| 摘要 |
PROBLEM TO BE SOLVED: To shorten a working time for drawing out or inserting a fuel rod from/into fuel assembly, apply it to any MOX(mixed oxide) fuel assembly of high dosage with low exposure, and being reusable without damaging the surface of the fuel rod in drawing out. SOLUTION: This assembling and disassembling method for the fuel assembly uses a release jig A composed of a prescribed length of a U-shaped member 1, having a notched hole 3 for relieving a hard stop dimple 7 in one of the both sides, and a notched hole 4 for relieving a soft stop dimple 8 and a soft stop push-up part 5 in the other side and the bottom. The release jig A is inserted inside the support grid cell 6 by being slid on the fuel rod R of the fuel assembly from the lower part side of the support grid B so as to avoid a hard stop, and the soft stop is pushed up in the direction of releasing the fuel rod R while avoiding the soft stop dimple 8 so that the fuel rod R is drawn out or inserted.
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