To suppress the corrosion and hydrogen absorption of a zircalloy used in a nuclear fuel assembly loaded in a water-cooled nuclear reactor.

A part, such as a fuel clad pipe 11 for use in the nuclear fuel assembly loaded in the water cooling nuclear reactor, is provided with a zircalloy portion 21 formed from a material containing zirconium as the main component, and a surface-coated layer 12, having as a main component an oxide that has oxygen partial pressure at equilibrium that is equivalent and not less than that of zirconium oxide and being other than zirconium oxide, the layer 12 being formed on the surface of the part in contact with cooling water, when the part is loaded in the nuclear reactor.