de|fu|el

de|fu|el «dih FYOO uhl», transitive verb, -eled, -el|ing or (especially British) -elled, -el|ling.

to remove the fuel rods of a nuclear reactor: »

Removal of the sump water, expected to be among the most difficult tasks of the clean-up operation, must be accomplished before full scale decontamination and defuelling of the reactor can begin (New Scientist).