A model to describe the irradiation-induced dimensional changes in polycrystalline graphites and carbons

A model is presented that describes the irradiation-induced dimensional changes of polycrystalline graphites and carbons in terms of the preferred orientation and shape change of the individual crystallites. It is assumed that the shape change of each crystallite arises from the additive effects of uninhibited irradiation growth and plastic deformation induced by internal stresses. Plastic deformation is assumed to occur by steady state creep varying as the nth power of the internally generated stresses. The predictions of the model agree well with experimental observations. (orig.)