876 research outputs found
Underground nuclear power plant siting
This study is part of a larger evaluation of the problems associated with siting nuclear power plants in the next few decades. This evaluation is being undertaken by the Environmental Quality Laboratory of the California Institute of Technology in conjunction with The Aerospace Corporation and several other organizations. Current efforts are directed toward novel approaches to siting plants within the State of California. This report contains the results of efforts performed by The Aerospace Corporation to provide input information to the larger evaluation relative to underground siting of large central station nuclear power plants.
Projections of electric power demand in California and the country as a whole suggest that a major increase in generating capacity will be required. The problem is complicated beyond that of a large but straightforward extension of capital investment by increased emphasis on environmental factors combined with the early stage of commercial application and regulation of nuclear power sources. Hydroelectric power generation is limited by the availability of suitable sites, and fossil fueled plants are constrained by the availability of high quality fuels and the adverse environmental and/or economic impact from the use of more plentiful fuels. A substantial increase in the number of nuclear power plants is now under way. This source of power is expected to provide the maj or portion of increased capacity. Other power sources such as geothermal and nuclear fusion are unlikely to satisfy the national needs due to technical problems and the lack of a comprehensive development program.
There are several problems associated with meeting the projected power demand. Chief among these is the location of acceptable and economic plant sites. Indeed a sufficient number of sites may not be found unless changes occur in the procedures for selecting sites, the criteria for accepting sites, or the type of site required. Placement of a nuclear plant underground has been suggested as an alternative to present siting practices. It is postulated that the advantages of underground siting in some situations may more than compensate for added costs so that such facilities could be preferred even where surface sites are available. By virtue of greater safety, reduced surface area requirements, and improved aesthetics, underground sites might also be found where acceptable surface sites are not available.
Four small European reactors have been constructed partially underground but plans for large size commercial plants have not progressed. Consequently, the features of underground power plant siting are not well understood. Gross physical features such as depth of burial, number and size of excavated galleries, equipment layout, and access or exit shafts/tunnels must be specified. Structural design features of the gallery liners, containment structure, foundations, and gallery interconnections must also be identified. Identification of the nuclear, electrical, and support equipment appropriate to underground operation is needed. Operational features must be defined for normal operations, refueling, and construction. Several magazine articles have been published addressing underground concepts. but adequate engineering data is not available to support an evaluation of the underground concept.
There also remain several unresolved questions relative to the advantages of underground siting as well as the costs and other possible penalties associated with this novel approach to siting. These include the degree of increased safety through improved containment; the extent and value of isolation from falling objects, e. g. aircraft; the value of isolation from surface storms and tidal waves; the value of protection from vandalism or sabotage; the extent by which siting constraints are relieved through reduced population-distance requirements or aggravated by underground construction requirements; and the value to be placed upon the aesthetic differences of a less visible facility.
The study described in this report has been directed toward some of these questions and uncertainties. Within the study an effort has been made to identify viable configurations and structural liners for typical light water reactor nuclear power plants. Three configurations are summarized in Section 3. A discussion of the underground gallery liner design and associated structural analyses is presented in Section 4. Also addressed in the study and discussed in Section 5 are some aspects of containment for underground plants. There it is suggested that the need for large separations between the plant and population centers may be significantly reduced, or perhaps eliminated.
Section 6 contains a brief discussion of operational considerations for underground plants. The costs associated with excavation and lining of the underground galleries have been estimated in Section 7. These estimates include an assessment of variations implied by different seismic loading assumptions and differences in geologic media. It is shown that these costs are a small percentage of the total cost of comparable surface plants. Finally, the parameters characterizing an acceptable underground site are discussed in Section 8. Material is also included in the appendices pertaining to foreign underground plants, span limits of underground excavations, potential siting areas for underground plants in the State of California, pertinent data from the Underground Nuclear Test Program, and other supporting technical discussions
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Rethinking Supply Chains as Neighborhoods
This paper explores the implication of a neighborhood model for interfirm interactions that explicitly tries to create an equality matching relationship among firms in an industry. The aim is to examine what would happen if these firms worked to gain trust with each other with an eye toward maximizing the value of the collaboration across projects rather than just maximizing revenues in individual projects. A review of extant literature and an analysis of in-depth interviews yielded three actionable strategies that support the creation of a sustainable neighborhood in the construction industry: 1) Hub Strategy, 2) Trust Exercise Strategy, and 3) Sustainable Neighborhood Strategy. As envisioned in this study, the hub is a concentrated, inter-organizational structure for supply chain participants in large, complex projects. Importantly, hub members engage in a variety of technical activities that infuse ongoing and future projects with innovation, scope optimization, and operational efficiencies. Additionally, other activities within the hub are designed to purposefully allow participants to develop trust through collaboration before or outside of their primary contractual engagements. At present, this model has been examined for construction megaprojects, but the general neighborhood concept could be applied to many different industries and settings including manufacturing supply chains and collaborations among communities engaging in economic development. Future work will explore whether mechanisms like the hub and trust exercises can be applied in these other settings as well.IC2 Institut
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Resources for Texas Sexual Assault Survivors: Inventory and Survey Findings on Services, Gaps, and Accessibility
Texas is a leader among states on the issue of sexual assault, and has promoted and funded
the study of sexual violence as well as created the Sexual Assault Survivors’ Task Force
(SASTF) through the Office of the Texas Governor (OOG). Sexual assault is clearly
established as a public health problem affecting 6.3 million women and men in the state, or
33.2% of adult Texans over their lifetime.1 This statistic comes from thorough research by
the Institute on Domestic Violence & Sexual Assault (IDVSA) at The University of Texas at
Austin on the prevalence and impact of sexual assault on Texans, service providers, and the
social and economic system at large.
