Recently, significant progress has been made in using finite-difference analysis cod es to simulate the responses of complex structures due to direct lightning. Advances have been made in interfacing a finite-difference code with commercial computer aided design tools, in suppressing a weak instability associated with the thin-wire algorithm for modeling conductors much smaller than a cell size, and in visualizing the results with color movies. Preliminary comparisons between the results of the finite-difference code and the results obtained during a recent rocket-triggered lightning test are also presented.
The US Department of Energy`s Nuclear Plant Lifetime Improvement Program is investigating the use of prognostic monitoring to extend the operational lifetime of specific equipment. Benefits of these achievements will include safer and more reliable nuclear Plants, reduced maintenance costs, and increased lifetime of equipment. This report describes the development and application of a monitoring system designed to predict starting system performance of Emergency Diesel Generators. The monitor system is evaluated on two different engines, each using a different method of starting.
Portable acoustic wave sensor (PAWS) systems are being developed for real-time, on-line monitoring of volatile organic compounds (VOC`s). These systems are built around acoustic wave (SAW) devices coated with viscoelastic polymers. Two independent responses of the SAW sensor, wave velocity and wave attenuation, are measured to provide information about the chemical species sorbed by the coating. Rapid, reversible detection of gas phase volatile organics has been demonstrated for process monitoring and waste minimization in environmentally conscious manufacturing (ECM) applications and for documenting contaminant concentrations in remediation efforts.
The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry/DOE cost shared projects of the Geothermal Drilling organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure drilling fluid outflow was tested extensively during Long Valley drilling. Results show that this meter is rugged, reliable, and can provide useful measurements of small differences in fluid inflow and outflow rates. By providing early indications of fluid gain or loss, improved control of blow-out and lost circulation problems during geothermal drilling can be expected. In the area of downhole tools for lost circulation control, the concept of a downhole injector for injecting a two-component, fast-setting cementitious mud was developed. DOE filed a patent application for this concept during FY 91. The design criteria for a high-temperature potassium, uranium, thorium logging tool featuring a downhole data storage computer were established, and a request for proposals was submitted to tool development companies. The fundamental theory of acoustic telemetry in drill strings was significantly advanced through field experimentation and analysis. A new understanding of energy loss mechanisms was developed.
Sandia National Laboratories (SNL) is in the final stages of developing a Universal Authenticated Item Monitoring System (AIMS). When completed, AIMS will provide applicable agencies in the US government, and those in the International arena, with a secure and convenient method of monitoring the physical status of selected items. The benefit derived from this development activity will be the commercial availability of an item monitoring system with the capability for ``quick set-up`` monitoring, as well as long-term unattended monitoring. The AIMS includes a variety of sensors, a robust and authenticated radio frequency (RF) communication link, a Receiver Processing Unit (RPU), and an inspector-friendly personal computer (PC) interface for collecting, sorting, viewing and archiving pertinent event histories. The system will provide the capability to monitor selected items in a real-time mode, a remotely interrogated mode, and a stand-alone, unattended data collection mode. The sensor suite under development includes advanced motion sensors, interior volumetric intrusion sensors, Re-usable, In-situ Verifiable Authenticated (RIVA) fiber-optic seal sensors, generic utility sensors (to accommodate contact closure inputs), and radiation and environmental sensors. A new generation authentication algorithm recently has been developed that provides a high degree of system security 121. The AIMS has potential safeguards applications in the areas of arms control and treaty verification military asset control, International Atomic Energy Agency (IAEA) and Euratom safeguards verification activities, as well as domestic nuclear safeguard activities. Commercial applications could include high-value inventory control and security systems. This paper describes the second-generation AIMS along with its recently expanded sensor suite and enhanced data collection capabilities.
In a joint effort conducted by Sandia National Laboratories, the International Atomic Energy Agency (IAEA), and the Japan Atomic Energy Research Institute (JAERI), an authentication system has been installed at the Fast Critical Assembly (FCA) facility in Tokai-mura, Japan. The purpose of this authentication system is to provide the IAEA with an independent means of authenticating the operator-provided Advanced Containment and Survellance (AC/S) system already in place at the facility. Authentication Controllers were installed at the AC/S Portal Monkor and Penetration Monitor to collect data and to randomly test sensor functions between IAEA inspections. During each inspection the authentication data is collected with an Inspector`s portable computer and printed for comparison to the data recorded by the AC/S system. Installation of the authentication equipment took place in November 1991 and a three-month field test began in December 1991. This paper will describe the authentication system, the operator interface, and the preliminary results of the field tests.
