At Casaccia’s Energy Research Center (CRE) of the Italian Commission for Nuclear and Alternative Energy Sources (ENEA), within the scope of testing activities for penetrating structures (mechanisms) of the Prova Elementi di Combustibile (PEC) reactor plug and of operating procedure acquisition for the PEC itself, a facility for the cleaning of mechanisms after in-sodium testing has been in operation for a number of years. The first phase of a component cleaning program is under way, based on the use of an organic solvent (2-butoxy-ethanol = ethylene glycol monobutyl ether = Butylcellosolve) and atomized water. Characterization activities were carried out in the laboratory on 2-butoxy-ethanol, and the sodium-2-butoxy-ethanol reaction rate was measured at from 35 to 60°C. A cleaning procedure for the prototypes of PEC mechanisms was defined after carrying out in-sodium test cycles. The final procedure used to clean the PEC mechanisms was developed by successive steps, and the entire task was divided as follows: 1. cleaning facility correspondence check 2. effectiveness of alcohol versus aqueous cleaning methods 3. effectiveness of vacuum procedure 4. effectiveness of the procedure for flood and alternate cycles of vacuum and pressurization on the 2-butoxy-ethanol liquid surface. The overall results of the testing have been used as the basis for determining a complete cleaning procedure suitable for all prototypes of the PEC mechanisms. The method selected is based on the utilization of 2-butoxy-ethanol. The nebulized water method is being used at present at Casaccia-CRE for cleaning other components with large values for the ratio of surface area to total sodium quantity. Nevertheless, a study is scheduled of a method using atomized water and carbon dioxide for the test cleaning of the fuel charge machine prototype.