Assessment of the Radiological Risks of Road Transport Accidents Involving Type a Packages

Abstract

An assessment and evaluation of the potential radiological risks of transport accidents involving Type A package shipments by road have been pelformed by five EU Member States, France, Germany, Sweden, The Netherlands, and the UK. The analysis involved collection and analysis of information on a national basis related to the type, volume, and characteristics of Type A package consignments, the associated radioactive traffic, and the expected frequency and consequences of potential vehicular road transport accidents. It was found that the majority of Type A packaged radioactive material shipments by road is related to applications of non-special form radioactive material, i.e. radiopharmaceuticals, radiochemicals etc., in medicine, research, and industry and special form material contained in radiography and other radiation sources, e.g. gauging equipment. The annual volumes of Type A package shipments of radiopharmaceuticals and radiochemicals by road differ considerably between the participating EU Member States from about 12,000 in Sweden to about 240,000 in the Netherlands. The broad range reflects to a large extent the supply of radioactive material for the national populations and the production and distribution operations prevailing in the participating EU Member States (some are producer countries, others are not!). Very few standard package designs weighing from about 1–25 kg are predominant in Type A package shipments in all participating countries. Type A packages contain typically a range of radioactivity from a few mega becquerels to a few tens of giga becquerels, the average package activity contents is in terms of fractions of A₂ about 0.01, i.e. about one hundredth of the Type A package contents limits. Based on a probabilistic risk assessment method it has been concluded that the expected frequencies of occurrence of vehicular road transport accidents with the potential to result in an environmental release—including radiologically insignificant quantities—range from about 0.002 per year for Sweden to about 0.08 per year for Germany; this is on average consistent with a chance of one severe accident event involving Type A packages shipments in 12 to 500 years on publicly accessible roads in the participating EU Member States. The expected likelihood of occurrence of vehicular road transport accidents on public roads severe enough to give rise to a significant environmental release is markedly lower. Information to describe accurately the potential accidental radiological consequences, e.g. in terms of the associated environmental radionuclide release or dose to the population, has been found to be incomplete at this stage of the assessment and requires further research work. However, the quantity of radioactive material contained in a Type A package is principally controlled by the provisions of the Regulations. The survey results available indicate that standard Type A packages contain on average only a fraction of about one hundredth of the maximum permissible Type A package contents limit (A₂-value). Therefore, the radiological consequences of potential transport accidents involving Type A package shipments are principally limited. The coordinated efforts undertaken within the EC-funded research project by several EU Member States have resulted in unique transport safety databases on Type A packaged radioactive material shipments. These databases are understood to be valuable to both national agencies and international organisations, e.g. the IAEA, with responsibilities for the safe transport of radioactive material by providing (a) input to the continuous regulatory review and revision process and (b) insight into the carriage of radioactive material by road which makes up a major fraction of radioactive material shipments worldwide. The collated material is also considered to be very valuable by supporting current international efforts in the development of transport safety databases on events, radioactive material shipments and radiation exposures by the International Atomic Energy Agency (IAEA). Research needs have been identified in the field to describe accurately the radiological consequences following a road transport accident depending on the likelihood of vehicular road transport accident events by severity, the shipping conditions of Type A packaged radioactive materials, the Type A package response and release behaviour for the credible range of impact load conditions prevailing in road transport accidents including fire and non-fire environments and the subsequent dispersal and population exposure conditions at the site of the accident.