Evaluation of the safety factors for radioactive material transport packagings under severe fire conditions

The international Regulations for the Safe Transport of Radioactive Materials guarantee a high level of safety, achieved mainly by a packaging design which is suited to the potential risk inherent in the materials being transported. In fact, many of the packages used at present are designed so that they behave satisfactorily in environmental conditions which are much more severe than the regulatory conditions. Any risk evaluation should be made with data which are as realistic as possible, including the behaviour of the packaging in relation to the nature of the accident (fire, collision, immersion and so on) and the associated source term. This is a basic objective for the validation of codes such as INTERTRAN developed by the IAEA. For all these reasons, a databank is needed on the behaviour of the main packagings used. Fire is an example of an accident environment which should be considered for two reasons: the probability of fires occurring with durations and temperatures greater than the conditions applied to Type B packages (800 deg. C for 30 min) is not insignificant, particularly in the case of air and sea transport, and the associated risk may be considerable (transfer by inhalation). Studies have been conducted to identify safety factors for the packagings. These studies have been carried out in some cases by calculations and in others by tests. The paper presents the results obtained for different types of packagings; they show a high safety factor by comparison with regulatory fire conditions (800 deg. C for 30 min). (author)