A mains electricity (AC-powered) device assembly designed for the in vitro irradiation of blood and/or blood components with ionizing radiation (e.g., gamma), typically used to treat cancer patients by inactivating lymphocytes and for the prevention of transfusion-associated graft-versus-host diseases. It typically includes a shielded, double encapsulated, long half-life radiation source (e.g., Cesium 137), blood/blood product containers, safety interlocks, a timing mechanism, and a means of retrieving samples.