Publications

A semiconductor laser coupled to an external cavity is investigated using a composite-cavity mode approach. Strong frequency hopping for small cavity length changes is obtained, indicating instability of the laser operation against cavity lengths fluctuations.

Results have been obtained on hydrogen dose, dose rate and substrate temperature dependence for hydrogen-assisted thermal donor formation in Czochralski Si. The study combined ion implantation and hydrogen plasma exposure to inject hydrogen, and infrared absorption and spreading resistance probe measurements to detect the donors. Near surface donor concentrations increase with dose and temperature between 350 and 400°C. The penetration depth for thermal donor formation exhibits a $\sqrt{t}$ dependence, and a thermal activation energy of 1.5 ± 0.2 eV.

Adhesion between diamond films synthesized by a CVD method and tungsten has been investigated by a scratch and pull testing methods. Diamond films have been deposited at temperatures from 1173 to 1323 K with a growth rate ranging from 0.2 to 0.45 μm/hour. The films are highly crystalline and are dominated by (100) faces at low temperatures, changing to (111) at higher temperatures. Grain size and residual stress in the films increases with increasing deposition temperature. X-ray diffraction shows the expected diamond diffraction peaks plus peaks attributed to WC and W₂C. Raman spectroscopy shows a sharp diamond band for all of the films, with a small broad peak, attributed to amorphous carbon. There is no distinct correlation between diamond/amorphous carbon intensity with deposition temperature. Scratch adhesion testing shows the expected failure mode for brittle coatings, but can not be quantified because of severe degradation of the diamond stylus tip. Sebastion pull testing shows that the failure mode of the films correlates with deposition temperature, but specific adhesion strength values do not. Efforts are continuing to correlate adhesion strength with deposition and structural parameters of the diamond films.

Rational interpolation is frequently useful for generating functions which have an extended range over an abbreviated domain of definition. A simple technique for continued fraction interpolating function evaluation can easily be modified to obtain the function's derivative. This is a useful technique for developing numerical solutions for certain stiff partial differential equations. 9 refs., 2 figs.

Accomodation of lattice mismatch is investigated for the case of large (ε{lunate}>0.02) mismatch. In particular, the regime where the separation D between misfit dislocations is much less than the strained layer thickness h is considered here. The conventional Matthews-Blakeslee mechanism for creation of misfit dislocations is found to be inadequate for the case of large lattice relaxation owing to interactions amongst the misfit dislocations at the interface. According to St. Venant's principle, the stress fields of the dislocation network are screened beyond a distance D from the dislocation cores. This observation has several consequences, including large densities of threading dislocations and the "melting" of moderately relaxed heterointerfaces at conventional semiconductor growth temperatures. A number of experimental observations may be explained via these models. © 1991.

This 1990 report contains monitoring data from routine radiological and nonradiological environmental surveillance activities. Summaries of significant environmental compliance programs in progress such as National Environmental Policy Act (NEPA) documentation, environmental permits, environmental restoration, and various waste management programs for Sandia National Laboratories in Albuquerque (SNL, Albuquerque) are included. The maximum offsite dose impact was calculated to be 2.0 {times} 10{sup {minus}3} mrem. The total 50-mile population received a collective dose of 0.82 person-rem during 1990 from SNL, Albuquerque, operations. As in the previous year, the 1990 SNL operations had no adverse impact on the general public or on the environment. This report is prepared for the US Department of Energy in compliance with DOE Order 5400.1. 97 refs., 30 figs., 137 tabs.

There is no routine radioactive emission from Sandia National Laboratories, Tonopah Test Range (SNL, TTR). However, based on the types of test activities such as air drops, gun firings, ground- launched rockets, air-launched rockets, and other explosive tests, possibilities exist that small amounts of depleted uranium (DU) (as part of weapon components) may be released to the air or to the ground because of unusual circumstances (failures) during testing. Four major monitoring programs were used in 1990 to assess radiological impact on the public. The EPA Air Surveillance Network (ASN) found that the only gamma ({gamma}) emitting radionuclide on the prefilters was beryllium-7 ({sup 7}Be), a naturally-occurring spallation product formed by the interaction of cosmic radiation with atmospheric oxygen and nitrogen. The weighted average results were consistent with the area background concentrations. The EPA Thermoluminescent Dosimetry (TLD) Network and Pressurized Ion Chamber (PIC) reported normal results. In the EPA Long-Term Hydrological Monitoring Program (LTHMP), analytical results for tritium ({sup 3}H) in well water were reported and were well below DOE-derived concentration guides (DCGs). In the Reynolds Electrical and Engineering Company (REECo) Drinking Water Sampling Program, analytical results for {sup 3}H, gross alpha ({alpha}), beta ({beta}), and {gamma} scan, strontium-90 ({sup 90}Sr) and plutonium-239 ({sup 239}Pu) were within the EPA's primary drinking water standards. 29 refs., 5 figs., 15 tabs.