A public-key Treaty Data Authentication Module (TDAM) based on the National Institute of Standards and Technology (NIST) Digital Signature Standard (DSS) has been developed to support treaty verification systems. The TDAM utilizes the Motorola DSP56001 Digital Signal Processor as a coprocessor and supports both the STD Bus and PC-AT Bus platforms. The TDAM is embedded within an Authenticated Data Communication Subsystem (ADCS) which provides transparent data authentication and communications, thereby concealing the details of securely authenticating and communicating compliance data and commands. The TDAM has been designed according to the NIST security guidelines for cryptographic modules. Public-key data authentication is important for support of both bilateral and multi-lateral treaties. 8 refs.
Parametric weld size predictions, in which weld size and shape are predicted given a knowledge of material and process parameters, offer a great deal of benefit to the welding engineer. This is so because the technique promises to replace expensive and time-consuming lab or shop activity followed by destructive examination with simple numeric or nomographic calculations. The work to be presented here uses a simple two-dimensional axisymmetric spot-on-plate computer simulation in which thermal diffusivity vs temperature is varied.
The change in the world military posture and the reduction in military personnel require the flexible and rapid deployment of priority defense assets. Air Force security personnel and operators must maintain the ability to secure these deployed assets and receive advanced warning of threats. The Air Force will meet this need through the Dispersed Integrated Security System (DISS). The system will be rapidly deployable, relocatable, support mission flexibility, and be capable of intrusion detection, area and alarm display, night assessment, and wireless data communications. Wireless links, as obtained through radio, are quickly deployed and cost less than their hardwire counterpart when labor cost and equipment reuse are considered. DISS communications systems will be flexible and have broad application. By integrating commercial components and using menu-driven setup procedures, low cost, versatile, easy-to-use communication systems will be implemented to meet Air Force user requirements and provide desired capabilities.
It has long been United States Government (USG) policy to actively support nuclear nonproliferation efforts, as evinced in the 1970 US ratification of the Nuclear I Nonproliferation Treaty (NPT) and the 1978 US Voluntary Treaty with the IAEA (INFCIRC/288). Under INFCIRC 288, US facilities without direct national security involvement are eligible for International Atomic Energy Agency (IAEA) safeguards. Throughout the past decade, the IAEA has selected one or two US facilities for implementation of IAEA safeguards at a given time. The facilities selected have generally been those which allowed the IAEA to test new or advanced safeguards techniques, facilities which were prototypical or similar to other nuclear facilities which they will have to safeguard in other countries, or facilities which have been engaged in international commerce in nuclear materials. The US is now actively addressing issues of the interim and permanent disposal of nuclear waste and spent nuclear fuel -- the back end of the open US nuclear fuel cycle. The Nuclear Waste Policy Act (NWPA) of 1982 designated the US Department of Energy (DOE) to be responsible for the long term storage and isolation from the biosphere of spent nuclear fuel (SNF) and high-level waste (HLW) and created the DOE Office of Civilian Radioactive Waste Management (OCRWM) to develop, construct, and manage the Civilian Radioactive Waste Management System (CRWMS). Refinements to the NWPA occurred in 1987 in the Nuclear Waste Policy Amendments Act of 1987. CRWMS facilities will be eligible for IAEA safeguards. They are likely to be selected because they will be among the first SNF and HLW disposal operations worldwide.
As the US nuclear stockpile is reduced, large numbers of nuclear components must be placed in storage. The necessity for periodic inventories of these components as well as the act of placement of the components in storage areas could result in increased radiation exposure to operations personnel. The use of robotics can significantly reduce or even eliminate such exposure. An automated system is being designed in a project at Sandia Laboratories to allow an operator to remotely stack and retrieve component containers in storage areas using a robotic loader and a portable control console. The operator need not enter the storage area. Operator commands for the loader would be implemented through a supervisory architecture that would insure that the loader did not violate safety constraints. Individual aspects of the loader`s activities would be automated to reduce possible operator errors for many repetitive tasks. The loader will be outfitted with appropriate sensors so that the supervisory controller can enforce safe operations. The system will be configured so that monitoring of components for accountability can be accomplished.
