Neutron absorber and neutron absorption control rod for nuclear reactor

A neutron absorption control rod for a nuclear reactor comprising:

• a first neutron absorber component which includes a first oxide-based neutron absorber including a first lanthanide-based rare earth element and a first Group 4 element and is placed in a lower portion, and
• a second neutron absorber component which includes a second oxide-based neutron absorber including a second lanthanide-based rare earth element and a second Group 4 element and is placed on the first neutron absorber component,
• wherein
• a mole ratio of the first lanthanide-based rare earth element to the first Group 4 element in the first oxide-based neutron absorber is 1.5:1 to 2.5:1, and a mole ratio of the second lanthanide-based rare earth element to the second Group 4 element in the second oxide-based neutron absorber is 3:1 to 20:1.

A method for manufacturing a neutron absorption control rod for a nuclear reactor, the method comprising:

• mixing an oxide including a first lanthanide-based rare earth element and an oxide including a first Group 4 element and molding the mixture to manufacture a first molded product,
• sintering the first molded product in an air atmosphere at 1400 to 1600° C. to manufacture a first sintered pellet;
• mixing an oxide including a second lanthanide-based rare earth element and an oxide including a second Group 4 element and molding the mixture to manufacture a second molded product;
• sintering the second molded product in an air atmosphere at 1400 to 1600° C. to manufacture a second sintered pellet;
• and
• stacking the second sintered pellet on the first sintered pellet in a longitudinal direction,
• wherein
• the first sintered pellet has a lower composition ratio of the lanthanide-based rare earth element and higher bulk density than the second sintered pellet, and the second sintered pellet has a higher composition ratio of the lanthanide-based rare earth element and lower bulk density than the first sintered pellet.