PC-1D is a software package for personal computers that uses finite-element analysis to solve the fully-coupled two-carrier semiconductor transport equations in one dimension. This program is particularly useful for analyzing the performance of optoelectronic devices such as solar cells, but can be applied to any bipolar device whose carrier flows are primarily one-dimensional. This User's Guide provides the information necessary to install PC-1D, define a problem for solution, solve the problem, and examine the results. Example problems are presented which illustrate these steps. The physical models and numerical methods utilized are presented in detail. This document supports version 3.1 of PC-1D, which incorporates faster numerical algorithms with better convergence properties than previous versions of the program. 51 refs., 17 figs., 5 tabs.

The disappearance of isocyanate groups in 20 lb/ft{sup 3} rigid polyurethane encapsulating foam (44402-20) was monitored by FTIR spectroscopy leading to an activation energy of 4 kcal/mole. The disappearance of isocyanates can be due to either crosslinking reactions or gas production. Attempting to separate these two reaction paths, we measured the gel time and volume change during cure leading to activation energies of 5 and 6 kcal/mole for the crosslinking and foaming mechanisms respectively. 3 refs., 16 figs.

This study examined the feasibility of the Safety Engineering Reactor for Accident Phenomenology (SERAPH), a research reactor with the capability to perform a wide array of safety experiments important in the design of commercial nuclear reactors. The study proceeded in two phases. In Phase 1, the experimental needs were examined and a wide-ranging survey of many fuel/coolant options for the SERAPH driver reactor was done. In Phase 2, the most promising candidates identified in Phase 1 were studied in more detail. A reactor with heavy-water coolant, BeO-PuO{sub 2} fuel matrix, and a standard pin geometry was found to have the required experiment capabilities while using relatively current technology. A reactor with helium coolant, BeO-PuO{sub 2} fuel matrix, and a unique geometrical configuration was found to have significantly higher capabilities but with greater technical risk. 5 refs., 34 figs., 36 tabs.

This report describes the results of high temperature steam testing and submergence testing of 12 different cable products that are representative of typical cables used inside containments of US light water reactors. Both tests were performed after the cables were exposed to simultaneous thermal and radiation aging, followed by exposure to loss-of-coolant accident simulations. The results of the high temperature steam test indicate the approximate thermal failure thresholds for each cable type. The results of submergence test indicate that a number of cable types can withstand submergence at elevated temperature, even after exposure to a loss-of-coolant accident simulation. 4 refs., 6 figs., 9 tabs.

This work documents a comparison of sensitivity and uncertainty analysis techniques that are likely to be used in support of repository performance assessments to determine compliance with the Nuclear Regulatory Commission (NRC) and the Environmental Protection Agency (EPA) regulations for high-level radioactive waste (HLW) repositories. A variety of parameter estimation and sensitivity analysis techniques were applied to a model of the Avra Valley aquifer, Arizona. Two approaches to sensitivity analyses were used, statistical and deterministic; these were applied to evaluate the sensitivity of the ground water travel time to changes in transmissivity. The effect of different boundary conditions on the calculated sensitivity derivatives was also evaluated. Parameter estimates and estimation errors were obtained via geostatistical and inverse techniques. The throughput'' of the kriging techniques suggests that the mean estimates derived from these techniques are frequently off the mark'' or inconsistent with the conceptual model. With no screening of the input parameter estimates for realism, non- conservative travel time estimates were obtained. The differential analysis sensitivity technique is shown to be dependent on the choice of design point, providing only a local measure of the sensitivity. The statistical approach to sensitivity identifies parameters which are both sensitive and uncertain, i.e., it shows when the uncertainty in a model parameter is important. Sensitivity estimates are also shown to be dependent on the choice of boundary conditions used. 92 refs., 55 figs., 13 tabs.

This report describes an architecture for compiling and representing electronic documents in a framework which accommodates knowledge about how the documents are composed, organized, and correlated. A general concept of referenceability is employed. While the concept is relevant to a wide range of application areas, it is described in familiar terms of an electronic document comprised of related textual information and graphics. The concept is applicable to all classes of objects which, together with their references, constitute the electronic document. The documents may themselves contain references to other documents, as well as to constituent object classes such as textual components, figures, footnotes, subject indexes, and the like. The objects and references can be dynamically combined according to a total logical structure representable within a window environment. The framework supports automatic resolution of references and display of related document objects through intercommunicating windows which constitute a relevant user view of a document. 6 refs., 9 figs.

This document describes the NEFTRAN-S computer code and is intended to provide the reader with enough information to use the code. NEFTRAN-S was developed for the United States Environmental Protection Agency for the assessment of ground-water flow and radionuclide transport from radioactive waste disposal in geologic formations. NEFTRAN-S is a successor to the NEFTRAN code. The code was developed in conjunction with NEFTRAN-2, which was developed recently for the United States Nuclear Regulatory Commission. As a result, some of the features contained in NEFTRAN-2 have been included in NEFTRAN-S. In particular, NEFTRAN-S includes an exponential-leach-rate source, decoupled time steps for source and transport, and an option for inputting pore-water velocities. Features unique to NEFTRAN-S include a user-friendly format for use on personal computers and coupling with statistical sampling and analysis using the SUNS software shell. This document was written to provide a comprehensive discussion of the NEFTRAN-S code including its history, the theory, its use and examples of possible applications. Minimal reference to previous documents is intended. 25 refs., 132 figs., 30 tabs.

