblies (EPAs). Also, an investigation of leakage due to ovalization of penetration sleeves has been conducted as a part of the scale model test. Currently, testing of the unseating equipment hatch of the 1:6-scale containment model is under way. 23 refs., 3 figs., 2 tabs.
The CONTAIN code is a system-level analysis tool developed for the USNRC, and is intended for best-estimate prediction of conditions which might occur in the containment building of a nuclear power plant during a severe accident. A key feature of the code is that it models the containment phenomena in an integrated manner. In particular, the CONTAIN code models some of the complex ways that thermal hydraulics and aerosol phenomena interact with each other. The Light Water Reactor Aerosol Containment Experiment (LACE) progarm is a program to aid researchers in their understanding of thermal hydraulic and aerosol behavior within containments. The purpose of this paper is to report on best-estimate LA-4 post-test calculations that have been completed with the most recent version of the CONTAIN code, version 1.11. An analysis of experimental data and review of the blind post-test CONTAIN calculations is used to justify a re-calculation of the experiment and to establish a best-estimate calculation. The best-estimate calculation shows that reasonably good agreement between thermal hydraulic predictions and data can be obtained with the current CONTAIN models by varying experimental parameters within their uncertainties. Furthermore, with the recently added solubility model for hygroscopic aerosols, the best-estimate calculation gives aerosol behavior that is in good agreement with aerosol data. 10 refs., 16 figs.
Sandia National Laboratories is in the process of upgrading the Central Computing Network, which is a large heterogeneous network providing scientific computing, file storage, output services, and remote access to network resources. The migration from the present HYPERchannel-50 technology to HYPERchannel-100 is currently in progress and plans to migrate to the Fiber Distributed Data Interface (FDDI) token ring architecture are being considered. A migration from a variety of proprietary protocols to a primarily TCP/IP environment is also in progress. In order to test the feasibility of the Network Systems Corporation FDDI technology platform, two test rings have been constructed. Ring A' consists of nine dual attached Data Exchange Units (DXUs) and ring B' consists of two dual attached DXUs. The rings are linked together using N715 DXUs. Other DXU models (with associated host computers where applicable) include N130s, an N220, N400s, and FE640 IP routers. Test data on fault isolation and recovery mechanisms, performance, IP routing (within and between rings), and monitor capabilities will be presented. Interoperability' data based on tests between DXUs and Sun FDDI workstations will also be presented. 14 figs.
Experiments at Sandia National Laboratories have studied the operation of the linear-induction accelerators, HELIA and Hermes 3, in positive polarity. These experiments have provided a unique opportunity to explore the consequences of multiple-cathode electron emission in magnetically insulated transmission lines. An examination of the total energy-canonical momentum distribution of the electrons explains the features of the magnetically insulated flow exhibited by these systems. Simple analysis based on the basic concept of pressure balance, in conjunction with particle-in-cell numerical simulations, shows how the line voltage is related to the anode and cathode currents. Two flow designations are introduced that can apply to multiple-cathode magnetically insulated transmission lines: full-gap flow (FGF), and locally emitted flow (LEF). 16 refs., 15 figs.
An extensive optical fiber (o.f.) cable plant has been constructed in the Central Computing Facility (CCF) of Sandia National Labs to support the NSC DX platform with the Fiber Distributed Data Interface (FDDI) network. The cable plant was designed to optimize flexibility, maintainability, expandability, performance, and capacity. More than 2km of fiber cable and over 3400 connectors were installed. Each component of the cable system was carefully evaluated in order to meet the design requirements and conform to standards. A detailed statement of work (SOW) was generated to assure proper implementation of the design by a qualified contractor. Following the installation of the o.f. cable plant, a heterogenous, production network was built to utilize the benefits of the new media and interfaces.
