Tribocorrosion in Pressurized High-Temperature Water: A Mass Flow Model Based on the Third-Body Approach

Pressurized water reactors (PWR) used for power generation are operated at elevated temperatures (280-300 degrees C) and under high pressure (120-150 bar). In addition to these harsh environmental conditions some components of the PWR assemblies are subject to mechanical loading (sliding, vibration and impacts) leading to undesirable and hardly controllable material degradation phenomena. In such situations wear is determined by the complex interplay (tribocorrosion) between mechanical, material and physical-chemical phenomena. Tribocorrosion in PWR conditions is at present little understood and models need to be developed in order to predict component lifetime over several decades. This paper present an attempt to model PWR tribocorrosion through the combination of a tribological third-body approach with a mechanistic description of the involved flows and the mass balance compartments corresponding to well-defined loci of the contact. The obtained model permits to gain better insight in the phenomenology and in the mechanisms of tribocorrosion of metals in PWR conditions. It also allows assessing the relative role of a variety of materials, mechanical and electrochemical parameters affecting the entire system. Quantitative predictions of the model were found to fit reasonably well experimental observations