COMPUTATIONAL INVESTIGATION OF THE STRESS-STRAIN STATE OF GRAPHITE BLOCKS IN LIGHT OF SUBSTANTIATION OF RBMK SERVICE-LIFE EXTENSION

摘要

To increase the service life of RBMK-1000 power-generating units to 45 years, it is necessary to substantiate lifetime of the reactor structures operating under irradiation. Specifically, computational work is needed to substantiate the strength and lifetime characteristics. The characteristic features of each type of reactor, and not only the general behavior of graphite under irradiation, are important for making more accurate predictions. It is desirable to rely on the finite-element model with three-dimensional finite elements, since graphite possesses anisotropic properties in different directions. This article describes a method and program, developed on the basis of the finite-element method, that takes account of the nonuniformity of the neutron field and temperature distributions over the cross-section of a graphite block and the nonuniform anisotropic shrinkage (swelling) and creep of graphite.