Publications

Before disposing of transuranic radioactive waste in the Waste Isolation Pilot Plant (WIPP), the United States Department of Energy (DOE) must evaluate compliance with applicable long-term regulations of the United States Environmental Protection Agency (EPA). Sandia National Laboratories is conducting iterative performance assessments (PAs) of the WIPP for the DOE to provide interim guidance while preparing for a final compliance evaluation. This volume of the 1992 PA contains results of uncertainty and sensitivity analyses with respect to migration of gas and brine from the undisturbed repository. Additional information about the 1992 PA is provided in other volumes. Volume 1 contains an overview of WIPP PA and results of a preliminary comparison with 40 CFR 191, Subpart B. Volume 2 describes the technical basis for the performance assessment, including descriptions of the linked computational models used in the Monte Carlo analyses. Volume 3 contains the reference data base and values for input parameters used in consequence and probability modeling. Volume 4 contains uncertainty and sensitivity analyses with respect to the EPA`s Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes (40 CFR 191, Subpart B). Finally, guidance derived from the entire 1992 PA is presented in Volume 6. Results of the 1992 uncertainty and sensitivity analyses indicate that, conditional on the modeling assumptions and the assigned parameter-value distributions, the most important parameters for which uncertainty has the potential to affect gas and brine migration from the undisturbed repository are: initial liquid saturation in the waste, anhydrite permeability, biodegradation-reaction stoichiometry, gas-generation rates for both corrosion and biodegradation under inundated conditions, and the permeability of the long-term shaft seal.

Experiment results are presented for unconfined compressive strength and elastic moduli of tuffaceous rocks from Busted Butte near Yucca Mountain, Nevada. The data have been compiled for the Yucca Mountain Site Characterization Project Site and Engineering Properties Data Base. Experiments were conducted on water-saturated specimens of the potential nuclear waste repository horizon Topopah Spring Member tuff (thermal/mechanical unit TSw2). The influence of strain rate on mechanical properties of the tuff was examined by loading six specimens in uniaxial compression at a strain rate of 10{sup {minus}9} s{sup {minus}1}. The experiments performed under ambient pressure and temperature conditions and conformed to Technical Procedure 91, titled ``Unconfined Compression Experiments at 22{degrees}C and a Strain Rate of 10{sup {minus}9} s{sup {minus}1}.`` The mean and standard deviation values of ultimate strength, Young`s modulus and Poisson`s ratio determined from these experiments are 85.4{plus_minus}21.7 MPa, 33.9{plus_minus}4.6 GPa, and 0.09{plus_minus}0.07, respectively.

Thermomechanical models are being developed to support the design of an Exploratory Studies Facility (ESF) and a potential high-level nuclear waste repository at Yucca Mountain, Nevada. These models are used for preclosure design of underground openings, such as access drifts, emplacement drifts, and waste emplacement boreholes; and in support of postclosure issue resolution relating to waste canister performance, disturbance of the hydrological properties of the host rock, and overall system performance assessment. For both design and performance assessment, the purpose of using models in analyses is to better understand and quantify some phenomenon or process. Therefore, validation is an important process that must be pursued in conjunction with the development and application of models. The Site Characterization Plan (SCP) addressed some general aspects of model validation, but no specific approach has, as yet, been developed for either design or performance assessment models. This paper will discuss a proposed process for thermomechanical model validation and will focus on the use of laboratory and in situ experiments as part of the validation process. The process may be generic enough in nature that it could be applied to the validation of other types of models, for example, models of unsaturated hydrologic flow.

Basaltic volcanism has been identified as a possible future event initiating a release of radionuclides from a potential repository at the proposed Yucca Mountain high-level waste repository site. The performance assessment method set forth in the Site Characterization Plan (DOE, 1988) requires that a set of scenarios encompassing all significant radionuclide release paths to the accessible environment be described. This report attempts to catalogue the details of the interactions between the features and processes produced by basaltic volcanism in the presence of the presumed groundwater flow system and a repository structure, the engineered barrier system (EBS), and waste. This catalogue is developed in the form of scenarios. We define a scenario as a well-posed problem, starting from an initiating event or process and proceeding through a logically connected and physically possible combination or sequence of features, events, and processes (FEPs) to the release of contaminants.

