PIV measurements of velocity distribution around wire wrapped fuel pins in a fuel subassembly for fast reactor

Hiyama, Tomoyuki ; Nishimura, Masahiro ; Kamide, Hideki ; Ohshima, Hiroyuki; Nagasawa, Kazuyoshi*; Imai, Yasutomo*

In high burn-up fuel subassemblies of sodium cooled fast reactor, deformation of fuel pin due to the swelling and thermal bowing may decrease local flow velocity via change of flow area in the subassembly. Therefore, it is important to developed detailed evaluation method of flow field in a wire wrapped pin bundle. In this study, water experiments were carried out to investigate the detailed velocity distribution in the wire wrapped pin bundle. The test section consists of an acrylic duct tube and fluorinated resin 3 pins which have nearly the same refractive index with that of water. The velocity distribution in the inner subchannel with the wrapping wire was measured by PIV. Furthermore, a detailed simulation code was applied to the experimental analysis and the calculated results were consistent with the experimental data. These data can contribute to construct the database to validate simulation codes.