| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem wherein, in the case where a fuel assembly is used under high burn-up, or for long hours, when a channel box is dismounted, a spacer on a center position in the longitudinal direction interferes with a lower end of the channel box owing to volume expansion of the spacer and bulge deformation of the channel box. SOLUTION: In this fuel assembly wherein spacers 3 for bundling respectively a plurality of fuel rods 1 so as to hold mutual horizontal direction intervals are provided plurally along the longitudinal direction of the fuel rods, and the plurality of fuel rods bundled through each spacer are enclosed by a cylindrical channel box 12, the thickness of the channel box is formed to be thin on a furthermore lower part than a spacer positioned on the lowermost part. Hereby, interference with the spacer is avoided by controlling deformation so that deformation to the outside of a channel box lower end at a bulge deformation time becomes large. COPYRIGHT: (C)2011,JPO&INPIT
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