The risks and consequences from the transport of low specific activity materials by truck

The packaging and transport category of low specific activity (LSA) material was conceived for radioactive materials (RAM) that were considered inherently safe for transport. Such materials could be transported in strong, tight packages. The primary concern for the radionuclide content in LSA materials was associated with the potential for inhalation of particulate radioactive material. Thus, the specifications for the category in terms of specific activity were structured to preclude excessive inhalation hazard. The current version of the International Atomic Energy Agency (IAEA) regulations maintains the inhalation-related limits but also shows concern that the restrictions on the LSA category may not preclude an excessive external radiation hazard for gamma-emitting materials. This paper presents the results of an investigation of the potential for such excessive external radiation hazards, particularly for LSA materials with specific activity levels near the current regulatory limit. This paper discusses analyses that were performed to evaluate the potential radiological impacts of highway accidents leading to the release of high radiation level-low specific activity (HRL-LSA) materials from their packagings. The results of the analyses are intended to provide a basis for evaluating restrictions on the quantity of gamma-emitting radionuclides that can be contained in an LSA shipment. Consequences of a very severe accident were estimated to gauge the relative impact of three potential LSA specifications: (1) the current regulatory restriction on specific activity (0.3 millicuries per gram per radionuclide); (2) the specific activity consistent with a package dose-rate restriction of 1 rem/hr at 3 m from the package; (3) the specific activity consistent with a package dose-rate restriction of 1 rem/hr at 1 m from the package