Application of Tomography for Nuclear Safety Applications

Computerized Tomography (CT) was pioneered by astrophysicists and medical diagnostics experts almost 60 years ago. It found its way quickly in the area of noninvasive measurements in multi-phase fluid-flow systems existing in many engineering applications. Nuclear reactor safety involves numerical prediction of thermodynamic parameters of reactors undergoing transients/accidents and one such property is cross-sectional void-faction distribution which plays a crucial role in the heat transfer aspects. The concept of CT provides an experimental non-invasive option to assess these numerical results. This exercise incorporates measurement of void-fraction distribution in flow cross sections that are expected in accident conditions. A simple three-phase (solid-liquid-gas) experiment was carried out at Leibniz University (Hannover) where X-ray CT system was used to image the cross-sectional distribution of void- fractions. This experiment has relevance to the nuclear industry two-phase (steam-water) flow situations. The results also include a novel way of estimating error in experimentally obtained tomographic images of void-fraction distributions