CORROSION AND DEPOSITION OF METAL OXIDES IN THE PRIMARY COOLANT SYSTEM OF PWR's

摘要

Regardless of how well processed and preconditioned reactor construction materials have been prior to operation, they will inevitably corrode. The products of corrosion, metal oxides with low thermodynamic solubility levels, can be found deposited throughout the reactor coolant circuit if they have not been removed by the plant's water treatment systems. Deposition of these corrosion products in the primary coolant circuit of a PWR represent a concern in terms of operational safety, efficiency, financial cost and longevity of the plant. The on-going work at the University of Birmingham seeks to study three main areas; fundamental corrosion behaviour of stainless steel, with specific focus on in the effect of surface pre-treatment, the solubility of the main metal oxides produced by stainless steels corroding, and the deposition of metal oxides within flow restrictions at high flow velocities. Several pieces of bespoke test equipment have been designed and built to address each area of interest individually. These include a rig for studying the corrosion of a particular material as a function of time, which consists of a series of cells into which samples are mounted and removed after a period of time and another rig for studying the solubility of a given metal oxide. Both of these pieces of equipment operate at up to 300 °C and can maintain a pressure of up to 120 bar. A water loop for the study of deposition of corrosion products within flow restrictions has also been built and is in operation; this loop is capable of producing flow rates in excess of 12ms~(-1) through a test section 6mm in diameter, while maintaining temperatures up to 300 °C and pressures of up to 120 bar.