Patent Number: 
Section: claims

1. A nuclear fuel rod comprising at least two fuel pellets, a cladding tube surrounding the fuel pellets, and at least two burnable absorbers inside the cladding tube,wherein each of the burnable absorbers consists of a burnable absorber material located in a cladding material which surrounds a perimeter edge, a top surface, and a bottom surface of the burnable absorber material,each of the burnable absorbers has a disk shape,the burnable absorber material of at least two burnable absorbers have a different surface area and/or volume,the cladding material is a zirconium-based alloy, each cladding material has a substantially same surface area and/or volume, andeach of the burnable absorbers is located on a respective one of the fuel pellets such that the burnable absorbers and the fuel pellets are stacked along a longitudinal direction of the nuclear fuel rod,and wherein a self-shielding effect is optimized by the different surface area and/or the volume of the burnable absorber material of the at least two burnable absorbers. 2. The nuclear fuel rod of claim 1, wherein in the nuclear fuel rod, each of the at least two burnable absorbers is located between at least two or more fuel pellets. 3. The nuclear fuel rod of claim 1, wherein the burnable absorber material comprises one or more selected from the group consisting of Gadolinium (Gd), gadolinia (Gd2O3), erbium (Er), Er2O3, and boron carbide (B4C). 4. The nuclear fuel rod of claim 1, wherein the diameter of each of the at least two burnable absorbers is equal to the diameter of the at least two fuel pellets. 5. The nuclear fuel rod of claim 1, wherein the thickness of each of the at least two burnable absorbers is approximately 0.1 mm-2.0 mm. 6. The nuclear fuel rod of claim 1, wherein in each of the at least two burnable absorbers, the diameter of the burnable absorber material is approximately 30-95% of the diameter of the at least two fuel pellets. 7. A nuclear reactor comprising the nuclear fuel rod of claim 1. 8. A method for manufacturing a nuclear fuel rod, the method comprising:preparing disk-shaped burnable absorbers, each consisting of a burnable absorber material located in a cladding material which surrounds a perimeter edge, a top surface, and a bottom surface of the burnable absorber material,the burnable absorber material of at least two burnable absorbers have a different surface area and/or volume,the cladding material being a zirconium-based alloy, each cladding material has a substantially same surface area and/or volume; andstacking, in a cladding tube along a longitudinal direction of the nuclear fuel rod, at least two fuel pellets and said at least two burnable absorbers, so that each of the burnable absorbers is located on a respective one of the fuel pellets;and wherein a self-shielding effect is optimized by the different surface area and/or the volume of the burnable absorber material of the at least two burnable absorbers.