1,552 Matching Results

Search Results

Influence of meteorology in assessing energy externalities: application of the damage function approach

Description: This paper describes a methodology for estimating energy externalities. These externalities are environmental, health, and other damages and benefits that traditionally have not been considered as part of the cost of producing and consuming goods and services. An example of externalities is the effect on human health from exposure to ozone formed by NO{sub x} and other emissions from electric power plants. These damages are valued adversely by individuals (and by society) but are not reflected in the price of electricity. The damage function approach is a methodology which is used for developing quantitative estimates of externalities. This paper describes the five major steps in the damage function approach, focuses on the use of ozone models in that framework, and points out the effects of meteorological variables on estimates of ozone concentrations.
Date: September 14, 1993
Creator: Lee, R.; Miller, R.L. & McIlvaine, C.M.
Partner: UNT Libraries Government Documents Department

On the use of diffusion synthetic acceleration in parallel 3D neutral particle transport calculations

Description: The linear Boltzmann transport equation (BTE) is an integro-differential equation arising in deterministic models of neutral and charged particle transport. In slab (one-dimensional Cartesian) geometry and certain higher-dimensional cases, Diffusion Synthetic Acceleration (DSA) is known to be an effective algorithm for the iterative solution of the discretized BTE. Fourier and asymptotic analyses have been applied to various idealizations (e.g., problems on infinite domains with constant coefficients) to obtain sharp bounds on the convergence rate of DSA in such cases. While DSA has been shown to be a highly effective acceleration (or preconditioning) technique in one-dimensional problems, it has been observed to be less effective in higher dimensions. This is due in part to the expense of solving the related diffusion linear system. We investigate here the effectiveness of a parallel semicoarsening multigrid (SMG) solution approach to DSA preconditioning in several three dimensional problems. In particular, we consider the algorithmic and implementation scalability of a parallel SMG-DSA preconditioner on several types of test problems.
Date: May 14, 1998
Creator: Brown, P. & Chang, B.
Partner: UNT Libraries Government Documents Department

SPHINX Measurements of Radiation Induced Conductivity of Foam

Description: Experiments on the SPHINX accelerator studying radiation-induced conductivity (RIC) in foam indicate that a field-exclusion boundary layer model better describes foam than a Maxwell-Garnett model that treats the conducting gas bubbles in the foam as modifying the dielectric constant. In both cases, wall attachment effects could be important but were neglected.
Date: December 14, 1998
Creator: Ballard, W.P.; Beutler, D.E.; Burt, M.; Dudley, K.J. & Stringer, T.A.
Partner: UNT Libraries Government Documents Department

Development of continuous glass melting for production of Nd-doped phosphate glasses for the NIF and LMJ laser system

Description: The NIF and LMJ laser systems require about 3380 and 4752 Nd-doped laser glass slabs, respectively. Continuous laser glass melting and forming will be used for the first time to manufacture these slabs. Two vendors have been chosen to produce the glass: Hoya Corporation and Schott Glass Technologies. The laser glass melting systems that each of these two vendors have designed, built and tested are arguably the most advanced in the world. Production of the laser glass will begin on a pilot scale in the fall of 1999.
Date: August 14, 1998
Creator: Campbell, J. H.; Ficini-Dorn, G.; Hawley-Fedder, R.; McLean, M. J.; Suratwala, T. & Trombert, J. H.
Partner: UNT Libraries Government Documents Department

Sequential charged-particle and neutron activation of Flibe in the HYLIFE-II inertial fusion energy power plant design

Description: Most radionuclide generation/depletion codes consider only neutron reactions and assume that charged particles, which may be generated in these reactions, deposit their energy locally without undergoing further nuclear interactions. Neglect of sequential charged-particle (x,n) reactions can lead to large underestimation in the inventories of radionuclides. PCROSS code was adopted for use with the ACAB activation code to enable calculation of the effects of (x,n) reactions upon radionuclide inventories and inventory-related indices. Activation calculations were made for Flibe (2LiF + BeF{sub 2}) coolant in the HYLIFE-II inertial fusion energy (IFE) power plant design. For pure Flibe coolant, it was found that (x,n) reactions dominate the residual contact dose rate at times of interest for maintenance and decommissioning. For impure Flibe, however, radionuclides produced directly in neutron reaction dominate the contact dose rate and (x,n) reactions do not make a significant contribution. Results demonstrate potential importance of (x,n) reactions and that the relative importance of (x,n) reactions varies strongly with the composition of the material considered. Future activation calculations should consider (x,n) reactions until a method for pre-determining their importance is established.
Date: June 14, 1996
Creator: Latkowski, J.F.; Tobin, M.T.; Vujic, J.L. & Sanz, J.
Partner: UNT Libraries Government Documents Department

