Fuel rods for nuclear reactor

Purpose: To avoid local stress concentration and thus prevent failures in fuel cans of a fuel rod consisting of hollow cylindrical fuel cans and cylindrical fuel pellets packed therein. Constitution: A fuel pellet is formed at its one end with a spherical protrusion and at its the other end with a concaved spherical shape corresponding to the above protrusion. A plurality of such pellets are packed into the fuel cans while alternately joining each of the protrusions and concaves in a rotatable manner. Individual pellets, if subjected to thermal stress, can rotate with a small force in the fuel can to thereby relax the stress due to thermal deformation. (Horiuchi, T.)