| 摘要 |
PURPOSE:To decrease the number of fuel failures by providing lattices of a lattice body for fuel exchange so as to align to the perpendicular line of the lattices of the reactor core lattice plates in the upper part of a reactor core shroud. CONSTITUTION:The lattice body for fuel exchange is put on the upper part of the reactor core by using a crane and tongue parts 16 before the fuel exchange is executed after the shut down of a nuclear reactor. Since a cylinder 11 for supporting the lattice plates has the same diameter as the diameter of the reactor core shroud, said cylinder can be installed in the form similar to the core shroud head to the top end of the core shroud 15 where the core shroud head is installed during operation. Guide pins 17 for the lower part of the cylinder 11 are provided in 0 deg. and 180 deg. positions to prevent the lattice direction of the lattice plates 12 for fuel exchange from deviating from the lattice direction of the lattice plates 19 in the upper part of the reactor core. These guide pins 17 are inserted into guide blocks 18 existing in the same position as the position of the shroud 15, by which the lattice body for fuel exchange can be surely installed in such a manner that the lattice directions face each other. The fuel exchange is executed by inserting a fuel clamper 5 hanging from a fuel exchanger into the cylinder from the spacings between the lattice plates 12 and clamping and lifting a fuel assembly 6.
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