A chemical potential approach, which took account of density effects in supersaturated solutions of point defects, was applied to interstitial loop formation kinetics in metals under homogeneous irradiation. The quasi-chemical rate equations were re-stated in terms of chemical potentials, rather than in terms of the concentrations of species that were involved in reactions. This extension of the rate equations was tested by considering a simpler model for bimolecular reactions. Density effects, such as the radiation-induced spontaneous clustering of interstitials, were investigated in irradiated metals within a background of interstitial loop formation that was described by conventional solutions to the rate equations. A phenomenon which involved the spontaneous formation of di-interstitials was expected to become noticeable at homologous irradiation temperatures of between 0.25 and 0.3; if the rate of defect generation was high enough. In the case of a steady-state solution, the density effect led to the formation of a higher number density of interstitial loops of smaller size.

E.A.Koptelov, S.Ishino, S.Iwata, N.Sekimura: Journal of Nuclear Materials, 1996, 232[2-3], 98-112