The mechanical properties of reactor graphite

Publisher Website
Google Scholar
Abstract
It is shown that after brief neutron irradiation the elastic constants of polycrystalline reactor graphite are reasonably consistent with the single crystal values in a uniform stress (Reuss) approximation. A method is proposed for dealing with the anisotropy of the polycrystalline aggregate by reference to the coefficients of thermal expansion. This leads to a consistent model of the behaviour of the elastic constants at higher irradiation doses and temperatures, and also of fracture. The model is extended to cover the phenomenon of irradiation creep. It is shown that reactor Grade A graphite is unlikely to crack at differential strain rates of less than 350 p.p.m./1020 neutrons/cm2 parallel and 600 p.p.m./1020 neutrons/cm2 perpendicular to extrusion. It should also withstand respective total differential strains of 0·4% and 0·65% and differential stresses of 0·65 Kg/mm2 and 0·47 Kg/mm2 without cracking. In pure compression the fracture stress is estimated at 2·5 Kg/mm2 and the strain 2·5%.

This publication has 27 references indexed in Scilit: