  New concept of radiation-induced emission of Schottky defects from extended
defects is proposed, which acts in the opposite direction compared with Frenkel
pair production, and it results in the radiation-induced recovery processes.
The vacancy emission from a void surface results in a shrinkage of the void
which is analogous to the thermal void shrinkage at high temperatures, but it
is expected to operate at low and medium temperatures and high sink densities,
when the radiation-induced vacancy emission from sinks becomes comparable with
the absorption of Frenkel defects produced in the bulk. As a result, the void
growth becomes negative below a threshold temperature (or above a threshold
flux), and saturates after a threshold irradiation dose, at a level, which
depends on the type of material. These effects have been observed
experimentally for a long time but could not be explained by the conventional
theory. One of the technologically important consequences of the new concept is
a mechanism of irradiation creep, based on the radiation and stress induced
preference emission, which is essentially temperature independent in contrast
to the well-known SIPA or elastodiffusion mechanisms that can yield a
significant irradiation creep only when recombination is negligible. The
efficiency of the radiation-induced Schottky defect emission is different for
different types of materials, which is shown to be one of the major causes of
their different responses to irradiation.
