Importance

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Abstract

A method of reconstituting a nuclear reactor fuel assembly having a top nozzle subassembly attached to the upper end of its control rod guide thimble wherein the subassembly includes an upper hold-down plate, a lower adapter plate, and a coils spring interposed between the two plates. A force is applied on the hold-down plate to compress the coil spring and transform the subassembly from its operation mode to a reconstitution mode. The wall of the thimble is severed just below a first attaching retainer mounted on the end of the thimble which defines the upward limit movement of the hold-down plate during the operation mode. Containing fingers are placed on the subassembly for removing it as a contained unit. The top nozzle subassembly or a new replacement subassembly is then replaced on the severed thimble in its reconstitution mode and a second attaching retainer is mounted on the upper end portion of the severed thimble in redefining the upward limit movement of the hold-down plate. The force is then released from the hold-down plate whereupon the top nozzle subassembly is transformed from its reconstitution mode to its operation mode.

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First Claim