Corrosion of Materials by Liquid NaK Coolant in a Nuclear Power System

Corrosion of the primary coolant structural materials in a nuclear power system is a potential concern when liquid metal is used as the coolant. For the current space reactor design, liquid sodium-potassium eutectic (NaK) has been selected as a candidate for the primary coolant and stainless steel as the structural material, so whether or not corrosion is a problem for this system must be determined. This paper documents a first step to understanding the extent of corrosion in the selected candidate design. Data available in the literature have been compiled and are analyzed, factors affecting corrosion are assessed, and a theoretical basis of the corrosion mechanisms by liquid metals is presented. This study provides some useful information for the design of NaK coolant systems and some recommendations for what additional experimental and theoretical work is needed to understand the corrosion mechanisms and limitations of using NaK as a primary coolant.