Cooling and stabilizing corium: IRSN initiates new research on the mitigation of core degradation in a damaged reactor
IRSN has recently launched a national program of experiments called PROGRES to determine how agglomerations of debris in a reactor core could be cooled by injecting water into the vessel.
Retaining the corium resulting from a core meltdown accident within the reactor vessel or containment represents a major safety objective for the protection of people and the environment.
For this reason, IRSN, as leader of the European IVMR project, has recently launched a national program of experiments called PROGRES to determine how agglomerations of debris in a reactor core could be cooled by injecting water into the vessel to enhance the retention strategy based on external vessel cooling.
Can the corium resulting from core degradation in a damaged reactor be cooled effectively enough to slow and prevent the progression of the accident towards total core meltdown and potential reactor vessel failure? Can it be stabilized and retained in the reactor vessel, even for higher power reactors (900 MWe and above)?
Expected to run for five years under IRSN’s leadership, the European IVMR project (In-Vessel Melt Retention), which brings together 23 partners, raises key questions regarding corium behavior in the vessel in the event of a severe accident.
In this context, one part of IRSN’s PROGRES program will study more specifically the cooling of the various types of debris agglomeration that may form in the vessel of a damaged reactor. Conducted at IRSN's PEARL facility, the program will subsequently extend beyond the vessel, assuming its failure. In fact, whether the debris bed is located inside the reactor core, at the bottom of the vessel or in the reactor pit, the phenomena surrounding corium cooling can be formulated in the same scientific terms.
This work forms part of a strategic IRSN goal – underpinned by the lessons learned from the Chernobyl and Fukushima accidents – to fill the remaining gaps in knowledge in order to help develop effective solutions to prevent, limit and control large radioactive releases in the event of a severe accident.