Nuclear fuel element having fuel can with outer surface made of amorphous metal

It is required that a fuel can (1) absorbes less thermal neutrons, (2) has excellent corrosion resistance in water at high temperature, (3) has excellent mechanical strength and (4) can provide high heat conductivity. In view of the above, if the outer surface of the fuel can is made of amorphous metal, improvement in the corrosion resistance can be expected also to water at high temeprature and high pressure. At first, laser beams are concentrated by way of an optical system to the outer surface of a fuel can, to rapidly heat and melt the surface in an extremely brief period of time under the irradiation of high energy density light. Since the thickness of the heated portion is extremely thin, the heat capacity is small and the cooling can be conducted at a high velocity to form an amorphous layer. Since amorphous metal generally has high toughness, it is possible to reduce the effect of injuries at the surface of a nuclear fuel element caused upon assembling, to produce fuels at high burnup degree and high working life and thereby reduce the power production cost as compared with usual cases. (N.H.)