Severe accidents of light water reactors with core degradation can lead to the formation of a so-called debris bed inside the reactor cavity. In the scenario of depleted residual water, the bed can partially melt and interact with the concrete underneath generating non-condensable gases (NCG) at the bottom of the particle bed, which will flow through the debris bed. The impact of additional gas on the quenching process can be considered in thermal-hydraulic system codes like ATHLET. However, there is still a need for experimental validation of respective models or verification of corresponding simulation results. In the frame of this work, specific quenching experiments on a monodispersed particle bed with various NCG injection rates and initial bed temperatures are carried out employing the FLOAT test facility to extend the existing experimental database. Furthermore, numerical simulations are carried out with COCOMO-3D for the prediction of the thermo-hydraulic conditions inside the debris bed, the quench front propagation as well as the total quenching times.

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