the invention relates to apparatus and a method for facilitating a scratchless insertion of a fuel rod into cellular grids of a nuclear fuel assembly . the apparatus comprises a thin - walled tubular member having an inner diameter substantially corresponding to the outer diameter of a fuel rod , and having a longitudinal slit formed in its wall so as to render the latter resiliently deflectable in a diameter - reducing sense . the method comprises the steps of mounting the thin - walled tubular member in position for protectively enveloping the fuel rod during insertion thereof ; inserting the fuel rod into the grids while the tubular member is in place to envelope it ; and withdrawing the tubular member from the inserted fuel rod .