Abstract: In a method and apparatus for cleaning nuclear fuel elements to remove carbonized pitch residue and the like, the cleaning operation preferably being conducted within an enclosure to permit containment of the removed residue, each fuel element being introduced into the enclosure through an airlock, the end surfaces and lateral surfaces of the fuel element being cleaned and one or more longitudinal passages within the fuel element being cleaned by means of a probe unit for initially determining the configuration and position of the longitudinal passages and causing cleaning elements to be aligned with the respective longitudinal passages and extended therethrough, the flow resistance of those longitudinal passages designed for gas flow being monitored by a gauging unit, clean fuel elements being removed from the enclosure through another air-lock.