A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, including a target elevator assembly including a body portion defining a central bore and an open bottom end, a center tube that is disposed within the central bore of the body portion, a target basket that is slidably receivable within the center tube, and a winch that is connected to the target basket by a cable, wherein the target basket is configured to receive the radioisotope target therein and be lowered into the vessel penetration of the reactor when irradiating the radioisotope target.