Publications

The energy-absorbing capability of impact limiters is an important part of radioactive waste transportation system. This document presents the results of the Basic Impact Limiter Study (BILS). The objective of this design development program was to increase the energy-absorbing capabilities of an external impact limiter for both axial and off-axis response. The impact limiter that was evaluated was made of stainless steel and was a right circular cylinder. The evaluation included computer analysis complemented by static and dynamic testing of quater-scale and half-scale models. The design development, analysis, and testing were conducted at Sandia National Laboratories.

Analyses have shown that early rupture of the Mark-I boiling water reactor containment-by the direct action of core debris depends strongly on the time that core debris is superheated above its liquidus. The analyses of the duration of superheat in the core debris are compared to predictions obtained with the CORCON-MOD 3 computer code. The predicitons of this computer code as functions of the core debris mass, composition, and initial superheat are used to create a polynomial response surface. This response surface is used in a Monte Carlo analysis to produce probability distributions for the duration of superheat in core debris in the drywell of a Mark-I containment. It is concluded that to a high level of confidence (>90%) the duration of superheating predicted with the CORCON-MOD 3 code is less than what has been used in the analyses of the threats to the Mark-I containment liner. Based on these results, to the extent superheat duration dictates the threat to the liner, analyses in NUREG/CR-5423 would appear to overestimate the threat to the liner in comparison to threats estimated using the predictions of the duration of superheating obtained with CORCON-MOD 3.

A postnotification record is required for all Highway Route Controlled Quantities of radioactive materials that are shipped in the United States. These reports, which are required by 49 CFR 172.203(d), are compiled in the Radioactive Materials Routing Report (RAMRT) database at the US Department of Transportation (DOT). Sandia National Laboratories` has developed an expanded version of the RAMRT which is entitled the Radioactive Materials Postnotification (RAMPOST) database. This paper provides the summary detail on the following topics: major carriers of highway route controlled quantities, major US Department of Energy (DOE) shippers, major US Nuclear Regulatory Commission (NRC) shippers and a breakdown of the types of Highway Route Controlled Quantities that have been shipped for the time period 1985--1990.

We describe the design and operation of an optical fiber accelerometer intended for environments inhospitable to electronic components. An overview of the device is presented along with descriptions of the optical, electronic, and mechanical components. The performance of the current prototype is equivalent to state of the art piezoelectric accelerometers. Improvements to the current design are discussed.

The possibility of formulating and validating a multi-site, multi- solute model for prediction of contaminant transport in groundwaters is being evaluated through experiments with simple analog systems. These systems consist of mixtures of well-characterized synthetic and natural materials in which the effects of sorption by ion exchange and amphoteric sites are isolated. Initial results are reported for studies of lead sorption by mixtures of goethite and montmorillonite, and Ni-Sr and Pb-Sr ion exchange by montmorillonite. The results of studies of simple clay-oxide mixtures indicate that the pH-dependent sorption behavior of Ni by mixtures of minerals containing amphoteric sites can be predicted from the properties of the component minerals.

Site characterization is an integral component of any environmental assessment or restoration project. However, it is often difficult to know how to prioritize site characterization activities. In the absence of a preliminary analysis, site characterization decisions are sometimes guided by little more than intuition. The objective of this paper is to show that a Performance Assessment Methodology, used very early in a project, can be a useful tool for guiding site characterization activities. As an example, a ``preliminary`` performance assessment for the Greater Confinement Disposal project is used to demonstrate implementation of the methodology.