The default format for the storage of x,y data for use with the UFO code is described. The format assumes that the data stored in a file is a matrix of values; two columns of this matrix are selected to define a function of the form y = f(x). This format is specifically designed to allow for easy importation of data obtained from other sources, or easy entry of data using a text editor, with a minimum of reformatting. This format is flexible and extensible through the use of inline directives stored in the optional header of the file. A special extension of the format implements encoded data which significantly reduces the storage required as compared wth the unencoded form. UFO supports several extensions to the file specification that implement execute-time operations, such as, transformation of the x and/or y values, selection of specific columns of the matrix for association with the x and y values, input of data directly from other formats (e.g., DAMP and PFF), and a simple type of library-structured file format. Several examples of the use of the format are given.

This report documents the findings of an experimental investigation of the effects of thermal aging on the fire damageability of electric cables. Two popular types of nuclear qualified cables were evaluated. For each cable type, both unaged (i.e., new off the reel) and thermally aged samples were exposed to steady-state elevated temperature environments until conductor-to-conductor electrical shorting was observed. Plots of the time to electrical failure versus the exposure temperature were developed and thermal damage thresholds were determined. For one cable type, the thermally aged cables were less vulnerable to thermal damage than were the unaged samples as demonstrated by an increase in the thermal damage threshold for the aged samples, and an extended survival time at exposure temperatures above the damage threshold for aged samples compared to unaged samples. For the second cable, the threshold of thermal damage was lowered somewhat by the aging process, an indication of an increased vulnerability to thermal damage due to aging. However, for the higher temperature exposures, no statistical difference between the damage times for aged and unaged cable samples was noted. For both cable types, the changes in the thermal damage threshold observed were not considered significant in terms of fire risk. 4 refs., 9 figs., 8 tabs.

The thrust of this progress report deals with the significant advances we have made in the past few months toward optimal radiating efficiency and optimal directionality from antenna arrays that fit inside a 5.5 in.-OD tool. The reasons spawning this development effort on antennas are the many uses for underground radar systems that can be built around such high-performance antennas. Targets of interest include large man-made voids, natural voids in strata, fractures zones in hard rock, edges and internal faults in salts domes and glaciers, etc. Recent progress includes observation of the radiation patterns of several dipole arrays which we designed to fit within a 5.5-inch OD borehole tool and to radiate efficiently at wavelengths in the band from 0.4 meter to 2 meters with optimal directionality. Front-to-back ratios of 15 dB are consistently observed in the horizontal plane of these arrays. These antennas are observed to radiate with high efficiencies, less than 1 dB loss, into air at 1.3 meter wavelength. 18 figs.

This report describes the finite difference computer code ZEPHYR3D, which is designed to solve three-dimensional, transient incompressible flow problems. ZEPHYR3D includes an energy equation that allows coupled thermal/fluid problems to be solved with the limits of the Boussinesq approximation. It also includes an implementation of the Smagorinsky subgrid scale turbulence model, which allows ZEPHYR3D to perform large eddy simulation of turbulent flows. This report includes the mathematical and numerical basis for ZEPHYR3D, a user's guide, and several example/benchmark problems. These problems include flow over a backward-facing step, free convection in an enclosure, and the collapse of a mixed region in a stratified environment. 22 refs., 32 figs., 2 tabs.

Early in 1990, J. A. Wilder, Supervisor of Sandia National Laboratories (SNLA), Division 2565 requested that a meeting of the scientists and engineers responsible for developing and producing switch tubes be set up to discuss in a semi-formal way the science and technology of switch tubes. Programmatic and administrative issues were specifically exempted from the discussions. L. Beavis, Division 7471, SNL and A. Shuman, EG G, Salem were made responsible for organizing a program including the materials and processes of switch tubes. The purpose of the Switch Tube Advanced Technology meeting was to allow personnel from Allied Signal Kansas City Division (AS/KCD); EG G, Salem and Sandia National Laboratories (SNL) to discuss a variety of issues involved in the development and production of switch tubes. It was intended that the formal and informal discussions would allow a better understanding of the production problems by material and process engineers and of the materials and processes by production engineers. This program consisted of formal presentations on May 23 and informal discussions on May 24. The topics chosen for formal presentation were suggested by the people of AS/KCD, EG G, Salem, and SNL involved with the design, development and production of switch tubes. The topics selected were generic. They were not directed to any specific switch tube but rather to all switch tubes in production and development. This document includes summaries of the material presented at the formal presentation on May 23.

The diffraction patterns produced by passing a laser beam through two different types of flowing gases are calculated. The first type of flow consists of periodic lines of gas flowing transverse to the beam's propagation. The second flow is turbulent. The measurable parameters in the diffraction patterns are derived and related to the gas temperature, pressure, velocity, and (in the case of the turbulent flow) to the flow's structure constant. A discussion on using the photorefractive effect to study turbulent flows is also given. In the latter case a method that relates the flow's structure constant to the decay time of the photorefractive crystal is given. 24 refs., 11 figs.

