2. Regulations governing the transport of radioactive substances Given that shipments can cross borders, the regulations governing the transport of radioactive substances are based on international requirements established by the International Atomic Energy Agency (IAEA). They are contained in the document entitled “Specific Safety Requirements – 6” (SSR-6), which constitutes the basis for European and French regulations on the subject. 2.1 Risks associated with the transport of radioactive substances The major risks involved in the transport of radioactive substances are: ∙ the risk of external irradiation of persons in the event of damage to the radiological shielding provided by the package (material which reduces the radiation in contact with the packages of radioactive substances); ∙ the risk of inhalation or ingestion of radioactive particles in the event of release of radioactive substances outside the packaging; ∙ contamination of the environment in the event of release of radioactive substances; ∙ the initiation of an uncontrolled nuclear chain reaction (criticality risk) that can cause serious irradiation of persons. This risk only concerns fissile substances. In addition, radioactive substances may also present a chemical risk. This, for example, is the case with shipments of natural uranium with low radioactivity, for which the major risk for humans is related to the chemical nature of the compound, more particularly if it is ingested. Similarly, UF6, used in the manufacture of fuels for NPPs can, in the event of release and contact with water, form hydrofluoric acid, a powerful corrosive and toxic agent. By their very nature, transport operations take place across the entire country and are subject to numerous contingencies that are hard to control or anticipate, such as the behaviour of other vehicles using the same routes. A transport accident at a given point in the country cannot therefore be ruled out, possibly in the immediate vicinity of the population. Unlike events occurring within BNIs, the personnel of the companies concerned are generally unable to intervene immediately, or even to give the alert (if the driver is killed in the accident) and the first responding emergency services are not in principle specialists in dealing with a radioactive hazard. To deal with these risks, specific regulations have been set up to regulate radioactive substance transport operations. 2.2 Principle of “Defence in Depth” In the same way as the safety of facilities, the safety of transport is based on the concept of “Defence in Depth”, which consists in implementing several technical or organisational levels of protection, in order to ensure the safety of the public, workers and the environment, in routine conditions, in the event of an incident and in the event of a severe accident. In the case of transport, “Defence in Depth” is built around three complementary levels of protection: ∙ The robustness of the package is designed to ensure that the safety functions are maintained, including in the event of a severe accident if the implications so warrant. To ensure this robustness, the regulations stipulate reference tests which the packages must be able to withstand. ∙ The reliability of the transport operations, which helps reduce the occurrence of anomalies, incidents and accidents. This reliability relies on compliance with the regulatory requirements, such as training of the various persons involved, the use of a quality assurance system for all operations, compliance with the package utilisation conditions, effective stowage of packages, etc. ∙ Management of emergency situations, so that the consequences of incidents and accidents are mitigated. For example, this third level entails the preparation and distribution of instructions to be followed by the various parties in the event of an emergency, the implementation of emergency plans and the performance of emergency exercises. The robustness of the packages is particularly important: the package must, as a last resort, offer sufficient protection to mitigate the consequences of an incident or accident (depending on the level of hazard represented by the content). 2.3 The requirements guaranteeing the robustness of the various types of package There are five main package types: excepted packages, industrial packages, type A packages, type B packages and type C packages. These package types are determined according to the characteristics of the material transported, such as total radiological activity, specific activity which represents the degree of concentration of the material, and its physicochemical form. The regulations define tests, which simulate incidents or accidents, following which the safety functions must still be guaranteed. The severity of the regulatory tests is graded according to the potential danger of the substance transported. Furthermore, additional requirements apply to packages carrying UF6 or fissile materials, owing to the specific risks these substances entail. 2.3.1 Excepted packages Excepted packages are used to transport small quantities of radioactive substances, such as very low activity radiopharmaceuticals. Due to the very limited safety implications, these packages do not undergo any reference tests. They must nevertheless comply with some general specifications, notably regarding radiation protection, to ensure that the level of radiation around the excepted packages remains very low. TABLE Breakdown of transported packages by type TYPE OF PACKAGE APPROXIMATE SHARE OF PACKAGES TRANSPORTED ANNUALLY Packages approved by ASN Type B packages, packages containing fissile materials and packages containing UF6 2% Packages not requiring approval by ASN Type A package not containing fissile radioactive substances 32% Industrial package not containing fissile radioactive substances 8% Excepted packages 58% 2 270 ASN Report on the state of nuclear safety and radiation protection in France in 2022 • 09 • Transport of radioactive substances 09
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