Boston's vast port nestles close to the skyscrapers of the city's financial district. 1, 500 vessels come in and out of here each month, mostly large container ships carrying gas and petroleum products.
Aside from the sheer inconvenience of having to call for assistance or hike to the nearest gas station (and hope they have a fuel container available), suddenly hitting empty can put a driver and passengers in peril.
Used fuel that has been cooled in a spent fuel pool for at least five years can be put into a container called a cask and surrounded with inert gas, providing leak-tight containment, according to the U.S. Nuclear Regulatory Commission.