Fuel Assembly and Reactor Loaded with the Same

Abstract

A fuel assembly capable of linearizing change of an infinite multiplication factor of a fuel and flattening excess reactivity while increasing average fissile plutonium enrichment of a MOX fuel, and a reactor loaded with the fuel assembly can be provided. A fuel assembly includes first fuel rods containing Pu and not containing burnable poison, a second fuel rod containing uranium and burnable poison and not containing Pu, a water rod, and a channel box accommodating the first and second fuel rods and the water rod in a bundle. The second fuel rod is disposed on an outermost periphery and/or adjacent to the water rod, of a fuel rod array in a horizontal section, N2<N1 (N2 is a positive integer including zero) is satisfied where the number of the second fuel rods arranged on the outermost periphery is N1 and the number of the second fuel rods arranged adjacent to the water rod is N2, and W2<N2+W0<W1 (W2 is a positive integer including zero) is satisfied where the number of the second fuel rods arranged without being vertically and/or horizontally adjacent to each other in the horizontal section is W0, the number of the second fuel rods arranged vertically and/or horizontally adjacent to only one second fuel rod in the horizontal section is W1, and the number of the second fuel rods arranged vertically and/or horizontally adjacent to two second fuel rods in the horizontal section is W2, of the second fuel rods arranged on the outermost periphery.

Dependencies are inferred from the claim text.