Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters (open access)

Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters

Integrated energy, environment and economics modeling suggests electrical energy use will increase from 2.4 TWe today to 12 TWe in 2100. It will be challenging to provide 40% of this electrical power from combustion with carbon sequestration, as it will be challenging to provide 30% from renewable energy sources. Thus nuclear power may be needed to provide ~30% by 2100. Calculations of the associated stocks and flows of uranium, plutonium and minor actinides indicate that the proliferation risks at mid-century, using current light-water reactor technology, are daunting. There are institutional arrangements that may be able to provide an acceptable level of risk mitigation, but they will be difficult to implement. If a transition is begun to fast-spectrum reactors at mid-century, without a dramatic change in the proliferation risks of such systems, at the end of the century proliferation risks are much greater, and more resistant to mitigation. The risks of nuclear power should be compared with the risks of the estimated 0.64oC long-term global surface-average temperature rise predicted if nuclear power were replaced with coal-fired power plants without carbon sequestration. Fusion energy, if developed, would provide a source of nuclear power with much lower proliferation risks than fission.
Date: March 3, 2010
Creator: Goldston, Robert J.
Object Type: Report
System: The UNT Digital Library
Detailed Chemical Kinetic Reaction Mechanisms for Primary Reference Fuels for Diesel Cetane Number and Spark-Ignition Octane Number (open access)

Detailed Chemical Kinetic Reaction Mechanisms for Primary Reference Fuels for Diesel Cetane Number and Spark-Ignition Octane Number

For the first time, a detailed chemical kinetic reaction mechanism is developed for primary reference fuel mixtures of n-hexadecane and 2,2,4,4,6,8,8-heptamethyl nonane for diesel cetane ratings. The mechanisms are constructed using existing rules for reaction pathways and rate expressions developed previously for the primary reference fuels for gasoline octane ratings, n-heptane and iso-octane. These reaction mechanisms are validated by comparisons between computed and experimental results for shock tube ignition and for oxidation under jet-stirred reactor conditions. The combined kinetic reaction mechanism contains the submechanisms for the primary reference fuels for diesel cetane ratings and submechanisms for the primary reference fuels for gasoline octane ratings, all in one integrated large kinetic reaction mechanism. Representative applications of this mechanism to two test problems are presented, one describing fuel/air autoignition variations with changes in fuel cetane numbers, and the other describing fuel combustion in a jet-stirred reactor environment with the fuel varying from pure 2,2,4,4,6,8,8-heptamethyl nonane (Cetane number of 15) to pure n-hexadecane (Cetane number of 100). The final reaction mechanism for the primary reference fuels for diesel fuel and gasoline is available on the web.
Date: March 3, 2010
Creator: Westbrook, C K; Pitz, W J; Mehl, M & Curran, H J
Object Type: Article
System: The UNT Digital Library
DEVELOPMENT OF BURN TEST SPECIFICATIONS FOR FIRE PROTECTION MATERIALS IN RAM PACKAGES (open access)

DEVELOPMENT OF BURN TEST SPECIFICATIONS FOR FIRE PROTECTION MATERIALS IN RAM PACKAGES

The regulations in 10 CFR 71 require that the radioactive material (RAM) packages must be able to withstand specific fire conditions given in 10 CFR 71.73 during Hypothetical Accident Conditions (HAC). This requirement is normally satisfied by extensive testing of full scale test specimens under required test conditions. Since fire test planning and execution is expensive and only provides a single snapshot into a package performance, every effort is made to minimize testing and supplement tests with results from computational thermal models. However, the accuracy of such thermal models depends heavily on the thermal properties of the fire insulating materials that are rarely available at the regulatory fire temperatures. To the best of authors knowledge no test standards exist that could be used to test the insulating materials and derive their thermal properties for the RAM package design. This paper presents a review of the existing industry fire testing standards and proposes testing methods that could serve as a standardized specification for testing fire insulating materials for use in RAM packages.
Date: March 3, 2010
Creator: Gupta, N.
Object Type: Article
System: The UNT Digital Library
Effects of warming on the structure and function of a boreal black spruce forest (open access)