To achieve the goal of remediating waste sites throughout its complex and of bringing its facilities into full compliance by the year 2019, the DOE has established the Office of Environmental Restoration and Waste Management (E). Within E, the Office of Technology Development (OTD) has been created to develop technologies that will support DOE`s cleanup goal. The OTD is accelerating remediation technology application by leveraging the expenditure of available funds through international technology development and demonstration projects. These projects will address EM`s environmental restoration and waste management needs. For this reason, the OTD has created the International Technology Exchange Program (ITEP) whose primary objective is to effect collaboration among governments, industries, and educational institutions to identify worldwide technologies suitable for this purpose. These technologies should also meet US commercial needs. The ITEP will also serve as a mechanism for transferring technologies developed under DOE sponsorship to US industry for ultimate application in the international arena.
The US Department of Energy (DOE) has committed to the remediation of waste sites throughout its complex, and has recognized that it can accelerate its technology development efforts and leverage the expenditure of available funds through an international cooperation among government entities, private industry, and educational institutions. To support the technology transfer of environmental information, the DOE has sponsored the development of EnviroTRADE - an international information system that will facilitate the exchange of environmental restoration and waste management technologies worldwide. During DOE`s fiscal year 1992, a beta prototype is being developed by Sandia National Laboratories (SNL). During fiscal year 1993 and beyond, the full system will be developed and networked among international users. The system will contain profiles on both environmental restoration/waste management needs and foreign/domestic technologies. Users will be able to identify matches between worldwide needs and available or emerging technologies. Where matches between needs and existing technologies are not found, the system will identify the potential for development of new and innovative technologies to address environmental problems. EnviroTRADE will also provide general information on international environmental restoration and waste management organizations, sites, activities, and contacts.
As part of the update of the Safety analysis Report (SAR) for the Annular Core Research Reactor (ACRR), operational limiting events under the category of inadvertent withdrawal of an experiment while at power or during a power pulse were determined to be the most limiting event(s) for this reactor. This report provides a summary of the assumptions, modeling, and results in evaluation of: Reactivity and thermal hydraulics analysis to determine the amount of fuel melt or fuel damage ratios; The reactor inventories following the limiting event; A literature review of post NUREG-0772 release fraction experiment results on severe fuel damages; Decontamination factors due to in-pool transport; and In-building transport modeling and building source term analysis.
As part of the Direct Optical Initiation (DOI) program, an assessment of the possibility of introducing lightning energy into an exclusion region via an Optical Barrier Feedthrough (OBF) is being carried out. One postulated penetration mechanism is the tracking of current past the OBF on the surface of the dielectric optical fiber itself. During September and October of 1991, a series of tests was conducted on a closed metallic cylindrical test object representing the electrical exclusion region of a weapon. Median-level (30-kA) and severe (200-kA) simulated lightning return strokes, singly, doubly, and in combination with a moderate continuing current, were attached directly to the exterior portion of a fiber optic cable, which penetrated through a hole of controlled size into the interior of the exclusion region. The thickness of the barrier surrounding the hole was 0.06 in. Attempts were made to measure any conducted current flowing on the fiber at distances of 1 and 4 inches from the interior surface of the stainless steel top of the cylinder. Test parameter variations included diameter of the penetration hole (475 and 500 microns), length of the exterior portion of the cable and whether or not its jacket was present, and the applied test currents. It is concluded that no signal above measurement noise was recorded on any of the data shots that made up the test series. Measurement resolution was of the order of several amperes. Based on the highest recorded response of 8.5 A, corresponding to a 200-kA input, the OBF can be characterized by a direct-strike lightning attenuation factor of approximately 5 {times} lO{sup {minus}5} or better. Based on the more typically observed noise level of a few amps, the attenuation is commensurately greater.
Detailed mineralogical studies of the matrix and fracture-fill materials of a large number of samples from the Rustler Formation have been carried out using x-ray diffraction, high-resolution transmission electron microscopy, electron microprobe analysis, x-ray fluorescence, and atomic absorption spectrophotometry. These analyses indicate the presence of four clay minerals: interstratified chlorite/saponite, illite, chlorite, and serpentine. Corrensite (regularly stratified chlorite/saponite) is the dominant clay mineral in samples from the Culebra dolomite and two shale layers of the lower unnamed member of the Rustler Formation. Within other layers of the Rustler Formation, disordered mixed chlorite/saponite is usually the most abundant clay mineral. Studies of the morphology and composition of clay crystallites suggest that the corrensite was formed by the alteration of detrital dioctahedral smectite in magnesium-rich pore fluids during early diagenesis of the Rustler Formation. This study provides initial estimates of the abundance and nature of the clay minerals in the Culebra dolomite in the vicinity of the Waste Isolation Pilot Plant.
