Abstract: A fuel rod for nuclear reactors which contains UO.sub.2 or a mixed-oxide (MOX) of UO.sub.2 and PuO.sub.2 as a nuclear fuel and a combustible reactivity control material e.g., Gd.sub.2 O.sub.3. A plurality of hollow UO.sub.2 or MOX pellets each having a hole along its central axis are spitted with a long bar of Gd.sub.2 O.sub.3 to form a pellet stack, which is inserted and sealed in a cladding tube to form the fuel rod of the present invention. Since the Gd.sub.2 O.sub.3 bar can be manufactured in a non-nuclear fuel manufacturing facility, it is not required to provide two separate lines, i.e., a line for handling Gd.sub.2 O.sub.3 and a line for handling UO.sub.2 or MOX fuel, in one manufacturing facility. The optimum design for the performance of the nuclear fuel is possible by changing the diameter and/or Gd.sub.2 O.sub.3 concentration of the Gd.sub.2 O.sub.3 bar depending on the desired performance of the nuclear fuel.