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 PWR PACTEL test facility is designed and constructed in 2009 to be used in the safety studies related to thermal hydraulics of pressurized water reactors with EPR type vertical steam generators

The test section of the facility consists of a scaled-down model of VVER-440 steam generator, which has a bundle of 38 tubes with inlet and outlet chambers (hot and cold chamber, respectively), and a secondary side with the steam outlet line but without droplet separators and steam dryers.

The STORM (Simplified Test On Resuspension Mechanism) facility was designed and operated by JRC-Ispra to work with high concentration of soluble and insoluble aerosol materials (up to 25 g/m3), a wide range of aerosol compositions, size distribution and density and high carrier gas and steam flow rate (about 1kg/s).

The objectives of the FOREVER (Failure Of REactor VEssel Retention) tests are to obtain multiaxial creep deformation and vessel failure data for the scaled reactor vessel geometry under prototypical thermal and pressure loading conditions during hypothetical severe accidents.

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 VERCORS programme, which involves tests with short fuel-rod samples, has proved to be a rich source of information regarding FP release and tranport.

VITI (‘‘VIscosity Temperature Installation’’) facility has been developed to measure viscosity, density and surface tension on corium up to 2600 C by aerodynamic levitation. But it is also used as small crucibles heating for material interactions tests. Samples of less than 100 g can be studied in VITI.

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 experimental programme named KAJET is being performed to investigate features of a pressurized melt jet and the interaction with substratum material. Compact melt jets, rather than a spray-type melt release, are simulated using iron and aluminium oxide instead of corium. The melt is generated by a thermite reaction. The experiments provide general information about erosion processes and data for the validation of computer codes (or, if possible, simplified correlations) which then are able to transfer the results to reactor conditions.

This facility comprises a water supply pipe, a quartz test section (110, 180 or 290 mm diameter) in which the debris bed is placed, together with its instrumentation, and a steam relief pipe. It is used to conduct refl ooding tests by means of injecting water onto a bed of metal particles heated by induction. The instrumentation measures the different temperatures and pressures in the debris bed, the fl ow of injected water and the fl ow of generated steam.

Experimental facility Figure &
A single sampler unit