Launched in 2007, the "Debris bed reflooding" (ex-PEARL) experimental research program aims to better understand the behaviour of steam and water flow in a porous medium composed of solid particles at very high temperature under conditions representative of a core melt accident (or severe accident).

This programme sets out to reduce uncertainties when evaluating the environmental release of radioactive products such as iodine or ruthenium following a core meltdown accident in a pressurised water reactor (PWR).

Complex measurements were performed at the integral high temperature test facility CODEX (COre Degradation Experiment) between 1995-2002 with electrically heated UO2 fuel rod bundles.

The general experimental procedurewas to establish the desired composition of gases in 1-L glass flasks, optionally to add surface coupons, to irradiate the glass flasks at given dose rates until the desired doses were reached, and to subsequently determine the final air radiolysis products concentrations by an off-line method.

SIMECO program at KTH was performed to investigate the heat transfer of natural convection in an internal heated liquid pool, simulating a molten corium pool which may be formed in the reactor lower plenum during a severe accident.

The Epicur programme (physicochemical studies on confined iodine under irradiation) aims at providing experimental data to validate the chemical models for iodine in the reactor containment under accident conditions. These models are integrated into the Iode model of the Astec computer code, jointly developed by IRSN and GRS.

The PHEBUS FP (Fission Products) international research programme was conducted between 1988 and 2010. Its purpose was to improve the understanding of the phenomena occurring during a core meltdown accident in a light water reactor and to validate the computational software used to represent these phenomena in reactor safety evaluations.

FARO (Furnace And Release Oven) experimental facility began the experiments of the LWR-MFCI phenomena in 1990 in collaboration with several reactor safety research organizations from European Union member countries and with the participation of the United States Nuclear Regulatory Commission.

The aim of the DEFOR (Debris Bed Formation) program is clarification of the phenomena that govern formation of the debris bed in different scenarios of corium melt release into a deep water pool and quantification of the debris bed properties related to coolability.

FARO (Furnace And Release Oven) experimental facility began the experiments of the LWR-MFCI phenomena in 1990 in collaboration with several reactor safety research organizations from European Union member countries and with the participation of the United States Nuclear Regulatory Commission.

The REKO-3 test facility allows the investigation of catalyst samples inside a vertical flow channel under well defined conditions comprising gas mixture, flow rate and inlet temperature.

The OECD-IAEA Paks Fuel Project aimed to support the understanding of fuel behaviour in accident conditions on the basis of analyses of the Paks-2 event. Numerical simulation of the most relevant aspects of the event and comparison of the calculation results with the available information was carried out between 2006 and 2007.