An Analysis of Dynamic Crack Propagation and Arrest in a Nuclear Pressure Vessel Under Thermal Shock Conditions

The inner wall of a nuclear pressure vessel can become embrittled during service due to irradiation effects. As a result, a small flaw could become critical during the thermal shock that would accompany a loss-of-coolant-accident. To assess the consequences of this possibility, elastodynamic computations were performed on the subsequent rapid unstable crack run-arrest events. One difficulty is the lack of reliable dynamic fracture toughness data as a function of crack speed and temperature. However, using plausible estimates, computational results were obtained for comparison with conventional quasi-static analyses. These indicate that the neglect of the dynamic effects is mildly anticonservative for this application.