Publications

This report describes Welch's method for computing Power Spectral Densities (PSDs). We first describe the bandpass filter method which uses filtering, squaring, and averaging operations to estimate a PSD. Second, we delineate the relationship of Welch's method to the bandpass filter method. Third, the frequency domain signal-to-noise ratio for a sine wave in white noise is derived. This derivation includes the computation of the noise floor due to quantization noise. The signal-to-noise ratio and noise flood depend on the FFT length and window. Fourth, the variance the Welch's PSD is discussed via chi-square random variables and degrees of freedom. This report contains many examples, figures and tables to illustrate the concepts. 26 refs.

Four expert-judgment teams have developed analyses delineating possible future societies in the next 10,000 years in the vicinity of the Waste Isolation Pilot Plant (WIPP). Expert-judgment analysis was used to address the question of future societies because neither experimentation, observation, nor modeling can resolve such uncertainties. Each of the four, four-member teams, comprised of individuals with expertise in the physical, social, or political sciences, developed detailed qualitative assessments of possible future societies. These assessments include detailed discussions of the underlying physical and societal factors that would influence society and the likely modes of human-intrusion at the WIPP, as well as the probabilities of intrusion. Technological development, population growth, economic development, conservation of information, persistence of government control, and mitigation of danger from nuclear waste were the factors the teams believed to be most important. Likely modes of human-intrusion were categorized as excavation, disposal/storage, tunneling, drilling, and offsite activities. Each team also developed quantitative assessments by providing probabilities of various alternative futures, of inadvertent human intrusion, and in some cases, of particular modes of intrusion. The information created throughout this study will be used in conjunction with other types of information, including experimental data, calculations from physical principles and computer models, and perhaps other judgments, as input to performance assessment.'' The more qualitative results of this study will be used as input to another expert panel considering markers to deter inadvertent human intrusion at the WIPP.

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 ({approx_equal} 100{degrees}C) and radiation ({approx_equal}0.10 kGy/hr) conditions. After the aging, the cables were exposed to a simulated accident consisting of high dose rate irradiation ({approx_equal}6 kGy/hr) followed by a high temperature steam exposure. A fourth set of cables, which were unaged, were 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 the tests indicate that the feasibility of life extension of many popular nuclear power plant cable products is promising and that mechanical measurements (primarily elongation, modulus, and density) were 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. This paper presents some recent experimental data that are not yet available elsewhere and a summary of findings from the entire experimental program.

Combustion of energetic materials involves processes in both gas and condensed phases and is governed by coupled thermal, physical, and chemical phenomena. Development of reliable models for design, performance, stability, and hazard analyses requires detailed understanding of three general chemical reaction regimes: (1) initial condensed-phase decomposition, (2) subsequent interaction of decomposition products with the remaining condensed phase, and (3) gas-phase reaction of decomposition products to form the ultimate combustion products. The first two regimes are the least understood and most difficult to study, particularly the initial condensed-phase decomposition. The basic difficulty in studying condensed phase phenomena has been the inability to probe directly chemistry in the condensed phase under isothermal condition and with the spatial and temporal resolution needed at higher temperatures and reaction rates. Thin-film samples provide a means to study condensed-phase chemistry at isothermal conditions and with microsecond temporal resolution. We are developing an experiment system that employs rapidly heated thin- film samples and multiple diagnostics to examine condensed-phase chemistry and monitor evolved gas species. Results from our initial work have been encouraging. Thin-film samples of several energetic materials have been prepared and appear to be representative of bulk materials. Furthermore, preliminary experiments indicate that all the use of these samples with two chemical diagnostic techniques, time-of- flight mass spectrometry (TOFMS) and time-resolved infrared spectral photography (TRISP), is viable. 5 refs., 8 figs.

The polarimetry problem (the measurement of the radar-cross-section polarization scattering matrix) is described. Two methods of calibrating a polarimetric radar are outlined. The first is a general multiple-calibration-target (MCT) method applicable to almost any radar system. The second is a simple, single-calibration-target (SCT) method applicable to systems which use a single antenna for both transmit/receive and a reciprocal RF network. The performance of the MCT method is examined through the use of Monte Carlo simulations. Finally, the SCT method is applied to measurements from the SCATTER facility, demonstrating about 40 dB isolation between polarization components in the frequency domain and in excess of 50 dB in the range domain.

Sandia National Laboratories, Albuquerque, manages the Utility Battery Exploratory Technology Development Program, which is sponsored by the US Department of Energy`s Office of Energy Management. In this capacity, Sandia is responsible for the engineering analyses and development of rechargeable batteries for utility-energy-storage applications. This report details the technical achievements realized during fiscal year 1991. Sodium/Sulfur, Zinc/Bromine, Nickel/Hydrogen, Aluminium/Air and Lead/Acid batteries are evaluated.

