Abstract: A shielded access door for a nuclear steam generator manway port having a beam of radiation streaming therethrough, the port being surrounded by a manway flange. The door comprises a bracket adapted to be removably connected to the flange. A plurality of swing arms have the first end portion thereof pivotally connected to the bracket. A first shield member is connected to the second end portions of the arms and is disposed parallel and adjacent to the port for shielding against the beam of radiation. The first shield member and the port define a gap therebetween for allowing access to the steam generator interiorly of the port while simultaneously shielding against the beam of radiation. The first shield member has a ventilation hole therethrough in communication with the port for ventilating the port, so that air-borne radioactive particles present interiorly of the steam generator are exhausted from the steam generator.