The design of nuclear transport frames for fatigue loadings utilising FEA

Nuclear transport packages are typically attached to the transport trailer through the use of a transport frame. The IAEA transport regulations do not provide guidance on the design of the Tie-Down System or Transport Frame during Routine Conditions of Transport. The onus therefore falls on the design of such systems to prove that the design is appropriate and able to withstand the loadings experienced during transport. TCSC 1006 provides some guidance on the design of such items for transport. The increased use of Finite Element Analysis to analyse these structures is increasingly prevalent. Such transport frames typically have complex load paths under a variety of loading conditions (such as normal and accident conditions of transport) which can cause premature failure if the correct design considerations are not implemented. As they are typically steel structures there is potential for fatigue failure to occur due to routine conditions of transport especially through design features such as the welds. This paper discusses an approach for assessing a nuclear transport frame for fatigue loadings that would typically be experienced during routine conditions of transport. The paper discusses the cyclic loadings caused by routine conditions of transport, their provenance and how these can be utilised in a FEA model to determine stresses within the system. The paper describes the application of BS 7608 to the analysis of such structures. The paper includes recommendations whereby the designer can improve fatigue life of the product through the application of various weld parameters and design features in order to provide a robust solution to the issues caused by fatigue loading.