PURPOSE: To more quickly and strongly eliminate oxide film of a cladding in a method in which the fuel rod cladding is degraded by hydrogen before finely cutting the fuel rod in reprocessing.

CONSTITUTION: A fuel rod is heated in vacuum at the temperature at least the β-transformation point of zirconium alloy constituting the cladding, the fuel rod is cooled in hydrogen flow and the oxide film on the clad is eliminated by making use of quick oxygen diffusion velocity in β metal mother phase.