A Mechanistic Basis for Irradiation Assisted Stress Corrosion Cracking

Irradiation assisted stress corrosion cracking (IASCC) refers to intergranular stress corrosion cracking that is accelerated under the action of irradiation in light water reactor core components. It is referred to as “assisted” because irradiation enhances, or accelerates the IGSCC process over the unirradiated state. IASCC has been a problem in the nuclear industry for the last 30 years and continues to occur due to a lack of understanding of its underlying mechanism. It is the single most important problem in core component cracking in boiling water reactors (BWR) [1] and is of growing importance in pressurized water reactors (PWR). Understanding the mechanism of IASCC is required in order to provide guidance for the development of mitigation strategies.

The IASCC problem has taken on new urgency with the proposal of more advanced water reactor concepts under the Generation IV program [2], such as the supercritical water reactor (SCWR). The SCWR represents a more demanding environment than LWRs in temperature, irradiation dose and the corrosiveness of the media itself. As such, there is an even more pressing need to develop a solution to the IASCC problem. However, in order to do so, the underlying mechanism must first be understood. This proposal aims to establish such an understanding, which will lead directly to mitigation strategies for current and future reactors. The objective is to determine whether deformation mode is a primary factor in the mechanism of irradiation assisted intergranular stress corrosion cracking of austenitic alloys in light water reactor core components.


Z. Jiao, J. T. Busby and G. S. Was, “Deformation Microstructure of Proton-Irradiated Stainless Steels,” J. Nucl. Mater., 361, No. 2-3, 218-227 (2007). G. S. Was, Z. Jiao and J. T. Busby, “Contribution of Localized Deformation to IGSCC and IASCC,” European Conference on Fracture – 16, Alexandroupolis, Greece, July 2006.