NEFTRAN-S was developed by Sandia National Laboratories for the United States Environmental Protection Agency as part of a program providing technical support for re-promulgation of the standard 40 CFR 191. The code is intended to provide realistic estimates of releases to the environment that could result from disposal of radioactive waste in geologic subsurfaces. One of the geologic environments that will be considered by the EPA in their analyses is unsaturated tuff. The information given in this report is intended to provide a conceptual model for the NEFTRAN-S code for calculations involving a generic site in unsaturated tuff. Information about the phenomena expected to dominate transport and methods for modeling transport in an unsaturated medium are presented. NEFTRAN-S calculations using this conceptual model are compared to TOSPAC calculations for three possible infiltration rates. TOSPAC is the code currently used in performance assessment for an unsaturated tuff site at Yucca Mountain in Nevada. 14 refs., 21 figs., 22 tabs.

The prediction of the chemical alteration of cementitious sealing materials and other cementitious components such as liners in the tuffaceous environment of Yucca Mountain is an essential element in understanding the longevity of these materials. This study uses a chemical equilibrium model to obtain information about the chemical reaction of ground water with concretes. Because concretes, cements, and grouts are metastable assemblages, it is expected that these materials will dissolve, cause secondary precipitations and react with the environment. These reactions will alter the porosity and hydraulic conductivity of the concretes. While the importance of these chemical and conductivity changes has not been completely assessed, this study provides insight into the importance of this chemical alteration.

Large-scale numerical simulations of turbulent flow past bare and appended submarine hulls have been completed with FIDAP versions 4.5 and 5.0. A standard k-ε turbulence model was employed to resolve the near-body flow field for all numerical calculations. Results from these simulations (profile plots and wake surveys of velocity, pressure and turbulent kinetic energy -- hull pressures and shear stresses -- total drag) are compared with data from dynamically similar experiments. The Reynolds number, based upon model length, for both simulation and experiment was 1.2 x 10⁷. Agreement between untuned numerical predictions and experimental data is remarkably close for several model geometries. In other cases, quantitative differences are attributed to the choice of turbulence model and the numerical implementation of boundary conditions.

Radiation measurement have been used for many years to aid in the characterization, handling, and processing of spent nuclear fuel. Applications have included radiation protection, international safeguards, fissile content estimation for reprocessing, and verification of records and calculations. The application of radiation measurements to support the identification of spent fuel assemblies for loading into burnup credit'' transport casks is of interest in the cask development program. A possible alternative to measurements is to use the administrative controls and operational procedures that have been used at reactor sites that make use of burnup credit for spent fuel storage. Experience at such sites needs to be carefully analyzed for its applicability to the misloading and misidentification probabilities. Since there are over 40,000 spent fuel assemblies stored at more than one hundred locations in the US, it is important to determine carefully the necessity for and applicability of any measurement requirement. It is imperative that any measurement system selected be as simple, inexpensive, quick, and non-intrusive as possible. In this report we will consider the information available from measurements of spent fuel that has cooled for more than ten years and examine the possible application of existing instrumentation to verifying the loading of burnup credit casks.

Sandia National Laboratories is conducting long-term aging research on representative samples of nuclear power plant Class 1E cables to determine the suitability of these cables for extended life (beyond the 40-year design basis) and to assess various cable condition monitoring techniques for predicting remaining cable life. This paper provides some results of mechanical measurements that were performed on cross-linked polyolefin (XLPO) cables and cable materials aged at relatively mild, simultaneous thermal and radiation exposure conditions for period of up to nine months. The mechanical measurements discussed in this paper include tensile strength, ultimate elongation, hardness, and compressive modulus. The modulus measurements were performed using an indenter developed at Franklin Research Center under EPRI sponsorship.

Reflux solar receivers for dish-Stirling electric power generation systems are currently being investigated by several companies and laboratories. In support of these efforts, the AEETES thermal performance numerical model has been developed to predict thermal performance of pool-boiler and heat-pipe reflux receivers. The formulation of the AEETES numerical model, which is applicable to axisymmetric geometries with asymmetric incident fluxes, is presented in detail. Thermal efficiency predictions agree to within 4.1% with test data from on-sun tests of a pool-boiler reflux receiver. Predicted absorber and sidewall temperatures agree with thermocouple data to within 3.3.% and 7.3%, respectively. The importance of accounting for the asymmetric incident fluxes is demonstrated in comparisons with predictions using azimuthally averaged variables. The predicted receiver heat losses are characterized in terms of convective, solar and infrared radiative, and conductive heat transfer mechanisms. 27 refs., 9 figs., 4 tabs.

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 advanced rechargeable batteries for stationary energy storage applications. This report details the technical achievements realized during fiscal year 1990. 82 figs., 40 tabs.