Sandia National Laboratories—a Department of Energy multiprogram national laboratory—has for over four decades applied its talents, tools, and techniques to solving technological problems of national scale. This publication provides information of interest about Sandia National Laboratories and the work being done there.

Commercial applications for advanced rechargeable batteries are constantly increasing. These applications include electric vehicles, large scale energy storage at electric utilities, storage of electrical energy produced by renewable energy resources such as solar or wind generators, and consumer electronics. Commercially available batteries are not able to meet the performance and/or cost requirements of many of these applications. To be successful, advanced battery technology need different combinations of high energy and power densities, long life, low cost, and little or no maintenance. In addition. completely safe operation must be assured.

There are many remote applications which require the dexterous manipulation of tools and materials in the field. These tasks range from the assembly and maintenance of space structures to the characterization and retrieval of hazardous materials here on Earth. Operations which involve the dexterous manipulation of hazardous materials in the field have, in the past, been completed by technicians. Use of humans in such hazardous operations is under increased scrutiny due to high costs and low productivity associated with providing protective clothing and environments. Traditional remote manual field operations have, unfortunately, proven to have very low productivity when compared with unencumbered human operators. Recent advances in the integration of sensors and computing into the control of remotely operated equipment have shown great promise for reducing the cost of remote systems while providing faster and safer remote systems. This paper discusses applications of such advances to remote field operations.

The Facilities Organization at Sandia has undergone many changes in the past five years. Management has made a commitment to improve the matrix management system and apply quality principles to the organization. This management commitment enabled Facilities to use project management tools for defining and documenting Facilities key processes. The resulting documentation included implementation plans for defining participant roles and responsibilities, identifying critical success factors, measuring performance, and ensuring continuous improvement. All of this resulted in benefits that demonstrate the value of project management and show how project management and quality are intertwined.

Centrifugally-cast concrete liners applied to the interiors of plain steel pipe sections were tested for corrosion performance in brine solutions. An American Petroleum Institute (API) standard concrete, with and without additions of a styrene-butadiene copolymer latex, was subjected to simulated service and laboratory tests. Simulated service tests used a mechanically pumped test manifold containing sections of concrete-lined pipe. Linear polarization probes embedded at steel-concrete interfaces tracked corrosion rates of these samples as a function of exposure time. Laboratory tests used electrochemical impedance spectroscopy to study corrosion occurring at the steel-concrete interfaces. Electron probe microanalysis (EPMA) determined ingress and distribution of damaging species, such as Cl, in concrete liners periodically returned from the field. Observations of concrete-liner fabrication indicate that latex loading levels were difficult to control in the centrifugal-casting process. Overall, test results indicate that latex additions do not impart significant improvements to the performance of centrifugally cast liners and may even be detrimental. Corrosion at steel-concrete interfaces appears to be localized and the area fraction of corroding interfaces can be greater in latex-modified concretes than in API baseline material. EPMA shows higher interfacial Cl concentration in the latex-modified concretes than in the API standard due to rapid brine transport through cracks to the steel surface.

A multimechanism constitutive model of creep has been developed which incorporates the workhardening and recovery transient creep behavior. This model has been applied to the creep of polycrystalline halite. The specific application of the model is in the calculation of the closure of underground rooms in layered salt deposits. Through the use of finite element calculations, this model, with appropriate laboratory material parameters and a Tresca flow potential, has predicted the measured closure of a number of large in situ experimental rooms.

