Application of quantitative measurement method to void fraction of two-phase flow in a rod bundle by neutron radiography

摘要

Quantitative void fraction measurement method based on the umbra method using a neutron absorber grid was applied to the void fraction measurement of two-phase flow in a 4 x 4 rod bundle. The grid 3 mm in width and 3 mm in interval was made from B{sub}4C. The details of the method was discussed in another paper of the present conference. The two-phase flow direction was vertical and the grid was placed vertically between the rod bundle and the neutron source. A cooled-CCD camera in the JRR-3M thermal neutron radiography system was used. CT reconstruction was carried out for sixty horizontal slices with a vertical interval of 3 mm. Cross sectionally averaged one-dimensional void fraction distributions along the flow direction were also calculated with 3 mm interval. Quantitative measurement with spatial resolution 0.18 mm, size of the image element, horizontally and 3 mm vertically was carried out.