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.
The microstructure of Al ion-implanted at room temperature with 17 at. % 0 has been characterized with TEM. The alloy has extremely small (1.5--3.5 nm) oxide precipitates whose crystal structure is interpreted to be a disordered version of {gamma}-Al{sub 2}O{sub 3} having a fcc lattice of O{sup 2{minus}} ions with Al{sup 3+} ions in random interstitial sites. The small sizes can account for the exceptionally high strength of as-implanted alloys: 2500--3300 MPa. Larger precipitates are found when the alloy is annealed 1/2 hour at 550{degree}C, which is consistent with its somewhat lower strength: 800--1600 MPa. 4 figs.
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.
The chemical bonding and isochronal annealing of H implanted into GaAs at 80 K has been investigated by infrared absorption measurements. Based upon the frequency shift when deuterium is substituted for H, and an equivalent band formation in InAs, assignment of a new band at 2029 cm{sup {minus}1} is made to As-H centers. Bonding of H at interstitial As of and As-vacancy pair which anneals between 150 and 250K is suggested as the structure for the defect. A previously-reported absorption band at 1834 cm{sup {minus}1} assigned to Ga-H centers in H-implanted GaAS increase in intensity when H is released from As-H centers. 15 refs., 5 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.
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.
A three generation family of CMOS silicon test chips for packaging diagnostics has been developed. These Assembly Test Chips (ATC) contain sensors that measure a number of variables associated with assembled IC degradation, including the degree of IC corrosion, handling damage, ESD threat, ppm, moisture, mechanical stress, mobile ion density, bond pad cratering, and high speed logic degradation. The ATC family are intended to give manufacturing feedback in four ways: direct feedback in evaluation of an Assembly Manufacturing Line in an objective, non-intrusive way; before and after comparisons on an assembly production line when an individual process, material, or piece of equipment has been changed; resident lifetime monitor for system package aging and ongoing reliability projection and thermal, mechanical, dc electrical, and high frequency mock-up evaluation of packaging (including multichip) schemes. 14 refs., 6 figs., 2 tabs.
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.