This document describes an automated, data acquisition system designed to test the performance of remote badge readers. These readers interrogate badges by transmitting and receiving energy. The performance of such readers is statistical and can be affected by geometrical and environmental variables. Characterization of performance, therefore, requires multiple measurements while the known variables are controlled. Automation makes this a practical task.
The contribution of essential service water (ESW) system failure to core damage frequency has long been a concern of the NRC. The objective of this study is to assess the safety significance of the loss of ESW systems in LWRs relative to core damage frequency (CDF) and perform a limited value/impact analysis of potential modifications to solve ESW vulnerabilities using a prototypical (pilot) plant. Previous studies indicate that service water systems contribute from < 1% to 65% of the total internal CDF. For the pilot plant analyzed, common ESW vulnerabilities are failure of standby service water pumps to start, backflow through check valves for cross-tied pumps, and failure of normally closed isolation valves in diesel generator cooling loops to open on demand. For the potential modifications evaluated for the pilot plant, the results showed that they could reduce the CDF by as much as 33 percent. However, the dollars per person REM measures resulting from various groups of these modifications significantly exceeded the current criteria of $1000. The results, since they only apply to the prot plant, are not typical of all LWRs. Due to the importance of service water to CDF and the plant specific nature of ESW systems, there could be plants for which there would be cost-effective modifications. Additional analysis would be required to identify them.
The low field (E{congruent}2kV/cm) Metal Oxide Varistor (MOV) is a voltage regulation device. This report describes a technique for performing DC characteristic measurements on a MOV. The varistor is in the feedback loop of a high voltage operational amplifier. A current source forces a staircase current waveform through a MOV. An operational amplifier provides the required applied voltage to maintain the desired values of current through the varistor. The current values change at a maximum rate of 33.3 readings per second and a high speed voltmeter measures the varistor voltage. The maximum available current and voltage at present are 5 mA and 10 kV respectively. Examples of its use are with data from the MC3596 and XMC4317.
The performance Assessment (PA) Department of Sandia National Laboratories annually compares the Waste Isolation Pilot Plant (WIPP) with the Environmental Protection Agency`s Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes, 40 CFR 191. To assist the analyst in these comparisons the PA Department developed CAMCON, the Compliance Assessment Methodology Controller, which creates an analysis system out of the diverse computer modeling codes needed for this interdisciplinary comparison. This reference manual describes the use of most of the codes in the CAMCON system that an analyst may use when performing the PA comparisons. Although some of the codes included in CAMCON have their own user`s guide, this manual summarizes these guides as well to provide the user with one comprehensive document of the codes within the CAMCON system.
Site-characterization, data interpretation, and modeling efforts have been conducted for the Waste Isolation Pilot Plant (WIPP), a US Department of Energy facility, in southeastern New Mexico as part of the evaluation of the suitability of the bedded salt of the Salado Formation for isolation of defense transuranic wastes. The Culebra Dolomite Member of the Rustler Formation is the most transmissive and laterally continuous hydrogeologic unit above the Salado Formation and is considered to be the principal offsite pathway for radionuclide transport in the subsurface, should a breach of the repository occur. The potential importance of this offsite pathway has motivated the design and implementation of tests to characterize the solute-transport properties of the Culebra dolomite. On a regional scale, long-term pumping tests have been performed and analyzed to provide information concerning the broad hydrologic flow characteristics of the Culebra dolomite. At the local (or hydropad) scale, conservative (i.e., nonreactive) tracer tests have been performed to characterize the solute-transport properties of the Culebra dolomite. The tracer-test interpretations presented in this report were performed by INTERA Inc. under contract to SNL. The tracer tests and their interpretation provide data for use in performance-assessment calculations of site suitability for waste isolation. In particular, transport parameters determined from these tests are used as input for offsite solute-transport simulations.
