Thermodynamic Equivalence Charts for Stress Corrosion Cracking Studies in Hydrogenated Steam, High Pressure and Supercritical Water

The evaluation of the materials performance for applications in pressurized water reactors (PWRs) primary water environment are often conducted in either low pressure superheated hydrogenated steam or in supercritical hydrogenated water in order to accelerate the stress corrosion cracking (PWSCC) mechanism and reduce experimental time. The high temperature accelerates SCC initiation, which is typically slow under real primary water conditions. However, both in hydrogenated steam and in supercritical hydrogenated water, it is important that the material attains environmental conditions and oxidizing potentials that are relevant to a primary water environment, so that the same PWSCC initiation mechanism operates. The aim of this paper is to establish a thermodynamic equivalence between laboratory systems, namely low pressure superheated hydrogenated steam and supercritical hydrogenated water, and the PWR primary water environments. Experimental data obtained from different sources in the literature are used to obtain thermodynamic relationships as a function of temperature and media. The applicability of these correlations is shown and discussed with examples, and equivalence charts have been generated for practical selection of experimental conditions.