An assumed failure of the main and the emergency core cooling systems of a light water reactor in the course of a hypothetical loss-of-coolant accident can cause core meltdown. In a scenario of this kind, the reactor pressure vessel would be reflooded as an accident management measure in order to quench the reactor core components. The QUENCH series of experiments are carried out at the Karlsruhe Research Center to studybundle behavior during reflooding, with the main emphasis being put on the analysis of the H-2 source term. On December 8, 2005, the QUENCH-11 experiment was performed within the framework of the EU-funded LACOMERA project, an evaporation experiment with subsequent reflooding at a low water feed rate. QUENCH-11 was carried out as a "semi-blind" code benchmark in the European SARNET NoE. The article presents the work performed with the ATHLET-CD accident analysis code at the Chair for Energy Systems and Power Economy of the Bochum Ruhr University. A brief introduction is followed by a description of the facility and the experiment before an outline is presented of the modeling performed with ATHLET-CD. Next, the results of computations are discussed and evaluated. It is seen that the code allows the experiment to be simulated in a good approximation to the measured results. Further development work is seen to be necessary in the area of H-2 production during reflooding.