Alkali metal heat-pipe receivers have been identified as a desirable interface to couple a Stirling-cycle engine with a parabolic dish solar concentrator. The reflux receiver provides power nearly isothermally to the engine heater heads while de-coupling the heater head design from the solar absorber surface design. The independent design of the receiver and engine heater head leads to high system efficiency. Heat pipe reflux receivers have been demonstrated at approximately 30 kW{sub t} power throughput by others. This size is suitable fm engine output powers up to 10 kW{sub e}. Several 25-kW{sub e}, Stirling-cycle engines exist, as well as designs for 75-kW{sub t} parabolic dish solar concentrators. The extension of heat pipe technology from 30 kW{sub t} to 75 kW{sub t} is not trivial. Heat pipe designs are pushed to their limits, and it is critical to understand the flux profiles expected from the dish, and the local performance of the wick structure. Sandia has developed instrumentation to monitor and control the operation of heat pipe reflux receivers to test their throughput limits, and analytical models to evaluate receiver designs. In the past 1.5 years, several heat pipe receivers have been tested on Sandia`s test bed concentrators (TBC`s) and 60-kW{sub t} solar furnace. A screen-wick heat pipe developed by Dynatherm was tested to 27.5 kW{sub t} throughput. A Cummins Power Generation (CPG)/Thermacore 30-kW{sub t} heat pipe was pushed to a throughput of 41 kW{sub t} to verify design models. A Sandia-design screen-wick and artery 75-kW{sub t} heat pipe and a CPG/Thermacore 75-kW{sub t} sintered-wick heat pipe were also limit tested on the TBC. This report reviews the design of these receivers, and compares test results with model predictions.

This paper compares the solderability performance and corrosions ion protection effectiveness of electroless tin coatings versus organic azole films after exposure to a series of humidity and thermal (lead-free solders) cycling conditions. The solderability of immersion tin is directly related to the tin oxide growth on the surface and is not affected by the formation of Sn-Cu intermetallic phases as long as the intermetallic phase is protected by a Sn layer. For a nominal tin thickness of 60{mu}inches, the typical thermal excursions associated with assembly are not sufficient to cause the intermetallic phase to consume the entire tin layer. Exposure to humidity at moderate to elevated temperatures promotes heavy tin oxide formation which leads to solderability loss. In contrast, thin azole films are more robust to humidity exposure; however upon heating in the presence of oxygen, they decompose and lead to severe solderability degradation. Evaluations of lead-free solder pastes for surface mount assembly applications indicate that immersion tin significantly improves the spreading of Sn:Ag and Sn:Bi alloys as compared to azole surface finishes.

A variety of industrial-standard and experimental concretes are being evaluated for use in brine disposal pipelines operated by the US Strategic Petroleum Reserve (SPR). This paper reports on interim performance results from on-going studies involving an American Petroleum Institute (API) standard calcium silicate-based (CS) concrete and a commercially available calcium aluminate-based (CA) concrete. Samples exposed to non-flowing SPR brine in the field were returned to the laboratory at regular intervals for analysis. Electron probe microanalysis (EPMA) determined the depth of brine penetration and the amount of concrete deterioration. Corrosion occurring at steel pipe/concrete interfaces during exposure to simulated brine has been studied on laboratory-constructed specimens using electrochemical impedance spectroscopy (EIS).

In December 1991, the Strategic Defense Initiative Organization (SDIO) decided to investigate the possibility of a US launch of a Russian Topaz II space nuclear power system. The primary mission goal would be to demonstrate and evaluate Nuclear Electric Propulsion technology to establish a capability for future civilian and military missions. A preliminary nuclear safety assessment, involving selected safety analyses, was initiated to determine whether or not a space mission could be conducted safely and within budget constraints. This paper describes the preliminary safety assessment results and the nuclear safety program now being established for the Nuclear Electric Propulsion Space Test Program (NEPSTP).

The PANDA code was used to develop an equation of state (EOS) for iron. Separate EOS tables were constructed for four solid phases and the fluid phase. The phase diagram and multiphase EOS table were then computed using the free energies. Results are in good agreement with thermophysical, static compression, phase boundary, and shock-wave measurements. Predicted pressures for the shock-induced {epsilon}-{gamma} and {gamma}-liquid transitions agree with those determined from sound speed measurements. Predicted melting temperatures fall in between two recent sets of experimental data which sharply disagree with one another.

