New sacrificial material for ex-vessel core catcher

Abstract A new functional (sacrificial) material has been developed in the Fe 2 O 3 –SrO–Al 2 O 3 –CaO system based on strontium hexaferrite ceramic in concrete matrix. The method of producing SM has been advanced technologically; this technological effectiveness allows the SM to be used in ex-vessel core catchers with corium spreading as well as in crucible-type core catchers. Critical properties regarding the efficiency of SM in ex-vessel core catchers, such as porosity, pycnometric density, apparent density, solidus and liquidus temperatures, and water content have been measured. Suitable fractions of SrFe 12 O 19 and high alumina cement (HAC) were found in the SM based on thermodynamic analysis of the SM/corium interaction. The use of sacrificial steel as an additional heat adsorption component in the core catcher allowed us to increase the mass fraction range of SrFe 12 O 19 in the SM from 0.3−0.5 to 0.3–0.85. The activation temperature of the SM/corium interaction has been shown to correspond to the liquidus temperature of the local composition at the SM/corium interface. The calculated value of this temperature was 1716 °C. Analysis of phase transformations in the SrO–Fe 2 O 3 system revealed advantages of the SrFe 12 O 19 –based sacrificial material compared with the Fe 2 O 3 -contained material owing to the time proximity of SrFe 12 O 19 decomposition and corium interaction activation.