Mechanistic modelling and validation of constant load C-ring apex stresses for stress corrosion cracking testing in supercritical water

Abstract

Canada is contributing significant research towards the Supercritical Water-cooled Reactor, one of the next-generation nuclear reactor designs, including characterization of stress corrosion cracking (SCC) resistance of candidate alloys in supercritical water at the operating conditions of 625 °C and 25 MPa. To quantify SCC resistance, a modified constant-load C-ring technique was developed through modeling and validated in both the finite-element software Abaqus and Monte-Carlo simulations. The proposed modification achieves the target C-ring apex stress with precision through thermal expansion and model-calculated initial deflection. From Monte-Carlo simulations, the apex stress is within 4.16 MPa of the target stress in 96.3% of experiments. Preliminary in-situ experimentation has found no SCC in 310 stainless steel samples after 500 hours at 600 °C and 25 MPa over a wide range of apex stress. The modified technique is stress-limited for some alloys with a yield-strength anomaly; suitable alloys include 316 SS, 310 SS and A800.