Thermal behavior of perlite concrete used in a sodium-cooled fast reactor

In this study, the thermal behavior of the perlite concrete used in a sodium-cooled fast reactor was investigated for obtaining information on a plant simulation system for safety assessment. The thermal stability and kinetic behavior of multistep thermally induced processes of perlite concrete were examined using thermoanalytical techniques and other complementary methods. The partially overlapping thermal decomposition process comprising seven reaction steps was characterized by kinetic deconvolution analysis based on a cumulative kinetic equation by determining the contribution and all kinetic parameters for each component reaction step. The thermal decomposition product was a mixture of amorphous and crystalline phases located in a CaO-rich region in the SiO2–CaO phase diagram. The softening or melting of the decomposition product was initiated at approximately 1520 K. The significance and reliability of the results obtained were discussed on the premise of their practical uses for the safety assessment.