Short fuel rod experiments were carried out in the framework of the EU 5FWP COLOSS Project. The simultaneous dissolution of UO2 pellets and ZrO2 by molten Zr was investigated with PWR and VVER samples.

The VULCANO facility is mainly composed of a furnace and a test section, which is thoroughly instrumented. In the experiments with prototypic material the furnace has the following characteristics:

• Capability to melt oxidic mixtures of various compositions (UO2, ZrO2, SiO2, FeOx) with the possible addition of metals.
• Liquidus temperature of the load between 1700 and 2900 °C.
• Capacity to melt & pour 100 kg. •Continuous low pouring rates (0.1–1 l/s).

The TOSQAN experimental vessel is a large stainless steel cylindrical enclosure (volume 7m3, height 4m, internal diameter 1.5m) with double walls. A coolant circulates in between the walls to regulate the wall temperature from 60 °C to 160 °C. Non radioactive aerosols, steam and non explosive gases can be injected at different controlled flow rates via diverse injection pipes located at different locations of the enclosure. Different instrumentation is used, namely PIV (particle image velocimetry), LDV (laser doppler velocimetry), rainbow refractometry, out of focus imaging and SRD (spontaneous Raman diffusion) spectrometry.

The DISCO-C facility serves to investigate melt dispersal from the reactor pit when the reactor pressure vessel lower head fails at low system pressure of less than 2 MPa. The fluid dynamics of the dispersion process is studied using model fluids, water or bismuth alloy instead of corium, and nitrogen or helium instead of steam. The effects of different breach sizes and locations, and different failure pressures on the dispersion can be studied.

The Mozart analytical test program, conducted from 2005 to 2007, was dedicated to the study of oxidation in air of nuclear fuel cladding. This study was part of the International Source Term Program initiated by the IRSN, whose aim is to reduce uncertainties concerning the evaluation of radioactive product emissions into the environment in the event of a core meltdown accident in a pressurized water reactor or a spent fuel storage pool accident.

(LWR OFF-NORMAL BEHAVIOUR INVESTIGATION) A Reactor Thermal-Hydraulic Safety Research Programme carried out by the Commission of the European Communities at the Ispra Site of the Joint Research Centre.

Boron carbide rod degradation test and associated releases.

The experimental programme becarre (2001-2010) belongs to the international “source term” programme. The becarre programme Objectives involve better understanding the degradation phenomena occurring in boron carbide (B4c) control rods during a core meltdown accident and determining the laws governing steam oxidation of B4c pellets and relocated mixtures. These laws will be used to both quantify the gases produced during oxidation, and estimate their potential effect upon iodine releases into the environment. The programme results will help improve the icare 2 code which is being developed by irsn.

Determination of the vaporization rate according to the composition and the thermodynamic conditions of the corium (with FP simulants) was the aim of the COLIMA (COrium LIquid and MAterials) experiments. The facility provided representative conditions of the aerosols suspended inside the containment of PWRs under a severe accident.

The MISTRA facility is a steel cylindrical vessel with a top flat cap and a curved bottom. The internal volume is 99.5m3, the internal diameter - 4.25m, the height - 7.4m. The vessel is thermally insulated, but the wall temperature is not controlled. Three cylindrical condensers are inserted inside the vessel, close to the wall and one above the other (so that they span over most of the vessel height). The facility is designed in such a way that almost all steam condensation is supposed to occur on the interior side of the condensers. The facility was additionally equipped with sprays located below the vessel ceiling. The instrumentation includes devices for measuring pressure, temperature, gas concentration and velocity (laser Doppler anemometry).

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 main advantages of the CODEX facility are the use of real UO2 pellets, the sophisticated data acquisition technique including aerosol measurements and the large flexibility in the selection of test conditions. The most imporant limitations are the use of fresh – non-irradited - fuel pellets and the application of electrical heating burdened with positive temperature feed-back effect.

Two-phase flow test facility was constructed to study the applicability of Particle Image Velocimetry (PIV) and Wire-Mesh Sensors (WMS) for different types of single- and two-phase flows

Condensation studies at LUT started with an open pool test facility (POOLEX) modeling the suppression pool of the BWR containment. During the years 2002-2006, the facility had several modifications and enhancements as well as improvements of instrumentation before it was replaced with a more versatile PPOOLEX facility in the end of 2006