Study of several potential exposure paths for on-site transport accident scenarios to define a French on-site Q-system
M.L. Perrin , Ph. Hubert , G. Sert
13th International Symposium on the Packaging and Transportation of Radioactive Materials, PATRAM 2001, September 3-7, 2001, Chicago, IL, USA
Following a request of the French Defence Transport Safety Committee, consideration has been given to the activity limits corresponding to exemption of package design approval by the competent authority for on site handling and transport of radioactive materials.
The study methodology is the same as the one used for the Q-system developed in the IAEA Safety Standards Series N° ST-2 under which a series of exposure routes are considered, each of which might lead to radiation exposure, either external or internal, to persons in the vicinity of a Type A package involved in a transport accident.
Specific assumptions concerning the exposure pathways are used along with radiological criteria which allow to determine, for individual radionuclides, the activity content limits for special form (non-dispersible) and non-special form (dispersible) authorised to be transported in Type A packages on a public road.
Then we reviewed the scenarios described in the Q-system, checked if the values of the parameters used in these scenarios (exposure times, distances, release fractions, etc.) should be kept or if they can be modified to make them correspond better to the real conditions of the transport performed within nuclear sites. When it was justified to modify some of the values, the impact of these changes on the activity contents limits was recalculated.
Finally we have built a system that is both consistent with the Q-system and specific to on site transports of radioactive materials. It yields to activity contents limits different from those authorised on a public road along with requirements specific to this type of transport, such as instructions to be applied by the drivers in case of on site incidents or accidents, transmission of alert, means of radiation detection or radiation protection equipment available to the drivers and the emergency staff.