Main outcomes on debris bed cooling from PRELUDE Experiment

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Ermsar 2013 / 2-4 octobre 2013, Avignon (France)

​Debris bed coolability is an important issue for stopping or at least slowing down a severe accident evolution. One of the major concerns of safety studies is to evaluate the consequences of water reflooding of a severely damaged reactor core, where a large part of the core has collapsed and formed a debris bed. Many experiments have been conducted to study two-phase flow and heat transfer in porous medium configuration. The “Institut de Radioprotection et de Sûreté Nucléaire”, has launched an experimental program PRELUDE, to validate simulation tools, as ASTEC, to get better confidence in safety studies results. Main physical parameters have been investigated: the effects of the initial temperature of the debris bed, the injected water flow rate, the specific power maintained during the reflooding, the particle size (monodispersed bed of stainless steel particles or polydispersed debris), the effect of the presence of a bypass around the debris and finally the configuration of the water supply (bottom or top injection) to be more representative of the reactor situations. These results will contribute to assess the possibility to stop the progression of in vessel core degradation in a Nuclear Power Plant and to the optimization of the Severe Accident Management strategy.