Performance indices of hot liquid sodium-exposed sacrificial surface layers in fast breeder reactors

Leakage accidents in sodium cooled fast breeder reactors trigger various thermo-chemical degradations of structural materials used for their construction. The interactions of hot liquid sodium with concrete at around 550 °C and above are investigated in this paper. Potential materials were designed and tested. Degradation mechanisms and extend of damages were identified, and subsequently, performance indices were developed. Four types of cement, eight different w/c ratios and geopolymer composites were investigated in this study. Comprehensive mechanical, physical, chemical and microstructural characterizations were performed before and after exposure. Microanalytical tools such as SEM (SE and BSE), TG/DTA, XRF, XRD and thin-section petrography were used for characterizing the degradation behavior. Study revealed that the performance rankings were influenced by composition of concrete and water to cement ratios used for the conventional cement-based systems. Performance indices for geopolymer composites were superior to the conventional cement-based systems in hot liquid sodium hostile environment.