  On the basis of studies of radiation-induced shape-change of reactor graphite
GR-280, through the series of measurements of samples with different
orientation of cutting with respect to the direction of extrusion, a conclusion
is made about the existence of polycrystal substructural elements - domains.
Domains, like graphite as a whole, possess the property of transverse isotropy,
but have different amplitudes of shape-change and random orientations of the
axes of axial symmetry. The model of graphite, constructed on the basis of the
concept of domains allowed to explain from a unified point of view most of
existing experimental data. It is shown that the presence of the disoriented
domain structure leads to the development of radiation-induced stresses and to
the dependence of the shape-change on the size of graphite samples. We derive
the relation between the shape-change of finite size samples and the actual
shape-change of macro-graphite.
