Experiments have been conducted to determine an upper limit to the dissolution rate of UO2 under reducing conditions appropriate to those in a geologic repository for spent fuel disposal in Finland and Sweden. Test duration ranged from 52 to 140 days. The total amount of U recovered in each test was converted into a dissolution rate per year for the sample. The dissolution rate was then used to calculate an expected lifetime for the samples under the test conditions. The dissolution rate did not depend on the length of the testing period. Rather, the dissolution rate appeared to decrease as the samples were exposed to sequential testing periods. This indicates that the results are still influenced by transient effects such as high-energy surface sites, which implies that the dissolution rates measured are upper limits. The sample lifetimes calculated from the last two testing periods, which had a total of 269 days, ranged from 7 to 10 million years. There was no indication of an effect of alpha radiolysis on the dissolution rate results for samples with doping levels of 0, 5, and 10% 233U.
|Place of Publication||Olkiluoto|
|Number of pages||28|
|Publication status||Published - 2005|
|MoE publication type||D4 Published development or research report or study|
Ollila, K., & Oversby, V. (2005). Dissolution of unirradiated UO2 and UO2 doped with 233U under reducing conditions. Posiva. Posiva Report, No. 2005-05 http://www.posiva.fi/files/284/Posiva_2005-05web.pdf