Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 2; Thermophysical properties of eutectic mixture containing of high concentration boron in a solid state

Takai, Toshihide  ; Furukawa, Tomohiro  ; Yamano, Hidemasa   

Eutectic melting behavior between boron carbide (BC) as control rod material and stainless steel (SS) as structural material and subsequent relocation behavior plays an important role to achieve an in-vessel retention concept which ensures long-term coolability of degraded core under core disruptive accident, because these behaviors are expected to reduce the neutronic reactivity significantly. However, these behaviors have never been simulated in severe accident computer codes before. Since 2016, JAEA has been conducting a research project to develop physical models that describe these behaviors. For the physical models' development, it is necessary to obtain thermophysical properties of SS-BC eutectic mixture with various BC concentration and maintain them as a database. In this work, the density and specific heat of SS-17 mass%BC in a solid state are obtained and compared with these of stainless steel containing 0 and 5 mass%BC.