Application of the Fokker-Planck approach for modelling of nano-structural defects in fusion materials

The materials used in the first wall of ITER and fusion power plants will be required to withstand neutron bombardment produced in fusion plasmas. The development of models describing the structural defects in fusion materials has become an important element in the development of a prototype of a fusion power reactor. Modeling of structural defects requires new modeling approaches giving theoretical predictions that could be experimentally validated. In this review paper, we propose the Fokker-Planck kinetic equation for modeling of nanovacancies, nanovoids and dislocation loops in fusion materials under cascade producing irradiation. It will be shown that in the simplest approximation that includes the effects of the statistical and cascade induced fluctuations, the kinetics of the evolution of the nanostructural defects can be described by the Fokker-Planck equation for the defect size distribution function. The proposed model can be applied to fusion materials under irradiation conditions that represent those of the first wall of a fusion reactor.