The skeletal structure of aerogel is determined before, during, and after the gel is formed. Supercritical drying of aerogel largely preserves the pore structure that is determined near the time of gelation. To better understand these gel formation mechanisms we carried out measurements of the time evolution of light scattering in a series of gels prepared without conventional acid or base catalysis. Instead, ultraviolet light was used to catalyze the formation of silica gels made from the hydrolysis of tetraethylorthosilicate and partly prehydrolyzed tetraethylorthosilicate in ethanol. Time evolution of light scattering provides information regarding the rate and geometrical nature of the assembly of the primary silica particles formed in the sol. UV-catalyzed gels show volumetric growth typical of acid-catalyzed gels, except when UV exposure is discontinued at the gel point, where gels then show linear chain formation typical of base-catalyzed gels. Long term UV exposure leads to coarsening of the pore network, a decrease in the clarity of the aerogel, and an increase in the surface area of the aerogel. Additionally, UV exposure up to the gel point leads to increased crystallinity in the final aerogel.

An important issue for the performance of underground nuclear waste repositories is the rate of seepage into the waste emplacement drifts. A prediction of this rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, because it is located in thick, unsaturated, fractured tuff formations. Underground opening in unsaturated media might act as capillary barriers, diverting water around them. In the present work, they study the potential rate of seepage into drifts as a function of the percolation flux at Yucca Mountain, based on a stochastic model of the fractured rock mass in the drift vicinity. A variety of flow scenarios are considered, assuming present-day and possible future climate conditions. They show that the heterogeneity in the flow domain is a key factor controlling seepage rates, since it causes channelized flow and local ponding in the unsaturated flow field.

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The high desert near Barstow, California, has witnessed the development of this country`s first two solar power towers. Solar One operated successfully from 1982 to 1988 and proved that power towers work efficiently to produce utility-scale power from sunlight. Solar Two was connected to the utility grid in 1996 and is operating today. Like its predecessor, Solar Two is rated at 10 megawatts. An upgrade of the Solar One plant, Solar Two demonstrates how solar energy can be stored in the form of heat in molten salt for power generation on demand. The experience gained with these two pilot power towers has established a foundation on which industry can develop its first commercial plants. These systems produce electricity on a large scale. They are unique among solar technologies because they can store energy efficiently and cost effectively. They can operate whenever the customer needs power, even after dark or during cloudy weather.

This country`s efforts to successfully develop and commercialize concentrating solar power (CSP) technologies depend on specialized research and testing capabilities. To Support this effort, the US Department of Energy`s Concentrating Solar Power Program maintains two major test facilities: the National Solar Thermal Test Facility at Sandia National Laboratories in Albuquerque, New Mexico, and the High Flux Solar Furnace at the National Renewable Energy Laboratory in Golden, Colorado. These test facilities combine to be instrumental in the development of parabolic dishes, troughs, and solar power towers.

The report describes the markets for concentrating solar power. As concentrating solar power technologies advance into the early stages of commercialization, their economic potential becomes more sharply defined and increasingly tangible.

This Management Work Plan (MWP) describes the process flow, quality assurance controls, and the Environment, Safety, and Health requirements of the Cesium Legacy Safety Project. This MWP provides an overview of the project goals and methods for repackaging the non-conforming Type W overpacks and packaging the CsCl powder and pellets. This MWP is not intended to apply to other activities associated with the CsCl Legacy Safety Program (i.e., clean out of South Cell).

Lockheed Martin Hanford Corporation is developing and implementing an integrated technical baseline for cleaning up environmental contamination at the Hanford Site in Washington State. The Hanford Site is located in Washington State and has been referred to as one of the largest Environmental Cleanup challenges in the US. It became contaminated with radioactive and dangerous wastes during the 40+ years it was being used to produce weapons grade plutonium in support of the US nuclear weapons program (See Figure 1). The US Department of Energy (US DOE) is responsible for cleanup of the Hanford Site with the Environmental Protection Agency (EPA) and the Washington State Department of Ecology (Ecology) both providing regulatory oversight. The US DOE, EPA and Ecology entered into an agreement in 1989 (Hanford Federal Facility Agreement and Consent Order, commonly referred to as the Tri-Party Agreement) that provides the framework for cleanup of the Hanford Site. However, since the inception of the Tri-Party Agreement, there have been numerous changes due to technical issues, funding issues, and priority changes within the cleanup mission. As a result, progress on the definition and execution of the cleanup work has been slower than anticipated and has resulted in some false starts, …

