| 摘要 |
PROBLEM TO BE SOLVED: To increase cooling capability by only attaching simple constitution parts to proper locations in spacers of fuel assembly for a boiling water reactor and removing sufficient heat from fuel rods of the fuel assembly with coolant and suppress the burnout generation on the fuel rods, even in high power operation by improving the limit power characteristics. SOLUTION: A plurality of specific number of outward projections 11, existing on the outer plate 3a of a spacer body and touching the inner wall surface 5a of a channel box 5 coupled by the outer plate are attached. According to this, the liquid film of the coolant flowing upward along the inner wall surface 5a is made to hit the outward projections 11 and dispersed into droplets. The droplets make the liquid film thicker on the outer surface 1c of the fuel rods 1, in the channel box 5 side exposed to very severe thermal conditions and attain increase in cooling effects by this.
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