Abstract: An end plug is inserted into the end of a nuclear fuel pin cladding tube after loading mixed oxide fuel pellets into the tube from a containment area. During the pellet loading operation, a disposable sleeve and an end plug carrier protect the external surfaces of the cladding tube and the end plug from contamination. The sleeve, mounted on the end of the cladding tube, is inserted into a seal arranged in a wall of the containment area. The end plug, located within a recess in the plug carrier, is then inserted into the end of the cladding tube by sliding the carrier through the sleeve. Upon removal of the cladding tube, the sleeve and the carrier are retained in the seal for ejection into the containment area during the next pellet loading operation.