Thorium oxide dissolution kinetics for hydroxide and carbonate complexation

In order to better understand the behavior of thorium breeder reactor fuel in a repository environment, the behavior of thorium oxide was investigated. The kinetics of crystalline thorium oxide dissolution were studied under argon and argon/10% CO2 over a broad pH range in 0.1 M ionic strength NaC1O4 solution. Samples were analyzed for thorium concentration using ICP-AES, ICP-MS, and NAA. Data was fit to a first order kinetics model. The kinetic rate constant under pure argon was 0.0107 ± 0.00123 h-1 for pH 2-3. Under 10% CO2, the rate constant was 0.00511 ± 0.000863 h-1. No kinetics results could be discerned from the data at higher pH. Under argon, solubility at pH greater than 3 was at nm/L levels, three orders of magnitude lower than at pH 3 and below. Under 10% CO2, solubilities decreased from 10 [mu]mol/L at pH 2.06 to 80 nm/Lat pH 3. Thorium oxide powder remnants from each experiment were analysed using XRD, FflR, and BET surface area analysis. Surface area analysis showed a 15% increase in surface area at pH 10 and higher under argon, and a uniform surface area increase of 15 to 30% under 10% CO2. XRD and FfIR spectra showed that the thorium oxide was otherwise identical to the untreated standards.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Curran, Virginia, 1977-

Advisor dc:contributor.advisor

• Kenneth R. Czerwinski.

• Nuclear Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8687

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8687