Relevancy of displacement cascades features to the long term point defect cluster growth

Displacement cascades in iron have been generated using a BCA code with PKA energies ranging from 5 to 100 keV as input for modelling long term evolution using an OKMC code. The size distributions of the fractions of vacancy and interstitial clustered in the long-term are not significantly dependent on the PKA energy in this range. Since subcascade formation, morphology and spatial extension, as well as the spatial correlations between point-defect positions, depend on PKA energy, the size distributions of clustered point-defect fractions in the long-term do not depend on these cascade features. In contrast, the size distributions of clustered point-defect fractions in displacement cascades are independent of the PKA energy while their spatial correlations strongly influence the cluster size distributions in the long-term. The use of a mean-field approximation in cluster kinetics predictions is thereby invalidated. Irradiation dose and dose-rate are also found to be factors governing long-term evolution.