We present results that correlate microstructure and mechanical evolution to variations of deformation rate, hold time and environmental effects on the thermomechanical fatigue (TMF) behavior of 60Sn-40Pb solder. The results are used to define valid conditions for performing accelerated TMF tests. TMF tests at deformation rates of 5.6{times}10{sup {minus}4}s{sup {minus}1}, 2.8{times}10{sup {minus}4}s{sup {minus}1} and 2.1{times}10{sup {minus}4}s{sup {minus}1} were performed. Deformation rates greater than 2.8{times}10{sup {minus}4}s{sup {minus}1} result in fewer cycles to failure. At low deformation rates, the microstructure heterogeneously coarsens at cell boundaries. At higher rates, the deformation mechanism changes, and heterogeneous coarsening occurs at a strain concentration in the joint, independent of the microstructure. TMF tests with hold times of 0, 3 and 6 min. at the temperature extremes were performed. At hold times 3 min. or longer the damage at cell boundaries is annealed, resulting in heterogeneous coarsening. With no hold times the TMF life was greatly enhanced as a result of limited coarsening. The effect of the oxygen environment was explored. The TMF life in the presence of oxygen was found to be extended. Valid acceleration conditions for a TMF test of solder are: a deformation rate of 2.8{times}10{sup {minus}4}s{sup {minus}1} or lower, with hold times of 3 mn. or longer.

The discrete Fourier transform and power spectral density are often used in analyzing data from analog-to-digital converters. These analyses normally apply a window to the data to alleviate the effects of leakage. This paper describes how windows modify the magnitude of a discrete Fourier transform and the level of a power spectral density computed by Welch`s method. For white noise, the magnitude of the discrete Fourier transform at a fixed frequency has a Rayleigh probability distribution. For sine waves with an integer number of cycles and quantization noise, the theoretical values of the amplitude of the discrete Fourier transform and power spectral density are calculated. We show how the signal-to-noise ratio in a single discrete Fourier transform or power spectral density frequency bin is related to the normal time-domain definition of the signal-to-noise ratio. The answer depends on the discrete Fourier transform length, the window type and the function averaged.

A new, laser-based system has been developed for rapid evaluation of monolithic thermoluminescence dosimetry (TLD) arrays. A precision controlled CO{sub 2} laser is used to sequentially heat 1.5 mm diameter, {approx} 0.04 mm thick TLDs deposited on a .125 mm thick polymer substrate in a 3 mm {times} 3 mm grid. Array areas up to 30 cm {times} 30 cm are used (> 10,000 TLD elements), with evaluation times of 45--90 minutes. Isodose contours and various analysis functions are available on the system-operating PC. This system allows for greatly expanded dosimetry compared to standard TLDs, simultaneously decreasing effort and record keeping. We compared the dosimetric characteristics of this system with standard techniques, using near Si-equivalent CaF{sub 2}:Mn TLD elements, in a test with 19 MeV end-point X radiation. The results show the laser system performs as well as the standard system. 4 refs.

The Chemical Waste Landfill (CWL) was used by Sandia National Laboratories (SNL), Albuquerque for disposal of hazardous chemicals from the years 1962 to 1985. Prompted by the detection of low levels of trichlorethylene (TCE) in groundwater samples from a water table aquifer approximately 146 meters below ground surface, a RCRA Site Investigation (RSI) and remediation of organic contaminants will be performed at the CWL prior to closure of this landfill. The RSI is focused on optimal characterization of the VOC and dense non-aqueous phase liquid (DNAPL) contamination at this site which will be possible through application of innovative strategies for characterization and promising new technologies. This paper provides a discussion of conceptual models of contaminant transport at the CWL, and an overview of our investigative strategy which is focused on characterizing transport of VOC and DNAPLS. Each stage of the RSI has been developed to gather information which will reduce the uncertainty in the design of each subsequent phase of the investigation. Three stages are described; a source characterization stage, unsaturated zone characterization stage, and a saturated zone characterization stage. The unsaturated zone characterization must provide all data necessary to make decisions concerning the necessity of a saturated zone characterization phase.

