Simulation of Co-60 uptake on stainless steel and alloy 690 using the OSCAR v1.4 code integrating an advanced dissolution-precipitation model

Abstract

The contamination of a nuclear cooling system by activated corrosion products (ACPs) is a process that involves many different mechanisms all interacting with each other. One of the most important mechanisms is dissolution-precipitation. This governs the transfer of soluble corrosion products between the circulating water and the immobile oxidized surfaces, and is strongly dependent on the water chemistry. The dissolution-precipitation model was improved in version 1.4 of the OSCAR computer code, which simulates the ACPs transfer in nuclear reactor systems. The OSCAR v1.4 code is now able to better calculate the incorporation of minor species (e.g., a cobalt isotope) into oxides using the chemistry module, PHREEQCEA, which determines the composition of an ideal solid solution and the equilibrium concentrations of elements in the aqueous solution. This model was challenged by comparing the results obtained using OSCAR v1.4 with the experimental results of a test performed in a dedicated loop by Studsvik Nuclear AB. Finally, with this model, the OSCAR v1.4 code accurately reproduces soluble 60Co uptake on stainless steel and alloy 690 under various experimental conditions (pH, Zn injection and flow rate).