Abstract
For the decommissioning of the French 1200 MWe Liquid Metal Fast Reactor SUPERPHENIX, twenty-five processes were selected to pierce liquid sodium trapping zones after draining of the main vessel. Four processes were chosen and closely studied: mechanical drilling, laser shooting, high pressure liquid cutting, replacement of liquid sodium by another heavier liquid.
Mechanical drilling was finally selected: some in-air tests at room temperature were performed with conventional machines, then some in-sodium tests at 180°C, using a prototype machine. The drilling conditions and tools, the chip recovering sequence and the efficiency of the scenario (four successive drilling operations in three piled plates) were validated: the liquid sodium was drained off.
