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Title: Critical Role of Water Content in the Formation and Reactivity of Uraniu, Neptunium, and Plutonium Iodates Under Hydrothermal Conditions: Implications for the Oxidative Dissolution of Spent Nuclear Fuel

Abstract

The reactions of {sup 237}NpO{sub 2} with excess iodate under acidic hydrothermal conditions result in the isolation of the neptunium(IV), neptunium(V), and neptunium(VI) iodates, Np(IO{sub 3}){sub 4}, Np(IO{sub 3}){sub 4}{center_dot}nH{sub 2}O{center_dot}nHIO{sub 3}, NpO2(IO3), NpO2(IO3)2(H2O), and NpO{sub 2}(IO{sub 3}){sub 2}{center_dot}H{sub 2}O, depending on both the pH and the amount of water present in the reactions. Reactions with less water and lower pH favor reduced products. Although the initial redox processes involved in the reactions between {sup 237}NpO{sub 2} or {sup 242}PuO{sub 2} and iodate are similar, the low solubility of Pu(IO{sub 3}){sub 4} dominates product formation in plutonium iodate reactions to a much greater extent than does Np(IO{sub 3}){sub 4} in the neptunium iodate system. UO{sub 2} reacts with iodate under these conditions to yield uranium(VI) iodates solely. The isotypic structures of the actinide(IV) iodates, An(IO{sub 3}){sub 4} (An = Np, Pu), are reported and consist of one-dimensional chains of dodecahedral An(IV) cations bridged by iodate anions. The structure of Np(IO3)4{center_dot}nH2O{center_dot}nHIO3 is constructed from NpO9 tricapped-trigonal prisms that are bridged by iodate into a polar three-dimensional framework structure. Second-harmonic-generation measurements on a polycrystalline sample of the Th analogue of Np(IO{sub 3}){sub 4}{center_dot}nH{sub 2}O{center_dot}nHIO{sub 3} reveal a response of approximately 12x thatmore » of {alpha}-SiO{sub 2}. Single-crystal magnetic susceptibility measurements of Np(IO{sub 3}){sub 4} show magnetically isolated Np(IV) ions.« less

Authors:
 [1];  [1];  [2];  [2];  [3];  [4];  [5];  [1];  [1]
  1. Auburn University, Auburn, Alabama
  2. Florida State University
  3. Argonne National Laboratory (ANL)
  4. University of South Alabama, Mobile
  5. {Dick} G [ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
930871
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; Journal Volume: 46; Journal Issue: 9
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; ANIONS; CATIONS; CHAINS; DISSOLUTION; IODATES; MAGNETIC SUSCEPTIBILITY; NEPTUNIUM; NUCLEAR FUELS; PLUTONIUM; PRISMS; SOLUBILITY; URANIUM; WATER

Citation Formats

Bray, T. H., Ling, Jie, Choi, E- Sang, Brooks, James S., Beitz, James V., Sykora, Richard E., Haire, Richard, Stanbury, David M., and Albrecht-Schmitt, Thomas E. Critical Role of Water Content in the Formation and Reactivity of Uraniu, Neptunium, and Plutonium Iodates Under Hydrothermal Conditions: Implications for the Oxidative Dissolution of Spent Nuclear Fuel. United States: N. p., 2007. Web. doi:10.1021/ic070170d.
Bray, T. H., Ling, Jie, Choi, E- Sang, Brooks, James S., Beitz, James V., Sykora, Richard E., Haire, Richard, Stanbury, David M., & Albrecht-Schmitt, Thomas E. Critical Role of Water Content in the Formation and Reactivity of Uraniu, Neptunium, and Plutonium Iodates Under Hydrothermal Conditions: Implications for the Oxidative Dissolution of Spent Nuclear Fuel. United States. doi:10.1021/ic070170d.
Bray, T. H., Ling, Jie, Choi, E- Sang, Brooks, James S., Beitz, James V., Sykora, Richard E., Haire, Richard, Stanbury, David M., and Albrecht-Schmitt, Thomas E. Mon . "Critical Role of Water Content in the Formation and Reactivity of Uraniu, Neptunium, and Plutonium Iodates Under Hydrothermal Conditions: Implications for the Oxidative Dissolution of Spent Nuclear Fuel". United States. doi:10.1021/ic070170d.
@article{osti_930871,
title = {Critical Role of Water Content in the Formation and Reactivity of Uraniu, Neptunium, and Plutonium Iodates Under Hydrothermal Conditions: Implications for the Oxidative Dissolution of Spent Nuclear Fuel},
author = {Bray, T. H. and Ling, Jie and Choi, E- Sang and Brooks, James S. and Beitz, James V. and Sykora, Richard E. and Haire, Richard and Stanbury, David M. and Albrecht-Schmitt, Thomas E.},
abstractNote = {The reactions of {sup 237}NpO{sub 2} with excess iodate under acidic hydrothermal conditions result in the isolation of the neptunium(IV), neptunium(V), and neptunium(VI) iodates, Np(IO{sub 3}){sub 4}, Np(IO{sub 3}){sub 4}{center_dot}nH{sub 2}O{center_dot}nHIO{sub 3}, NpO2(IO3), NpO2(IO3)2(H2O), and NpO{sub 2}(IO{sub 3}){sub 2}{center_dot}H{sub 2}O, depending on both the pH and the amount of water present in the reactions. Reactions with less water and lower pH favor reduced products. Although the initial redox processes involved in the reactions between {sup 237}NpO{sub 2} or {sup 242}PuO{sub 2} and iodate are similar, the low solubility of Pu(IO{sub 3}){sub 4} dominates product formation in plutonium iodate reactions to a much greater extent than does Np(IO{sub 3}){sub 4} in the neptunium iodate system. UO{sub 2} reacts with iodate under these conditions to yield uranium(VI) iodates solely. The isotypic structures of the actinide(IV) iodates, An(IO{sub 3}){sub 4} (An = Np, Pu), are reported and consist of one-dimensional chains of dodecahedral An(IV) cations bridged by iodate anions. The structure of Np(IO3)4{center_dot}nH2O{center_dot}nHIO3 is constructed from NpO9 tricapped-trigonal prisms that are bridged by iodate into a polar three-dimensional framework structure. Second-harmonic-generation measurements on a polycrystalline sample of the Th analogue of Np(IO{sub 3}){sub 4}{center_dot}nH{sub 2}O{center_dot}nHIO{sub 3} reveal a response of approximately 12x that of {alpha}-SiO{sub 2}. Single-crystal magnetic susceptibility measurements of Np(IO{sub 3}){sub 4} show magnetically isolated Np(IV) ions.},
doi = {10.1021/ic070170d},
journal = {Inorganic Chemistry},
number = 9,
volume = 46,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}