Effects of warming on the structure and function of a boreal black spruce forest

A strong argument can be made that there is a greater need to study the effect of warming on boreal forests more than on any other terrestrial biome. Boreal forests, the second largest forest biome, are predicted to experience the greatest warming of any forest biome in the world, but a process-based understanding of how warming will affect the structure and function of this economically and ecologically important forest biome is lacking. The effects of warming on species composition, canopy structure and biogeochemical cycles are likely to be complex; elucidating the underlying mechanisms will require long-term whole-ecosystem manipulation to capture all the complex feedbacks (Shaver et al. 2000, Rustad et al. 2001, Stromgren 2001). The DOE Program for Ecosystem Research funded a three year project (2002-2005) to use replicated heated chambers on soil warming plots in northern Manitoba to examine the direct effects of whole-ecosystem warming. We are nearing completion of our first growing season of measurements (fall 2004). In spite of the unforeseen difficulty of installing the heating cable, our heating and irrigation systems worked extremely well, maintaining environmental conditions within 5-10% of the specified design 99% of the time. Preliminary data from these systems, all designed and built …
Date: March 3, 2010
Creator: T.Gower, Stith
Object Type: Report
System: The UNT Digital Library
Implementation and assessment of turbine wake models in the Weather Research and Forecasting model for both mesoscale and large-eddy simulation (open access)

Implementation and assessment of turbine wake models in the Weather Research and Forecasting model for both mesoscale and large-eddy simulation

Flow dynamics in large wind projects are influenced by the turbines located within. The turbine wakes, regions characterized by lower wind speeds and higher levels of turbulence than the surrounding free stream flow, can extend several rotor diameters downstream, and may meander and widen with increasing distance from the turbine. Turbine wakes can also reduce the power generated by downstream turbines and accelerate fatigue and damage to turbine components. An improved understanding of wake formation and transport within wind parks is essential for maximizing power output and increasing turbine lifespan. Moreover, the influence of wakes from large wind projects on neighboring wind farms, agricultural activities, and local climate are all areas of concern that can likewise be addressed by wake modeling. This work describes the formulation and application of an actuator disk model for studying flow dynamics of both individual turbines and arrays of turbines within wind projects. The actuator disk model is implemented in the Weather Research and Forecasting (WRF) model, which is an open-source atmospheric simulation code applicable to a wide range of scales, from mesoscale to large-eddy simulation. Preliminary results demonstrate the applicability of the actuator disk model within WRF to a moderately high-resolution large-eddy simulation study …
Date: March 3, 2010
Creator: Singer, M; Mirocha, J; Lundquist, J & Cleve, J
Object Type: Article
System: The UNT Digital Library
Merged Sounding Value-Added Product (open access)

Merged Sounding Value-Added Product

The Merged Sounding value-added product (VAP) uses a combination of observations from radiosonde soundings, the microwave radiometer (MWR), surface meteorological instruments, and European Centre for Medium-Range Weather Forecasts (ECMWF) model output with a sophisticated scaling/interpolation/smoothing scheme in order to define profiles of the atmospheric thermodynamic state at one-minute temporal intervals and a total of 266 altitude levels.
Date: March 3, 2010
Creator: Troyan, D.
Object Type: Report
System: The UNT Digital Library
THE ODTX SYSTEM FOR THERMAL IGNITION AND THERMAL SAFETY STUDY OF ENERGETIC MATERIALS (open access)

THE ODTX SYSTEM FOR THERMAL IGNITION AND THERMAL SAFETY STUDY OF ENERGETIC MATERIALS

Understanding the response of energetic material to thermal event is very important for the storage and handling of energetic materials. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) can precisely measure times to explosion and minimum ignition temperatures of energetic materials at elevated temperatures. These measurements provide insight into the relative ease of thermal ignition and allow for the determination of kinetic parameters. The ODTX system can potentialy be a good tool to measure violence of the thermal ignition by monitoring the size of anvil cavity. Recent ODTX experimental data on various energetic materials (solid and liquids) are reported in this paper.
Date: March 3, 2010
Creator: Hsu, P C; Hust, G; Howard, M & Maienschein, J L
Object Type: Article
System: The UNT Digital Library
A Pilot Plant: The Fastest Path to Commercial Fusion Energy (open access)

A Pilot Plant: The Fastest Path to Commercial Fusion Energy

Considerable effort has been dedicated to determining the possible properties of a magneticconfinement fusion power plant, particularly in the U.S.1, Europe2 and Japan3. There has also been some effort to detail the development path to fusion energy, particularly in the U.S.4 Only limited attention has been given, in Japan5 and in China6, to the options for a specific device to form the bridge from the International Thermonuclear Experimental Reactor, ITER, to commercial fusion energy. Nor has much attention been paid, since 2003, to the synergies between magnetic and inertial fusion energy development. Here we consider, at a very high level, the possibility of a Qeng ≥ 1 Pilot Plant, with linear dimensions ~ 2/3 the linear dimensions of a commercial fusion power plant, as the needed bridge. As we examine the R&D needs for such a system we find significant synergies between the needs for the development of magnetic and inertial fusion energy.
Date: March 3, 2010
Creator: Goldston, Robert J.
Object Type: Report
System: The UNT Digital Library