This document presents the quality assurance (QA) philosophy and procedures for software used by the Performance Assessment Division of the Nuclear Waste Technology Department (NWTD) of Sandia National Laboratories, which directly supports the Waste Isolation Pilot Plant (WIPP). Software procedures described herein will be incorporated into the general Performance Assessment Quality Assurance Procedures (QAP 2-2) and will apply to all Sandia and Sandia contractor activities related to Performance Assessment (except where the contractor has its own NWTD-approved QA procedures). This report presented the philosophy behind the QA procedures, provides the standards adopted for Performance Assessment software, discusses the implementation of these standards, and summarizes the software executive package, CAMCON, which aids in implementing the standards. 24 refs., 6 figs., 5 tabs.

Our charged particle simulation models a relativistic electron beam for which the field solution is local and thus requires no grid. We have implemented the simulation on a CRAY and on two parallel machines, a nCUBE 2 and Connection Machine. We present implementation details and contrast the approaches necessary for the three architectures. On the parallel machines a dynamic load-balancing problem arises because the beam grows uniformly in one dimension from a few hundred to hundreds of thousands of particles as the simulation progresses. We discuss a folded Gray-code mapping of the processors to the length scale of the simulation that expands (or shrinks) as the beam changes length so as to minimize inter-processor communication. This improves the efficiency of the nCUBE version of the simulation which runs at 10x the speed of the vectorized CRAY version.

Surry was used as a representative dry containment plant for the evaluation of possible ways that containment performance could be improved. Sensitivity studies using the NUREG-1150 models and methodologies were used to estimate the reduction of risk potentials resulting from bypass scrubbing and DCH partial depressurization. These studies showed that the greatest reduction of risk occurs when bypass releases are mitigated by scrubbing or prevented. High-pressure DCH are also important. The CONTAIN code was used to estimate reduction in peak containment pressure resulting from mitigation actions including venting, partial depressurization and ~3 bar with igniters. Limited studies of the benefits of venting and inerting were made, but additional investigations are needed to complete this area of investigation. A brief discussion regarding concepts to mitigate the consequences of bypass is presented. CONTAIN-code calculations were performed to investigate the possible overpressurization of the containment for the station blackout scenario.

Difficulties in the accurate heat transfer computation of high speed, blunt body flows have been encountered by numerous researchers. The primary reason for these difficulties has been shown to be the grid dependency of the wall flux quantities. Obviously, the accuracy of the computed heat fluxes will, to a certain extent, depend on the particular numerical scheme employed. This article will be limited to the investigation of the flux vector splitting technique. An attempt has been made to develop procedures which will provide guidelines for selecting appropriate grid systems and, in particular, the grid line distribution near the surface for accurate heat transfer computations. The results have clearly shown the dependency of the heat flux quantities on the grid system. In addition, it is shown that changes in flow Mach number and/or Reynolds number may require further refinement of the grid system.

Analytical equations for explosively accelerated flyer plates are used to generate graphical solutions to flyer problems. Given the problem geometrical configuration, explosive weight, flyer weight, tamping weight and Gurney velocity, the graphical representation of the calculated data allows for a fast approximation of the final or maximum flyer velocity. The graphical solution for flyer velocity is particularly useful when a computer is not available. The graphical analysis scheme can be used with any explosive, tamper and flyer materials. Analytical data are presented for grazing, spherical, cylindrical, open, symmetric and asymmetric sandwich explosive configurations. 13 refs., 7 figs., 4 tabs.

Al with additions of Cu is commonly used as the conductor metallizations for integrated circuits (ICs). As the packing density of ICs increases, interconnect lines are required to carry ever higher current densities. Consequently, reliability due to electromigration failure becomes an increasing concern. Cu has been found to increase the lifetimes of these conductors, but the mechanism by which electromigration is improved is not yet fully understood. In order to evaluate certain theories of electromigration it is necessary to have a detailed description of the Cu distribution in the Al microstructure, with emphasis on the distribution of Cu at the grain boundaries. In this study analytical electron microscopy (AEM) has been used to characterize grain boundary regions in an Al-2 wt.% Cu thin film metallization on Si after a variety of thermal treatments. The results of this study indicate that the Cu distribution is dependent on the thermal annealing conditions. At temperatures near the θ phase (CuAl₂) solvus, the Cu distribution may be modelled by the collector plate mechanism, in which the grain boundary is depleted in Cu relative to the matrix. At lower temperatures, Cu enrichment of the boundaries occurs, perhaps as a precursor to second phase formation. Natural cooling from the single phase field produces only grain boundary depletion of Cu consistent with the collector-plate mechanism. The kinetic details of the elemental segregation behavior derived from this study can be used to describe microstructural evolution in actual interconnect alloys.

