DSNF AND OTHER WASTE FORM DEGRADATION ABSTRACTION (open access)

DSNF AND OTHER WASTE FORM DEGRADATION ABSTRACTION

Several hundred distinct types of DOE-owned spent nuclear fuel (DSNF) may potentially be disposed in the Yucca Mountain repository. These fuel types represent many more types than can be viably individually examined for their effect on the Total System Performance Assessment for the License Application (TSPA-LA). Additionally, for most of these fuel types, there is no known direct experimental test data for the degradation and dissolution of the waste form in repository groundwaters. The approach used in the TSPA-LA model is, therefore, to assess available information on each of 11 groups of DSNF, and to identify a model that can be used in the TSPA-LA model without differentiating between individual codisposal waste packages containing different DSNF types. The purpose of this report is to examine the available data and information concerning the dissolution kinetics of DSNF matrices for the purpose of abstracting a degradation model suitable for use in describing degradation of the DSNF inventory in the Total System Performance Assessment for the License Application. The data and information and associated degradation models were examined for the following types of DSNF: Group 1--Naval spent nuclear fuel; Group 2--Plutonium/uranium alloy (Fermi 1 SNF); Group 3--Plutonium/uranium carbide (Fast Flux Test Facility-Test Fuel …
Date: November 19, 2004
Creator: CUNNANE, J.
Object Type: Report
System: The UNT Digital Library
Vessel Eddy Current Measurement for the National Spherical Torus Experiment (NSTX) (open access)

Vessel Eddy Current Measurement for the National Spherical Torus Experiment (NSTX)

A simple analog circuit that measures the NSTX axisymmetric eddy current distribution has been designed and constructed. It is based on simple circuit model of the NSTX vacuum vessel that was calibrated using a special axisymmetric eddy current code which was written so that accuracy was maintained in the vicinity of the current filaments. The measurement and the model have been benchmarked against data from numerous vacuum shots and they are in excellent agreement. This is an important measurement that helps give more accurate equilibrium reconstructions.
Date: November 19, 2004
Creator: Gates, D.A.; Menard, J. & Marsala, R.
Object Type: Report
System: The UNT Digital Library
TIME-LAPSE MODELING AND INVERSION OF CO2 SATURATION FOR SEQUESTRATION AND ENHANCED OIL RECOVERY (open access)

TIME-LAPSE MODELING AND INVERSION OF CO2 SATURATION FOR SEQUESTRATION AND ENHANCED OIL RECOVERY

In the fourth quarter of this DOE NETL project, they have developed an algorithm for generating time-lapse seismic anomalies from changes in fluid properties over time. This forward-modeling algorithm constitutes the first step in the inversion procedure of Phase III of the project. Examples were generated illustrating the flexibility of this approach. Additional activities in this reporting period included a trip by the Principal Investigator to the 7th International Conference on Greenhouse Gas Control Technologies (GHGT-7) in Vancouver, Canada, September 5-9, 2004. In the next quarter, they will work on the second step of the inversion procedure, namely, the inversion of the seismic time-lapse anomalies to obtain changes in fluid properties, and will continue investigating alternative methods for calculating properties of oil/brine/CO{sub 2} and brine/CO{sub 2} systems.
Date: November 19, 2004
Creator: Meadows, Mark A.
Object Type: Report
System: The UNT Digital Library
Large basis ab initio shell model investigation of 9Be and 11Be (open access)

Large basis ab initio shell model investigation of 9Be and 11Be

We are presenting the first ab initio structure investigation of the loosely bound {sup 11}Be nucleus, together with a study of the lighter isotope {sup 9}Be. The nuclear structure of these isotopes is particularly interesting due to the appearance of a parity-inverted ground state in {sup 11}Be. Our study is performed in the framework of the ab initio no-core shell model. Results obtained using four different, high-precision two-nucleon interactions, in model spaces up to 9{h_bar}{Omega}, are shown. For both nuclei, and all potentials, we reach convergence in the level ordering of positive- and negative-parity spectra separately. Concerning their relative position, the positive-parity states are always too high in excitation energy, but a fast drop with respect to the negative-parity spectrum is observed when the model space is increased. This behavior is most dramatic for {sup 11}Be. In the largest model space we were able to reach, the 1/2{sup +} level has dropped down to become either the first or the second excited state, depending on which interaction we use. We also observe a contrasting behavior in the convergence patterns for different two-nucleon potentials, and argue that a three-nucleon interaction is needed to explain the parity inversion. Furthermore, large-basis calculations of …
Date: November 19, 2004
Creator: Forssen, C; Navratil, P; Ormand, W E & Caurier, E
Object Type: Article
System: The UNT Digital Library
Direct FuelCell/Turbine Power Plant Annual Technical Progress Report: 2004 (open access)

