The in-vessel fuel manipulators

The task of the two in-vessel fuel handling machines is to move fuel assemblies in the vessel between the core, the in-vessel fuel storage and the (un)loading stations. The fuel handling is performed under the bottom of the core.

The core compactness and the fact that the room situated directly above the core will be occupied by lots of instrumentation and IPS's + the interference of the core with the spallation loop and proton beam, means there is no room for a fuel handling machine to (un)load the core from above. Furthermore, due to the buoyancy force of the heavy PbBi, the fuel assemblies will float up if they would be simply dropped without locking on a support plate. Therefore it was opted for a system in which the fuel handling is performed from the bottom of the core. In this concept, the fuel assemblies rest by buoyancy under the core support plate. The two in-vessel fuel transfer machines are inserted in a penetration of the reactor cover on opposite sides of the core. Each system has a rotating plug (with rotation amplitude of at least 270°) with an offset arm and gripper.

The arm can rotate in the rotating plug (also with a rotation possibility of at least 270°) and so has access to half of the core. The arm can move up and down (vertical motion of about 2 m) to extract the assemblies from the core. The extremity of the arm has a gripper which gives the adequate orientation to the fuel assembly (rotation amplitude of at least 180°) before its insertion into the core. The gripper is foreseen with a nozzle aligning mechanism (two angular plates), and with a locking mechanism (two sliding tubes with groove and balls) and with a notch/pin system to assure the correct orientation of the fuel assembly.