REVIEW OF MATERIAL REQUIREMENTS OF THE IAEA TRANSPORT REGULATIONS FOR LSA-II AND LSA-III

In accordance with the safety concept of the IAEA Transport Regulations the package as combination of packaging and contained radioactive material has to provide required safety functions in all conditions of transport. Since Type IP-2 packages and Type IP-3 packages only have to protect against loss or dispersal of their contents under normal conditions of transport, IP packagings for LSA-II and LSA-III have only limited accident resistance. Consequently, the material properties required for LSA-II and LSA-III are mainly based on accident considerations and limitation of potential radiological consequences. Examples are: • limiting the specific activity of LSA material to 10-4 A2/g for solid LSA-II and to 2×10-3 A2/g for LSA-III, • homogeneity requirements regarding the distribution of radioactivity within the LSA material, • for LSA-III only solid materials are allowed and powders are explicitly excluded, • the requirement of a leaching test for LSA-III materials, • the dose rate limit for the unshielded LSA-II or LSA-III material, • conveyance activity limits for the transport of combustible LSA-II and LSA-III materials. In the case of LSA-II material it is quite apparent by review of the historical development and current advisory material that the specific activity limit of 10-4 A2/g was introduced regarding transport and handling accidents connected with airborne release. In contrast, the corresponding reasoning for the justification of the 20-fold higher specific activity limit of 2×10-3 A2/g for LSA-III materials is not that evident since the leaching test examines a material property which has hardly any connection with the majority of accident sequences and with airborne release. The LSA-II and LSA-III material requirements were introduced into the Regulations in the early 70s of last century. In the meantime much progress has been achieved internationally regarding knowledge of material characteristics of LSA-II and LSA-III and release behavior in accident conditions. It is shown that the factor of 20 in specific activity of LSA-III material compared to LSA-II has sufficient safety margins and results from other currently required material properties than those involved in the leaching test.