This report presents the results of single-well hydraulic tests performed in seven wells in the vicinity of the Waste Isolation Pilot Plant (WIPP) site in southeastern New Mexico in 1988 and 1989. The tests discussed in this report were performed in four of the five members of the Rustler Formation. The tests include: a slug-withdrawal test of the unnamed lower member of the Rustler ate well H-16; slug-withdrawal and slug-injection tests of the Culebra Dolomite Member at well AEC-7; slug-injection tests of the Culebra at well D-268; a pumping test of the Culebra at well H-18; pulse-injection, slug-injection, and slug-withdrawal tests of Magenta Dolomite Member at well H-2b1; pulse-withdrawal, slug-withdrawal, and slug-injection tests of the Magenta at well H-3b1; and pulse-withdrawal and slug-withdrawal tests of the Forty-niner Member at well H-3d. The tests were intended to provide data on the transmissivities of the Rustler members for use in regional-scale modeling of groundwater flow through the Rustler.

The ES&H Training Catalog is a tool to assist managers in determining which training courses they require their employees to complete. The narrative description under ``Who Shall Attend`` describes the characteristics of the employees and contractors under the direction of Sandia who are required by law, regulation, DOE Order, or SNL Directive to complete the training in order to be in compliance. The narrative is ``Who Should Attend`` describes the individuals for which the course is `highly recommended,`` although they are not mandated to attend.

SANET is a computer program intended for use in constructing, evaluating, and printing event trees for safety and reliability studies. SANET allows the user to graphically construct event trees, assign probabilities to the branches on the tree and include a variety of labels. Fast, publication quality printed output can be obtained. SANET requires an IBM compatible PC with a 80286, 80386 or 80486 processor, VGA graphics, a mouse and an HP Laserjet printer.

The technological innovation process comprises a range of stages, steps, and activities extending fro generation of new ideas through successful practical application of those ideas. This process constitutes the larger context within which technology transfer programs must necessarily operate if the goal is to transform new knowledge and technology into products which are competitive in the emerging global marketplace. A basic grasp of the principles and issues involved in the total innovation process is essential for developing and improving programs, prioritizing activities, and making strategic and operational decisions which will be appropriate and effective. This report attempts to provide a relatively brief overview of the total innovation process and related issues. This focus follows from the intent of the federal technology transfer initiative, which is essentially to facilitate the rapid advance of technological progress and to enhance national economic competitiveness. It is important to recognize that the transfer of technology between organizations or individuals is only one part of the complete process, although possibly a critical part in some situations. From an economic standpoint, technology transfer without resulting successful commercialization is meaningless. This report should be useful primer for people from any sector of the economy, even though it is intended to address the context for the transfer of federal laboratory technology in particular.

Two laboratory tests were designed to study the behavior of SnTe and CsOH in steam at {approximately}1230 K with the reactor materials Inconel 600, 304 stainless steel, silver and nickel, a nonoxidizing constituent of Inconels and steels in reactor accident environments. Thermochemical calculations examined the sensitivity of species in the H-O-Cs-Te-Sn system to temperature, to hydrogen and SnTe concentrations and to total system pressure. Test results indicate that should SnTe be formed from fission product tellurium and the tin in zircaloy cladding, it may not remain stable in steam in the presence of unoxidized (or lightly oxidized) metals. Calculations show a small amount of SnTe, in equilibrium with steam, decomposes to primarily Te and SnO. It is felt that these decomposition producets react with the reactor materials since Sn and Te are seen to be deposited separately and not as SnTe. The deposition velocity for SnO vapor in the system was estimated to be 0.57 m/s. The response of CsOH in the system was similar to behavior observed previously: some cesium combined with silicon found in Inconel and stainless steel oxides. At lower temperatures ({le}940 K) CsOH corroded Inconel, stainless steel and nickel providing enhanced surface area for additional trapping of species. There was no experimental evidence for the formation of cesium telluride; vapor equilibrium calculations did not predict formation either. 33 refs., 29 figs, 7 tabs.

An analytical expression and an integral representation are presented for the contribution, Y{sup (n)} = {Sigma}{sup (n)}{delta}{Omega}{sub n}, of n-event multiple scattering chains to the observed backscattering spectrum in heavy-ion backscattering (HIBS) measurements. The approximations introduced in deriving the results are chosen such that an upper limit is placed on Y{sup (n)} by the expressions. The Rutherford elastic scattering cross section is used to describe individual collisions between incident projectiles and target atoms. Screening of the Rutherford scattering cross section is included in an approximate fashion which maintains the upper limit estimate. Inelastic energy loss between collision events is assumed proportional to the projectile velocity. Specific application of theses expressions is made to HIBS detection of trace amounts of heavy atom impurities on a Si by 200--400 keV C{sup +} beams. The predicted multiple scattering background for this applications is compared with the predicted single scattering signal for 10{sup 10} atoms/cm{sup 2} of Fe, Cu, Zr, Sn, or Au, as surface impurity. The comparison shows that the multiple scattering background poses no barrier to extending the sensitivity of HIBS detection of impurities in this mass range to levels as low as 10{sup 8} atoms/cm{sup 2} for the upper part of the energy range considered. Comparison of calculations with and without screening included show that the screening of the Rutherford cross section by atomic electrons is a significant factor in preventing multiple scattering effects from interfering with HIBS spectrometry at impurity levels in the 10{sup 10} atoms/cm{sup 2} range.

