Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Non-optical Imaging of Flow, Boiling, and Salt Deposition in a Simulated Debris Bed

Determining flow and heat transfer characteristics in a debris bed or a packed bed is difficult due to the lack of optical access. Non-optical imaging methods, such as x-ray or neutron imaging, can be used to observe flow characteristics and particle deposition, as well as boiling in a packed bed. An amorphous Silicon detector based digital radiography camera can be used to image with either x-rays or neutrons at up to 100 frames per second. The digital radiography camera, coupled with digital image analysis techniques was used to characterize fluid fraction and flow rates in a simulated debris bed. A water percolation experiment was performed where a test section filled with 1-3 mm glass particles was used as a simulated debris bed, and properties such as packing fraction, volumetric flow rate, and evaporation rate were calculated both physically and using data from the images. The values obtained using the images were benchmarked against the physically calculated values and found to be in agreement, validating the image processing algorithms.