Measurement of the water-vapor void fraction in a unheated rod bundle

Nagatake, Taku ; Yoshida, Hiroyuki  

In recent years, computational fluid dynamics (CFD) codes have been used to evaluate two-phase flow behavior inside a fuel bundle for nuclear core design and accident management. A space-time distribution of void fraction and interfacial velocity in bundle systems at high temperatures and pressures, are important for validation of two-phase flow CFD codes. However, it is difficult to obtain a space-time distribution of void fraction and interfacial velocity in a bundle system at high temperature and pressure conditions. We have so far developed an experimental apparatus with a unheated rod bundle by adapting a through-rod WMS to measure distributions of a void fraction and an interfacial velocity in high pressure conditions. We newly measured distributions of the void fraction and interfacial velocity in the water-vapor system under high pressure up to 2.6 MPa by the developed apparatus. It has been confirmed that reasonable results were obtained by the experimental apparatus.