Monolithic structural ceramics and continuous fiber ceramic matrix composites (CMCs) are being developed for application in many thermally and chemically aggressive environments where structural reliability is paramount. We have recently developed advanced nondestructive evaluation (NDE) methods that can detect distributed ''defects'' such as density gradients and machining-induced damage in monolithic materials, as well as delamination, porosity, and throughwall cracks, in CMC materials. These advanced NDE methods utilize (a) high-resolution, high-sensitivity thermal imaging; (b) high-resolution X-ray imaging; (c) laser-based elastic optical scattering; (d) acoustic resonance; (e) air-coupled ultrasonic methods; and (f) high-sensitivity fluorescent penetrant technology. This paper discusses the development and application of these NDE methods relative to ceramic processing and ceramic components used in large-scale industrial gas turbines and hot gas filters for gas stream particulate cleanup.

Austenitic stainless steels are used extensively as structural alloys in reactor pressure vessel internal components because of their superior fracture toughness properties. However, exposure to high levels of neutron irradiation for extended periods leads to significant reduction in the fracture resistance of these steels. This paper presents results of fracture toughness J-R curve tests on four heats of Type 304 stainless steel that were irradiated to fluence levels of {approx}0.3 and 0.9 x 10{sup 21} n cm{sup {minus}2} (E >1 MeV) at {approx}288 C in a helium environment in the Halden heavy water boiling reactor. The tests were performed on 1/4-T compact tension specimens in air at 288 C; crack extensions were determined by both DC potential and elastic unloading compliance techniques.

There are three basic ways to protect the public from the hazards of exposure to radionuclides in nuclear waste: completely contain the waste; limit the rate at which radionuclides are released; and, once radionuclides are released, minimize their impact by reducing concentrations and retarding transport. A geologic repository system that implements all three provides maximum protection for the public: if one element fails, the others serve to protect. This is ''defense-in-depth.'' Demonstrating confidence in the ability of a designed system to provide the requisite safety to the public must rely on a combination of the following aspects relating to engineered and natural system components: 1 Knowledge or understanding of properties and processes 2 Uniformity of (or ability to understand or control) the range of variability associated with each component 3 Experience over time This paper proposes a tool based on defining a ''confidence region'' determined by these three essential aspects of confidence. The defense-in-depth decision-making tool described identifies the portion of the ultimate confidence region that is not well demonstrated and indicates where there is potential for changing a specific component's confidence region, therefore providing in-formation for decisions on emphasis--either for demonstrating performance or for focusing on further studies. The …

Materials for gas turbine engines are required to meet a wide range of temperature and stress application requirements. These alloys exhibit a combination of creep resistance, creep rupture strength, yield and tensile strength over a wide temperature range, resistance to environmental attack (including oxidation, nitridation, sulphidation and carburization), fatigue and thermal fatigue resistance, metallurgical stability and useful thermal expansion characteristics. These properties are exhibited by a series of solid-solution-strengthened and precipitation-hardened nickel, iron and cobalt alloys. The properties needed to meet the turbine engine requirements have been achieved by specific alloy additions, by heat treatment and by thermal mechanical processing. A thorough understanding of the metallurgy and metallurgical processing of these materials is imperative in order to successfully fusion weld them. This same basic understanding is required for repair of a component with the added dimension of the potential effects of thermal cycling and environmental exposure the component will have endured in service. This article will explore the potential problems in joining and repair welding these materials.

The MicroTechnology Center at Lawrence Livermore National Laboratory is developing a variety of MEMS-Based analytical instrumentation systems in support of programmatic needs, along with numerous external customers. Several of the applications of interest are in the area of biochemical identification and analysis. These applications range from DNA fragment analysis and collection in support of the Human Genome Project, to detection of viruses or biological warfare agents. Each of the applications of interest has focused in micro-machined MEMS technology for reduced cost, higher throughput, and faster results. Development of these analytical instrumentation systems will have long term benefits for the medical community as well. The following describes the technologies several specific applications.

