Corium Behaviour Research at CEA Cadarache: The PLINIUS prototypic corium experimental platform; International Conference Nuclear Energy for New Europe 2002, Kranjska

ABSTRACT In the hypothetical case of a Light Water Reactor severe accident, the reactor core could melt and form with structure materials, and eventually concrete, a complex mixture called corium. The knowledge of corium behaviour is one of the key to increase the safety of the nuclear reactors. In the framework of severe accident studies, CEA has undertaken for many years a large R&D program devoted to this topic. At CEA-Cadarache, a specific platform, called PLINIUS, has been developed and is dedicated to studies of prototypic corium (i.e. with uranium dioxide). In this paper, the PLINIUS platform four facilities and the experiments on corium behaviour are described

Experiments on interactions of molten steel with suboxidized corium crust for in-vessel melt retention

International audienceIn the framework of the European IVMR project, dedicated to the assessment of In-Vessel Retention (IVR) strategy for high power reactors, VITI-CORMET tests, performed in VITI facility (CEA-Cadarache/PLINIUS Severe Accident Platform), intend to study the interaction between a molten 304L stainless steel droplet and suboxidized solid corium crust, referred to as C-70 ((U$_{0.54 ,}$ Zr$_{0.46}$)O$_{1.74}$). In the present paper, original experimental results on molten steel penetration through a corium crust are presented. Identification of penetration mechanisms is performed by SEM/EDX analyses, and has shown that molten steel can penetrate through pre-existing cracks or by a dissolution process. The latter is found to be the dominant penetration mechanism and involves material transport from the crust to molten steel. Penetration kinetics is studied by measuring the average penetration length at different exposure times. It is found that the penetration by dissolution decelerates with time, while U and Zr contents tend to reach an equilibrium value within the metallic droplet

Greenland surface mass balance simulated by a regional climate model and comparison with satellite derived data in 1990-1991

The 1990 and 1991 ablation seasons over Greenland are simulated with a coupled atmosphere-snow regional climate model with a 25-km horizontal resolution. The simulated snow water content allows a direct comparison with the satellite-derived melt signal. The model is forced with 6-hourly ERA-40 reanalysis at its boundaries. An evaluation of the simulated precipitation and a comparison of the modelled melt zone and the surface albedo with remote sensing observations are presented. Both the distribution and quantity of the simulated precipitation agree with observations from coastal weather stations, estimates from other models and the ERA-40 reanalysis. There are overestimations along the steep eastern coast, which are most likely due to the “topographic barrier effect”. The simulated extent and time evolution of the wet snow zone compare generally well with satellite-derived data, except during rainfall events on the ice sheet and because of a bias in the passive microwave retrieved melt signal. Although satellite-based surface albedo retrieval is only valid in the case of clear sky, the interpolation and the correction of these data enable us to validate the simulated albedo on the scale of the whole Greenland. These two comparisons highlight a large sensitivity of the remote sensing observations to weather conditions. Our high-resolution climate model was used to improve the retrieval algorithms by taking more fully into account the atmosphere variability. Finally, the good agreement of the simulated melting surface with the improved satellite signal allows a detailed estimation of the melting volume from the simulation