Abstract: A process is, herein, disclosed for separating a particular isotope from a mixture of different isotopes by selective excitation and ionization of the particular isotope with a single laser beam, said process comprising heating the mixture, converting the resulting atomic vapor to a highly directional atomic beam by suitable means, causing said atomic beam to travel through a vacuum, crossing the atomic beam with a high-intensity laser beam having a specific wavelength, selectively exciting the particular isotope with a first photon having that specific wavelength while the other isotopes remaining in the ground state, allowing the excited isotope to absorb a second photon to be excited to a virtual energy level, causing the so excited isotope to absorb a third photon to ionize said isotope, and recovering the ionized isotope by use of an electric or electromagnetic field.

Abstract: A process for the preparation of graphite-clad nuclear fuel rods comprising coating fine particles of a nuclear fuel such as uranium oxide or thorium oxide with a matrix material containing graphite powder and a binder to form matrix material-coated globules, charging the thus-formed globules, without or after being pre-molded into a green rod-like fuel compact, into the rubber mold of a rubber press molding machine, charging a similar matrix material in the gap between the globules or rod-like fuel compact and the inner wall of the rubber mold, compressing the whole mass in the direction from the side face of the whole mass to the axis thereof to form a green, graphite coat material-coated fuel compact, baking the thus-formed green fuel compact at a temperature of up to 1800.degree. C and, if desired, impregnating the baked product with a resin followed by being rebaked at a temperature of up to 1800.degree. C; and the graphite-clad nuclear fuel rods.