MCO CLOSURE TOOL: A PNEUMATIC/HYDRAULIC TOOL FOR CLOSING THE CANISTERS AT HANFORD

The U.S. Department of Energy is retrieving spent nuclear fuel from the Hanford K Basins for storage in specially designed Multi-Canister Overpacks (MCOs). An MCO Closure Tool system was developed to close and seal the MCOs by semi-manually installing a 400 lb locking/lifting ring. The tool must apply a 70 ton force to compress a metal closure seal. The locking/lifting ring has an external buttress thread around its periphery and is installed by threading into the top collar of the MCO canister. Both the locking/lifting ring and the collar are fabricated from austenitic stainless steel, thus having potential to gall during the ring installation process. To minimize this, design criteria were established to suspend the ring in a manner that removes virtually all of the weight of the locking/lifting ring from the threads. The tool operation accomplishes this task by suspending the closure tool and the locking/lifting ring payload assembly directly above the canister collar via a low internal friction pneumatic cylinder. The cylinder, in conjunction with a precision relieving regulator, is pressurized until the 925 lb load is precisely balanced and can extend or retract effortlessly in the vertical direction. This nearweightless condition largely eliminates the galling tendency. After the threading operation is complete, an integral hydraulic cylinder applies the 70 ton force to compress the seal while the securing operation is completed to permanently hold the sealing load.