X-Ray Imaging Calibration for Fuel-Coolant Interaction Experimental Facilities

During a severe accident in either sodium-cooled or water-cooled nuclear reactors, jets of molten fuel may impinge on the coolant resulting fuel-coolant interactions (FCI). Experimental programs are being conducted to study this phenomenology and support development models. Due optical opacity test section walls, sodium coolant, apparent water presence intense ebullition, high-speed X-ray imaging is preferred technique for FCI visualization. The configuration these systems, whereby installed between fan-beam source scintillator-image intensifier projecting an image visual spectrum onto camera, entails certain artefacts uncertainties. requires precise calibration enable detailed quantitative characterization FCI. To end, ‘phantom’ models have been fabricated using polyethylene, steel hafnia powder, empty cavities represent sodium, vapor phases respectively. A checkerboard phantom enables correction lens distortion which magnify features towards edge field view. Polydisperse ball configurations determination lower limit detection estimation parallax errors introduce uncertainty object’s silhouette dimensions. Calibration experiments at MELT facility determined limits order 4 mm spheres, 1.7-3.75 films around jet.