Extensive work has been performed in the past which demonstrates that various metal alloys can be used to detect different toxic, hazardous, and flammable gases. Work has been performed using Pd, Pt, Ir, PdNi, PdAg and Pt/Pd for detecting things such as Hydrogen, Hydrazine, Hydrogen Sulfide, Deuterium, Tritium, Ethanol and Hexane. Perhaps the most familiar is the use of Pd and PdNi for the detection of Hydrogen. These devices work by examining the effect of the gases on the material properties of the metal alloys. Two of the most common material properties examined in these sensors are the resistance of thin film resistors, and the flatband or threshold voltage shifts of MOS structures fabricated with a particular alloy as the gate material. While research into these sensing techniques has shown much promise, few manufacturable, fieldable devices have resulted. These sensing techniques are prone to drift problems due to temperature variations, and typically have large sample to sample variations in performance due to process control issues. Typically, these sensors require significant external instrumentation for measurement and control, making the systems large and expensive. Sandia National Laboratories has designed, fabricated and demonstrated complete functionality of a generic microelectronic based smart sensor platform intended to effectively exploit the research mentioned above into high performance, manufacturable, fieldable devices. This smart sensor platform technology fabricates 2 {mu}m CMOS digital and analog control electronics, sensing elements, and temperature control elements on the same silicon integrated circuit. Our initial demonstration of this technology incorporates PdNi as the sensing alloy for the detection of hydrogen.

The RADionuclide Transport, Removal, And Dose (RADTRAD) code is designed for US Nuclear Regulatory Commission (USNRC) use to calculate the radiological consequences to the offsite population and to control room operators following a design-basis accident at Light Water Reactor (LWR) power plants. This code utilizes updated reactor accident source terms published in draft NUREG-1465, ``Accident Source Terms for Light-Water Nuclear Power Plants.`` The code will track the transport of radionuclides as they are released from the reactor pressure vessel, travel through the primary containment and other buildings, and are released to the environment. As the radioactive material is transported through the primary containment and other buildings, credit for several removal mechanisms may be taken including sprays, suppression pools, overlying pools, filters, and natural deposition. Simple models are available for these different removal mechanisms that use, as input, information about the conditions in the plant and predict either a removal coefficient ({lambda}) or decontamination factor. The user may elect to use these models or input a single value for a removal coefficient or decontamination factor.

A preconceptual design for an Accelerator Production of Tritium (APT) facility is currently under development by several national laboratories in conjunction with industry. The design consists of an accelerator that bombards a spallation target with high energy protons. Neutrons are produced in the spallation target and are absorbed in a blanket material to produce tritium. Two spallation targets are currently under investigation: (1) a tungsten neutron source target and (2) a lead neutron source target. In the tungsten target the neutrons are captured in helium-3, which is circulated through the system, thus producing tritium. The lead target is surrounded with a lithium-aluminum blanket and the tritium is produced in the lithium-6. The investigation of possible radiological impacts on the public is being performed as a part of the safety evaluations of the preconceptual design. These studies include the estimation of releases of radioactive materials from the two spallation targets and the possible impacts on the public.

A research and development program is being conducted by the University of Kentucky/Center for Applied Energy Research, Sandia National Laboratories, LDP Associates and CONSOL Inc. to improve current coal liquefaction technology by physical and chemical pretreatments of the coal and recycle oil. These pretreatment steps include: (1) agglomeration of the coal with ash-containing recycle oil to simultaneously reject coal ash and recycle-oil ash, (2) fluid coking of the distillation bottoms (ash-purge) stream and recycle of the coker overhead, (3) dewaxing of the distillate portion of the recycle oil, and (4) low-severity hydrotreatment of the coker overhead and dewaxed oil using hydrogen from an in-situ water-gas shift reaction. These pretreatment steps will remove the ash and unconverted coal, reducing the ash load in the system and simultaneously recovering the maximum amount of organics. Dewaxing and hydrotreatment will yield a high-quality recycle oil distillate. These pretreatment steps are being evaluated technically and economically to develop an improved conceptual liquefaction process. The baseline process to which the improved process will be compared is the Two-Stage Liquefaction Process as it was practiced at the Wilsonville, AL, USA Advanced Coal Liquefaction Test Facility.

This paper examines the role of the control objective and the control time in determining fuel-optimal actuator placement for structural vibration suppression. A general theory is developed that can be easily extended to include alternative performance metrics such as energy and time-optimal control. The performance metric defines a convex admissible control set which leads to a max-min optimization problem expressing optimal location as a function of initial conditions and control time. A solution procedure based on a nested Genetic Algorithm is presented and applied to an example problem. Results indicate that the optimal locations vary widely as a function of control time and initial conditions.