This document is a compilation of presentation packages and white papers for the Flammable Gas Double Shell Tank Expert Elicitation Workshop {number_sign}2. For each presentation given by the different authors, a separate section was developed. The purpose for issuing these workshop presentation packages and white papers as a supporting document is to provide traceability and a Quality Assurance record for future reference to these packages.

This report is the technical basis for the accident and consequence analyses used in the Hanford Tank Farms Basis for Interim Operation. The report also contains the scientific and engineering information and reference material needed to understand the organic solvent safety issue. This report includes comments received from the Chemical Reactions Subcommittee of the Tank Advisory Panel.

Buildings account for more than one third of the energy used in the United States each year, consuming vast amounts of electricity, natural gas, and fuel oil. Given this level of consumption, the buildings sector is rife with opportunity for alternative energy technologies. The US Department of Energy`s Solar Buildings Program was established to take advantage of this opportunity. The Solar Buildings Program is engaged in research, development, and deployment on solar thermal technologies, which use solar energy to produce heat. The Program focuses on technologies that have the potential to produce economically competitive energy for the buildings sector.

Solar dish/engine systems convert the energy from the sun into electricity at a very high efficiency. Using a mirror array formed into the shape of a dish, the solar dish focuses the sun`s rays onto a receiver. The receiver transmits the energy to an engine that generates electric power. Because of the high concentration ratios achievable with parabolic dishes and the small size of the receiver, solar dishes are efficient at collecting solar energy at very high temperatures. Tests of prototype systems and components at locations throughout the US have demonstrated net solar to electric conversion efficiencies as high as 30%. This is significantly higher than any other solar technology.

Hanford`s missions are to safely clean up and manage the site`s legacy wastes, and to develop and deploy science and technology. Through these missions Hanford will contribute to economic diversification of the region. Hanford`s environmental management or cleanup mission is to protect the health and safety of the public, workers, and the environment; control hazardous materials; and utilize the assets (people, infra structure, site) for other missions. Hanford`s science and technology mission is to develop and deploy science and technology in the service of the nation including stewardship of the Hanford Site. Pollution Prevention is a key to the success of these missions by reducing the amount of waste to be managed and identifying/implementing cost effective waste reduction projects. Hanford`s original mission, the production of nuclear materials for the nation`s defense programs, lasted more than 40 years, and like most manufacturing operations, Hanford`s operations generated large quantities of waste and pollution. However, the by-products from Hanford operations pose unique problems like radiation hazards, vast volumes of contaminated water and soil, and many contaminated structures including reactors, chemical plants and evaporation ponds. The cleanup activity is an immense and challenging undertaking, which includes characterization and decommissioning of 149 single shell storage …

Tank Characterization Technical Sampling Basis (this document) is the first step of an in place working process to plan characterization activities in an optimal manner. This document will be used to develop the revision of the Waste Information Requirements Document (WIRD) (Winkelman et al. 1997) and ultimately, to create sampling schedules. The revised WIRD will define all Characterization Project activities over the course of subsequent fiscal years 1999 through 2002. This document establishes priorities for sampling and characterization activities conducted under the Tank Waste Remediation System (TWRS) Tank Waste Characterization Project. The Tank Waste Characterization Project is designed to provide all TWRS programs with information describing the physical, chemical, and radiological properties of the contents of waste storage tanks at the Hanford Site. These tanks contain radioactive waste generated from the production of nuclear weapons materials at the Hanford Site. The waste composition varies from tank to tank because of the large number of chemical processes that were used when producing nuclear weapons materials over the years and because the wastes were mixed during efforts to better use tank storage space. The Tank Waste Characterization Project mission is to provide information and waste sample material necessary for TWRS to define …

