A method includes operating a gas loading system with a source of one or more isotopes of hydrogen, a gas loading chamber containing a number of metallic nanoparticles, the metallic nanoparticles being selected to provide for a predetermined hydrogen cluster formation density, a vacuum system, and a valve system in communication with the gas loading chamber, the source of one or more isotopes of hydrogen and the vacuum system; providing the gas loading chamber with a first quantity of the one or more isotopes of hydrogen from the source of one or more isotopes of hydrogen; monitoring an operating temperature; and cycling a loading pressure of the gas loading chamber using the source of one or more isotopes of hydrogen in response to providing the gas loading chamber and monitoring the operating temperature.