| 摘要 |
PROBLEM TO BE SOLVED: To obtain a fuel assembly with high dryout performance and a small pressure loss. SOLUTION: A fuel assembly for a boiling water reactor loads a plurality of rod elements containing fuel rods arranged in parallel between an upper tie-plate and a lower tie-plate in a bundle state by the aid of spacers holding those rod elements with mutual gaps. In the case the distance between the upper and the lower tie-plates in the axial direction of the rod elements is separated at 7 points which are named as the first point to seventh point from the upstream to the downstream in the direction of coolant flow, spacers with low pressure loss are used at the first and the seventh points and spacers with large effect of coolant mixing are used at the second to the sixth points.
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