A risk assessment for the transportation of radioactive materials in the USA

The radiological risk of transporting radioactive materials in the United States has been evaluated in terms of expected additional latent cancer fatalities (LCF). Two risks were estimated: that resulting from normal (accident-free) transport and that resulting from transportation accidents involving radioactive shipments. A standard shipment model was devised to represent the radioactive material shipping industry. The calculation of the normal transport risk included estimates of exposures to aircraft passengers and crew, truck drivers, cargo handlers, and population along the transport link. The accident risk calculation incorporated accident probabilities and package release fraction estimates. Dispersible materials were assumed to be aerosolized in severe accidents and the aerosol cloud transported downwind according to a Gaussian diffusion model. An annual normal transport risk of 9600 person-rem, or 1.2 LCF, resulted primarily from radiopharmaceutical shipments. The annual risk due to accidents was 5.6X10-4 LCF, resulting almost entirely from PuO2 shipments. (author)