Fusion research: the past is prologue

Description: At this juncture fusion research can be viewed as being at a turning point, a time to review its past and to imagine its future. Today, almost 50 years since the first serious attempts to address the daunting problem of achieving controlled fusion, we have both an opportunity and a challenge. Some predictions place fusion research today at a point midway between its first inception and its eventual maturation - in the middle of the 21st century - when fusion would become a major source of energy. Our opportunity therefore is to assess what we have learned from 50 years of hard work and use that knowledge as a starting point for new and better approaches to solving the fusion problem. Our challenge is to prove the "50 more years" prophesy wrong, by finding ways to shorten the time when fusion power becomes a reality. The thesis will be advanced that in the magnetic confinement approach to fusion open-ended magnetic confinement geometries offer much in responding to the challenge. A major advantage of open systems is that, owing to their theoretically and experimentally demonstrated ability to suppress plasma instabilities of both the MHD and the high-frequency wave-particle variety, the confinement becomes predictable from "classical," i.e., Fokker-Planck-type analysis. In a time of straitened budgetary circumstances for magnetic fusion research now being faced in the United States, the theoretical tractability of mirror-based systems is a substantial asset. In pursuing this avenue it is also necessary to keep an open mind as to the forms that mirror-based fusion power plants might take. For example, one can look to the high-energy physics community for a possible model: This community has shown the feasibility of constructing large and complex particle accelerators using superconducting magnets, vacuum chambers and complicated particle-handling technology, housed in underground tunnels that ...
Date: October 14, 1998
Creator: Post, R F
Partner: UNT Libraries Government Documents Department

Target area design issues for implementing direct drive on the National Ignition Facility

Description: NIF will be configured in its baseline design to achieve ignition and gain using the indirect drive approach. However, the requirements require the design to not preclude the conduct of inertial confinement fusion experiments using direct drive. This involves symmetrical illumination of an ICF capsule, where each beam fully subtends the capsule. The re-directing of 24 of the 48 NIF beamlines (2x2 beamlet group each) from 30 and 50{degree} cone angles to 75{degree} cone angles near the chamber `equator` is required. This would be done by adjusting intermediate transport mirrors so that the beams intercept different final mirrors in the Target Bay and be directed into final optics assemblies attached to chamber ports positioned at the new port locations. Space for converting from one irradiation scheme to another is a problem; also NIF user needs cannot be compromised by direct drive needs. Target for direct drive, absent a hohlraum, emits much fewer cold x rays than for indirect drive. Further, the irradiation scheme may not result in the absorption of all the 3{omega} light and this may create a hazard to the NIF chamber first wall. This paper describes possible design features of the NIF Target Area to allow conversion to direct drive and discusses some differences in post-shot conditions created compared to indirect drive.
Date: June 14, 1996
Creator: Tobin, M.; Karpenko, V.; Burnham, A. & Peterson, R.
Partner: UNT Libraries Government Documents Department

Development and test of the ITER conductor joints

Description: Joints for the ITER superconducting Central Solenoid should perform in rapidly varying magnetic field with low losses and low DC resistance. This paper describes the design of the ITER joint and presents its assembly process. Two joints were built and tested at the PTF facility at MIT. Test results are presented, losses in transverse and parallel field and the DC performance are discussed. The developed joint demonstrates sufficient margin for baseline ITER operating scenarios.
Date: May 14, 1998
Creator: Martovetsky, N.
Partner: UNT Libraries Government Documents Department

A study of CR-39 track response to charged particles from NOVA implosions

Description: We have exposed CR-39 track recording material to a number of NOVA implosions. Radiation from the implosion passed through an array of ranging filters, which aided identification of the incident particles and their energies. The etching procedure was calibrated by including a piece of track exposed to DD protons from a small accelerator. For the same shots, we quantitatively compare the DD neutron yield with the DD proton yield determined from the track. In DT implosions, tracks produced by neutron interactions prevent observation of charged-particle tracks that are produced by the processes of knock-on, secondary or tertiary fusion.
Date: June 14, 1996
Creator: Phillips, T.W.; Cable, M.D.; Hicks, D.G.; Li, C.K.; Petrasso, R.D. & Seguin, F.H.
Partner: UNT Libraries Government Documents Department

Cost avoidance techniques through the Fernald controlled area trash segregation program and the RIMIA solid waste reduction program