This paper summarizes the results of aging, condition monitoring, and accident testing of Class 1E cables used in nuclear power generating stations. Three sets of cables were aged for up to 9 months under simultaneous thermal ({approximately}100{degrees}C) and radiation ({approximately}0.10 kGy/hr) conditions. After the aging, the cables were exposed to a simulated accident consisting of high dose rate irradiation ({approximately}6 kGy/hr) followed by a high temperature steam (up to 400{degrees}C) exposure. A fourth set of cables, which were unaged, was also exposed to the accident conditions. The cables that were aged for 3 months and then accident tested were subsequently exposed to a high temperature steam fragility test (up to 400{degrees}C), while the cables that were aged for 6 months and then accident tested were subsequently exposed to a 1000-hour submergence test in a chemical solution. The results of these tests do not indicate any reason to believe that many popular nuclear power plant cable products cannot inherently be qualified for 60 years of operation for conditions simulated by this testing. Mechanical measurements (primarily elongation, modulus, and density) are more effective than electrical measurements for monitoring age-related degradation. In the high temperature steam test, ethylene propylene rubber (EPR) cable materials generally survived to higher temperatures than crosslinked polyolefin (XLPO) cable materials. In dielectric testing after the submergence testing, the XLPO materials performed better than the EPR materials.

Numerous investigations have studied the potential for chaotic vibrations of nonlinear systems. It has been shown for many simple nonlinear systems, that when they are excited severely enough, or with the appropriate parametric combinations, that they will execute chaotic vibrations. The present investigation considers the potential for the occurrence of chaos in a practical nonlinear system -- the isolated accelerometer. A simple, first order model is proposed for the isolated accelerometer, and it is shown that chaos can occur in the isolated accelerometer. A preliminary investigation into the bearing that this chaos potential has on the measurement of shock response is summarized. 7 refs.

Carrier-driven photochemical reactions require direct participation of free carriers for the chemical reaction to proceed. Therefore, they can be selectively suppressed by increasing the carrier recombination rate through creation of defects using ion implantation. The residual defect concentration following ion implantation should correlate with etching suppression. Changes in the Raman LO-phonon lineshape correlate well with the degree of etching suppression and predict etching behavior better than defect concentrations calculated with the Monte Carlo code, TRIM. Raman spectroscopy may be a useful pre-etch diagnostic to predict the degree of etching suppression resulting from a given implantation treatment. 11 refs.

Direct containment heating (DCH) has recently been studied at Sandia National Laboratory`s Surtsey facility in a number of experiments in which high-temperature thermite melts are ejected by pressurized steam from a melt generator into scaled reactor cavities. Steam blowdown from the melt generator disperses at least part of the melt into the Surtsey vessel. Efficient team-metal chemical reaction was observed in many of the experiments. Analysis of the results suggests that hydrogen generation occurs primarily in the cavity can actually reduce hydrogen generation by separating the debris from the blowdown steam. Debris-gas heat transfer appears to include both a component that takes place in the cavity in proportion to the hydrogen generation, and a second component that takes place in the Surtsey vessel itself. The magnitude of the latter depends upon the amount of debris dispersed and the length of the unobstructed flight path in the Surtsey vessel. Some possible implications of these results are discussed.

A Senate Committee requested assistance from Sandia in determining the adequacy of the investigation of the incident aboard the USS IOWA. This currently unexplained explosion occurred in Turret 2 of the battleship on April 19, 1989, killing 47 crewmen. The investigation included material characterization of debris found after the explosion, ignition experiments to characterize the propellant, and analytic modeling of the mechanics, interior ballistics and ignition. The analytic modeling is described in this paper. The modeling of the incident was concerned with the mechanics of the ramming equipment used to load the 16 inch guns, and the interior ballistic and ignition of the propellant. Many separate analyses were performed to explain the crushing of the propellant grains, the dynamics and location of ignition of the propellant train, and the presence of damage after the incident. The goal of this modeling was to assess the feasibility of the various events in the turret, and to identify the cause of the incident. An item of particular interest was damage to the rammer control handle quadrant. The US Navy conjectured that the blast propelled the rammermans seat into the quadrant in such a way as to suggest low speed ram during the incident. The speed of the ram was discovered to be very important in determining the probability of ignition during an overram, and an analysis of the rammermans seat motion was completed. In order to understand how the seat impacts the quadrant, a three-dimensional finite element analysis was completed using ABAQUS/Explicit. The loading of the seat was due to two-phase gas and propellant flow through the bag train and into the turret volume. The results showed that impact onto the quadrant probably first occurred at the rear, dislodging it from its mount. This analysis was pivotal in the examination of the incident, and was the final evidence that the cause of the explosion could not be conclusively determined.