Direct FuelCell/Turbine Power Plant Annual Technical Progress Report: 2004

This report includes the progress in development of Direct Fuel Cell/Turbine. (DFC/T.) power plants for generation of clean power at very high efficiencies. The DFC/T power system is based on an indirectly heated gas turbine to supplement fuel cell generated power. The DFC/T power generation concept extends the high efficiency of the fuel cell by utilizing the fuel cell's byproduct heat in a Brayton cycle. Features of the DFC/T system include: electrical efficiencies of up to 75% on natural gas, 60% on coal gas, minimal emissions, simplicity in design, direct reforming internal to the fuel cell, reduced carbon dioxide release to the environment, and potential cost competitiveness with existing combined cycle power plants. FCE successfully completed testing of the pre-alpha sub-MW DFC/T power plant. This power plant was constructed by integration of a 250kW fuel cell stack and a microturbine. Following these proof-of-concept tests, a stand-alone test of the microturbine verified the turbine power output expectations at an elevated (representative of the packaged unit condition) turbine inlet temperature. Preliminary design of the packaged sub-MW alpha DFC/T unit has been completed and procurement activity has been initiated. The preliminary design of a 40 MW power plant including the key equipment layout …
Date: November 19, 2004
Creator: Ghezel-Ayagh, Hossein
Object Type: Report
System: The UNT Digital Library
Investigation of microstructure and V-defect formation inInxGa1-xN/GaN MQW grown using temperature-gradient MOCVD (open access)

Investigation of microstructure and V-defect formation inInxGa1-xN/GaN MQW grown using temperature-gradient MOCVD

Temperature-gradient Metalorganic Chemical Vapor Deposition was used to deposit In{sub x}Ga{sub 1-x}N/GaN multiple quantum well structures with a concentration gradient of indium across the wafer. These multiple quantum well structures were deposited on low defect density (2 x 10{sup 8} cm{sup -2}) GaN template layers for investigation of microstructural properties and V-defect (pinhole) formation. Room temperature photoluminescence and photomodulated transmission were used for optical characterization which show a systematic decrease in emission energy for a decrease in growth temperature. Triple-axis X-ray diffraction, scanning electron microscopy and cross-section transmission electron microscopy were used to obtain microstructural properties of different regions across the wafer. Results show that there is a decrease in crystal quality and an increase in V-defect formation with increasing indium concentration. A direct correlation was found between V-defect density and growth temperature due to increased strain and indium segregation for increasing indium concentration.
Date: November 19, 2004
Creator: Johnson, M. C.; Liliental-Weber, Z.; Zakharov, D. N.; McCready, D. E.; Jorgenson, R. J.; Wu, J. et al.
Object Type: Article
System: The UNT Digital Library
The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS Observations (open access)

The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS Observations

We present results of near infrared imaging of the disk-galaxy-merger NGC 6240 using adaptive optics on the Keck II Telescope and reprocessed archival data from NICMOS on the Hubble Space Telescope. Both the North and South nuclei of NGC 6240 are clearly elongated, with considerable sub-structure within each nucleus. In K' band there are at least two point-sources within the North nucleus; we tentatively identify the south-western point-source within the North nucleus as the position of one of the two AGNs. Within the South nucleus, the northern subnucleus is more highly reddened. Based upon the nuclear separation measured at 5 GHz, we suggest that the AGN in the South nucleus is still enshrouded in dust at K' band, and is located slightly to the north of the brightest point in K' band. Within the South nucleus there is strong H{sub 2} 1-0 S(1) line emission from the northern sub-nucleus, contrary to the conclusions of previous seeing-limited observations. Narrowband H{sub 2} emission-line images show that a streamer or ribbon of excited molecular hydrogen connects the North and South nuclei. We suggest that this linear feature corresponds to a bridge of gas connecting the two nuclei, as seen in computer simulations of …
Date: November 19, 2004
Creator: Max, C. E.; Canalizo, G.; Macintosh, B. A.; Raschke, L.; Whysong, D.; Antonucci, R. et al.
Object Type: Article
System: The UNT Digital Library
High-Pressure Magnetic Susceptibility Experiments on the Heavy Lanthanides Gd, Tb, Dy, Ho, Er, and Tm (open access)

High-Pressure Magnetic Susceptibility Experiments on the Heavy Lanthanides Gd, Tb, Dy, Ho, Er, and Tm

The high pressure magnetic properties of the heavy lanthanide elements Gd, Tb, Dy, Ho, Er, and Tm have been investigated using ac magnetic susceptibility with a diamond anvil cell. It is found that the magnetic transition temperatures monotonically decrease with increasing pressure. In addition, the amplitudes of the magnetic transition signals decrease with increasing pressure, with the signals all eventually disappearing at pressures by 20 GPa. In contrast to previous studies, we see no evidence of any pressure-induced transitions from one magnetically ordered phase to another in Gd, Tb, Dy, or Ho. The transition temperatures, T{sub crit} are all found to drop at a rate proportional to their de Gennes factor, and the values of T{sub crit}/T{sub crit}(P = 0) vs P/P{sub crit}, where P{sub crit} is the pressure where the magnetic transition disappears, all sit on a single phase diagram.
Date: November 19, 2004
Creator: Jackson, D. D.; Malba, V.; Weir, S. T.; Baker, P. A. & Vohra, Y. K.
Object Type: Article
System: The UNT Digital Library