A device and method for inactivating pathogens in therapeutic fluids with sterilizing radiation in a continuous flow arrangement while exhibiting radiation dose uniformity and narrow residence time distribution of the fluid within the device. The device (10) comprises a radiation permeable cylindrical tube (12) having a concentric cylindrical rotor (14) disposed therein, thereby providing a thin gap (16) therebetween. A top plate (18) having a fluid outlet (26) and a bottom plate (20) having a fluid inlet (24) seal the cylindrical tube (12). The inlet (24) and outlet (26) are both in fluid communication with the thin gap (16). A rotor shaft (36) is diposed axially through the cylindrical rotor (14) and is connected to a motor (30). A pump provides fluid flow through the device (10). A radiation source provides sterilizing radiation to the fluid through the cylindrical tube (12). As the fluid flows, the motor (30) drives the rotor (14) to impart Taylor vortices to the fluid flow, which exchanges the fluid closer to the cylindrical tube (12) with the fluid closer to the rotor (14).