The MELCOR code has been used to simulate the FLECHT SEASET natural circulation experiments done in a scale-model Westinghouse-PWR test facility, with code results compared to experimental data. Sensitivity studies have been done, for both single-phase and two-phase natural circulation conditions, on time step effects and machine dependencies; nodalization studies and studies on several code modelling options were also done. Good agreement is found between prediction and observation for steady-state, single-phase liquid natural circulation. The code could reproduce the major thermal/hydraulic response characteristics in two-phase natural circulation, but only through a number of nonstandard input modelling modifications; MELCOR cannot reproduce the requisite physical phenomena with ``normal`` input models. Because the same response is observed in similar tests at other facilities over a range of scales and is expected to occur in full-scale plants as well, the ability of the user to ``match`` the observed behavior through a small set of nonstandard input modelling changes allows MELCOR to be used in PRA studies in which such physics are expected to be encountered, while awaiting corrections to the code models involved. The time step control algorithm in MELCOR does not run this problem efficiently; a substantial reduction in time step results in significantly less oscillation predicted at only a small increase run time.

The Waste Isolation Pilot Plant (WIPP) is planned as a mined geologic repository for the disposal of transuranic (TRU) radioactive wastes generated by defense programs of the United States Department of Energy. One of the criteria for evaluating the suitability of the WIPP for disposal of TRU wastes is compliance with the United States Environmental Protection Agency`s (EPA) standards for such facilities. The Containment Requirements of those standards require calculating cumulative releases of radionuclides to the accessible environment by all combinations of events and processes (scenarios) that may affect the escape and transport of radionuclides from the repository for 10, 000 years after decommissioning of the facility. Because the release limits established by the EPA are probabilistic, scenario probabilities are also required. A panel of experts was convened to estimate the probabilities of occurrence of the events used in scenario development and to identify additional human-intrusion events for inclusion in a safety assessment of the WIPP. This report documents the background presentations that were made to the panel about the WIPP program, regulatory guidelines, and performance-assessment program, and site-specific and regional geologic and hydrologic characteristics that may affect the WIPP disposal system.

This report is a revision and update of the original geologic site characterization report that was published in 1980. Many of the topics addressed in the earlier report were predictive in nature and it is now possible to reexamine them some 12 years later, using the data from 17 new caverns and more than ten years of SPR storage experience. Revised maps of the salt configuration show on overhand and faults on the north side of the dome, defining more clearly the edge relationships with respect to the SPR caverns. Caprock faults may locally influence the pattern of subsidence, which is occurring primarily as a result of cavern creep closure. The greater subsidence rate occurring at West Hackberry will likely require mitigative action within a few years. Seismicity of low intensity recurs infrequently at West Hackberry, but a small earthquake in 1983 caused dish rattling in the immediate vicinity.

Excavation stability in an underground nuclear waste repository is required during construction, emplacement, retrieval (if required), and closure phases to ensure worker health and safety, and to prevent development of potential pathways for radionuclide migration in the post-closure period. Stable excavations are developed by appropriate excavation procedures, design of the room shape, design and installation of rock support reinforcement systems, and implementation of appropriate monitoring and maintenance programs. In addition to the loads imposed by the in situ stress field, the repository drifts will be impacted by thermal loads developed after waste emplacement and, periodically, by seismic loads from naturally occurring earthquakes and underground nuclear events. A priori evaluation of stability is required for design of the ground support system, to confirm that the thermal loads are reasonable, and to support the license application process. In this report, a design methodology for assessing drift stability is presented. This is based on site conditions, together with empirical and analytical methods. Analytical numerical methods are emphasized at this time because empirical data are unavailable for excavations in welded tuff either at elevated temperatures or under seismic loads. The analytical methodology incorporates analysis of rock masses that are systematically jointed, randomly jointed, and sparsely jointed. In situ thermal and seismic loads are considered. Methods of evaluating the analytical results and estimating ground support requirements for all the full range of expected ground conditions are outlines. The results of a preliminary application of the methodology using the limited available data are presented. 26 figs., 55 tabs.

The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, for which many design options are being considered, including shafts, drifts, and ramps. The information in this report pertains to: (1) engineering calculations of the potential distribution of residual water from constructing the shafts and drifts; (2) numerical calculations predicting the movement of residual construction water from the shaft and drift walls into the rock; and (3) numerical calculations of the movement of residual water and how the movement is affected by ventilation. This document contains information that has been used in preparing Appendix 1 of the Exploratory Studies Facility Design Requirements document for the Yucca Mountain Project.

