REGULATORY CRITICALITY SAFETY REVIEW OF URANIUM HEXAFLUORIDE TRANSPORT PACKAGE APPLICATIONS

Uranium hexafluoride (UF6) has been safely transported across the world in 30B cylinders for many decades; however past history, although a good indication, does not guarantee future performance. As a UK regulator for the transport of radioactive material, applications for UK transport package approval are received from all over the world. Judgement of their safety can only be made on the information provided in the safety case. The criticality safety of a number of uranium hexafluoride transport applications have been recently reviewed. Assumptions have been made regarding the thickness of the 30B cylinder steel shell, the distribution of the hydrogen fluoride (HF) impurities and the potential for the uranium hexafluoride residues to hydrolyse. These assumptions each have an impact on the criticality safety of the package and will be discussed in turn. From the results presented in this paper, it is considered that criticality safety cases which do not claim for the presence of the overpack will have difficulty in justifying that transporting uranium hexafluoride in these packages will be acceptable from a criticality safety perspective.