Publications

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.

This volume presents the methodology and results of the internal event accident sequence analysis of the LaSalle Unit II nuclear power plant performed as part of the Level III Probabilistic Risk Assessment being performed by Sandia national laboratories for the Nuclear Regulatory commission. This report describes the new techniques developed to solve the very large and logically complicated fault trees developed in the modeling of the LaSalle systems, for evaluating the large number of cut sets in the accident sequences, for the application of recovery actions to these cut sets, and for the evaluation of the effects of containment failure on the systems and the resolution of core vulnerable accident sequences.

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.

Short communication.

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.

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.

Short communication.

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.