Description: The Fernald Environmental Management Project is a Department of Energy owned facility that produced high quality uranium metals for military defense. The Fernald mission has changed from one of production to remediation. Remediation is intended to clean up legacy (primary) waste from past practices. Little opportunity is available to reduce the amount of primary waste. However, there is an opportunity to reduce secondary waste generation, primarily through segregation. Two programs which accomplish this are the Controlled Area Trash Segregation Program and the RIMIA Solid Waste Reduction Program. With these two programs now in place at the FEMP, it has been estimated that a 60% reduction has been achieved in unnecessary clean waste being disposed as Low Level Waste at the Nevada Test Site. The cost savings associated with these programs (currently 79,000 cubic feet, $428,000) could easily run into the millions of dollars based on the upcoming restoration activities to be undertaken. The segregation of non-radiological waste in the radiologically Controlled Area not only establishes a firm commitment to send only low-level radioactive waste to the Nevada Test Site, but also results in substantial cost avoidance.
Date: May 14, 1997
Creator: Menche, C.E.
Partner: UNT Libraries Government Documents Department

Study of the Effects of Neutrals in Alcator C-Mod Plasmas

Description: Recently, much effort has been dedicated to understanding the bifurcation involved in the transition from a low to high confinement regime. While several theories have been brought forward, many factors remain to be elucidated, one of which involves the role played by neutral particles in the evolution of a transport barrier near the edge of the plasma. Alcator C-Mod is especially well suited for the study of neutral particle effects, mainly because of its high plasma and neutral densities, and closed divertor geometry. Alcator C-Mod employs ICRF as auxiiiary heating for obtaining a high confinement regime, although ohmic H-modes are routinely obtained as well. The neutrals can enter the edge dynamics through the particle, momentum and energy balance. In the particle balance, the source of neutrals has to be evaluated vis-8-vis the formation of the edge density pedestal. It is widely believed that plasma rotation is an important factor in reducing transport. In this case, neutrals could act as a momentum sink, through the charge-exchange process. That same process can also modify the energy balance of the plasma near the edge by increasing the cross-field heat flux. These effects are quite difficult to measure experimentally, in large part because neutral particle diagnosis is not an easy task, and because of the inherent 3-dimensional aspect of the problem. Consequently, the neutral´┐Żs spatial and energy distributions are usually not well known. In Alcator C-Mod, we recently implemented a series of diagnostics for the purpose of measuring these distributions. They include measurements of the neutral pressure at many locations around the tokamak, and spatially resolved measurements of Lyman-a and charge-exchange power emission. A high-resolution multichord (20 channels) tangential view of neutral deuterium emission (Lyman-a) has been recently installed near the midplane. The viewing area covers approximately 4 cm across the separatrix, with a ...
Date: June 14, 1999
Creator: Boivin, R.L.; Boswell, C.; Goetz, J.A.; Hubbard, A.E.; Irby, J.; LaBombard, B. et al.
Partner: UNT Libraries Government Documents Department

Update of the measurement of the t tbar cross section at {radical}s =1.96 TeV

Description: A measurement of the t{bar t} cross section at {radical}s = 1.96 TeV is carried out on a data sample of {approx}100 pb{sup -1} in the dilepton and lepton+jets channels. Overall, 46 events are observed, with an expected background of 23.7 {+-} 3.0. The t{bar t} production cross section is measured to be: {sigma}{sub p{bar p}{yields}t{bar t}} = 8.1 {sub -2.0}{sup +2.2} (stat) {sub -1.3}{sup +1.6} (sys) {+-} 0.8 (lumi) pb. The preliminary measurement of the t{bar t} cross section at a center-of-mass energy of 1.96 TeV presented at the 2003 winter conferences [1] is updated with improved object identification algorithms and a larger data sample of approximately 100 pb{sup -1}. The analyses reported herein are based on data sets taken from August 2002, until July 2003, where {approx}190 pb{sup -1} were delivered to the experiment and {approx}130 pb{sup -1} were recorded and reconstructed. As the various analysis channels have different trigger criteria and quality requirements, the integrated luminosity corresponding to each channel varies. The trigger requirements are the same as those reported in [1]. The run data quality requirements that were applied in [1] are also applied to this larger dataset and are supplemented by additional data quality requirements based on smaller units of data called luminosity blocks ({approx}1 minute of data taking). These requirements reduce the effective data sample by 6%. The most prominent change in the analyses occurred in the identification of electrons, where a likelihood is now used to combine individual criteria, such as electromagnetic cluster x{sup 2} [1], spatial track matching, the E/p matching [1], the fraction of electromagnetic energy of the cluster [1], the distance of closest approach to the primary vertex (DCA) used to select primary high transverse momentum electrons originating from the primary interaction vertex, and the isolation with respect to nearby ...
Date: October 14, 2003
Creator: al., Victor Abazov et
Partner: UNT Libraries Government Documents Department

