Investigation of CO₂ leak accident in SFR coupled with S-CO₂ Brayton cycle

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Various research organizations have performed feasibility studies for applying the supercritical CO<SUB>2</SUB> (S-CO<SUB>2</SUB>) Brayton cycle to the Sodium-cooled Fast Reactor (SFR) system and the studies revealed several technical challenges. The preceding studies are reviewed to identify the current status of overcoming the identified challenges and highlight knowledge gaps. One of the most challenging issues is to comprehend the CO<SUB>2</SUB> leak mechanism initiated from the pressure boundary failure in a Na-CO<SUB>2</SUB> heat exchanger. Thus, an isentropic critical flow model expanding from supercritical phase to gas phase was evaluated. To validate the selected critical flow model, an experiment of CO<SUB>2</SUB> critical flow under supercritical condition was performed and the experimental and numerical results correspond to each other reasonably. Another identified technical issue is removing Na-CO<SUB>2</SUB> reaction product from the system to improve the system economics and plant availability. In this study, candidates that can form eutectic with Na-CO<SUB>2</SUB> reaction product was newly identified. As a result, it was found that Li<SUB>2</SUB>CO<SUB>3</SUB>-Na<SUB>2</SUB>CO<SUB>3</SUB> or Li<SUB>2</SUB>CO<SUB>3</SUB>-Na<SUB>2</SUB>CO<SUB>3</SUB>-K<SUB>2</SUB>CO<SUB>3</SUB> eutectic systems can act as a potential cleaning agent to eliminate Na-CO<SUB>2</SUB> reaction product within the operating temperature range of SFR. The performance was confirmed with simple experiments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Previous studies on Na-CO<SUB>2</SUB> reaction are reviewed and limitations are identified. </LI> <LI> An isentropic critical flow model for CO<SUB>2</SUB> at supercritical phase is evaluated. </LI> <LI> An experiment is conducted to validate the critical flow model under S-CO<SUB>2</SUB> condition. </LI> <LI> Potential candidates to remove Na-CO<SUB>2</SUB> reaction product are identified. </LI> </UL> </P>