Control rod for nuclear reactor and method of manufacturing control rod

Abstract

A control rod for nuclear reactors includes four wings including neutron absorbers containing hafnium, a front end structural member which has a cross shape in cross section and includes brackets bonded to the leading ends of the wings, and a terminal end structural member which has a cross shape in cross section and includes brackets bonded to the tailing ends of the wings. The four wings are bonded to a wing-bonding member including a cross-shaped center shaft so as to form a cross shape. The front end structural member and the wing-bonding member are made of a zirconium alloy. The wings include neutron-absorbing plates having neutron-absorbing portions and each have an outer surface which is opposed to a fuel assembly and at which a hafnium-zircaloy composite member covered with zircaloy is disposed. The neutron-absorbing plates are opposed to each other with trap spaces disposed therebetween.

1 . A control rod for nuclear reactors comprising:
 a neutron absorber constituting a structural member of a control rod, the neutron absorber being of a composite member including a hafnium plate and at least one zirconium plate bonded to the hafnium plate.   
     
     
         2 . The control rod according to  claim 1 , wherein the neutron absorber has a cross shape in horizontal cross section. 
     
     
         3 . The control rod according to  claim 1 , wherein the zirconium plate is disposed on a surface of the neutron absorber that is configured to contact a reactor water. 
     
     
         4 . The control rod according to  claim 1 , further comprising wings fixed with fixing members in a thickness direction of each wing, wherein the fixing members are disposed at positions in a vicinity of bases of the wings and arranged in a longitudinal direction. 
     
     
         5 . The control rod according to  claim 1 , further comprising wings fixed with fixing members in a direction of a base of each wing, wherein the fixing members are disposed at positions arranged in a longitudinal direction and located at the bases of the wings which are opposed to each other. 
     
     
         6 . The control rod according to  claim 4 , further comprising a terminal end structural member and a front end structural member including a handle, wherein the wings are formed from the composite member so as to provide a cross shape and the front end structural member is fixed to upper portions of the wings with the fixing members or the terminal end structural member is fixed to lower portions of the wings with the fixing members. 
     
     
         7 . The control rod according to  claim 5 , further comprising a terminal end structural member and a front end structural member including a handle, wherein the wings are formed from the composite member so as to provide a cross shape and the front end structural member is fixed to upper portions of the wings with the fixing members or the terminal end structural member is fixed to lower portions of the wings with the fixing members. 
     
     
         8 . The control rod according to  claim 6 , wherein the front end structural member is formed from the composite member. 
     
     
         9 . The control rod according to  claim 1 , wherein the at least one zirconium plate is bonded to the hafnium plate by hot rolling. 
     
     
         10 . The control rod according to  claim 1 , wherein the at least one zirconium plate is bonded to a first surface of the hafnium plate, and the neutron absorber of the composite member includes another different zirconium plate, that is bonded to a second surface of the hafnium plate, the at least one zirconium plate and the another different zirconium plate sandwiching the hafnium plate. 
     
     
         11 . A control rod for nuclear reactors comprising:
 a neutron absorber of a composite member including a hafnium plate, a first zirconium plate, and a second zirconium plate, the first zirconium plate being bonded to a top surface of the hafnium plate, and the second zirconium plate being bonded to a bottom surface of the hafnium plate, the top surface and the bottom surface of the hafnium plate being covered by the first and second zirconium plates, respectively, without side surfaces of the hafnium plate being covered by the zirconium plates.