Overview of the EPRI-NRC Ni-Base Alloy Primary Water Stress Corrosion Cracking Initiation Testing Project

Abstract

The Electric Power Research Institute (EPRI) and the U.S. Nuclear Regulatory Commission (NRC), working under a memorandum of understanding, are conducting cooperative research on the primary water stress corrosion cracking (PWSCC) initiation of nickel-base alloys Alloy 600/182 and Alloy 690/52/152. Specifically, EPRI and NRC are co-funding PWSCC initiation testing at the Pacific Northwest National Laboratory. The objectives of the research are to (1) verify some of the effects-based modeling parameters used in the PWSCC initiation models developed for the probabilistic pipe rupture xLPR Code, and (2) confirm the factors of improvement (FOIs) proposed for the use of Alloy 690/52/152 as a replacement for Alloy 600/182. FOIs are proposed for use to develop potential revised inspection intervals for plant components. This paper provides the details of the PWSCC initiation project testing including the materials and testing parameters for the effects-based parameters of interest (e.g., temperature, stress, etc.). Some of the results obtained to date are presented such as applied stress effects, temperature effects, dissolved hydrogen effects and materials performance comparisons (i.e., FOIs).