The optimized C{sub 2v} geometry of ortho-carborane, 1,2-C{sub 2}B{sub 10}H{sub 12}, is determined from Hartree-Fock calculations. For this geometry, a carbon atom is substituted for a boron atom at one of the 4 inequivalent boron sites and the ground-state unrestricted Hartree-Fock eigenvalues and molecular orbitals are found. One thus obtains the valence structure of the B(1s) core-excited molecule according to the Z + 1 approximation. The eigenvalue of the highest occupied molecular orbital is then subtracted from the experimental B(1s) ionization energy of the same site in ortho-carborane. This determines the excitation energy of the most tightly bound exciton for that site. Three of the sites yield nearly identical excitation energies of 191.9 eV; the fourth site yields an excitation energy of 190.9 eV. 8 refs., 1 fig., 2 tabs.
A large area surface source of Lithium plasma for use as an ion source in the PBFA-2 ion beam diode is described. BOLVAPS produces a 1--2 mm thick layer of Li vapor with a density approaching 1 {times} 10{sup 17} cm{sup {minus}3} by rapid ohmic heating of a thin film laminate, one layer of which contains Li. The principal design issues of the vapor source being built for use on the PBFA-2 accelerator are described. LIBORS uses 670.8 nm laser light to efficiently ionize the Li vapor. The results of small-scale Physics tests and full-scale component development are summarized. 13 refs., 6 figs.
An applied B-field ion diode has been operated at 21 TW on PBFA 2 to study beam generation and transport physics. The radial focusing 15-cm-radius diode utilized a pair of magnet coils in disc cathode structures to produce an axial B-field to minimize electron loss in the 16 mm anode-cathode gaps. The diode was different than used in the past with the cathodes 20% closer together and the B-field increased to 3.3 T at the midplane. The 2.5 MA beam originated from a 5-cm-tall ion emitting region and was transported toward the axis in a 12.5-cm-radius gas cell with 2-{mu}m-thick mylar window and a 5-Torr-argon gas fill. A surface flash-over plasma created by electron loss on wax-filled grooves in the anode produced a beam with comparable currents of proton and carbon ions. The experimental results include the spatial uniformity and time dependence of proton and carbon beam emission from the anode and the divergence and focusability of both beams. 10 refs., 13 figs.
Anomalous dispersion (the decrease in refractive index which is associated with absorption) can be used to produce a phase-matched condition for second harmonic generation. This process also gives rise to large increases in the useful second order hyperpolarizability. A new, soluble NLO dye with exceptionally low absorption near 400 nm has been used for anomalous dispersion phase-matching studies in thin films.
The weldability of alloys based on Ni{sub 3}Al and Fe{sub 3}Al is discussed. Both of these ordered alloy systems may experience problems associated with welding. In the case of Ni{sub 3}Al alloys, limited hot ductility contributes to heat-affected zone cracking. Fe{sub 3}Al alloys experience similar difficulties in zone cracking. Fe{sub 3}Al alloys experience similar difficulties in welding due to excessive grain embrittlement due to the presence of water vapor. Advances in both alloying and substructural refinement to improve the weldability are reviewed. 18 refs., 10 figs.
Methods of preparing non-agglomerated powders for three systems -- yttria, titania, and yttria-stabilized zirconia -- are reviewed. The non-agglomerated nature of these powders should make it possible to sinter them into dense ceramic bodies with nanocrystalline grain sizes. Experiments with yttria-stabilized zirconia have shown that this is indeed the case, with mean linear intercept grain sizes of 60 nm resulting from original powder particle diameters of 13 nm. This ultrafine-grained zirconia is shown, in turn, to have superplastic forming rates 34 times faster than a 0.3 {mu}m-grained commercial zirconia of the same composition. 7 refs., 9 figs.
The first commercially available GaAs 8K ROM has been designed and manufactured using GigaBit Logic's 3-level metal E/D process. The worst case clock frequency of 650 MHz has been obtained with a power dissipation of 3.5 W. The ROM is organized as 1K X 8 bits, and on-chip translation logic enables the ROM to have an effective 4K X 8 resolution when used a a sine look-up table. The ECL compatible ROM is packaged in GigaBit Logic's standard 40 pin package.