An essential part of the license application for a geologic repository will be the demonstration of compliance with the standards set by the Environmental Protection Agency. The performance assessments that produce the demonstration must rely on models of various levels of detail. The most detailed of these models are needed for understanding thoroughly the complex physical and chemical processes affecting the behavior of the system. For studying the behavior of major components of the system, less detailed models are often useful. For predicting the behavior of the total system, models of a third kind may be needed. These models must cover all the important processes that contribute to the behavior of the system, because they must estimate the behavior under all significant conditions for 10,000 years. In addition, however, computer codes that embody these models must calculate very rapidly because of the EPA standard`s requirement for probabilistic estimates, which will be produced by sampling thousands of times from probability distributions of parameters. For this reason, the total-system models must be less complex than the detailed-process and subsystem models. The total-system performance is evaluated through modeling of the following components: Radionuclide release from the engineered-barrier system. Fluid flow in the geologic units. Radionuclide transport to the accessible environment. Radionuclide release to the accessible environment and dose to man.
A sensor-based intelligent control system is described that utilizes a multiple degree-of-freedom robotic system for the automated remote manipulation and precision docking of large payloads such as waste canisters. Computer vision and ultrasonic proximity sensing are used to control the automated precision docking of a large object with a passive target cavity. Real-time sensor processing and model-based analysis are used to control payload position to a precision of {plus_minus} 0.5 millimeter.
Historical and projected inventories of spent fuel from commercial light-water nuclear reactors exhibit diverse decay characteristics and ages. This report summarizes a preliminary reexamination of a method for determining equivalent thermal loads for the range of spent fuel expected at a potential underground repository. The method, known at the Equivalent Energy Density (EED) concept, bases its equivalence criteria on the assumption that a given waste will produce worst-case thermomechanical effects equal to worst-case thermomechanical effects produced by a baseline waste, provided that the thermal energy deposited in the host rock over a specified deposition period is the same for both waste descriptions. To test this assumption, temperature histories at representative locations within the host rock were calculated using layouts defined by the EED concept and four deposition periods (20, 50, 100, and 300 years). It was found that the peak temperatures at near-field locations were best matched by the shorter deposition periods of 20 and 50 years. However, due to the sensitivity of the near-field environment to short-term canister-to-canister interactions, caution,should be used when choosing a near-field deposition period. At the location chosen to represent the far-field, a 300-year deposition period provided reasonable correspondence of peak temperature responses for all waste descriptions examined.
LLUVIA-II is a program designed for the efficient solution of two- dimensional transient flow of liquid water through partially saturated, porous media. The code solves Richards equation using the method-of-lines procedure. This document describes the solution procedure employed, input data structure, output, and code verification.
A complete edge-weighted directed graph on vertices 1,2,...,n that assigns cost c(i,j) to the edge (i,j) is called Monge if its edge costs form a Monge array, i.e., for all i < k and j < l, c[i, j]+c[k,l]{le} < c[i,l]+c[k,j]. One reason Monge graphs are interesting is that shortest paths can be computed quite quickly in such graphs. In particular, Wilber showed that the shortest path from vertex 1 to vertex n of a Monge graph can be computed in O(n) time, and Aggarwal, Klawe, Moran, Shor, and Wilber showed that the shortest d-edge 1-to-n path (i.e., the shortest path among all 1-to-n paths with exactly d edges) can be computed in O(dn) time. This paper`s contribution is a new algorithm for the latter problem. Assuming 0 {le} c[i,j] {le} U and c[i,j + 1] + c[i + 1,j] {minus} c[i,j] {minus} c[i + 1, j + 1] {ge} L > 0 for all i and j, our algorithm runs in O(n(1 + 1g(U/L))) time. Thus, when d {much_gt} 1 + 1g(U/L), our algorithm represents a significant improvement over Aggarwal et al.`s O(dn)-time algorithm. We also present several applications of our algorithm; they include length-limited Huffman coding, finding the maximum-perimeter d-gon inscribed in a given convex n-gon, and a digital-signal-compression problem.
This report documents the lightning threat warning system at the Tonopah Test Range and the technology it uses. The report outlines each of the system's individual components and the information each contributes.
Three seals constructed of compressed crushed salt blocks have been successfully emplaced vertically down in three 97-cm (38.2-in.) diameter boreholes drilled from the repository horizon of the Waste Isolation Pilot Plant. All three seals are designed to allow fluid flow measurements and two of the seals are heavily instrumented with pressure and hole closure gages. The seals are providing structural and fluid flow data useful for evaluating predictive models and long-term crushed salt seal performance. Results to date, 1100 to 1450 days after seal emplacement, indicate the current average densities of the seals to be about 85% of intact rock salt. Relative densities have increased about 2% since emplacement. The results to date are consistent with previous laboratory and modeling studies of crushed salt behavior. This report provides information necessary for evaluating these data including as-built test configurations, construction histories, and instrumentation descriptions. Seal and instrumentation installation techniques are also described.
