In February 1995, Japan took back its first shipment of vitrified HLW, resulting from spent fuel reprocessing, from France. Plans are for one or two shipments a year from France or Britain until 2010, for a total of about 3,000 canisters. Plans also include avoidance of U.S. waters. At a number of these stages for example, as yellowcake or UO2 the material poses very little hazard, radioactive or otherwise. National and international regulations concentrate on the more hazardous stages, such as UF6 and spent fuel.
Extra safety comes from overpacks of foam cushioning material.
Transport of highly radioactive spent fuel and separated plutonium is the most stringently regulated. Safety, from a regulatory point of view, always relies on the integrity of packaging, not on the means of transport. They can be 20 feet or more in length and 3.5 to 8 feet in diameter. Exposure to an environment of 1,475 degrees F for 30 minutes. Submersion in 50 feet of water for not less than eight hours.