Lienert, T.J.; Robino, C.V.; Hills, C.R.; Cieslak, M.J.
The weldability, solidification behavior, and solidification microstructures of Hastelloy{asterisk} Alloy B-2 and Hastelloy{asterisk} Alloy W have been investigated. Susceptibility to fusion zone hot-cracking was determined by autogenous Varestraint testing. High temperature phase transformations, including solidification events, were identified by differential thermal analysis (DTA). After testing, the microstructures of various specimens were examined by optical metallography, scanning electron microscopy (SEM), electron microprobe analysis, and analytical electron microscopy (AEM). Results of this study showed that Hastelloy B-2 has exceptional resistance to hot cracking, comparable to that of Hastelloy C-4 and 304 stainless steel, while Hastelloy W proved to be somewhat more susceptible to hot cracking, exhibiting behavior similar to Alloy 625. The solidification process in both Hastelloy B-2 and Hastelloy W was found to be dominated by the segregation of Mo which gives rise to the formation of terminal eutectic-like constituents. This pattern of segregation is consistent with that of previous work on other Ni--Mo--Cr alloys. The microstructural constituents associated with hot-cracking in each alloy have been identified. 13 refs., 8 figs.
The weldability of Haynes {reg sign} Alloy No. 242 {trademark}, a new alloy derived from the Ni-Mo-Cr system, was investigated. Susceptibility to fusion zone hot cracking was determined by Varestraint testing, and hot ductility was characterized by Gleeble testing. Solidification phase transformation data was recorded with differential thermal analysis (DTA). Weld microstructures were characterized with scanning electron microscopy (SEM), analytical electron microscopy (AEM), and electron probe microanalysis (EPMA). The results of this study indicate that this alloy has better hot cracking resistance than high strength nickel base superalloy 718; however, it has lower resistance than other alloys derived from the Ni-Cr-Mo ternary such as the Hastelloy alloys B2, C-4, C-22, C-276, and W. Segregation patterns in weld microstructures agree well with established information concerning this family of alloys. Prediction of solidification products with the Ni-Mo-Cr phase diagram based on a chemical equivalence was unsuccessful due to the higher carbon content of this alloy which favors the formation of M{sub 6}C. Solidification in Alloy 242 terminates with the formation of two eutectic-like constituents: (1) a M{sub 6}C/austenite eutectic, and (2) a second eutectic with austenite and an undetermined phase. This latter phase has a composition similar to the M{sub 6}C phase, but with a different crystal structure (cubic, ao = 6.6 {Angstrom}). 11 refs., 10 figs., 4 tabs.
In the Recirculating Linear Accelerator, we will inject a 10-kA to 20-kA electron beam, and then focus and guide it with an IFR plasma channel, which is created with a low energy electron beam. The REB will be transported through a closed racetrack or a spiral beam line to be re-accelerated by the ringing waveform of dielectric cavities. By adding more accelerating cavities along the beam line, high energies can be achieved. Experiments are in progress to study IFR beam transport issues. A new injector is needed for beam re- acceleration experiments. We are presently installing this new REB injector which will-provide a higher amplitude ({approximately}4 MV), longer duration ({approximately}40-ns FWHM), more rectangularly shaped({approximately}25-ns full width at 90% peak) waveform and a colder beam than were achievable with the previous 1.5-MV injector. The resultant constant beam energy can be more efficiently matched the guiding IFR plasma channel in the beam line and to the turning section magnetic fields. We are now developing new cavities that produce accelerating voltage pulses with improved waveform flatness, width, and amplitudes that do not suffer unacceptable degradation over the first four ringing periods. This effort requires network solver and electrostatic field stress analysis computer codes, and a scaled test model to compare actual waveforms to those predicted by the simulations. 10 refs., 9 figs.
Prior research has concentrated on damage at the Si--SiO{sub 2} interface caused by photoinjection of electrons into the oxide by near UV light. The damage processes involved may be similar to those responsible for degradation in the Stanford type, point contact solar cell (PCSC). 7 refs., 6 figs.