A 70/30 wt% salt/bentonite mixture is shown to be preferable to pure crushed salt as backfill for disposal rooms in the Waste Isolation Pilot Plant (WIPP). This report discusses several selection criteria used to arrive at this conclusion: the need for low permeability and porosity after closure, chemical stability with the surroundings, adequate strength to avoid shear erosion from human intrusion, ease of emplacement, and sorption potential for brine and radionuclides. Both salt and salt/bentonite are expected to consolidate to a final state of impermeability (i.e., {le} 10{sup {minus}18}m{sup 2}) adequate for satisfying federal nuclear regulations. Any advantage of the salt/bentonite mixture is dependent upon bentonite's potential for sorbing brine and radionuclides. Estimates suggest that bentonite's sorption potential for water in brine is much less than for pure water. While no credit is presently taken for brine sorption in salt/bentonite backfill, the possibility that some amount of inflowing brine would be chemically bound is considered likely. Bentonite may also sorb much of the plutonium, americium, and neptunium within the disposal room inventory. Sorption would be effective only if a major portion of the backfill is in contact with radioactive brine. Brine flow from the waste out through highly localized channels in the backfill would negate sorption effectiveness. Although the sorption potentials of bentonite for both brine and radionuclides are not ideal, they are distinctly beneficial. Furthermore, no detrimental aspects of adding bentonite to the salt as a backfill have been identified. These two observations are the major reasons for selecting salt/bentonite as a backfill within the WIPP. 39 refs., 16 figs., 6 tabs.

We present an algorithm for the QR factorization of a dense matrix without column pivoting on a hypercube multiprocessor. The algorithm combines the optimal numerical efficiency of Householder reflections with the excellent communication properties of the torus wrap mapping. Analytical results indicate that the communication cost for this algorithm is less than that for other common approaches. Numerical results on an nCUBE 2 confirm the efficiency of our technique. 23 refs., 5 figs., 1 tab.

This memorandum is a synopsis of the description and operation of the equipment used, and the events occurring during the calibration of an accelerometer on the 1000 G centrifuge. 2 refs., 1 tab.

The objective of this study was to perform a systematic sampling of the intergranular brines that slowly weep'' from four of the main stratigraphic units exposed in the WIPP. This information was added to the data base on brine compositions used in performance assessment and also employed in characterizing Salado Formation hydrology at the repository horizon. Concentrations of Na, K, Mg, Ca, Cl, SO₄, and Br were all highly variable. It was also established that this variability reflects neither post-excavation evaporation nor imprecision in the analytical techniques. Compositional variability on the length scale of a few tens of centimeters is as large as that found over several hundreds of meters. Stratigraphy did not appear to exert any control over weep brine compositions. Programmatically relevant applications of these results are: (1) a valid performance assessment must consider the possibility of a wide range of brines, rather than carry out evaluations using a single best'' average brine, and (2) the Salado appears not to function as a continuous aquifer since brines originating millions of years ago have failed to homogenize though separated by only short distances.

In September 1990, the President's Office of Science and Technology released a document that bears on the future of our nation's technological vigor and economic performance. Entitled, US Technology Policy, it is a statement of a set of broad principles that will constitute the federal government's technology policy for the 1990s. One of the leading principles of this policy is the imperative for cooperation and teamwork among government, industry, and academia, including an active, partnership role for the national laboratories in the mainstream US technology community. Until now, the nation's technology policy has never been explicit, although a tacit technology policy of one sort or another has at all times been in effect. The federal government has consistently been willing to create and fund institutions and programs to promote important national technology goals. Historical examples of such sponsorship include atomic energy, agriculture, aeronautics and space, energy, and medicine. The recognition in US Technology Policy that government has an active role to play in fostering technology development is a particularly significant admission. The vision of a partnership between the federal government and the private sector, as the policy outlines, provides a foundation upon which the national laboratories of the Department of Energy (DOE) can build to play a stronger role in enhancing US economic competitiveness. 6 refs.

A number of metal oxides were evaluated for their ability to immobilize molten LiCl-KCl eutectic in electrolyte-binder (EB) mixes used in thermally activated batteries. These metal oxides included fumed silicas, alumina, and a titania (all prepared by steam hydrolysis of the halides), floated silicas, MgO, and an alumina molecular sieve. The characteristics of the EB powders that were used as metrics were flow properties, homogeneity, BET surface area, particle-size distribution, and moisture content. The characteristics of EB pellets used as metrics were deformation at 530{degrees}C under an applied pressure and tendency for electrolyte leakage at 400{degrees}C. Many of the same characterization techniques used for EB powders were applied to the LiCl-KCl eutectic, its component halides, and the metal oxides as well. The reproducibility of the properties of several of the standard Sandia EB mixes was evaluated for materials prepared at a number of thermal-battery manufacturing facilities following the same processing procedures. 13 refs., 14 figs., 18 tabs.

A new technique for tunnel detection and location has recently been theoretically modeled and experimentally demonstrated. The objective of this research is to develop a general method for remotely detecting the presence of unauthorized tunneling activities using one or more boreholes and a surface source. A line current or dipole-dipole array, positioned on or near the surface of the earth, is used as the TE current source. Subsurface electric and magnetic field measurements are made in a borehole that is situated near a suspected tunnel location. The presence of a tunnel causes subsurface scattering of the field components created by the source. Both the electric and magnetic field strength and phase data is perturbed by the presence of a nearby tunnel. The scattered fields are observed on both sides of the tunnel relative to the source position. This paper will describe the development electromagnetic scattering models using a buried cylinder to represent a tunnel. A homogeneous whole-space model will be used.