The ECM Newsletter is published at Sandia National Laboratories to disseminate information obtained from research and development programs and demonstration, testing, and evaluation projects at research facilities on environmentally conscious manufacturing processes. This issue covers the topics of Life Cycle Assessment, etching processes for Kovar, cleaning of plutonium surfaces, non- chromate conversion coatings for aluminum,, and circuit board manufacturing.
The Mixed-Waste Landfill Integrated Demonstration (MWLID) has been assigned to Sandia National Laboratories (SNL) by the US Department of Energy (DOE) Office of Technology Development. The mission of the MWLID is to assess, implement and transfer technologies and systems that lead to quicker, safer, and more efficient remediation of buried chemical and mixed-waste sites. The MWLID focus is on two landfills at SNL in Albuquerque, New Mexico: The Chemical Waste Landfill (CWL) and the Mixed-Waste Landfill (MWL). These landfills received chemical, radioactive and mixed wastes from various SNL nuclear research programs. A characterization system has been designed for the definition of the extent and concentration of contamination. This system includes historical records, directional drilling, and emplacement membrane, sensors, geophysics, sampling strategy, and on site sample analysis. In the remediation task, in-situ remediation systems are being designed to remove volatile organic compounds (VOC`s) and heavy metals from soils. The VOC remediation includes vacuum extraction with electrical and radio-frequency heating. For heavy metal contamination, electrokinetic processes are being considered. The MWLID utilizes a phased, parallel approach. Initial testing is performed at an uncontaminated site adjacent to the CWL. Once characterization is underway at the CWL, lessons learned can be directly transferred to the more challenging problem of radioactive waste in the MWL. The MWL characterization can proceed in parallel with the remediation work at CWL. The technologies and systems demonstrated in the MWLID are to be evaluated based on their performance and cost in the real remediation environment of the landfills.
The structural, electrical and magnetic properties are compared for three superconducting Tl-Ca-Ba-Cu-O thin films prepared by different deposition and sintering protocols. One film containing a mixture of Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub x} and Tl{sub 2}Cu{sub 1}Ba{sub 2}Cu{sub 2}O{sub y} structural phases has the best superconducting properties. Deposition of a Tl-free Ca-Ba-Cu-O precursor film followed by sintering in Tl-O vapor may be the preferred protocol to obtain a single structural phase.
Sandia National Laboratories (SNL) designs, tests and operates a variety of accelerators that generate large amounts of high energy Bremsstrahlung radiation over an extended time. Typically groups of similar accelerators are housed in a large building that is inaccessible to the general public. To facilitate independent operation of each accelerator, test cells are constructed around each accelerator to shield it from the radiation workers occupying surrounding test cells and work-areas. These test cells, about 9 ft. high, are constructed of high density concrete block walls that provide direct radiation shielding. Above the target areas (radiation sources), lead or steel plates are used to minimize skyshine radiation. Space, accessibility and cost considerations impose certain restrictions on the design of these test cells. SNL Health Physics division is tasked to evaluate the adequacy of each test cell design and compare resultant dose rates with the design criteria stated in DOE Order 5480.11. In response SNL-Health Physics has undertaken an intensive effort to asses existing radiation shielding codes and compare their predictions against measured dose rates. This paper provides a summary of the effort underway and its results.
Here at Sandia, I design new weapon components using PRO-ENGINEER and find that not only am I responsible for the initial design, but that I must be able to justify that design and show that I have analyzed the design for stress, considering thermal, static, and dynamic conditions. I must be able to create models at a reasonable cost using stereolithography. I must be able to create vivid graphic arts presentations for managements approval, if I want the design to be accepted. I must be able to communicate my design to the production people for comment. These problems, plus others must be done in a timely manner with a minimum of paper involved, and less money than ever before. Therefore, Rapid Prototyping takes on an more important stature than originally proposed, and I would like to show you a rapid prototyping process using PRO-ENGINEER as the fundamental base from which to operate.
A previous paper showed that for condensed phase explosives, the C-J density of the detonation product gases correlates to the initial density of the unreacted explosive by a simple power function. This paper extends that correlation to the very low density region which includes detonation of suspended particles of explosives in air as well as gas phase detonations. Extending this correlation of experimental data by an additional three orders of magnitude caused a slight change in the empirical constants of the correlation.
