Thermal diffusion of iodine in UO(2) and UO(2+x)
An inter-laboratory comparison has provided enhanced confidence in a novel out-reactor method that has been developed for investigating the migration behaviour of fission products in oxide nuclear fuels. Changes in the distribution of ion-implanted fission products caused by thermal annealing or radiation damage are precisely determined using high-performance secondary ion mass spectrometry. Accurate measurements of iodine thermal diffusion in stoichiometric UO(2) - on single-crystal as well as polycrystalline ceramic samples over the temperature range 1200-1650 C for periods ranging from 1 h to 24 h - have yielded a refined Arrhenius relationship. An increase in both the solubility and diffusion rate of iodine by two orders of magnitude compared to stoichiometric fuel was found when the annealing was performed at 1400 C under slightly oxidizing conditions sufficient to achieve a nominal O/U ratio of 2.02. These effects are consistent with the increase in the population of uranium lattice vacancies predicted by a thermodynamic model for the defect structure of UO(2+x).
Bibliographic Reference: An article published in: Journal of Nuclear Materials, Volume 372, Issues 2-3 (2008), 11 pp.
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://dx.doi.org/doi:10.1016/j.jnucmat.2007.03.272
Record Number: 200819864 / Last updated on: 2008-06-24
Original language: en
Available languages: en