Solubility of thorium from Th3UO8 and ZrTh3UO10 ceramics

• Published in: Radiochimica acta Vol. 91; no. 4; pp. 203 - 210
• Main Authors: Curran, G., Rattray, W., Czerwinski, K.R.
• Format: Journal Article
• Language: English
• Published: De Gruyter Oldenbourg 01.01.2003
• ISSN: 0033-8230; 2193-3405
• DOI: 10.1524/ract.91.4.203.19972

The solubility of thorium from Th UO and ZrTh UO ceramics was studied to evaluate the solubility constants for the materials. Zirconium was added in order to investigate potential additional stabilization of the thorium matrix from ZrO . Studies were performed from pH 4 to pH 9 under both 100 Argon and 10 CO /90 Ar at 25°C in 0.1M NaClO . Reaction kinetics and equilibrium concentrations were evaluated for each condition. Rate constants increased with pH and varied from 6×10 hr to 4×10 hr . The surface area normalized dissolution rate decreased with increasing pH, the highest being 5×10 gm d at pH 4. The solubility product constants calculated from the equilibrium concentrations for the two ceramics were equivalent, with }= -48.30.4 and = -47.90.9. The data was used to calculate the Th solution phase concentration. The result was compared to the dissolution of UO from pH 5-9 in 0.1M NaClO under a 1 CO atmosphere at 25°C. It was found that the U from the UO had a higher solution phase concentration than Th at high pH and was highly dependent upon the solution of the evaluated conditions.