The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

J J Bucher - One of the best experts on this subject based on the ideXlab platform.

  • distribution and solubility of radionuclides in waste forms for disposition of plutonium and spent nuclear fuels preliminary results
    Journal of the American Ceramic Society, 1999
    Co-Authors: Xiangdong Feng, Hong Li, Linda L Davis, Liyu Li, John G Darab, Michael J Schweiger, John D Vienna, Bruce C Bunker, P G Allen, J J Bucher
    Abstract:

    Successful immobilization of actinides (Am, Cm, Th, Pu, U, Np, etc.) in crystalline and amorphous host matrices with appropriate Neutron Absorbers (B, Hf, Gd, etc.) requires sound scientific knowledge of the local chemical environments of both the actinides (An) and the Neutron Absorbers and their interaction with the host matrices. This understanding leads to a more systematic and efficient approach to predicting solubilities than the strictly empirical approach currently used. The goals of this ongoing research are to determine solubility limits of representative actinides (Pu and U) and Neutron Absorbers (Hf and Gd) in crystalline and amorphous matrices and to determine solution mechanisms of these species in the two types of systems. Understanding of the chemical systematics of in the two systems will make it possible to calculate the solubility of actinides, Neutron Absorbers, and, we would suggest, other metal species in glass and ceramic waste form, which have been determined empirically for the past. The research results of the ongoing project will be presented, including solubility of Neutron Absorbers, Hf(IV) and Gd(III), and local structures of these species in comparison to those of Pu(IV) and Pu(III) in glass. Effect of glass composition, in terms of peralkallinity, Na2O/(Na2O+Al2O3), on dissolutionmore » of Hf(IV) and Gd(III)and glass microstructure development will be also presented.« less

Xiangdong Feng - One of the best experts on this subject based on the ideXlab platform.

  • distribution and solubility of radionuclides in waste forms for disposition of plutonium and spent nuclear fuels preliminary results
    Journal of the American Ceramic Society, 1999
    Co-Authors: Xiangdong Feng, Hong Li, Linda L Davis, Liyu Li, John G Darab, Michael J Schweiger, John D Vienna, Bruce C Bunker, P G Allen, J J Bucher
    Abstract:

    Successful immobilization of actinides (Am, Cm, Th, Pu, U, Np, etc.) in crystalline and amorphous host matrices with appropriate Neutron Absorbers (B, Hf, Gd, etc.) requires sound scientific knowledge of the local chemical environments of both the actinides (An) and the Neutron Absorbers and their interaction with the host matrices. This understanding leads to a more systematic and efficient approach to predicting solubilities than the strictly empirical approach currently used. The goals of this ongoing research are to determine solubility limits of representative actinides (Pu and U) and Neutron Absorbers (Hf and Gd) in crystalline and amorphous matrices and to determine solution mechanisms of these species in the two types of systems. Understanding of the chemical systematics of in the two systems will make it possible to calculate the solubility of actinides, Neutron Absorbers, and, we would suggest, other metal species in glass and ceramic waste form, which have been determined empirically for the past. The research results of the ongoing project will be presented, including solubility of Neutron Absorbers, Hf(IV) and Gd(III), and local structures of these species in comparison to those of Pu(IV) and Pu(III) in glass. Effect of glass composition, in terms of peralkallinity, Na2O/(Na2O+Al2O3), on dissolutionmore » of Hf(IV) and Gd(III)and glass microstructure development will be also presented.« less

R C Elphic - One of the best experts on this subject based on the ideXlab platform.

  • a revised algorithm for calculating tio2 from clementine uvvis data a synthesis of rock soil and remotely sensed tio2 concentrations
    Journal of Geophysical Research, 2003
    Co-Authors: J J Gillis, Bradley L Jolliff, R C Elphic
    Abstract:

    [1] Investigating mare basalt compositions, at both the sample and remote-sensing level for the Apollo and Luna mare sites, reveals the need for a more complex regression procedure than previously proposed in order to extract accurate TiO2 concentrations from Clementine spectral reflectance (CSR) data. The TiO2 algorithm of Lucey and coworkers is modified by using two different sets of regression parameters to relate measured regolith compositions from sampling locations to the CSR properties of these sites. One regression trend fits the majority of Apollo data, and the second regression is a fit to the Apollo 11, Luna 16, and Luna 24 data, which were considered to be anomalous in previous TiO2 calibrations. These three sites have unusually low albedo compared to other mare landing sites, and some 32% of nearside mare regions appear to share this characteristic. Possible reasons for these differences related to proximity of the other sites to mare-highland boundaries are discussed. Using the dual-regression method, we find (1) that TiO2 concentrations calculated for the basaltic landing sites faithfully reproduce a bimodal distribution as seen in the sample data, (2) that when coupled with the effects of other thermal Neutron Absorbers, Ti concentrations are more consistent with observed epithermal-to-thermal Neutron-flux ratios than are previous Clementine-based derivations of TiO2 for basaltic regions, and (3) that basalts of intermediate-TiO2 concentrations occur most frequently in the Oceanus Procellarum region and that these intermediate concentrations appear to be inherent to the flows underlying the regolith and presumably to the basalt source regions.

Hong Li - One of the best experts on this subject based on the ideXlab platform.

  • distribution and solubility of radionuclides in waste forms for disposition of plutonium and spent nuclear fuels preliminary results
    Journal of the American Ceramic Society, 1999
    Co-Authors: Xiangdong Feng, Hong Li, Linda L Davis, Liyu Li, John G Darab, Michael J Schweiger, John D Vienna, Bruce C Bunker, P G Allen, J J Bucher
    Abstract:

    Successful immobilization of actinides (Am, Cm, Th, Pu, U, Np, etc.) in crystalline and amorphous host matrices with appropriate Neutron Absorbers (B, Hf, Gd, etc.) requires sound scientific knowledge of the local chemical environments of both the actinides (An) and the Neutron Absorbers and their interaction with the host matrices. This understanding leads to a more systematic and efficient approach to predicting solubilities than the strictly empirical approach currently used. The goals of this ongoing research are to determine solubility limits of representative actinides (Pu and U) and Neutron Absorbers (Hf and Gd) in crystalline and amorphous matrices and to determine solution mechanisms of these species in the two types of systems. Understanding of the chemical systematics of in the two systems will make it possible to calculate the solubility of actinides, Neutron Absorbers, and, we would suggest, other metal species in glass and ceramic waste form, which have been determined empirically for the past. The research results of the ongoing project will be presented, including solubility of Neutron Absorbers, Hf(IV) and Gd(III), and local structures of these species in comparison to those of Pu(IV) and Pu(III) in glass. Effect of glass composition, in terms of peralkallinity, Na2O/(Na2O+Al2O3), on dissolutionmore » of Hf(IV) and Gd(III)and glass microstructure development will be also presented.« less

Linda L Davis - One of the best experts on this subject based on the ideXlab platform.

  • distribution and solubility of radionuclides in waste forms for disposition of plutonium and spent nuclear fuels preliminary results
    Journal of the American Ceramic Society, 1999
    Co-Authors: Xiangdong Feng, Hong Li, Linda L Davis, Liyu Li, John G Darab, Michael J Schweiger, John D Vienna, Bruce C Bunker, P G Allen, J J Bucher
    Abstract:

    Successful immobilization of actinides (Am, Cm, Th, Pu, U, Np, etc.) in crystalline and amorphous host matrices with appropriate Neutron Absorbers (B, Hf, Gd, etc.) requires sound scientific knowledge of the local chemical environments of both the actinides (An) and the Neutron Absorbers and their interaction with the host matrices. This understanding leads to a more systematic and efficient approach to predicting solubilities than the strictly empirical approach currently used. The goals of this ongoing research are to determine solubility limits of representative actinides (Pu and U) and Neutron Absorbers (Hf and Gd) in crystalline and amorphous matrices and to determine solution mechanisms of these species in the two types of systems. Understanding of the chemical systematics of in the two systems will make it possible to calculate the solubility of actinides, Neutron Absorbers, and, we would suggest, other metal species in glass and ceramic waste form, which have been determined empirically for the past. The research results of the ongoing project will be presented, including solubility of Neutron Absorbers, Hf(IV) and Gd(III), and local structures of these species in comparison to those of Pu(IV) and Pu(III) in glass. Effect of glass composition, in terms of peralkallinity, Na2O/(Na2O+Al2O3), on dissolutionmore » of Hf(IV) and Gd(III)and glass microstructure development will be also presented.« less