High spatial resolution x-ray microanalysis in the analytical electron microscope (AEM) describes a technique by which chemical composition can be determined on spatial scales of less than 50 nm. Dependent upon the size of the incident probe, the energy (voltage) of the beam, the average atomic number of the material being analyzed, and the thickness of the specimens at the point of analysis it is possible to measure uniquely the composition of a region 2--20 nm in diameter. Conventional thermionic (tungsten or LaB{sub 6}) AEMs can attain direct spatial resolutions as small as 20 nm, while field emission (FEG) AEM`s can attain direct spatial resolutions approaching 2 nm. Recently, efforts have been underway to extract compositional information on a finer spatial scale by using massively parallel Monte Carlo electron trajectory simulations coupled with AEM measurements. By deconvolving the measured concentration profile with the calculated x-ray generation profile it is possible to extract compositional information at near atomic resolution.

Chemical and physical transformations involved in ion implantation processes in glasses determine changes in mechanical. and tribological properties, in network dilatation, in induced optical absorption and luminescence and in the composition and chemical behavior as a function of different experimental conditions (ion, energy, dose, target temperature). Variations of chemical etch rate in HF are related to radiation damages and formation of compounds. A systematic study of the etch rate changes in silica due to Ar, N, Si plus N implants has been performed. Structure modifications at depths greater than the corresponding implanted ion ranges are evidenced for nuclear deposited energy greater than 10{sup 22} keV cm{sup {minus}3}. Formation of silicon oxynitrides reduces the etch rate values.

Archimedes is a prototype mechanical assembly system which generates and executes robot assembly programs from a CAD model input. The system seeks to increase flexibility in robotic mechanical assembly applications by automating the programming task. Input is a solid model of the finished assembly, augmented by additional design information such as weld specifications. 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 plan compiler then converts the generic plan into code specific to an application environment. Other outputs include fixture designs, workcell layout information, object-recognition (vision) routines, grasp plans, and executable code for controlling the robot and workcell accessories. Lessons from operating and demonstrating the system are presented, with a particular emphasis on the implications for future systems. 12 refs.

Isolated accelerometer measurement systems are used to measure environments composed of a wide spectrum of frequencies including the natural frequency of the isolated accelerometer. Because the isolated accelerometer measurement system is a nonlinear system, it is subject to the potential for chaotic vibrations. it is clear that this potential if realized, affects the response of the measurement system to vibration input and perhaps to shock input also. This paper explores the effects that the potential for chaotic vibrations and nonlinear response, in general, has on the random vibration response of the isolated accelerometer measurement system. Specifically, the system response to white noise is investigated and assessed in terms of response histogram and response spectral density. 6 refs.

In the Federal Register, Volume 51, Number 168, NRC has intended the use of IMPACTS-BRC to evaluate petitions for evaluating radioactive waste streams as below regulatory concern. IMPACTS-BRC is a generic radiological assessment code that allows calculation of potential impacts to maximum individuals, waste disposal workers, and the general population resulting from exemption of very low-level radioactive waste from regulatory control. The code allows calculations to be made of human exposure to the waste by many pathways and exposure scenarios. This document describes the code history and the quality assurance work that has been carried out on IMPACTS-BRC. The report includes a summary of all the literature reviews pertaining to IMPACTS-BRC up to Version 2.0. The new code and data verification work necessary to produce IMPACTS-BRC, Version 2.1 is presented. General comments about the models and treatment of uncertainty in IMPACTS-BRC are also given.

