Characterization of a gas elliptic jet in a nuclear safety scenario

► We study a subsonic jet expanding in a tube bundle from an axial-type tube breach. ► The scenario is key to assess retention of radioactivity in SGTR nuclear accidents. ► PIV characterized the flow between the breach & the closest tubes for ReD = 8-27 × 104. ► Jet expansion in a tube-free space and with other type of breach was also analyzed. ► It shows tophat profiles & asymmetric entrainment highly influenced by the tubes.