The evolution of the Rayleigh-Taylor (RT) instability in a compressible medium has been investigated at an accelerating embedded interface and at the ablation front in a series of experiments on the Nova laser. The x-ray drive generated in a gold hohlraum ablatively accelerated a planar target consisting of a doped plastic pusher backed by a higher density titanium payload with perturbations placed at the plastic-Ti interface. The targets were diagnosed by face-on and side-on radiography. In previous work focusing on single mode perturbations, wavelengths as short as 10 m have been observed to grow strongly at the embedded interface. Here multimode perturbations consisting of either 2, 10 or 20 modes superposed in phase have been investigated.

In this paper the authors present data on the non-thermal plasma processing of two representative VOCs: carbon tetrachloride and methanol. The investigation used a compact electron beam reactor, and two types of discharge reactors: a pulsed corona and a dielectric-barrier discharge. To the knowledge of the authors, this is the first comparison of the energy efficiency of electron beam, pulsed corona and dielectric-barrier discharge processing of these VOCs under identical gas conditions. For most electrical discharge reactors the analysis suggests that the attainable electron mean energy is rather limited and cannot be significantly enhanced by changing the electrode configuration or voltage waveform. The experimental data confirms that there is no significant difference in the performance of the pulsed corona and dielectric-barrier discharge reactors. The authors observe that electron beam processing is remarkably more energy efficiency than electrical discharge processing in decomposing either of these VOC molecules. During electron beam processing, the specific energy consumption is consistent with the energy required for the ionization of the background air molecules. For carbon tetrachloride, the dominant decomposition pathway is dissociative electron attachment. For methanol, the dominant decomposition pathway is dissociative charge exchange.

This statement summarizes Lawrence Livermore National Laboratory`s committment to making important scientific, technological, and business contributions to global sustainability. The quest has many aspects, some socio-political or economic and some technological, and some in which the soft and hard sciences become indistinguishable, as in visionary national strategies, like Holland`s, and futuristic regional and city development plans, like those of Kagoshima and Chattanooga.

U.S. Department of Energy facilities were visited to determine their specific packaging needs. Those individual site needs were analyzed to determine widespread packaging needs. Those packaging needs are: replacements for aging Type B packagings, plutonium packaging, overpacks for large containers, heavily shielded Type B packaging, large radioactive liquid packaging, standardized waste packaging, and packaging for explosives.

A Rossi-{alpha} experiment was performed on the zero-power, XIX-2 assembly at the Fast Critical Assembly (FCA) facility operated by the Japan Atomic Energy Research Institute (JAERI), Tokai-mura, Japan. The XIX-2 assembly is a plutonium/natural uranium system comprised of plutonium/natural uranium core surrounded by a depleted uranium dioxide blanket (referred to as the soft blanket). The soft blanket is surrounded by an outer blanket comprised of depleted uranium dioxide blanket (referred to as the depleted blanket). Because the neutron lifetime in the soft and depleted blankets are significantly larger than the neutron lifetime in the core region, multiple decay modes were observed during this experiment. The first decay mode was measured with reasonable accuracy; however, because of the high intrinsic source strength produced by the large amounts of Pu-240 contained in the core region, the intrinsic source background was reached very rapidly, thus precluding the second decay mode from being resolved well enough to estimate the average system lifetime. Nevertheless, using the first decay mode (i.e., the rapid die-away time constant), the alpha at delayed critical for this root was measured to be 13,100 +/- 134 s{sup -1}. This root is associated with the prompt neutron lifetime of the core region. …

This paper describes experiences at Los Alamos National Laboratory during the process of planning and executing decommissioning and decontamination activities on a number of properties constructed as part of the Manhattan project. Many of these buildings had been abandoned for many years and were in deteriorating condition, in addition to being contaminated with asbestos, lead based paints and high explosive residues. Due to the age and use of the structures they were evaluated against criteria for the National Register of Historic Places. This process is briefly reviewed, along with the results, as well as actions implemented as a result of the condition and safety of the structures. A number of the structures have been decontaminated and demolished. Planning is still ongoing for the renovation of one structure, and the photographic and drawing records of the properties is near completion.

