Abstract: Selected isotopes of zirconium are separated by irradiating vapor of material consisting of hydrolysis-resistant compounds dicyclopentadienyl zirconium dichloride, dicyclopentadienyl zirconium di-isopropoxide and/or dicyclopentadienyl zirconium di-tert-butoxide with a laser beam tuned to vibration of an excitable band of the component of the compounds including the selected isotope. The component of the material including the excited band is separated from the remainder of the material. Parts for a nuclear reactor are made of zirconium derived from the separated material or from the remainder, whichever has the lower neutron-absorption cross section.