An Evaluation of Analysis Methodologies for Predicting Cleavage Arrest of a Deep Crack in an RPV Subjected to PTS Loading Conditions

Abstract

Several calculational procedures are compared for predicting cleavage arrest of a deep crack in the wall of a prototypical reactor pressure vessel (RPV) subjected to pressurized-thermal-shock (PTS) types of loading conditions. Three procedures examined in this study utilized the following models: 1) a static finite-element model (full bending); 2) a radially constrained static model; and 3) a thermo-elastic dynamic finite-element model. A PTS transient loading condition was selected that produced a deep arrest of an axially oriented initially shallow crack according to calculational results obtained from the static (full-bending) model. Results from the static models were compared with those generated from detailed thermoelastic dynamic finite-element analysis. The dynamic analyses modeled cleavage-crack propagation using a node-release technique and an application-mode methodology based on dynamic fracture toughness curves generated from measured data. Comparisons presented here indicate that the degree to which the dynamic solutions can be approximated by the static models is highly dependent on several factors, including the material dynamic fracture curves and the propensity for cleavage reinitiation of the arrested crack under PTS loading conditions. Additional work is required to develop and validate a satisfactory dynamic fracture toughness model applicable to post cleavage arrest conditions in an RPV.