We have used a combination of methods to probe the structure and kinetics of electron beam induced damage in a monolayer of PF{sub 3} on Ru(001). This is a particularly rich system, in which molecularly adsorbed PF{sub 3} is reduced to PF{sub 2}, PF and P by electron bombardment. The concentrations and kinetics of damage by 550 eV electrons are measured as a function of surface temperature (100 to 300 K) and PF{sub 3} coverage using soft x-ray photoemission spectroscopy (SXPS) excited by synchrotron radiation. Structures of fragments and ion desorption kinetics are measured using electron stimulated desorption ion angular distribution (ESDIAD). Evidence is seen for quenching of Desorption induced by electronic transitions (DIET) processes via intermolecular interactions at high coverages. Damage rates and product distributions vary with temperature, due to a competition between DIET and thermal kinetic processes.
This bulletin presents fabrication methods helpful to industry. This issue contains articles on the use of computers in fast casting, techniques for optimizing encapsulation, high quality electroformed parts, improved welding with detection of contaminants, and special machine guards for enhanced safety. (GHH)
Probabilistic risk assessment studies are being extended to include a wider spectrum of reactor plants than was considered in NUREG-1150. There is a need for computationally simple models of direct containment heating (DCH) that could be used for screening studies aimed at identifying potentially significant contributors to overall risk. The two-cell kinetic model developed here is an extension of the two-cell equilibrium model developed previously, which captured a major mitigating feature due to containment compartmentalization. This extension of the equilibrium model represents additional mitigating features resulting from two kinetic competitions: time-of-flight limitations to debris/gas heat transfer and debris oxidation, and the noncoherence or reactor coolant system blowdown with debris residence in the atmosphere. Predictions of containment pressurization and hydrogen production are compared to experiment data taken in the Surtsey facility located at Sandia National Laboratories.
Epitaxial films of Ba{sub 2}YCu{sub 3}O{sub 7-{delta}} (BYCO) as thin as 250 {Angstrom} and with J{sub c}`s approaching those of the best in situ grown films can be formed by co-evaporating BaF{sub 2}, Y, and Cu followed by a two-stage anneal. High quality films of these thicknesses become possible if low oxygen partial pressure [p(O{sub 2}) = 4.3 Torr] is used during the high temperature portion of the anneal (T{sub a}). The BYCO melt line is the upper limit for T{sub a}. The use of low p(O{sub 2}) shifts the window for stable BYCO film growth to lower temperature, which allows the formation of smooth films with greater microstructural disorder than is found in films grown in p(O{sub 2}) = 740 Torr at higher T{sub a}. The best films annealed in p(O{sub 2}) = 4.3 Torr have J{sub c} values a factor of four higher than do comparable films annealed in p(O{sub 2}) = 740 Torr. The relationship between the T{sub a} required to grow films with the strongest pinning force and p(O{sub 2}) is log [p(O{sub 2})] {proportional_to} T{sub a}{minus}{sup 1a} independent of growth method (in situ or ex situ) over a range of five orders of magnitude of p(O{sub 2}).
We have used 2.0-{mu}sec microwave pulses at a frequency of 2.856 GHz to rapidly heat thin amorphous yttrium-barium-copper-oxide (YBCO) films deposited onto silicon substrates. The samples were irradiated inside a WR-284 waveguide by single-pass TE{sub 10} pulses in a traveling wave geometry. X-ray diffractometry studies show that an amorphous-to-crystalline phase transition occurs for incident pulse powers exceeding about 6 MW, in which case the amorphous YBCO layer is converted to Y{sub 2}BaCuO{sub 5}. Microscopy of the irradiated film reveals that the phase transition is brought about by melting of the YBCO precursor film and crystallization of the molten layer upon solidification. Time-resolved in situ experiments of the microwave reflectivity (R) and transmissivity (T) show that there is an abrupt change in R for microwave pulse powers exceeding the melt threshold, so that measurements of R and T can be used to monitor the onset of surface melting.
This paper reports the phase-one results of a planned longitudinal study of the incidence of entrepreneurship among inventors who were employees of national laboratories. A survey of 192 inventors employed by national laboratories and 24 ex-employee inventors who became entrepreneurs provided data for comparison of situational and attitudinal variables. Significant differences in attitudes (as measured by the Entrepreneurial Attitude Orientation Scale) were found between inventors who have not become entrepreneurs and those who have. The differences in perceptions of situational variables between the two groups was significant for only two of the seven dimensions tested.
