| 摘要 |
PROBLEM TO BE SOLVED: To provide a fuel assembly of which the thermal margin of a fuel rod located in the outermost layer of fuel rod array can be improved even when a fissile material loading amount of the fuel rod located in the outermost layer of fuel rod array is increased.SOLUTION: In a fuel assembly, a plurality of fuel rods containing a fissile material are bundled by a fuel spacer. The fuel rods are arranged in 10 lines and 10 columns surrounding two large-diameter water rods arranged at a center part of a cross section of the fuel assembly. Flow resistors 15 are arranged at the center part of the cross section at upper ends of partial long fuel rods which are a part of the fuel rods. The flow resistors 15 are arranged, respectively, among mutual round cells 9 formed by arranging resistance members 16 in six lines and six columns in diagonal directions of the flow resistors 15. Resistance members 17 are arranged among the round cells 9 at the periphery of the flow resistors 15. By installation of the resistance members 16, 17, pressure loss of an internal region on the cross section of the fuel assembly increases, and a flow rate of gas-liquid two-phase flow in an external region surrounding the internal region increases. |
