Atomistic model of xenon gas bubble re-solution rate due to thermal spike in uranium oxide

W Setyawan and MWD Cooper and KJ Roche and RJ Kurtz and BP Uberuaga and DA Andersson and BD Wirth, JOURNAL OF APPLIED PHYSICS, 124, 075107 (2018).

DOI: 10.1063/1.5042770

Atomistic simulations are performed to study the response of Xe gas bubbles in UO2 to ionizing fission products through the thermal spike approximation. A portion of the total electronic stopping power (S-e) is taken as the thermal spike energy through a ratio variable zeta. The thermal spike energy causes extreme melting within the fission track cylindrical region. Molecular dynamics is employed to quantify the probability of a Xe gas atom to be re-solved (re-dissolved) back into the UO2 matrix. Subsequently, a re-solution model is developed and parametrized as a function of bubble radius (R), off-centered distance (r), and thermal spike energy (zeta S-e). The off-centered distance measures the shift of the thermal spike axis from the bubble center. To evaluate the re-solution model, independent fission product yield of U-235 fission due to thermal neutrons (0.0253 eV), taken from the JEFF-3.3 database, is used. The kinetic energy of the fission products is taken from the EXFOR database. Subsequently, the decay of S-e over distance for each fission product is simulated. Finally, the evaluated re-solution rate (re-solution probability per second) is presented as a function of bubble radius for a range of zeta. Published by AIP Publishing.

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