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The solubility of Th(IV) and U(IV) hydrous oxides in concentrated NaHCO{sub 3} and Na{sub 2}CO{sub 3} solutions

Book ·
OSTI ID:382894
; ; ;  [1]
  1. Pacific Northwest Lab., Richland, WA (United States)

The solubility of Th(IV) and U(IV) hydrous oxide was studied in the aqueous HCO{sub 3}{sup {minus}}-CO{sub 3}{sup 2{minus}}-OH{sup {minus}}-H{sub 2}O system extending to high concentration. The solubility of the Th(IV) and U(IV) hydrous oxides increases dramatically in both high bicarbonate and carbonate solutions and decreases with the increase in hydroxide at a fixed carbonate concentration. In general, the observed solubility of Th(IV) hydrous oxide at a given total carbonate concentration was three to four of magnitude higher than the solubility of U(IV) hydrous oxide. In the studies of the U(IV) system, extreme caution was used to ensure that the dissolved U was present as U(IV). Oxidation state analyses and systematic trends in the U(IV) solubility data similar to those for Th(IV), which is not redox sensitive, indicated that the dissolved U was present as U(IV).

DOE Contract Number:
AC06-76RL01830
OSTI ID:
382894
Report Number(s):
CONF-941075--; ISBN 1-55899-253-7
Country of Publication:
United States
Language:
English