Eight samples of 4.5 in. steel oil well drill pipe which had perforated or fractured in use were analyzed to determine the reasons for failure. These pipe sections were used for drilling in the Permian Basin fields of southeastern New Mexico and western Texas. Six of the eight samples failed by a common mechanism: stress corrosion cracks initiated at the insides of the pipes at the bottoms of large corrosion blisters which formed under a plastic protective layer. Stress corrosion cracking (SCC) was driven by a differential oxygen concentration cell between the drilling fluid (high oxygen) and the bottom of the blisters (low oxygen). The stress corrosion process occurs by a film rupture-plastic slip-electrochemical dissolution mechanism. Thus crack propagation rates may be altered by chemical modification of drilling fluids. Additional crack extension occurred by fatigue in some samples; the extent of fatigue cracking apparently was determined by the later cyclic history of the pipe. Treatment of the drilling fluids to lower the oxygen concentration and thus the driving force for SCC has been shown to decrease drill pipe loss by perforation in limited drilling to date. 16 refs., 8 figs.

The purpose of this report is to provide general approaches and concepts that can be applied in validation of models used in performance assessment of high-level waste (HLW) repositories. The approaches are based on a validation strategy that Sandia National Laboratories has implemented as participants in the International Transport Validation Study (INTRAVAL). This strategy focuses on the demonstration that performance assessment models are adequate representations of the real systems they are intended to represent, given the pertinent regulatory requirements rather than proving absolute correctness from the purely scientific point of view. Positions that are taken consist of the following: due to the relevant time and space scales, models that are used to assess the performance of a HLW repository can never be validated; therefore, validation is a process that consists of building confidence in these models and not providing "validated" models; in this context, model validation includes comparisons to "reality," however, adequacy for the given purpose is the overall goal; comparisons to "reality" consist of comparing model predictions against laboratory and field experiments, natural analogues, and site-specific information; when comparing experimental data to model predictions, a model can be either "invalid" or "not invalid," based on the null hypothesis concept, however, confidence in the model arises in finding a model to be "not invalid" over a wide range of conditions; an attempt should be made to consider in the validation process all plausible conceptual models; and when comparing experimental data to model predictions, a logical systematic approach should be followed. This report discusses the definition of validation in the context of performance assessment for HLW repositories, the need for validation, an approach to validation, and an approach to comparing model predictions with experimental data proposed by the authors.

During 1990, the Sandia Transportable Triggered Lightning Instrumentation Facility (SATTLIF) was designed, fabricated, and fielded at the Kentucky Space Center (KSC) rocket-triggered lighting test range in Florida. In preparation for lighting tests of a specially fitted munitions storage bunker during 1991, instrumentation for directly measuring lightning channel currents and response currents in structures was evaluated and demonstrated to function well. A set of 77-mil-thick 2024-T3 aluminum and 35-mil-thick 4130 steel metallic samples was exposed to measured triggered lighting flash currents. The resultant damage spots on these specimens represent the first such data points produced by known lighting currents. They are intended for use as benchmarks against which to improve and quantify the fidelity of laboratory simulations of lightning penetration. Two particularly significant results were obtained. In the first, a damage spot of approximately 0.3-inch diameter and >0.01-inch depth was produced by a continuing current of well less than median-level severity that transferred less than 13.6 coulombs of charge. In the second case, one of the steel samples was virtually burned through under a return-stroke/continuing current combination transferring an eightieth percentile charge of approximately 49 coulombs. Photographic evidence of upward-going streamers preceding return strokes initiated by dart leaders was also obtained and is presented.

An investigation of the impact of thermal aging on the flammability of two common types of nuclear grade electrical cables has been performed. Four large-scale flammability tests were performed with each of the two cable types tested in both an unaged (i.e., new off the reel) and a thermally aged (artificially aged) condition. In all cases, the fire was observed to consume virtually all of the combustible cable jacket and insulation material present. However, for both cable types tested, the thermal aging process caused a decrease in the cable flammability as demonstrated by decreases in the rate of fire growth, peak fire intensity, total heat released and near fire temperatures. This result is consistent with past cable aging studies because it has been observed that the thermal aging process will drive off certain of the more volatile constituents of a polymeric material. Presumably, when these aged materials are subjected to a fire, the evolution of volatile combustible gases is reduced as compared to the unaged materials, and hence, flammability is reduced. The results of these tests indicate that, at least for the two cable types tested, the evaluation of cable flammability using unaged cable samples will remain a conservative indicator of cable flammability in a thermally aged condition.