Numerical results are presented for the Performance Assessment Calculational Exercise (PACE-90). One- and two-dimensional water and solute transport are presented for steady infiltration into Yucca Mountain. Evenly distributed infiltration rates of 0.01, 0.1, and 0.5 mm/yr were considered. The calculations of solute transport show that significant amounts of radionuclides can reach the water table over 100,000 yr at the 0.5 mm/yr rate. For time periods less than 10,000 yr or infiltrations less than 0.1 mm/yr very little solute reaches the water table. The numerical simulations clearly demonstrate that multi-dimensional effects can result in significant decreases in the travel time of solute through the modeled domain. Dual continuum effects are shown to be negligible for the low steady state fluxes considered. However, material heterogeneities may cause local amplification of the flux level in multi-dimensional flows. These higher flux levels may then require modeling of a dual continuum porous medium.

In support of the development of American National Standards Institute standards for the transport of radioactive materials, Sandia has a program to characterize the normal transport environment. This program includes both analytical modeling of package and trailer responses, and over-the-road tests to measure those responses. This paper presents the results of a series of over-the-road tests performed using Chem-Nuclear equipment in the Barnwell, SC, area. The test events included a variety of road types such as rough concrete, shock events such as railroad grade crossings, and driver responses such as sharp turns. The response of the package and trailer to these events was measured with accelerometers at various locations to determine the inertial loads. Either load cells or strain gages were used to measure tiedown response. These accelerations and loads were measured on systems with flexible and ``rigid`` tiedowns. The results indicated that while significant accelerations occur on the trailer bed, these do not translate into equivalent loads in either the package or the tiedown system. This indicates that trailer-bed response should not be used in determining the load factor for fatigue calculations of the package components or in determining design loads for tiedowns.

Currently, there are several Greater Confinement Disposal (GCD) boreholes at the Radioactive Waste Management Site (RWMS) for the Nevada Test Site. These are intermediate-depth boreholes used for the disposal of special case wastes, that is, radioactive waste within the Department of Energy complex that do not meet the criteria established for disposal of high-level waste, transuranic waste, or low-level waste. A performance assessment is needed to evaluate the safety of the GCD site, and to examine the feasibility of the GCD disposal concept as a disposal solution for special case wastes in general. This report documents the effort in defining all the waste inventory presently disposed of at the GCD site, and the inventory and release model to be used in a performance assessment for compliance with the Environmental Protection Agency`s 40 CFR 191.

Cementitious materials, together with other materials, are being considered to seal a potential repository at Yucca Mountain. A concern with cementitious materials is the chemical and mineralogic changes that may occur as these materials age while in contact with local ground waters. A combined theoretical and experimental approach was taken to determine the ability to theoretically predict mineralogic changes. The cementitious material selected for study has a relatively low Ca:Si ratio approaching that of the mineral tobermorite. Samples were treated hydrothermally at 200{degrees}C with water similar to that obtained from the J-13 well on the Nevada Test Site. Post-test solutions were analyzed for pH as well as dissolved K, Na, Ca, Al, and Si. Solid phases formed during these experiments were characterized by scanning electron microscopy and X- ray diffraction. These findings were compared with predictions made by the geochemical modeling code EQ3NR/E06. It was generally found that there was good agreement between predicted and experimental results.

Two years ago, researchers at Sandia National Laboratories showed that a massively parallel computer with 1024 processors could solve scientific problems more than 1000 times faster than a single processor. Since then, interest in massively parallel processing has increased dramatically. This review paper discusses some of the applications of this emerging technology to important problems at Sandia. Particular attention is given here to the impact of massively parallel systems on applications related to national defense. New concepts in heterogenous programming and load balancing for MIMD computers are drastically increasing synthetic aperture radar (SAR) and SDI modeling capabilities. Also, researchers are showing that the current generation of massively parallel MIMD and SIMD computers are highly competitive with a CRAY on hydrodynamic and structural mechanics codes that are optimized for vector processors.

Analysis of an intermittent failure to write the "1" state to a particular memory location at low temperature (-55° C) in a 16K x 1 CMOS SRAM is presented. The failure was found to be due to an open metallization at a metal-to-silicon contact. The root cause of the failure was poor step coverage of the metallization over an oxide step. A variety of failure analysis techniques including dynamic electron beam analysis at low temperature using a Peltier cold stage were employed to study the intermittently failing SRAM. The failure site was located by using capacitive coupling voltage contrast analysis. PSPICE simulation, light emission microscopy, scanning electron microscopy, and focused-ion beam techniques were used to confirm the failure mechanism and location. The write cycle time of the failed IC was abnormally long, but within the allowable tester limit. The vulnerability of other ICs to failure by open metallization in metal-to silicon contacts is reviewed.

We present calculations which show the radial dependence of the KVV and L₂₃VV Auger matrix elements of silicon. We find greatly differing dependences, converging within ~1 a.u. of the nucleus in the case of the KVV, but not until ~4 a.u. in the case of the L₂₃VV, well beyond the bond midpoint of ~2.2 a.u. We also find quite different dependences for the various elements within a particular CVV transition. Because the local density of states (LDOS) is dependent on the radius of the sphere of integration, our results suggest that different CVV Auger processes on the same atom in fact probe different LDOSs, as do even different contributions within the same transition. (This effect is separate from the well-known matrix element property which weights angular-momentum components differently.) These results call into question both the single-site LDOS approximation when used in the interpretation of low-energy (<100 eV) Auger spectra, and the application to high-energy spectra of local densities of states obtained by integration over muffin-tin or Wigner–Seitz spheres which have a large radius compared to the region probed by the Auger process.