Radiological Characterization Methodology for INEEL-Stored Remote-Handled Transuranic (RH TRU) Waste from Argonne National Laboratory-East

Description: An Acceptable Knowledge (AK)-based radiological characterization methodology is being developed for RH TRU waste generated from ANL-E hot cell operations performed on fuel elements irradiated in the EBR-II reactor. The methodology relies on AK for composition of the fresh fuel elements, their irradiation history, and the waste generation and collection processes. Radiological characterization of the waste involves the estimates of the quantities of significant fission products and transuranic isotopes in the waste. Methods based on reactor and physics principles are used to achieve these estimates. Because of the availability of AK and the robustness of the calculation methods, the AK-based characterization methodology offers a superior alternative to traditional waste assay techniques. Using the methodology, it is shown that the radiological parameters of a test batch of ANL-E waste is well within the proposed WIPP Waste Acceptance Criteria limits.
Date: January 14, 2003
Creator: Kuan, P. & Bhatt, R.N.
Partner: UNT Libraries Government Documents Department

Assessing Groundwater Model Uncertainty for the Central Nevada Test Area

Description: The purpose of this study is to quantify the flow and transport model uncertainty for the Central Nevada Test Area (CNTA). Six parameters were identified as uncertain, including the specified head boundary conditions used in the flow model, the spatial distribution of the underlying welded tuff unit, effective porosity, sorption coefficients, matrix diffusion coefficient, and the geochemical release function which describes nuclear glass dissolution. The parameter uncertainty was described by assigning prior statistical distributions for each of these parameters. Standard Monte Carlo techniques were used to sample from the parameter distributions to determine the full prediction uncertainty. Additional analysis is performed to determine the most cost-beneficial characterization activities. The maximum radius of the tritium and strontium-90 contaminant boundary was used as the output metric for evaluation of prediction uncertainty. The results indicate that combining all of the uncertainty in the parameters listed above propagates to a prediction uncertainty in the maximum radius of the contaminant boundary of 234 to 308 m and 234 to 302 m, for tritium and strontium-90, respectively. Although the uncertainty in the input parameters is large, the prediction uncertainty in the contaminant boundary is relatively small. The relatively small prediction uncertainty is primarily due to the small transport velocities such that large changes in the uncertain input parameters causes small changes in the contaminant boundary. This suggests that the model is suitable in terms of predictive capability for the contaminant boundary delineation.
Date: June 14, 2002
Creator: Pohll, Greg; Pohlmann, Karl; Hassan, Ahmed; Chapman, Jenny & Mihevc, Todd
Partner: UNT Libraries Government Documents Department

Materials integration issues for high performance fusion power systems.

Description: One of the primary requirements for the development of fusion as an energy source is the qualification of materials for the frost wall/blanket system that will provide high performance and exhibit favorable safety and environmental features. Both economic competitiveness and the environmental attractiveness of fusion will be strongly influenced by the materials constraints. A key aspect is the development of a compatible combination of materials for the various functions of structure, tritium breeding, coolant, neutron multiplication and other special requirements for a specific system. This paper presents an overview of key materials integration issues for high performance fusion power systems. Issues such as: chemical compatibility of structure and coolant, hydrogen/tritium interactions with the plasma facing/structure/breeder materials, thermomechanical constraints associated with coolant/structure, thermal-hydraulic requirements, and safety/environmental considerations from a systems viewpoint are presented. The major materials interactions for leading blanket concepts are discussed.
Date: January 14, 1998
Creator: Smith, D. L.
Partner: UNT Libraries Government Documents Department

The Plutonium Transition from Nuclear Weapons to Crypt

Description: With the end of the ''Cold War'' thousands of nuclear warheads are being dismantled. The National Academy of Sciences termed this growing stockpile of plutonium and highly enriched uranium ''a clear and present danger'' to international security. DOE/MD selected a duel approach to plutonium disposition--burning MOX fuel in existing reactors and immobilization in a ceramic matrix surrounded by HLW glass. MOX material will be pits and clean metal. The challenges come with materials that will be transferred to Immobilization--these range from engineered materials to residues containing < 30% Pu. Impurity knowledge range from guesses to actual data. During packaging, sites will flag ''out of the ordinary'' containers for characterized. If the process history is lost, characterization cost will escalate rapidly. After two step blending and ceramic precursor addition, cold press and sintering will form 0.5-kg ceramic pucks containing {le}50 g Pu. Pucks will be sealed in cans, placed into magazines, then into HLW canisters; these canisters will be filled with HLW glass prior to being transported to the HLW repository. The Immobilization Program must interface with DP, EM, RW, and NN. Overlaid on top of these interfaces are the negotiations with the Russians.
Date: March 14, 2000
Creator: Gray, L.W.
Partner: UNT Libraries Government Documents Department