In order to resolve questions regarding the source of the extended linear viscosity-concentration regime in rod-like systems the distribution of orientations in confined systems has to be determined and related to changes in viscosity. In this work we describe our experimental and computer simulation studies on systems of neutrally buoyant suspensions of rod-like particles confined by the walls of a cylindrical container.
Recent results from light ion fusion experiments on the Particle Beam Fusion Accelerator (PBFA II) are reported. Intense proton beams have been used to drive two different types of targets. In the thermal source targets, the proton beam heated a low-density foam. The specific power deposition of the proton beam in the foam exceeded 100 TW/gm. In the spherical hydrodynamic targets, the proton beam heated a thin-walled deuterium gas-filled target directly, producing a radial convergence of the deuterium of about 6. In order to increase the specific power deposition in the target, we are developing focused lithium beams. A preformed lithium ion source has been produced using a two-step laser evaporation and ionization approach. This preformed source provides the basis for experiments being planned to reduce the divergence of the lithium beam, a critical step in demonstrating the feasibility of light ion fusion.
The first major round of target experiments driven by intense light ion beams was conducted during August and September 1991. In these experiments, intense proton beams were used to drive two different types of targets. We attempted to obtain information on the two separable issues of ion deposition and implosion hydrodynamics. Ion deposition was studied using a low density hydrocarbon foam contained within a cylindrical gold shell. Implosion hydrodynamics was studied using an ion driven exploding pusher configuration in which the ion beam heated the shell directly, exploding it both outward and inward. One of the main objectives of the experiments was to determine the extent to which we could diagnose the ion deposition and the subsequent behavior of the targets. The diagnostics included time-integrated and time-resolved x-ray pinhole cameras, time-integrated and time-resolved grazing incidence x-ray spectrometers, an 11-channel filtered x-ray diode (XRD) array, an 11-channel PIN diode array, an energy-resolved 1-dimensional imaging x-ray streak camera, a transmission grating spectrometer, an elliptical crystal x-ray spectrograph, and a bolometer. Intense beam diagnostics included an ion movie camera and an off-axis 1D slit imaging magnetic spectrograph for obtaining Rutherford-scattered ion images, momenta, and ion power densities.
The last decade has offered many challenges to the welding metallurgist: new types of materials requiring welded construction, describing the microstructural evolution of traditional materials, and explaining non-equilibrium microstructures arising from rapid thermal cycle weld processing. In this paper, the author will briefly review several advancements made in these areas, often citing specific examples of where new insights were required to describe new observations, and to show how traditional physical metallurgy methods can be used to describe transformation phenomena in advanced, non-traditional materials. The paper will close with comments and suggestions as to the needs required for continued advancement in the field.
An improved technology to extract VOCs from the unsaturated zone has developed into a cooperative Environmental Restoration and Technology Development effort. This cooperation is important because the timing of an innovative technology demonstration is critical to the transfer of that technology into an ER remedial action decision. The Mixed-Waste Landfill Integrated Demonstration (MWLID) Program will be demonstrating a Thermal Enhanced Vapor Extraction System that will improve existing vacuum vapor extraction technology by applying in-situ soil heating. Combined demonstrations of vacuum vapor extraction and both powerline frequency and radiofrequency soil heating technologies began in FY92.
SAFSIM (System Analysis Flow SIMulator) is a FORTRAN computer program that provides engineering simulations of user-specified flow networks at the system level. It includes fluid mechanics, heat transfer, and reactor dynamics capabilities. SAFSIM provides sufficient versatility to allow the simulation of almost any flow system, from a backyard sprinkler system to a clustered nuclear reactor propulsion system. In addition to versatility, speed and robustness are primary goals of SAFSIM. The current capabilities of SAFSIM are summarized, and some illustrative example results are presented.
Lost circulation is the loss of drilling fluid from the wellbore to fractures or pores in the rock formation. In geothermal drilling, lost circulation is often a serious problem that contributes greatly to the cost of the average geothermal well. The Lost Circulation Technology Development Program is sponsored at Sandia National Laboratories by the US Department of Energy. The goal of the program is to reduce lost circulation costs by 30--50% through the development of mitigation and characterization technology. This paper describes the technical progress made in this program during the period April 1991--March 1992. 8 refs.