A nuclear reactor fuel rod is disclosed in which fission gases from the nuclear reaction are retained for a short time period to permit decay of the radioactivity present in the gases and then permit the removal of the gases from the rod. To accomplish this one of the end caps of the rod has a hole drilled in it and is connected to a fission gas removal system in the reactor. A separate container, containing pressed filter material such as, activated carbon, is metallurgically connected to the perforated end cap. At least on the side of the filter into which the fission products initially pass, a porous element is used to permit the fission products to pass into the filter material in a finely divided state without a large pressure drop.