As the systems engineering activities at the US Department of Energy`s Hanford reservation have matured, they have been placed in many positions within the management structure. Some of these have been more successful than others. This paper describes the organizational evolution of systems engineering over the last few years to its current successful configuration. Background The US Department of Energy (DOE) owns the 640 square mile Hanford reservation located in southeast Washington State (Figure 1). The Site has been operated for DOE by a team of contractors, who read like a Who`s Who in American Industry. Throughout its history from its founding in 1943 until 1991, Hanford`s primary mission was to produce special nuclear material for the nuclear weapons program. This mission resulted in significant quantities of radioactive and mixed waste that is stored on the site in a variety of forms. In addition much of the surface area, subsurface soil, and groundwater are contaminated to various degrees. The Reservation is located on the banks of the Columbia River, and the avoidance of contaminating the waterway that services the Pacific Northwest is a national concern. In 1991, the mission of the Hanford Site was changed from production to environmental cleanup. …

The Hanford Tank Waste Remediation Systems (TWRS) Characterization Program is responsible for coordinating the sampling and analysis of the 177 large underground storage tanks at the Hanford site. The 222-S laboratory has been the primary laboratory for chemical analysis of this highly-radioactive material and has been accumulating these samples for many years. As part of the Fiscal Year 1998 laboratory work scope, the 222-S laboratory has performed a formal physical inventory of all tank characterization samples which are currently being stored. In addition, an updated inventory/archive program has been designed. This program defines sample storage, retention, consolidation, maintenance, and disposition activities which will ensure that the sample integrity is preserved to the greatest practical extent. In addition, the new program provides for continued availability of waste material in a form which will be useful for future bench-scale studies. Finally, when the samples have exceeded their useful lifetime, the program provides for sample disposition from,the laboratory in a controlled, safe and environmentally compliant manner. The 222-S laboratory maintains custody over samples of tank waste material which have been shipped to the laboratory for chemical analysis. The storage of these samples currently requires an entire hotcell, fully dedicated to sample archive storage, …

The rate of oxidation of spent nuclear fuel stored in the K Basin water is an important parameter when assessing the processes and accident scenarios for preparing the fuel for dry storage. The literature provides data and rate laws for the oxidation of unirradiated uranium in various environments. Measurement data for the dry air oxidation of K Basin fuel is compared to the literature data for linear oxidation in dry air. Equations for the correlations and statistical bounds to the K Basin fuel data and the literature data are selected for predicting nominal and bounding rates for the dry air oxidation of the K Basin fuel. These rate equations are intended for use in the Spent Nuclear Fuel Project Technical Data book.

Solar Two is a concentrating solar power plant that can supply electric power on demand to the local utility, Southern California Edison Company. It can do so because it operates not only during sunny parts of the day, but it can store enough thermal energy from the sun to operate during cloudy periods and after dark, for up to three hours, at its rated output of 10 megawatts (MW). For the first time ever, a utility scale solar power plant can supply electricity when the utility needs it most, to satisfy the energy requirements of its customers.

Helium is present in the earth's atmosphere at about 5 parts per million. (ref. Technology of liquid helium, NBS monograph 111). The D-Zero detector uses helium for the cryogenic cooling of its superconducting magnet and visible light photon counter (VLPC) electronics chips. In addition, the tevatron accelerator has superconducting magnets that use helium Due to the possibility of leaks or releases of helium from these helium lines and components, the background helium level in the collision hall may exceed the natural level of 5 ppm. This engineering note will quantify the probability and level of helium background in the D-Zero detector. The photomultiplier tubes used in the D-Zero detector are sensitive to an elevated helium atmosphere. This is due to the permeation rate of helium gas through the glass tube, into the vacuum space inside. It is very important for the helium atmosphere surrounding the photomultiplier tubes is known and controlled. If the level of helium in the vacuum tube reaches a level above 5 ppm, then the photomuliplier tube may no longer work as designed. The process is an irreversible one.

