| 摘要 |
During unrodded refueling, the drive rods and the control rods and coolant-displacement rods, attached to the drive rods, are removed from a fuel assembly, preliminary to the transfer of the fuel assembly, and are reinserted in the reactor after a replacement fuel assembly has been positioned in the reactor. Prior to the transfer of a fuel assembly, a lifting rig is secured to the upper-internals support. A lift plate is removeably mounted on latches in a lower position of the lifting rig. The latches are released and the lift plate is connected to the drive rods. The lift plate is then raised and removeably mounted on latches in an upper position on the lifting rig. In this position, the control rods and coolant-displacement rods are in the guides in the upper internals of the reactor. During the lift-plate raising operation, the loading on the drive rods is monitored and if the loading exceeds a predetermined magnitude, the excess loading is indicated. After the lift plate and the rods suspended from it are positioned on the latches in the upper position, the lifting rig and the upper internals and rods attached to the lift plate are removed from the reactor so that the unrodded transfer of the fuel assemblies may proceed. The replacement of the rods proceeds reversely. In this case, the device which indicates excess loading of a drive rod operates to indicate that the control rod or coolant-displacement rod connected to the drive rod has encountered an obstruction.
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