Materials currently used in nuclear power plants are reliable and are generally resistant to
environmental degradation. However, occurrences of environmental degradation have been
observed as the current fleet of reactors age. Degradation of materials by mechanisms such as
intergranular stress corrosion cracking (IGSCC) and primary water stress corrosion cracking
(PWSCC) create both technical and regulatory issues. This paper provides an overview of the
most significant technical and regulatory issues associated with materials degradation from the
perspective of the Nuclear Regulatory Commission. It also addresses the need for additional
research to support regulation.