Patent Number: 051768771
Section: abstract

A nuclear fuel assembly for a nuclear reactor has a plurality of vertically extending fuel rods arranged side by side in a square array and containing fissile material. The array has two adjacent first sides which are next to a control rod region of the core and two adjacent second sides which are next to a non-control rod region of the core. When the rods of the array as seen in horizontal cross section, excluding the rods lying on the diagonal line joining the opposite corners of the array at which the control rod region meets the non-control rod region, is divided into four regions which are. a: the rods in the row and column of said array adjoining said first sides; PA0 b: the rods lying between said region a and said diagonal line; PA0 c: the rods lying between said region d and said diagonal line, PA0 d: the rods in the row and column of said array adjoining said second sides and; over at east part of the height containing fissile material, the average concentration of fissile material per fuel rod is higher in said region b than said region c and by at least 5% and, among all said regions a, b, c, d, is a minimum in said region a. This provides good control rod worth and low local power peaking.