Two-dimensional Acousto-Optic (AO) correlators differ from the frequency plane correlators in that multiplying, shifting, and adding, rather than Fourier transforming are used to obtain the correlations. Thus, many of the available composite filter design techniques are not aimed at designing filters for use in AO correlators since they yield frequency-domain functions. In this paper, a method is introduced for designing filter impulse responses of arbitrary extent for implementation on AO correlators. These filters are designed to yield sharp correlation peaks. Simulation results are included to illustrate the viability of the proposed approach. Also included are some initial results from the first successful use of grey-scale composite filters on an AO correlator.

Two active Li/SOCl2 cells for use in artillery-fired atomic projectiles are being developed. Voltage delay is the primary mode of electrochemical failure in these cells at -35°C. To minimize this anode polarization, the anode passivation is inhibited by adding chloromethyl chlorosulfate (CMCS) to the sulfur dioxide complex of lithium tetrachloroaluminate (LiAlCl4-SO2) in the cell electrolyte. One battery powers the telemetry system (TM battery) and the other powers a projectile event timer circuit (PET battery). The authors utilize the PET battery and PET load profile to demonstrate the effect of electrolyte additives on anode passive film growth and associated voltage delay. Similar effects were also observed in the TM battery. A limited number of PET prototypes was available for this study. Therefore, several tests were performed in hermetically sealed prismatic laboratory test cells which were constructed using the same electrochemical components which are used in the PET cells.

The Waste Isolation Pilot Plant (WIPP), in southeastern New Mexico, is a research and development facility to demonstrate safe disposal of defense-generated transuranic waste. The US Department of Energy will designate WIPP as a disposal facility if it meets the US Environmental Protection Agency's standard for disposal of such waste; the standard includes a requirement that estimates of cumulative releases of radioactivity to the accessible environment be incorporated in an overall probability distribution. The WIPP Project has chosen an approach to calculation of an overall probability distribution that employs the concept of scenarios for release and transport of radioactivity to the accessible environment. This report reviews the use of Monte Carlo methods in the calculation of an overall probability distribution and presents a logical and mathematical foundation for use of the scenario concept in such calculations. The report also draws preliminary conclusions regarding the shape of the probability distribution for the WIPP system; preliminary conclusions are based on the possible occurrence of three events and the presence of one feature: namely, the events attempted boreholes over rooms and drifts,'' mining alters ground-water regime,'' water-withdrawal wells provide alternate pathways,'' and the feature brine pocket below room or drift.'' Calculation of the WIPP systems's overall probability distributions for only five of sixteen possible scenario classes that can be obtained by combining the four postulated events or features.

A combined experimental and analytical study of strains developed in encapsulated assemblies during casting, curing and thermal excursions is described. The experimental setup, designed to measure in situ strains, consisted of thin, closed-end, Kovar tubes that were instrumented with strain gages and thermocouples before being over-cast with a polymeric encapsulant. Four bisphenol A (three diethanolamine cured and one anhydride cured) epoxy-based materials and one urethane elastomeric material were studied. After cure of the encapsulant, tube strains were measured over the temperature range of {minus}55{degrees}C to 90{degrees}C. The thermal excursion experiments were then numerically modeled using finite element analyses and the computed strains were compared to the experimental strains. The predicted strains were over estimated (conservative) when a linear, elastic, temperature-dependent material model was assumed for the encapsulant and the stress free temperature T{sub i} was assumed to correspond to the cure temperature {Tc} of the encapsulant. Very good agreement was obtained with linear elastic calculations provided that the stress free temperature corresponded to the onset of the glassy-to-rubbery transition range of the encapsulant. Finally, excellent agreement was obtained in one of the materials (828/DEA) when a viscoelastic material model was utilized and a stress free temperature corresponding to the cure temperature was assumed. 13 refs., 20 figs., 3 tabs.

Surface damage has been observed on the rails of rocket sled tracks and on the barrels of high-velocity guns. The phenomenon is generally referred to as ``ongoing``. Damage to a stationary surface (guider) is created from the oblique impact of a high-velocity object (slider) moving over its surface. The surface damage (gouge) is typically a shallow crater in the shape of a teardrop with the leading edge characterized by the wider end and a slightly raised lip. For rocket sleds, rail gouging occurs when the sled velocity is greater than 1.5 km/sec; while in guns, barrel gouging occurs when the velocity exceeds 4 km/sec. A model is developed to describe the phenomenon of gouging. An unbalanced slider randomly causes a shallow-angle, oblique impact between the slider and the guider. At sufficiently high velocity, the impact produces a thin, but very hot, layer of soft material at the contact surface. Under the action of a moving load, the soft layer lends itself to an antisymmetric deformation and a gouge is formed when this soft material is over-run by the slider. The model is simulated numerically with a hydrodynamic (CTH) code. The results of the simulations are in good agreement with the observed phenomena. Based on the simulated temperature and pressure profiles at the contact surface, design criteria for gouge mitigation are developed in this study. 45 refs., 29 figs., 1 tab.

