Measurements of flow in an air model of a partly blocked fast reactor subassembly

Coolant flow in the vicinity of blockages in a large-scale model of part of a fast reactor fuel subassembly has been visualized by a paint-flow technique, and measured with a pressure probe and a hot wire anemometer. Four blockages of different porosity, from impervious to 33% free area, were investigated. Compared with an impervious blockage, a little porosity elongates the recirculating region, reduces the pressure perturbation, and slightly reduces the turbulence. More porosity eliminates the recirculation and greatly reduces the pressure perturbation and turbulence. The high turbulence introduces significant errors into the pressure and velocity measurements, and the determination of the turbulence itself is subject to very large uncertainty. (author)