Significance of primary irradiation creep in graphite

Preliminary design analysis workflow for Division 5 HHA-3200 requirements for graphite core components

“…-GeneralizedKelvinVoigtModelGraphite à Describes the primary and secondary creep behavior of graphite using a Kevin-Voigt material model (the full method is described in [7]). This source file also calculates the anisotropic elastic tensor as a function of dpa.…”

“…o Compute the inelastic stress from creep strains as described in [7], and the elastic stresses from any mechanical load applied on graphite, using the linear elastic model. The thermal and Wigner strains are eigenstrains (residual strains) and therefore do not contribute to the stresses in the material.…”

“…The graphite design analysis does not require either the selection of stress classification lines nor the decomposition of loads as in the design rules for metallic components because it directly analyzes the stresses at each point of the FEA model, using an equivalent stress that is based on the Maximum Deformation Energy theory [7], [8]:…”

Modeling irradiation creep of graphite using rate theory

“…Equations ( 2) and (3) form the backbone of most creep models that are currently in use; differential forms, in contrast to closed form expressions, are also employed in some analyses [16]. The twocontribution model has been further extended to include structural and radiolytic oxidation changes to Young's modulus for improving the model predictions [13].…”