A description of the Remote Area Monitoring System utilized on nuclear tests conducted by Sandia National Laboratories and the Defense Nuclear Agency is presented. The configuration of the detectors as used on a test is described, as well as the system hardware. Calibration of the detectors before fielding is also discussed.

The annular Core Research Reactor (ACRR) Source Term (ST) Experiment program was designed to obtain time-resolved data on the release of fission products from irradiated fuels under well-controlled light water reactor severe accident conditions. The ST-1 Experiment was the first of two experiments designed to investigate fission product release. ST-1 was conducted in a highly reducing environment at a system pressure of approximately 0.19 MPa, and at maximum fuel temperatures of about 2490 K. The data will be used for the development and validation of mechanistic fission product release computer codes such as VICTORIA.

There are four papers contained in this report which were presented at the Nuclear Energy Agency (NEA) Gas Workshop to provide information about studies of waste-generated gas being conducted for the Waste Isolation Pilot Plant (WIPP). The paper by Davies et al. provides a general overview of the physical conditions pertinent to waste-generated gas and of the coupling of chemical, hydrologic, and structural processes. The paper by Brush et al. describes specific gas-generation processes and the laboratory- and bin-scale experiments being carried out to characterize these processes. The paper by Mendenhall et al. describes coupled modeling of gas generation and room closure, and provides an analysis of the potential for fracture generation and growth. the paper by Webb describes a series of sensitivity calculations carried out to assess the importance of hydrologic parameters, such as formation permeability and two-phase characteristic curves. Together, these papers provide an overview of the present (September 1991) status of waste-generated gas studies for the WIPP.

A three dimensional pretest finite element analysis of the Intermediate Scale Borehole Test has been performed. In the analysis, the 7.7 years simulation period includes the mining of Rooms C1 and C2, and the N1420 cross drift, at time zero; drilling of the borehole between the two rooms at 5.7 years; and 2 years of post-drilling response. An all salt configuration was used in the calculation. The 1984 Waste Isolation Pilot Plant (WIPP) reference elastic-secondary creep law, with reduced elastic moduli, was used to model the creeping response of the salt. Results show that after mining of the rooms and cross drift a relatively high von Mises stress state exists around the perimeter of the pillar. However, by 5.7 years, or immediately prior to drilling of the borehole, the pillar has relaxed to an almost uniform von Mises stress of about 7--8 MPa. After the borehole is drilled, a relatively high von Mises stress field is once again set up in the immediate vicinity of the hole. This drives the creep closure of the borehole. The hole closes more in the vertical direction than in the horizontal direction, resulting in ovalling of the hole. At the end of the simulation, the von Mises stress around the borehole is still higher than that in the remained of the pillar. Thus, the closure rates are relatively high at the end of the simulation time.

A parametric model for releases of radionuclides from spent-nuclear-fuel containers in a waste repository is presented. The model is appropriate for use in preliminary total-system performance assessments of the potential repository site at Yucca Mountain, Nevada; for this reason it is simpler than the models used for detailed studies of waste-package performance. Terms are included for releases from the spent fuel pellets, from the pellet/cladding gap and the grain boundaries within the fuel pellets, from the cladding of the fuel rods, and from the radioactive fuel-assembly parts. Multiple barriers are considered, including the waste container, the fuel-rod cladding, the thermal ``dry-out``, and the waste form itself. The basic formulas for release from a single fuel rod or container are extended to formulas for expected releases for the whole repository by using analytic expressions for probability distributions of some important parameters. 39 refs., 4 figs., 4 tabs.

The design of the potential Yucca Mountain repository is subject to many thermal goals related to the compliance of the site with federal regulations. This report summarizes a series of sensitivity studies that determined the expected temperatures near the potential repository. These sensitivity studies were used to establish an efficient loading scheme for the spent fuel canisters and a maximum areal power density based strictly on thermal goals. Given the current knowledge of the site, a design-basis areal power density of 80 kW/acre can be justified based on thermal goals only. Further analyses to investigate the impacts of this design-basis APD on mechanical and operational aspects of the potential repository must be undertaken before a final decision is made.

The electrical and test properties of several logic gate open circuit defect structures were measured. Results indicate that tunneling current across fine geometry discontinuities enables low frequency operation of Integrated Circuits (ICs). No significant capacitive coupling was observed for adjacent metal interconnect or for large metal opens on the gate interconnects. These results indicate the need for different methods of open circuit defect detection during test.

A previous investigation of laser-induced damage mechanisms and corresponding thresholds in step-index, multimode fibers was motivated by an interest in optical systems for firing explosives. In the initial study, the output from a compact, multimode Nd/YAG laser was coupled into fiber cores of pure fused silica. End-face polishing steps were varied between successive fiber lots to produce improved finishes, and each fiber was subjected to a sequence of progressively increasing energy densities up to a value of more than 80 J/cm². Essentially all of the tested fibers experienced a 'laser conditioning' process at the front fiber face, in which a visible plasma was generated for one or more laser shots. Rather than produce progressive damage at the front surface, however, this process would eventually cease and leave the surface with improved damage resistance. Once past this conditioning process, the majority of fibers damaged at the rear end face. Other modes of damage were observed either at locations of fixturing stresses or at a location of high static tensile stress resulting from bends introduced to the fiber. Although the previous results were encouraging in terms of achieving useful damage thresholds, a number of areas for further study were indicated. In the present study, a similar experimental procedure was used to address these areas. The relative permanence of front-surface laser conditioning was examined by re-testing fibers that had experienced this process at least a year previously. End-face mechanical polishing was again examined by testing fibers prepared using a refined polishing schedule. Attempts to use a single fixture to hold an entire lot of fibers throughout end-face polishing and damage testing met with mixed results, with fiber positions subjected to fixturing stresses likely sites for initial damage. In an effort to prepare fiber faces with the improved damage resistance observed with front faces following 'laser conditioning,' two schedules for CO₂-laser polishing of end faces were developed and evaluated. Finally, to improve resistance to damage at sites with significant static stresses, fiber samples which passed a much higher tensile proof test during manufacturing were tested. The current experiments were conducted with a new laser having a shorter pulse width and a significantly different mode structure. The beam was injected into the fiber using a geometry that had been successful in the previous study in minimizing a damage mechanism which can occur at the core/cladding interface with the first few hundred fiber diameters. However, the different mode structure of the new laser apparently resulted in this mechanism dominating the current results.

The refractory metals of Groups 5B and 6B and their alloys display a variety of unique physical and mechanical characteristics in addition to their high melting points. In turn, these characteristics make these materials strong candidates for severe service and specialized applications. However, these materials also present a variety of challenges with respect to both fabrication weldability and the in-service behavior of weldments, many of which are related to the dominant effects of interstitial impurities. This work reviews current understanding of the physical and joining metallurgy of these metals and their alloys with emphasis on fusion welding. Of specific interest are the role of impurities and alloy chemistry in fabrication and service weldability, the material processing route, eg. vacuum melting vs. powder metallurgy, the importance of welding process procedures and variables, weldment mechanical properties, and fracture behavior. Specific examples from the various alloy systems are used to illustrate general metallurgical and joining characteristics of this class of materials.

Resistance Welding (RW) has been known for about a century and in common use for much of that time. Much knowledge has been accumulated concerning many aspects of the process. However, upon examining contemporary RW handbooks, a few subjects that have been "overlooked" were found. Usually, this oversight will not be important; however, when the RW process is being applied at its limits, these factors may become critical. In this paper we will discuss such overlooked'' factors as the Peltier and Thomson effects, and the dynamics of welding head motions and how they are affected by the current pulse. Examples taken from sheet metal and microwelding applications will be given as examples.

Basic to our knowledge of the science of welding is an understanding of the melting efficiency, which indicates how much of the heat deposited by the welding process is used to produce melting. Recent calorimetric studies of GTAW, PAW, and LBW processes have measured the net heat input to the part thereby quantifying the energy transfer efficiency and in turn permitting an accurate determination of the melting efficiency. It is indicated that the weld process variables can dramatically affect the melting efficiency. This limiting value is shown to depend on the weld heat flow geometry as predicted by analytical solutions to the heat flow equation and as demonstrated by the recent empirical data. A new dimensionless parameter is used to predict the melting efficiency and is shown to correlate extremely well with recent empirical data. This simple prediction methodology is notable because it requires only a knowledge of the weld schedule and the material properties in order to estimate melting efficiency.

Current and future needs in automative, aircraft, space, military, and well logging industries require operation of electronics at higher temperatures than today's accepted limit of 395 K. Without the availability of high-temperature electronics, many systems must operate under derated conditions or must accept severe mass penalties required by coolant systems to maintain electronic temperatures below critical levels. This paper presents ongoing research and development in the electronics community to bring high-temperature electronics to commercial realization. Much of this work was recently reviewed at the First International High-Temperature Electronics Conference held 16--20 June 1991 in Albuquerque, New Mexico. 4 refs., 1 tab.

Upward Feedback is a program that gives employees and opportunity to anonymously provide their manager with feedback concerning the manager's job performance. It is an opportunity for managers to receive confidential feedback evaluating their implementation of corporate values and management behaviors as perceived by those who work for them. This feedback can come from employees who report directly to the manager, that is, one level below them (referred to as direct reports), or from those two reporting levels below them (referred to as skip-level reports). Managers then share information with their employees in feedback meetings and develop action plans to address areas of concern. Sandia National Laboratories has developed and implemented an Upward Feedback Pilot Program and follow up survey. This paper discussed the program and the lessons learned.

