| 摘要 |
PURPOSE: To replace a faulty fuel rod easily by cutting the upper part of each guide tube under the bulging part thereof and, after replacing a faulty fuel rod, introducing a new upper end part of a short tube having inside diameter slightly larger than the outside diameter of cut tube into the reactor and then receiving a corresponding guide tube and jointing the new upper end part thereto. CONSTITUTION: An upper end part 8 is released from the frame and a guide tube 10 in a hole 35 is cut off at the height of a line 52 below a corrugated groove 36 of guide tube 10 and then the upper end part 8 is removed together with the guide tube 10. A new upper end part 53 provided with a large number of short tubes 54 having inside diameter slightly larger than the outside diameter of guide tube 10 is then introduced and each short tube 54 is fitted over the guide tube 10 which is thereby covered with the upper end part 53. Subsequently, the upper part of guide tube 10 and the short tube 54 are deformed by rolling, for example, such that an annular bulging part 56 is obtained in the radial direction and the upper end part 53 is secured firmly to each guide tube 10 of assembly through the short tube 54.
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