The ARISG-I was developed to estimate the aerosol deposition in the near-field of tube breach under dry conditions. It was based on ‘filter concept’, which means that aerosol flowing through a bundle of obstacles is submitted to forces that tend to clean up the gas by removing particles onto obstacle surfaces. Under SGTR conditions, the major deposition mechanisms in the break stage are turbulent deposition and inertial impaction.

Passive Containment Cooling System (PCCS) removes residual heat from upper drywell of the containment to the liquid pool surrounding the PCCS heat exchanger. It also has an important role in mitigating the offsite dose by retention of a fission product release in the containment. The operation of the PCCS is based on density differences between the containment and water pool

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.

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).

Facility consists of the hemispherical test vessel, a volumetric heating system in the test vessel to simulate the decay heat, a heating furnace to generate and pour the simulated corium melt, and a multitude of instrumentation to characterize the status of the melt. The test vessel is a 1:5 scaled RPV of a typical PWR with no penetrations of the lower head, and is equipped with different measurement techniques like heat flux sensors and thermocouples. The hemispherical bottom is closed by an upper lid and different openings in this upper lid allow the pour of melt to the central region or close to the perimeter of the lower head. Test vessel can be cooled by water or air at the outer surface, as it is surrounded by a second cooling vessel.

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). Experiments are conducted using the PRELUDE and PEARL test facilities of the IRSN's THEMA platform.

The KROTOS test facility is a relatively small scale experimental installation dedicated to the study of:

• (a) molten fuel-coolant pre-mixing either with prototypic reactor melts or simulants such as alumina up to 5 kg;
• (b) progression and energetics of spontaneous and triggered fuel-coolant interactions (vapor explosions).

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. They are used to predict the behaviour of different types of possible accidents and related releases of radioactive products.

Experimental facility Figure &
A single sampler unit

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.

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

The separate effect studies of vertical steam generators have been conducted in the CIEMAT PECA facility, which was properly modified and conditioned for that purpose. The PECA facility set-up used in the SGTR separate effect tests basically consists of:
1. Two injection lines, one designed for supplying air at relatively high flow rates from a compressor, and the other for the aerosol injection.
2. The vessel, containing the tube mini-bundle.
3. The associated instrumentation and sampling stations.