In a postulated severe accidental condition of sodium-cooled fast reactor (SFR), eutectic melting between boron carbide (B4C) as control rod element and stainless steel (SS) as control rod cladding or related structure may take place. Thus, kinetic behavior of B4C-SS eutectic melting is one of the important phenomena to be considered when evaluating the core disruptive accidents in SFR.
In this study, for the first step to obtain the fundamental information on kinetic feature of B4C-SS eutectic melting and compare the pervious findings, the thermal analysis using the pellet type samples of B4C and Type 316L SS as different experimental technique was performed up to 1773 K at different heating rates of 2.5–10 K/min. The differential thermal analysis (DTA) endothermic peaks for the B4C-SS eutectic melting appeared from 1483K to 1534K and systematically shifted to higher temperatures when increasing heating rate. Based on this kinetic feature, apparent activation energy and pre-exponential factor for the B4C-SS eutectic melting were determined by Kissinger method. It was found that the kinetic parameters obtained by thermal analysis were comparable to the literature values of thinning experiment at high temperatures.
In addition, the microstructure and element distribution formed in the interdiffusion layer composed of the B4C / SS system were analyzed by the electron probe microanalyzer (EPMA), which can provide key validation data on elemental interdiffusion behavior in the early stage of the eutectic melting.