A new type of nuclear fuel rods. The rod cladding has an elliptical section transverse to its longitudinal direction and each nuclear fuel pellet has a truncated elliptical shape along the major axis of the cladding, the minor axis of the pellets is the same as the length of the minor axis of the cladding except for the assembly clearance j, the difference in length between the major axis of the cladding and the truncated major axis of the pellets is very much larger than the assembly clearance j. Also disclosed is a method of manufacturing nuclear fuel rods and stacking them in the cladding so as to form a nuclear fuel rod.