Stowage during transport. A proposal for harmonization

For stowage and retention during transport, the International Atomic Energy Agency (IAEA) transport regulations (SSR-6) only require that the package shall be securely stowed. Additional information is given in the IAEA guidance material (SSG-26), that includes specific load factors that should be considered in the safety demonstrations. Nevertheless, applicants commonly use other load factors to justify the design of the packaging attachment points. In particular, acceleration values vary between different countries and this may lead to difficulties during the validation of foreign approval certificates. Discussions with applicants identified that the load factors presented in the IAEA guidance material are not necessarily relevant for the different transport modes. For some modes, the load factors are representative of situations occurring in routine conditions of transport. For other modes, the load factors are more representative of situations occurring in normal or accident conditions of transport. Furthermore, the origins of the specified values are not clear. In this context, some IAEA TRANSSC members decided to review the stowage guidance. An international working group was constituted in 2013, including representatives of competent authorities, technical support organizations, and transport stakeholders. Several topics were discussed and many questions were raised during the two year review. For example, some discussions focused on the conditions which have to be considered for stowage design, both as relevant to the load factors used for strength and fatigue analysis, as well as the criteria which have to be considered for the package attachment points. In addition, related questions on operational aspects were also discussed. Overall, the working group concluded that new guidance material was warranted as input into SSG-26. As a result of those discussions, the international working group produced new guidance material for stowage in transport, addressing each of these topics. The proposal to modify the IAEA guidance material (SSG-26, Appendix IV), presented by France to the TRANSSC in the 2015 initiated review cycle of the Regulations, was unanimously accepted and will be implemented in the next edition of the guidance material. (author)