Replacement of split-pin assemblies in nuclear reactor

Abstract

A pick-and-put tool, new-nut hopper and pin-insertion/torque tool for completing the installation of the new split-pin assembly in a lower guide tube under water after the old split-pin assembly has been severed into fragments. One fragment, located in the upper counterbore of the LGT, includes a portion of the old nut and the portion of the pin on which it is threaded. The pick-and-put tool includes a clamp and hydraulic cylinders for moving the clamp between a home position and an advanced position and for pivoting the clamp in each position. There is also a cylinder for raising or lowering the clamp in each position. The pick-and-put tool has stops which stop the movement of the clamp precisely in the home position or the advanced position and in their pivoted positions. The pick-and-put tool is mounted in the pool such that it can properly align with both the LGT and hopper. The clamp is first moved from the home position to the advanced position. In this position the clamp is precisely set by a stop to be pivoted into engagement with the LGT thus locating the jaws of the clamp about the fragment. After the clamp engages the fragment it is raised, raising the fragment from its counterbore in the LGT and clearing the LGT. The clamp is then returned to the home position where it is lowered and the fragment is released into a trash chute. After the upper counterbore is cleaned, the clamp is pivoted and precisely stopped so that it engages a new nut in the hopper. The clamp is raised then and is moved to the advanced position and then pivoted over the counterbore. The new nut is deposited in the counterbore.