FUEL ASSEMBLY OF BOILING WATER REACTOR

PROBLEM TO BE SOLVED: To obtain a fuel assembly which improves stability and economy without lowering safety of a BWR by taking in advantage of a tight-pitch core on the basis of fuel design and manufacturing technology of a BWR developed so far such as partial length fuel rods, thick diameter water rods, etc. SOLUTION: In fuel assemblies for a boiling water reactor in which long-size fuel rods 40a of a maximum effective length A and partial length fuel rods having an effective length shorter than the maximum effective length A and over 1/2 of A are arranged in a rectangular matrix of N×N and the fuel rods arranged in the rectangular matrix of N×N are surrounded by a channel box, short-size fuel rods having a maximum effective length C shorter than the partial length fuel rods and under 1/2 of the maximum effective length A of the long-size fuel rods are arranged in a space in a region H from a height 0 of the fuel assembly to under 1/2 of the maximum effective length A of the long-size fuel rods where no fuel rod of N×N are arranged. COPYRIGHT: (C)2006,JPO&NCIPI