Abstract:

The diffusion of La, a trivalent cation dopant, actinide surrogate, and high-yield fission product, in CeO2, a UO2 nuclear fuel surrogate, during 1.8 MeV Kr+ ion bombardment over a temperature range from 673 K to 1206 K has been measured with secondary ion mass spectroscopy. The diffusivity under these irradiation conditions has been analyzed with a model based on a combination of sink-limited and recombination-limited kinetics. This analysis yielded a cation vacancy migration energy of ~0.4 eV below ~800 K, were recombination-limited kinetics dominated the behavior. The thermal diffusivity of La in the same system was measured over a range of 873 to 1073 K and was characterized by an activation enthalpy of ~1.4 eV. The measurement of both the migration enthalpy and total activation enthalpy separately allows the vacancy formation enthalpy on the cation sublattice to be evaluated as ~1 eV. The mixing parameter under energetic heavy ion bombardment at room temperature was measured as well and found to be ~4x10-5 nm5/eV.

Brief bio:

BS, MS, Ph.D (1990) all in nuclear engineering from the Univ. Michigan
Staff scientist Univ. Missouri Research Reactor 1991-1994
Faculty nuclear engineering department Univ. Illinois 1994-present