RECALCULATION OF CORIUM DISPERSION EXPERIMENTS AT LOW SYSTEM PRESSURE

The DISCO-H experiments simulate melt ejection scenarios under low system pressure in severe accidents in Light Water Reactors. An analytical program with the code AFDM accompanies the tests. The molten corium is simulated by thermite. Prior to the details of the recalculations of the experiments, a description of the experimental apparatus and of all relevant physical phenomena introduces the reader to the scenario. The description reflects the present understanding. The paper describes the most important models that have been added to the code in order to treat the physical phenomena that have been identified before. Then, the paper gives an overview over the recalculations of three thermite experiments of the present DISCO-H series. The comparison between measured and calculated results focus on the pressures, the dispersed melt fractions, the oxidation and combustion processes, and the droplet sizes. For the dispersed melt fractions, a single parameter set of the physical models has been maintained for the majority of water and thermite experiments, and an overview over the results is given. The paper shows that it is possible to match measured pressures if the parameters of the oxidation processes are chosen correctly. It concludes with a comparison of major integral results. 1