When restricted to cost arrays possessing the sum Monge property, many combinatorial optimization problems with sum objective functions become significantly easier to solve. Examples include the usual sum-objective-function versions of the assignment problem, the transportation problem, the traveling-salesman problem, and several shortest-path problems. Furthermore, the more general algebraic assignment and transportation problems, which are formulated in terms of an ordered commutative semigroup (H, *, {le}), are similarly easier to solve given cost arrays possessing the corresponding algebraic Monge property, which requires that for all i < k and j < {ell}, a[i,j] * a[k,{ell}] {le} a[i,{ell}] * a[k,j]. In this paper, we show that Monge-array results for two sum-of-edge-costs shortest-path problems can likewise be extended to a general algebraic setting, provided the problems` ordered commutative semigroup (H, *, {le}) satisfies one additional restriction. We also show how our algorithms can be modified to solve certain bottleneck shortest-path problems, even though the ordered commutative semigroup ({Re}, max, {le}) naturally associated with bottleneck problems does not satisfy our additional restriction. We also provide improved algorithms for several other bottleneck combinatorial optimization problems whose cost arrays possess the strict bottleneck Monge property. Finally, we show how our bottleneck shortest-path techniques can be used to obtain fast algorithms for a variant of Hirschberg and Larmore`s optimal paragraph formation problem, a processor-allocation problem first formulated by Bokhari, and a special case of the bottleneck traveling-salesman problem.

Robotics technology is being developed to assist in remediating high-level radioactive wastes stored in large tanks at the Department of Energy`s Hanford, Washington facility. Remediation activities will likely employ a remotely controlled long reach manipulator, capable of extending over 40 feet from its base, to deploy remediation end-effectors and sensors. Waste inside the tanks consists of hazardous vapor, liquid, sludge, solidified crystal, and various steel pipes and miscellaneous hardware. On November 10--12, 1992, a demonstration by Sandia National Laboratories of environmental sensor scanning and robot manipulated steel pipe cutting was performed on a tank mockup located at the Hanford facility. This paper describes the Sandia developed technology implemented at this demonstration.

The Analytic System and Software for Evaluation of Safeguards and Security (ASSESS) Facility module records site information in the path elements and areas of an Adversary Sequence Diagram. The ASSESS Outsider evaluation module takes this information and first calculates performance values describing how much detection and delay is assigned at each path element and then uses the performance values to determine most-vulnerable paths. This paper discusses new Outsider capabilities that allow the user to view how elements are being defeated and to modify some of these values in Outsider. Outsider now displays how different path element segments are defeated and contrasts the probability of detection for alternate methods of defeating a door (e.g., the lock or the door face itself). The user can also override element segment delays and detection probabilities directly during analysis in Outsider. These capabilities allow users to compare element performance and to verify correct path element performance for all elements, not just those on the most-vulnerable path as is the case currently. Improvements or reductions in protection can be easily checked without creating a set of new facility files to accomplish it.

Sandia National Laboratories (SNL) has shown that an automated personnel tracking and material monitoring system enhances protection of sensitive and classified parts against an insider. Such a system also significantly reduces the number of required, manual physical inventories at Department of Energy (DOE) sites while increasing assurance that material has not been diverted. SNL`s Insider Technology Department developed and is enhancing its generic, real-time, personnel tracking and material monitoring system. The system consists of facility selectable modules. This paper presents an overview of the modules, evaluation results, user`s suggestions, and future modules.

Although plasma cleaning is a recognized substitute for solvent cleaning in removing organic contaminants, some universal problems in plasma cleaning processes prevent wider use of plasma techniques. Lack of understanding of the fundamental mechanisms of the process, unreliable endpoint detection techniques, and slow process times make plasma cleaning processes less than desirable. Our approach to address these plasma cleaning problems is described. A comparison of plasma cleaning rates of oxygen and oxygen/sulfur hexafluoride gases shows that fluorine-containing plasmas can enhance etch rates by 400% over oxygen alone. A discussion of various endpoint indication techniques is discussed and compared for application suitability. Work toward a plasma cleaning database is discussed. In addition to the global problems of plasma cleaning, an experiment where the specific mixed-waste problem of removal of machine oils from radioactive scrap metal is discussed.