Assesment of safety distances to be implemented in case of accident in radioactive material transportation
G. SERT, F. RANCILLAC , T. CLEACH, PATRAM, Berlin, 20-24th sept. 2004
ln order to improve the management of severe accidents in radioactive material transportation, France has reviewed the guide for drafting the transport emergency response plans of local authorities (PSS- TMR : Dedicated Response Plan -Radioactive Material Transportation). This guide includes instructions to the first teams acting on the site of an accident to set up a safety perimeter matching the hazards. The shape and amplitude of this perimeter has been evaluated by IRSN using the following pattern.
-Part One concerns the applicable dose criteria, in accordance with the existing regulations, so that the doses delivered to members of the public and response teams do not exceed the authorized thresholds.
-Part Two details the accident scenarios selected to represent most typical or possible accidents. A literature survey was conducted and about nine scenarios were selected for calculating the safety distances.
These scenarios cover the following situations:
.atmospheric release of radionuclides, either involving fire or DOt,
.increased radiation intensity following a damage to radiation protection.
-Part Three covers the calculation of safety distances associated with the selected scenarios. For each selected scenario, the paper describes the safety distances to be implemented as a result of the assumptions and calculation methods which are mentioned.
The results show that with some scenarios, no specific distance needs to be determined. But, with regard to low probability scenarios involving type B packages in more severe situations than the IAEA test conditions, safety distances appear highly sensitive to the release of radioactivity or to the damage to the radiation protection of the packaging. Also, the release scenarios associated with uranium hexafluoride and uranyl nitrate are characterized by safety distances in the order of one kilometre.