We describe the response of the scrape-off layer (SOL) plasma to variations in the intensity, and geometry of an intrinsic carbon source in DIII-D. Using the multi species 2-D fluid plasma code UEDGE we find plasma modes which are similar to those seen experimentally. At high sputtering coefficient the plasma discontinuously transitions to a state in which the radiation power exceeds the input power and no steady state solution is obtained. We believe this corresponds to the MARFE (Multifaceted Asymmetric Radiation from Edge) state seen experimentally, in which the core confinement is reduced.

The authors use optical pump, coherent terahertz probe spectroscopy to transiently excite nonequilibrium populations of quasiparticles in YBa{sub 2}Cu{sub 3}O{sub 7.{delta}} and monitor, with picosecond resolution, the superfluid and quasiparticle dynamics.

Successful techniques have been developed for simulating some experimental shipboard fires. The experimental fues were staged in Holds 4 and 5 of the Mayo Lykes, a test ship operated by the United States Coast Guard Fire and Safiety Test Detachment at Little Sand Island in Mobile Bay, Alabama. The tests simulated an engine-room or galley fire in the compartment adjacent to simulated hazardous cargo. The purpose of these tests was to determine the effect the fires in Hold 4 had on the cargo in Holds 4 and 5. The simulation is done with CFX, a commercial computational fluid dynamics code. Analyses show that simulations can accurately estimate a maritime fire environment for radioactive materials packaging. Radiative heat transfer dominates the hold-fue environment near the hot bulkhead. Flame temperatures between 800 and 1000°C give heat fluxes and temperatures typical of the measured fire environment for the simulated radioactive materials package. The simulation predicted the occurrence of flow patterns near the calorimeter (simulated radioactive materials package) similar to those observed during the experiment. The simulation was also accurate in predicting a heated fluid layer near the ceiling that increases in thickness as time passes.

The authors report ultrafast scanning tunneling microscopy using a low-temperature-grown GaAs tip photoexcited by 100-fs, 800-nm pulses. They use this tip to detect picosecond transients on a coplanar stripline and demonstrate a temporal resolution of 1.7 ps. A dependence of the transient signal upon spatial position of the tip is revealed, indicating that the signal arises from areas on the sample smaller than {approximately}20nm.

We have constructed a humidity-controlled chamber in which deflections of polysilicon cantilever beams are observed by interferometry, resulting in in-situ adhesion measurements within a fracture mechanics framework. From adhesion energy measurements for uncoated hydrophilic beams, we demonstrate an exponential dependence of adhesion on relative humidity (RH). We can explain this trend with a single-asperity model for capillary condensation. For coated hydrophobic beams, adhesion is independent of RH up to a threshold value which depends on the coating used. However, we have found that exposure to very high RH ({ge}90%) ambients can cause a dramatic increase in adhesion, surprisingly with a stronger effect for perfluorodecyltrichlorosilane (FDTS, C{sub 10}H{sub 4}F{sub 17}SiCl{sub 3}) than octadecyltrichlorosilane (ODTS, C{sub 18}H{sub 37}SiCl{sub 3}). Newly developed computational mechanics to measure adhesion in the presence of an applied load allow us to explore how the adhesion increase develops. We believe that water adsorption at silanol sites at the FDTS/substrate interface, possibly exacerbated by coupling agent migration, leads to water islanding and the subsequent adhesion increase at very high RH levels.

The goal of this research is the understanding of elementary chemical and physical processes important in the combustion of fossil fuels. Interest centers on reactions involving short-lived chemical intermediates and their properties. High-resolution high-sensitivity laser absorption methods are augmented by high temperature flow-tube reaction kinetics studies with mass spectrometric sampling. These experiments provide information on the energy levels, structures and reactivity of molecular flee radical species and, in turn, provide new tools for the study of energy flow and chemical bond cleavage in the radicals in chemical systems. The experimental work is supported by theoretical and computational work using time-dependent quantum wavepacket calculations that provide insights into energy flow between the vibrational modes of the molecule.

