Most models for commercial spent nuclear fuel dissolution are based on data obtained from single-pass flow-through tests. These tests are designed to have a high water volume to fuel surface area ratio so that the concentration of radionuclides in solution are below solubility limits and thus back reactions and the formation of alteration products are minimized. While this method is ideal for determining the dependence of the dissolution rate on various parameters, it is important to examine the differences between these tests and the realistic scenarios that will exist in a geologic repository. Many of the inherent conservatisms that are part of the models are examined. These conservatisms include: limited water, short-term vs. long-term rates, groundwater effects, non-congruent release, radiolysis, and fuel chemistry effects. Each of these conservatisms has the potential to decrease the currently modeled dissolution rates by between a factor of 2 and 200. The combined effects are unknown, but, if quantified, could significantly improve the waste form performance relative to current models.
Revised: August 30, 2010 |
Published: August 19, 2008
Citation
Hanson B.D. 2008.Examining the Conservatisms in Dissolution Rates of Commercial Spent Nuclear Fuel. In Proceedings of the 2008 International High-Level Radioactive Waste Management Conference, 2, 404-411. La Grange, Illinois:American Nuclear Society.PNNL-SA-61337.