Three-dimensional void fraction distributions of a steady air-water tw
o-phase flow in a 4 x 4 rod-bundle with circular ferrule type spacers
were measured by neutron radiography using a CT method. The high flux
thermal neutron radiography system at JRR-3M in JAERI was used. Two-ph
ase flow was visualized with a SIT tube camera and time-averaged one-d
imensional cross sectional averaged void fraction distributions were c
alculated. Visualization with high spatial resolution up to 0.18 mm wa
s carried out by using a cooled CCD camera. Projections in 250 directi
ons were obtained and were reconstructed by a filtered back projection
method after using some image processing techniques. Animations were
made to show the three-dimensional distributions. One-dimensional and
three-dimensional void fraction distributions of the steady state two-
phase flow in the rod bundle near the spacer were clearly visualized.
(C) 1998 Elsevier Science S.A. All rights reserved.