A system and method for storing high level waste. In one aspect, the invention is a system comprising: an outer shell having an open top end and a hermetically closed bottom end; an inner shell forming a cavity, the inner shell positioned inside the outer shell so as to form a space between the inner shell and the outer shell; at least one passageway connecting the space and a bottom portion of the cavity; at least one passageway connecting an ambient atmosphere and a top portion of the space; a lid positioned atop the inner shell, the lid having at least one passageway connecting the cavity and the ambient atmosphere; and a seal between the lid and the inner shell so at form a hermetic lid-to-inner shell interface.