  An atomistically informed mean field cluster dynamics model has been
presented to investigate the nucleation and growth of defect loops in
irradiated {\alpha}-U. TEM analysis of neutron irradiated {\alpha}-U shows the
evolution of SIA and vacancy loops on (010) and (100) crystallographic planes
respectively, resulting in an anisotropic swelling of the face-centered
orthorhombic crystal. The accumulation of such loops, on irradiation, has been
closely estimated using the cluster dynamics model. Parameters of the model,
namely, the binding energy of point defects, i.e., Ui and VU, to SIA and
vacancy loops respectively and the diffusivity of point defects govern the
energetics and kinetics of the defect clustering phenomenon. We have studied
the crystallography of defect loops and computed the binding energy of point
defects to such loops using an angular dependent EAM potential in classical MD
simulations. Using bond-boost hyperdynamics in LAMMPS, the anisotropic
diffusion of Ui and VU in {\alpha}-U has been investigated. The mechanisms of
point defect diffusion and the associated migration energies have also been
reported and compared with previous DFT studies. Our CD model uses the computed
parameters, within their error ranges, to predict the population of defect
clusters with a dose-rate and temperature similar to the neutron irradiation
experiments. The predictions show an accumulation of small sized vacancy loops
along with a population of large and growing SIA loops which closely
corresponds to the TEM observations.