C++ is the first object-oriented programming language which produces sufficiently efficient code for consideration in computation-intensive physics and engineering applications. In addition, the increasing availability of massively parallel architectures requires novel programming techniques which may prove to be relatively easy to implement in C++. For these reasons, Division 1541 at Sandia National Laboratories is devoting considerable resources to the development of C++ libraries. This document describes the first of these libraries to be released, PHYSLIB, which defines classes representing Cartesian vectors and (second-order) tensors. This library consists of the header file physlib.h, the inline code file physlib.inl, and the source file physlib.C. The library is applicable to both three-dimensional and two-dimensional problems; the user selects the 2-D version of the library by defining the symbol TWO D in the header file physlib.h and recompiling physlib.C and his own code. Alternately, system managers may wish to provide duplicate header and object modules of each dimensionality. This code was produced under the auspices of Sandia National Laboratories, a federally-funded research center administered for the United States Department of Energy on a non-profit basis by AT T. This code is available to US citizens, and institutions under research, government use and/or commercial license agreements.

This is the user's guide to CEPXS/ONELD Version 1.1, a code package for coupled electron-photon transport in one-dimensional slab geometry. The code package consists of the multigroup cross-section generating code, CEPXS; the preprocessor code, PRE1D; the discrete ordinates code, ONELD; and the postprocessor code, POST1D. In Version 1.1, new features have been implemented through several new keywords. Since Version 1.0 keywords are still applicable, this document should be considered as an addendum to the Version 1.0 User's Guide. 5 refs.

This report presents a precursory examination of a number of issues pertaining to socket contacts in hermetic connectors. The principal issues addressed are high-contact resistance and contact chatter (circuit discontinuities). Efforts examining the characteristics of the existing socket contact design, the possibility of connector/contact rework, quick-fix solutions, and contact redesigns are summarized.

A model that predicts the final velocity of high-power, pulsed-laser-driven thin flyers is described. The required input parameters can either be obtained from standard handbooks or simply extracted from one set of data. The model yields a number of features and scaling laws that are well verified by experiment. Specific comparisons of model predictions with experimental results illustrate excellent agreement for variations of laser fluence and pulse width as well as flyer diameter and thickness.

The goal of the Limited Flight Path (LFP) test series was to investigate the effect of reactor subcompartment flight path length on direct containment heating (DCH). The test series consisted of eight experiments with nominal flight paths of 1, 2, or 8 m. A thermitically generated mixture of iron, chromium, and alumina simulated the corium melt of a severe reactor accident. After thermite ignition, superheated steam forcibly ejected the molten debris into a 1:10 linear scale the model of a dry reactor cavity. The blowdown steam entrained the molten debris and dispersed it into the Surtsey vessel. The vessel pressure, gas temperature, debris temperature, hydrogen produced by steam/metal reactions, debris velocity, mass dispersed into the Surtsey vessel, and debris particle size were measured for each experiment. The measured peak pressure for each experiment was normalized by the total amount of energy introduced into the Surtsey vessel; the normalized pressures increased with lengthened flight path. The debris temperature at the cavity exit was about 2320 K. Gas grab samples indicated that steam in the cavity reacted rapidly to form hydrogen, so the driving gas was a mixture of steam and hydrogen. These experiments indicate that debris may be trapped in reactor subcompartments and thus will not efficiently transfer heat to gas in the upper dome of a containment building. The effect of deentrainment by reactor subcompartments may significantly reduce the peak containment load in a severe reactor accident. 8 refs., 49 figs., 6 tabs.

The Department of Energy's Solar Thermal Program has as one of its program elements the development and evaluation of conversion device technologies applicable to dish-electric systems. The primary research and development combines a conversion device (heat engine), solar receiver, and generator mounted at the focus of a parabolic dish concentrator. The Stirling-cycle heat engine was identified as the conversion device for dish-electric with the most potential for meeting the program's goals for efficiency, reliability, and installed cost. To advance the technology toward commercialization, Sandia National Laboratories has acquired a Stirling Thermal Motors, Inc., kinematic Stirling engine, STM4-120, for evaluation. The engine is being bench-tested at Sandia's Engine Test Facility and will be combined later with a solar receiver for on-sun evaluation. This report presents the engine characteristics, finite element analyses of critical engine components, test system layout, instrumentation, and preliminary performance results from the bench test.

The purpose of this NUREG is to present technical information that should be useful to NRC licensees in designing interior intrusion detection systems. Interior intrusion sensors are discussed according to their primary application: boundary-penetration detection, volumetric detection, and point protection. Information necessary for implementation of an effective interior intrusion detection system is presented, including principles of operation, performance characteristics and guidelines for design, procurement, installation, testing, and maintenance. A glossary of sensor data terms is included. 36 figs., 6 tabs.

Different insert (insulator) materials are undergoing evaluation to replace the Fiberite E-3938 BE96 material currently used. Also being evaluated is the reconfiguration of the insert and metal shell-edge geometries for the purpose of reducing the alleged interference principally responsible for insert damage.