In-bundle void distribution measured by ultra fast X-ray CT scanner

This paper presents measured results on void distribution of air-water flow in a 3 x 3 rod bundle equipped with model grid spacers. These results are given by a developed advanced type ultra-fast X-ray computed tomography (CT) scanner system. This advanced type system can operate under the minimum scanning time of 0.5 milliseconds and is applicable for the measurement of multi-phase flow with velocity up to 4-5 m/s. The obtained results shows the effect of grid spacer on the void distribution. Such experimental results are useful for assessment or improvement of a two-phase flow analysis code and a grid spacer model for a mechanistic CHF prediction method. (author)