The bipartisan passage of HB 1590 (86R)
B
signifies a continued commitment by Texas
lawmakers to serve sexual assault survivors. Lawmakers and Texans alike acknowledge the
seriousness of sexual assault crimes. With the research findings derived from this project,
survivors and their families, professionals supporting survivors, and lawmakers can better
see the landscape of resources, service provision gaps, and unmet needs across our state.
The specific project aims were to:
• Inventory the sexual assault services available in Texas.
• Assess sexual assault survivors’ needs by region for the 11 Texas regions.
• Develop a sexual assault services resource inventory.
IDVSA accomplished those aims by:
• Developing and implementing a statewide survey to a broad and diverse set of
providers who serve survivors of sexual violence.
• Conducting a collaborative analysis of the survey findings with a specific focus on
service availability and service gaps, and presenting those in this report to the OOG.
• Developing an HB 1590 Inventory List of the resources available to survivors across
the state and delivering it to the OOG to inform the creation of a comprehensive
statewide service directory in the futureInstitute on Domestic Violence and Sexual Assault (IDVSA
Spitzer Secondary Eclipse Observations of Five Cool Gas Giant Planets and Empirical Trends in Cool Planet Emission Spectra
In this work we present Spitzer 3.6 and 4.5 micron secondary eclipse
observations of five new cool (<1200 K) transiting gas giant planets:
HAT-P-19b, WASP-6b, WASP-10b, WASP-39b, and WASP-67b. We compare our measured
eclipse depths to the predictions of a suite of atmosphere models and to
eclipse depths for planets with previously published observations in order to
constrain the temperature- and mass-dependent properties of gas giant planet
atmospheres. We find that the dayside emission spectra of planets less massive
than Jupiter require models with efficient circulation of energy to the night
side and/or increased albedos, while those with masses greater than that of
Jupiter are consistently best-matched by models with inefficient circulation
and low albedos. At these relatively low temperatures we expect the atmospheric
methane to CO ratio to vary as a function of metallicity, and we therefore use
our observations of these planets to constrain their atmospheric metallicities.
We find that the most massive planets have dayside emission spectra that are
best-matched by solar metallicity atmosphere models, but we are not able to
place strong constraints on metallicities of the smaller planets in our sample.
Interestingly, we find that the ratio of the 3.6 and 4.5 micron brightness
temperatures for these cool transiting planets is independent of planet
temperature, and instead exhibits a tentative correlation with planet mass. If
this trend can be confirmed, it would suggest that the shape of these planets'
emission spectra depends primarily on their masses, consistent with the
hypothesis that lower-mass planets are more likely to have metal-rich
atmospheres.Comment: 16 pages, 14 figures, accepted for publication in Ap
A chronometric exploration of high-resolution ‘sensitive TMS masking’ effects on subjective and objective measures of vision
Transcranial magnetic stimulation (TMS) can induce masking by interfering with ongoing neural activity in early visual cortex. Previous work has explored the chronometry of occipital involvement in vision by using single pulses of TMS with high temporal resolution. However, conventionally TMS intensities have been high and the only measure used to evaluate masking was objective in nature. Recent studies have begun to incorporate subjective measures of vision, alongside objective ones. The current study goes beyond previous work in two regards. First, we explored both objective vision (an orientation discrimination task) and subjective vision (a stimulus visibility rating on a four-point scale), across a wide range of time windows with high temporal resolution. Second, we used a very sensitive TMS-masking paradigm: stimulation was at relatively low TMS intensities, with a figure-8 coil, and the small stimulus was difficult to discriminate already at baseline level. We hypothesized that this should increase the effective temporal resolution of our paradigm. Perhaps for this reason, we are able to report a rather interesting masking curve. Within the classical-masking time window, previously reported to encompass broad SOAs anywhere between 60 and 120 ms, we report not one, but at least two dips in objective performance, with no masking in-between. The subjective measure of vision did not mirror this pattern. These preliminary data from our exploratory design suggest that, with sensitive TMS masking, we might be able to reveal visual processes in early visual cortex previously unreported
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