Environmental effects on the reliability of an AISI 304 structure

Abstract

This work is based on the application of probabilistic fracture mechanics models to predict the reliability of pressure pipelines in nuclear power reactors. The simulation of cracking of stainless steel piping under the conditions of intergranular stress corrosion cracking (IGSCC) is based on the improved modified piping reliability analysis including seismic events (PRAISE) code. The IGSCC is characterized by a unique damage parameter that depends on residual stresses and environmental conditions. Case studies of IGSCC failures in nuclear power plants are presented and the contribution of environmental effects on crack initiation and leakage is discussed. For small damages we observed that the change in temperature or oxygen concentration does not affect the initiation process but their decrease contribute favourably to the decrease in the leakage probabilities.

Enhancing Piping System Reliability Through Material Upgrades and ANN-Based Damage Parameter Estimation

“…For each material, the crack growth rates and times-to-initiation are compared against "DPs, " which combine the various contributions of various individual parameters. The DPs used in this work are multiplicative relationships between various terms that each describe how different phenomena, such as the environment (specifically coolant temperature, dissolved oxygen content, and levels of impurities), applied loads (including both constant and variable loads to account for steady-state operation and, respectively, plant loading or unloading), residual stresses, and material sensitization) affect SCC behavior [5], [24], [27]. To accomplish this, a two-step approach is suggested.…”