This work describes the collection, handling, transportation, thermal desorption, and analysis of explosive vapors using quartz collection tubes. A description of the sampling system is presented, along with the collection efficiency of the quartz tubes and some of the precautions necessary to maintain the sample integrity. The design and performance characteristics of the thermal desorption system are also discussed. Collection of explosive vapor using empty, 0.25 inch O.D. by 5.25 inch long quartz tubes at a flow rate of 200 mL min-1 is quite different. Thermal desorption of the explosive vapor molecules using a furnace that allows control of the gas phase chemistry in the IMS has been shown to provide a reliable, reproducible means of analysis. Empty quartz tubes provide a sharper desorption profile than packed collection tubes, resulting in a better signal-to-noise ratio, and perhaps, a lower detection limit than packed quartz tubes. Both the ion drift time of the explosive and its desorption characteristics can provide a means of identification. Sample handling, packaging, and transportation methods which minimize sample loss and contamination have been developed and evaluated.

This report contains the purchasing and materials management operating highlights for Fiscal Year 1991. Included in the report are compiled data on: personnel; type of procurement; small business procurements; disadvantaged business procurements; woman-owned business procurements; New Mexico commercial business procurements; Bay Area commercial business procurements; commitments by states and foreign countries to commercial suppliers; and, transportation activities. Other statistical data tables enumerate the following: the twenty-five commercial contractors receiving the largest dollar commitments; commercial contractors receiving commitments of $1000 or over; integrated contractor and federal agency commitments of $1000 or over from Sandia National Laboratories-Albuquerque and Livermore; and, transportation commitments of $1000 or over from Sandia National Laboratories-Albuquerque and Livermore.

This white paper addresses the issue of banning lead from solders used in electronics manufacturing. The current efforts by legislative bodies and regulatory agencies to curtail the use of lead in manufactured goods, including solders, are described. In response to a ban on lead or the imposition of a tax which makes lead uneconomical for use in solder alloys, alternative technologies including lead-free solders and conductive epoxies are presented. The recommendation is made that both users and producers of solder materials join together as partners in a consortium to address this issue in a timely and cost-effective manner.

The MELCOR code has been used to simulate the ST-1 and ST-2 in-pile product source term experiments performed in the ACRR facility. As expected, there were no major differences observed in the results calculated for the different test conditions. The CORSOR, CORSOR-M and CORSOR-Booth release models all were tested, and the effect of including the surface-volume correction term was evaluated. MELCOR results were compared to test data and to VICTORIA results, and also directly to the correlations and to ST-1/ST-2 results predicted by Battelle using their stand-alone CORSOR code to verify that the models have been implemented correctly in MELCOR. The release rates and total release fractions calculated by MELCOR generally agreed well with the test data, for both volatile and refractory species, with none of the release model options available yielding consistently better agreement with data for species. Sensitivity studies checking for time step and noding effects and machine dependencies were done, and some machine dependencies associated with very small numbers were identified and corrected in the code. Additional sensitivity studies were run on parameters affecting core heatup and core damage, including both variations in code models such as convective heat transfer coefficients, radiation view factors, candling assumptions, and in experimental conditions such as pressures, flow rates, power levels, and insulation thermal conductivity. Code and user input modeling errors encountered in these analyses are described.

This paper presents a method to solve partial differential equations governing two-phase fluid flow by using a genetic algorithm on the NCUBE/2 multiprocessor computer. Genetic algorithms represent a significant departure from traditional approaches of solving fluid flow problems. The inherent parallelism of genetic algorithms offers the prospect of obtaining solutions faster than ever possible. The paper discusses the two-phase flow equations, the genetic representation of the unknowns, the fitness function, the genetic operators, and the implementation of the genetic algorithm on the NCUBE/2 computer. The paper investigates the implementation efficiency using a pipe blowdown test and presents the effects of varying both the genetic parameters and the number of processors. The results show that genetic algorithms provide a major advancement in methods for solving two-phase flow problems. A desired goal of solving these equations for a specific simulation problem in real time or faster requires computers with an order of magnitude more processors or faster than the NCUBE/2`s 1024.