Nuclear reactor control rod

Purpose: To obtain nuclear reactor control rod of excellent mechanical strength and surely prevent the reduction of the reactivity. Constitution: In a long lifetime control rod, plate-like neutron absorber elements inserted in the sheath comprise a set of neutron absorber plates constituted with a plurality of Hf plates, in which gaps for introducing water as moderators and coolants are disposed between each of the absorber plates by means of spacers. The spacers comprise top-shaped spacers arranged dispersingly such that the gap width between each of the absorber plates is not reduced and linear spacers arranged along the lateral direction of the central tie rod. The outer surface of the absorber plate and the inner surface of the sheath are aparted by means of dimplings to allow the passage of coolants. (Kawakami, Y.)