The U.S. Department of Energy (DOE) requires all employees who hold a security clearance and have access to classified information and/or special nuclear material to be trained in the area of Safeguards and Security. Since the advent of the World Wide Web, personnel who are responsible for training have capitalized on this communication medium to develop and deliver Web-based training. Unlike traditional computer based training where the student was required to find a workstation where the training program resided, one of Web-based training strongest advantage is that the training can be delivered right to the workers desk top computer. This paper will address reasons for the driving forces behind the utilization of Web-based training at the Laboratory with a brief explanation of the different types of training conducted. Also discussed briefly is the different types of distance learning used in conjunction with Web-based training. The implementation strategy will be addressed and how the Laboratory utilized a Web-Based Standards Committee to develop standards for Web-based training applications. Web-based problems resulting from little or no communication between training personnel across the Laboratory will be touched on and how this was solved. Also discussed is the development of a ''Virtual Training Center'' where …

The grain size and strain dependence of work hardening in Type 304L stainless steel were analyzed between 200 and 250 K where hydrogen damage is greatest. Tensile data were obtained for specimens of several grain sizes, both with and without prior exposure to hydrogen gas at 69 MPa pressure. The analysis suggests that hydrogen has little influence on lattice friction stress but has a large effect on dislocation interaction and the back stress of dislocation pileups. This report discusses this study.

The goal of this research is the understanding of elementary chemical and physical processes important in the combustion of fossil fuels. Interest centers on reactions and properties of short-lived chemical intermediates. High-resolution, high-sensitivity, laser absorption methods are augmented by high- temperature, flow-tube reaction kinetics studies with mass-spectrometic sampling. These experiments provide information on the energy levels, structures and reactivity of molecular free radical species and in turn, provide new tools for the study of energy flow and chemical bond cleavage in the radicals involved in chemical systems. The experimental work is supported by theoretical studies using time-dependent quantum wavepacket calculations, which provide insight into energy flow among the vibrational modes of polyatomic molecules and interference effects in multiple-surface dynamics.

We have observed 1 event consistent with the signature expected of the rare decay of a positive kaon to a positive pion and a neutrino anti-neutrino pair. In the examined momentum region of 211 to 230 MeV/c in the center of mass of the kaon we estimated the backgrounds to be about 0.08 &plusmn; 0.03 events. From this observation we estimate the branching ratio to be 4.2<SUP>+9.7</SUP><SUB>-3.5</SUB> x 10<SUP>-10</SUP>. In this presentation I will explain the experiment, and the analysis techniques. I will also discuss the expected improvements in the near future from the analysis of new data sets.

Field, laboratory and engineering data confirmed the efficacy of chemical reduction and air stripping as an ultralow concentration mercury treatment concept for water containing Hg(II). The simple process consists of dosing the water with low levels of stannous chloride (Sn(II)) to cover the mercury to Hg degrees. This mercury species can easily be removed from the water by air stripping or sparging.

Hydrogen solubility was directly measured in specimens of Types 304L, 21-6-9, and modified A-286 austenitic stainless steels saturated with hydrogen at 69 MPa pressure at 470 K. Nitrogen in Type 21-6-9 stainless steel and precipitate morphology in the modified Type A-286 stainless steel altered the hydrogen solubility. Cold work and surface treatment had only minor effects on hydrogen solubility in the three stainless steels. This reports discusses this study.

Balance confirmation tests usually include eccentricity, linearity, and repeatability. The latter is a measure of the random variability of the instrument. Further, repeatability is usually based on 10 consecutive measurements of a mass standard in a short period of time. The test results are used to verify the balance performs within manufacturer's specifications. These test results are often used in calculating an estimate of the uncertainty in measurements made with the balance. Uncertainty estimates, used to quantify the quality of measurements, must accurately estimate the magnitude of these errors. Does the repeatability test provide a realistic estimate of the random variation in the weighing process? The authors had concerns that it may not. The reproducibility estimate of the balance needs to be determined for the variables that will change between measurements of the same material while the other parameters are held constant by procedures and training.