The Multi-Purpose Canister (MPC) has been the workhorse for the dry spent fuel storage industry in the United States since the mid-90s. The MPC is an all-welded stainless steel container with the final closure lid welded to the shell after the fuel is loaded inside. The field weld (lid-to-shell) is given an extra layer of protection by welding a closure ring or plate that completely envelopes the primary MPC lid weld. Hundreds of Holtec MPCs have been deployed across the U.S. and overseas without a single report of in-storage leakage. However, some utilities may wish for the added protection of a second barrier, as adopted by Energoatom in Ukraine and EDF in the United Kingdom.