The purpose of this analysis is to outline and recommend two standby generator systems. These systems shall provide power during a utility outage to critical Alcove No.5's thermal test loads and to subsurface flow through ventilation loads. Critical loads that will be supported by these generator systems will be identified and evaluated. Additionally, other requirements from the Exploratory Studies Facilities Design Requirements (ESFDR) document will be evaluated. Finally, the standby generator systems will be integrated into the existing ESF subsurface distribution system. The objective of this analysis is to provide design inputs for an efficient and reliable standby generator systems which will provide power for critical loads during a power outage; specifically, Alcove No.5's thermal test loads and the subsurface flow through ventilation loads. Additionally, preliminary one-line diagrams will be developed using this analysis as a primary input.

Extracellular matrix and extracellular matrix-degrading matrix metalloproteinases play a key role in interactions between the epithelium and the mesenchyme during mammary gland development and disease. In patients with breast cancer, the mammary mesenchyme undergoes a stromal reaction, the etiology of which is unknown. We previously showed that targeting of an autoactivating mutant of the matrix metalloproteinase stromelysin-1 to mammary epithelia of transgenic mice resulted in reduced mammary function during pregnancy and development of preneoplastic and neoplastic lesions. Here we examine the cascade of alterations before breast tumor formation in the mammary gland stroma once the expression of the stromelysin-1 transgene commences. Beginning in postpubertal virgin animals, low levels of transgene expression in mammary epithelia led to increased expression of endogenous stromelysin-1 in stromal fibroblasts and up-regulation of other matrix metalloproteinases, without basement membrane disruption. These changes were accompanied by the progressive development of a compensatory reactive stroma, characterized by increased collagen content and vascularization in glands from virgin mice. This remodeling of the gland affected epithelial-mesenchymal communication as indicated by inappropriate expression of tenascin-C starting by day 6 of pregnancy. This, together with increased transgene expression, led to basement membrane disruption starting by day 15 of pregnancy. We propose that …

We study the large N limit of the interacting superconformal field theories associated with N M5 branes or M2 branes using the recently proposed relation between these theories and M theory on AdS spaces. We first analyze the spectrum of chiral operators of the 6d (0, 2) theory associated with M5 branes in flat space, and find full agreement with earlier results obtained using its DLCQ description as quantum mechanics on a moduli space of instantons. We then perform a similar analysis for the D{sub N} type 6d (0, 2) theories associated with M5 branes at an R{sup 5}/Z{sub 2} singularity, and for the 3d N = 8 superconformal field theories associated with M2 branes in flat space and at an R{sup 8}/Z{sub 2} singularity respectively. Little is known about these three theories, and our study yields for the first time their spectrum of chiral operators (in the large N limit).

The objectives of this three-phase project were to design, develop, and demonstrate a monitoring system capable of detecting and quantifying tritium in situ in ground and surface waters, and in water from effluent lines prior to discharge into public waterways. The tritium detection system design is based on measurement of the low energy beta radiation from the radioactive decay of tritium using a special form of scintillating optical fiber directly in contact with the water to be measured. The system consists of the immersible sensor module containing the optical fiber, and an electronics package, connected by an umbilical cable. The system can be permanently installed for routine water monitoring in wells or process or effluent lines, or can be moved from one location to another for survey use. The electronics will read out tritium activity directly in units of pico Curies per liter, with straightforward calibration. In Phase 1 of the project, we characterized the sensitivity of fluor-doped plastic optical fiber to tritium beta radiation. In addition, we characterized the performance of photomultiplier tubes needed for the system. In parallel with this work, we defined the functional requirements, target specifications, and system configuration for an in situ tritium beta detector …

This project provides coal samples and accompanying analytical data for research by DOE contractors and others. All 56 samples have been purged with argon before storage, and the 33 samples in the DECS series are heat-sealed in foil laminate bags and stored under refrigeration. Eleven DECS samples have been collected under the current contract. Basic characterization, standardized liquefaction analyses and organic geochemical analyses have been completed. Distribution of samples and data is continuing, with processing of samples being performed as needed. Requests during this quarter were heavily skewed toward database activity; 139 data printouts and individual data items from 2549 additional samples were distributed.