This investigation involves the development of a general two- dimensional continuum model to describe jointed rock mass. Chen recently developed a model for the analysis of rock mass containing two orthogonal joint sets. Development of the orthogonal joint set model followed the general formulation of Morland and the special single joint set implementation of Morland`s model by Thomas. Although the orthogonal joint set model has proven useful for analyzing field-scale problems, it remains restrictive in terms of the general field conditions. In this paper, the orthogonal joint set model has been extended to a more general model where the orthogonality restriction has been relaxed. Fundamental approaches remain the same for both models. However, as the general model becomes capable of treating physically more complicated problems, it becomes mathematically more complex. This complexity provides the potential to study more completely the interaction of various parameters representing the characteristics of jointed rock mass behavior. The equation governing the solution of the problem has been given, and example problems have been solved. The behavior of the rock mass predicted by the orthogonal joint set model has been compared to the general model. This model has been developed to aid in characterizing the site of the repository at Yucca Mountain, Nevada, for the potential geologic disposal of radioactive waste. Disposal of high-level nuclear waste is currently being considered by the Yucca Mountain Project, administered by the Nevada Operations Office of the US Department of Energy.

The distribution of moisture beneath a two-dimensional strip source is analyzed by applying the quasi-linear approximation. The source is described by specifying either the moisture content or the infiltration rate. A water table is specified at some depth, D, below the surface, the depth varying from shallow to semi-infinite. Numerical solutions are determined, via the boundary integral equation method, as a function of material sorptivity, α, the width of the strip source, 2L, and the depth to the water table. The moisture introduced at the source is broadly spread below the surface when αL $\ll$ 1, for which absorption by capillary forces is dominant over gravity-induced flow. Conversely, the distribution becomes finger-like along the vertical when αL $\gg$ 1, where gravity is dominant over absorption. For a source described by specifying the moisture content, the presence of a water table at finite depth influences the infiltration through the source when αD is less than about 4; infiltration rates obtained when the water table depth is semi-infinite are of sufficient accuracy for greater values of αD. When the source is described by a specified infiltration flux, the maximum allowable value of this flux for which the material beneath the source remains unsaturated is determined as a function of nondimensional sorptivity and depth to the water table.

This report presents a summary of the conduct and findings of the Exploratory Shaft Alternatives Study. The study basis and findings are presented in sufficient detail to allow the Department of Energy to make an informed decision as to the Exploratory Shaft Facility (ESP)/Repository design option to be used as the basis for resumption of ESF Title 2 design. As a result of the desire for a rigorous, logically defensible analysis and the complexity of the required evaluation, a multi-attribute utility analysis was used as the primary decision-aiding tool. Over 2500 regulations, requirements and concerns were considered under four broad objectives. The analysis resulted in the ranking of 34 options, in accordance with the extent to which each option could achieve the objectives. Additional findings regarding design features that were identified as key elements in an options ability to provide good overall performance are also discussed. 4 figs., 9 tabs.

The objective of this work was to investigate whether a subsurface plume may be detected and followed using crosshole and surface-to-borehole electromagnetic geophysical techniques. both of these techniques were experimentally demonstrated to be feasible. The presence of the injected plume was easily detected with these methods but additional work must be done to refine the techniques. 5 refs., 15 figs., 1 tab.

The USDOE initiated the Production Risk Evaluation Program (PREP) at Sandia National Laboratories (SNL) to assess quantitatively the potential for serious production disruption as the result of random failures, accidents, natural disasters, or sabotage at its facilities. SNL developed a procedure incorporating both network and fault tree models that identifies production vulnerabilities. For each production step, a steady-state flow model computers the "critical time,'' which is the maximum period a step can be shut down without preventing the system from achieving production goals. The critical time is then used in fault tree analysis to determine the failure modes that can stop the process for longer than this period. Modular logic modeling is used for constructing the fault trees. Equipment restorable within its critical time need not be considered critical even though it may perform significant work. This paper focuses on sabotage, but the methodology is applicable to analyzing the other production system vulnerabilities mentioned above. The PREP models can be used to identify those plant areas to which a saboteur would need to gain access. A security strategy using graded protection based on a PREP analysis potentially could reduce security costs. PREP methods also provide quantitative insights to develop protection measures that do not infringe upon the liberties of personnel or complicate work practices.

Environmentally Conscious Manufacturing (ECM) refers to those processes that reduce the harmful environmental impacts of manufacturing, including minimization of hazardous waste, reduction of energy consumption, improvement of materials utilization efficiency, and improvement of operational safety. Approaches involve substitution of non-hazardous for hazardous materials, replacement of existing processes with new, waste-free processes, and increased use of recycle. Reducing waste at the source, through ECM, saves energy and money -- and provides value-added for the production and process. End-of-the-pipe treatment is much more expensive than waste minimization and ECM. Protecting the environment by reducing or eliminating waste is industrially efficient. Industry must create cleaner processes and products that contribute to profitability, rather than just focusing on pollution control. By expanding the return-on-investment equation, it can be shown that manufacturing products without producing hazardous wastes will result in an increase in industrial competitiveness. The optimum time to consider waste minimization is when a manufacturing process is first conceived. A significant and economically beneficial goal would be the development of zero effluent or closed loop manufacturing processes. Several programs at Sandia National Laboratories (SNL) are addressing the issues of waste minimization and pollution prevention through the application of ECM. Many of these programs involve collaboration with other national laboratories, industry, universities, and the production agencies. The following sections will provide a synopsis of Sandia's activities in ECM. 14 refs.