Characterization of prototypic corium sample simulating fukushima daiichi unit 2 lower head composition
Résumé
Prototypic fuel debris samples have been fabricated to represent the lower head corium composition estimated in Fukushima Daiichi Unit 2. The average from BSAF benchmark calculations have been considered. It corresponds to a zirconium oxidation ratio of about 25%. In this test, depleted uranium oxide has been used, fission products have been represented by their natural isotopic composition and cerium has been used as surrogate for transuranium elements. The load, made from 19 different raw materials, has been melted by induction heating in the VULCANO facility under a nitrogen flow representative of BWR containment atmosphere. 11 kg of in-vessel prototypic fuel debris blocks have been fabricated.
Scanning Electron Micrography of samples from these fuel debris prototypes has been carried out in conjunction with Energy Dispersive Spectrometry and X-Ray Diffraction. Quantitative phase analysis were realized with Rietveld method. This provides insights on the composition of these debris and the large number of phases (Uranium-zirconium oxides, uranium-zirconium oxynitrides, zirconium boride, metallic phases …) present in them.