Ultra fast electron beam X-ray CT scanner for two-phase flow measurement

Two-phase flows are of primary importance in the understanding of thermal hydraulic phenomena in nuclear light water reactors. The qualification of CFD codes for the simulation of stationary and even transient two-phase flows in complex three dimensional geometries requires extending our knowledge toward the details of the flow structure under various thermal hydraulic conditions. At Forschungszentrum Dresden-Rossendorf the thermal hydraulic test facility TOPFLOW is currently extensively used to conduct two-phase flow experiments which aim at the disclosure of fine flow structure details in generic and also more complex geometries. Consequently, we have extended our measurement technology for two-phase flow to highspeed X-ray tomography which offers non-intrusive flow measurement at high pressure and high temperatur at a speed comparable to the wire-mesh sensor [2], [3], [4], [5]. For that reason we have developed a scanned electron beam X-ray apparatus where a electron beam is swept around an object on a circular X-ray target. Thus a rapidly moving X-ray spot is generated. The apparatus can perform cross-sectional imaging at high frame rates and will in the future be extended to other measurement features, such as multi-plane tomography, phase velocity measurement, higher scanning diameters and high energy X-rays. This paper introduce the scanner design, discuss major performance parameters along with an application example and show how this scanner will be applied to air-water and steam-water two-phase flow measurement in a vertical test section of the TOPFLOW facility.