There is an upper limit of radiation dose emitting from the transport package that is limited by federal regulation. This creates an upper bounding radiation limit, such that no member of the public can be exposed to unacceptable levels of radiation no matter how close they are to the transport package, e.g., in the rail yard, at railway crossings etc. The limit is only slightly more than a typical chest x-ray and is not considered harmful. Actual dose rates vary depending on the cask, but are typically much lower than the upper limit. The NRC conducted a comprehensive risk analysis (NUREG – 2125, Spent Fuel Transportation Risk Assessment) for the transportation of spent nuclear fuel under routine and accident conditions. The analysis concluded the radiation dose to members of the public for routine spent fuels shipments would be less than 1/1000 the amount of radiation the general public receives from background radiation annually.
