22.08.2015   Comprehensive nuclear materials

Early Radiation Damage Theory Model

The chemical reaction RT was used very early to model the damage accumulation under irradiation (Brailsford and Bullough92 and Wiedersich93). The main assumptions were as follows: (1) the incident irradiation produces isolated FPs, that is, single SIAs and vacancies in equal numbers, (2) both SIAs and vacancies migrate 3D, and (3) the efficiencies of the SIAs and vacancy absorption by different sinks are different because of the differences in the strength of

where

 
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2

 

the corresponding PD-sink elastic interactions. Thus, the preferential absorption of SIAs by dislocations (i. e., the dislocation bias) is the only driving force for microstructural evolution in this model, which is a variant of the FP3DM. It should be emphasized that, in the framework of the FP3DM, no distinction is made between different types of irradiation: ^1MeV electrons, fission neutrons, and heavy-ions. It was believed that the initial damage is produced in the form of FPs in all these cases. Now we under­stand the mechanisms operating under different conditions much better and make clear distinction between electron and neutron/heavy-ion irradiations (see Singh et a/.,1,22 Garner et al.,33 Barashev and Golubov,35 and references therein for some recent advances in the development of the so-called PBM). However, the FP3DM is the simplest model for dam­age production and it correctly describes 1 MeV elec­tron irradiation. It is therefore useful to consider it first. The more comprehensive PBM includes the FP3DM as its limiting case.

following section, we present examples of such a

treatment based on the so-called lossy-medium

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approximation.