Wastage and Self-Plugging by a Potential CO2 Ingress in a Supercritical CO2 Power Conversion System of an SFR

For a CO2 ingress accident into liquid sodium in a supercritical CO2 power conversion system coupled with a sodium-cooled fast reactor, we investigated two major design issues: i) a wastage phenomenon in regard to structural damage adjacent to the leaking position, and ii) potential channel plugging due to the formation of a particulate reaction product. In order to understand the factors affecting the occurrence of these issues, two kinds of experiments were carried out: a wastage effect test and a self-plugging test. All experimental conditions were chosen to reasonably represent the normal operating conditions and realistic design parameters of the reference plant. The test results indicate the absence of wastage, which will not lead to additional tube ruptures and damage propagation. In the current experiment, the self-plugging of PCHE channels only took place under two limited conditions: i) the sodium temperature is over 500 degrees C and ii) the equivalent diameter of the crack opening is less than 1.5 mm with a small leakage rate of far less than 1 g/s of CO2 ingress.