Goldberg [G7] has listed a number of procedures that have been used for removing or deactivating sodium adhering to LMFBR assemblies. Use of a relatively nonvolatile alcohol, such as the я-butyl ether of ethylene glycol, is reported [C8] to remove sodium metal and oxide completely in 24 h. A difficulty is subsequent complete removal of solvent. Reaction with water vapor carried by an inert gas such as argon has been used extensively to deactivate sodium adhering to fuel assemblies. The principal disadvantage is the residue of sodium hydroxide, which reacts with acid in subsequent dissolution. Amalgamation with mercury has been used in the United Kingdom and the United States. In one application, mercury removed sodium from a 40-fuel-pin batch in 0.5 h [В15]. In the Soviet Union [S12], molten lead at 400 to 500°C has been used to wash sodium from fuel assemblies and as a substitute for water in storage of fast-reactor fuel for extended periods. A disadvantage in reprocessing is the layer of lead that coats the fuel. Sodium was washed from fuel assemblies from the Enrico Fermi LMFBR [K2] by ultrasonic cleaning with a high-boiling hydrocarbon oil at a temperature above the melting point of sodium. A disadvantage is the need to remove the flammable oil before voloxidation.

Thus, all methods have disadvantages. Deactivation with moist argon seems the simplest.