Modeling the Plastic Strain of 48\" UF 6 Cylinders Exposed to the IAEA Fire Test

As part of the continuing review of its regulations for the transport of radioactive materials, the IAEA has established a Coordinated Research Programme to study the behaviour of UF 6 cylinders under fire exposure conditions. This Paper provides a review of recent work by British Nuclear Fuels pic, associated with that CRP. Earlier modelling studies have shown that the bounds of uncertainty on the available models meant that neither survival nor failure of a fully loaded 48\" UF 6 cylinder, exposed to the standard IAEA fire test, could be confidently predicted. Plastic strain analysis, taking account of thermal and pressure stresses, has been carried out for the UF 6 cylinder. This finite element computation included heat transfer, thermal stress, and mechanical stress analyses to predict the temperatures, stresses, displacements and strains that could be induced into the structure of the container after 30 minutes exposure to an 800°C fire.