Hydrogen Gas Generation Model for Fuel-Based Remote-Handled Transuranic Waste Stored at the INEEL

Description: The Idaho National Environmental and Engineering Laboratory (INEEL) initiated efforts to calculate the hydrogen gas generation in remote-handled transuranic (RH-TRU) containers in order to evaluate continued storage of unvented RH-TRU containers in vaults and to identify any potential problems during retrieval and aboveground storage. A computer code is developed to calculate the hydrogen concentration in the stored RH-TRU waste drums for known configuration, waste matrix, and radionuclide inventories as a function of time.
Date: January 14, 2003
Creator: Khericha, S.; Bhatt, R. & Liekhus, K.
Partner: UNT Libraries Government Documents Department

Elevated tritium levels at the World Trade Center

Description: Traces of tritiated water (HTO) were detected at [the]World Trade Center (WTC) ground zero after the 9/11/01 terrorist attack. A method of ultralow-background liquid scintillation counting was used after distilling HTO from the samples. A water sample from the WTC sewer, collected on 9/13/01, contained 0.174 plus or minus 0.074 (2s) nCi/L of HTO. A split water sample, collected on 9/21/01 from the basement of WTC Building 6, contained 3.53 plus or minus 0.17 and 2.83 plus or minus 0.15 nCi/L, respectively. Several water and vegetation samples were analyzed from areas outside the ground zero, located in Manhattan, Brooklyn, Queens, and Kensico Reservoir. No HTO above the background was found in those samples. All these results are well below the levels of concern to human exposure.
Date: May 14, 2002
Creator: Semkow, Thomas M.; Hafner, Ronald S.; Parekh, Pravin P.; Wozniak, Gordon J.; Haines, Douglas K.; Husain, Liaquat et al.
Partner: UNT Libraries Government Documents Department

Feasibility of natural circulation heat transport in the ENHS.

Description: An analysis has been carried out of natural circulation thermal hydraulics in both the primary and intermediate circuits of the Encapsulated Nuclear Heat Source (ENHS). It is established that natural circulation enhanced by gas injection into the primary coolant above the core, or the intermediate coolant above the heat exchange zone, is effective in transporting the nominal core power to the steam generators without the attainment of excessive system temperatures. Uncertainties in thermophysical properties and wall friction have a relatively small effect upon the calculated best estimate primary and intermediate coolant system temperature rises.
Date: February 14, 2002
Creator: Sienicki, J.J.
Partner: UNT Libraries Government Documents Department

Optimal use of information for measuring M(t) in lepton + jets t anti-t events

Description: The observation of the top (t) quark served as one of the major confirmations of the validity of the standard model (SM) of particle interactions. Through radiative corrections of the SM, the mass of the top quark, along with that of the W boson, provide the best indication for the value of the mass of the hypothesized Higgs boson. The mass of the W is known to a precision of < 0.1%, while the uncertainty on the mass of the top quark is at the 4% level. Improvements in both measurements are required to limit the range of mass that the Higgs boson can assume in the SM, and, of course, to check whether that agrees with expectation. It is therefore important to develop techniques for extracting the mass of the top quark that can provide the sharpest values possible.
Date: October 14, 2003
Creator: Estrada, Juan
Partner: UNT Libraries Government Documents Department

Dynamic Group Diffie-Hellman Key Exchange under standard assumptions

Description: Authenticated Diffie-Hellman key exchange allows two principals communicating over a public network, and each holding public-private keys, to agree on a shared secret value. In this paper we study the natural extension of this cryptographic problem to a group of principals. We begin from existing formal security models and refine them to incorporate major missing details (e.g., strong-corruption and concurrent sessions). Within this model we define the execution of a protocol for authenticated dynamic group Diffie-Hellman and show that it is provably secure under the decisional Diffie-Hellman assumption. Our security result holds in the standard model and thus provides better security guarantees than previously published results in the random oracle model.
Date: February 14, 2002
Creator: Bresson, Emmanuel; Chevassut, Olivier & Pointcheval, David
Partner: UNT Libraries Government Documents Department