ASN Report 2017

314 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 11  - Transport of radioactive substances ཛྷ ཛྷ contamination of the environment in the event of a release of radioactive substances; ཛྷ ཛྷ the onset of an uncontrolled nuclear chain reaction (criticality risk) that can cause serious irradiation of persons. This risk only concerns fissile substances. Radioactive substances can also present a chemical risk. This, for example, is the case with shipments of natural uraniumwith 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, uranium hexafluoride, used in the manufacture of fuels for nuclear power plants can, in the case 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 Basic Nuclear Installations (BNI), the personnel of the companies concerned are generally unable to intervene immediately, or even 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 handle 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 guarantee 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: ཛྷ ཛྷ The robustness of the package is designed to ensure that the safety functions are maintained, including in the event of a severe accident and if the implications so warrant. To guarantee this robustness, the regulations stipulate reference tests which the packages must be able to withstand. ཛྷ ཛྷ The reliability of the transport operations minimises the occurrence of anomalies, incidents and accidents. This reliability is guaranteed by 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. ཛྷ ཛྷ Emergency situationmanagement enables the consequences of incidents and accidents to be 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. A transport accident can in theory occur anywhere and could be remote from specialised emergency response services. Consequently, the robustness of the packages is particularly important: the package must, as a last resort, offer sufficient protection tomitigate 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 severe accidents, following which the safety functions must still be guaranteed. The severity of the regulation tests is appropriate to the potential danger of the substance transported. Furthermore, additional requirements apply to packages carrying uranium hexafluoride 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 issues, these packages are not subject to any qualification tests. They must nevertheless comply with a certain number of general specifications, notably with regard to radiation protection, to guarantee that the radiation around the excepted packages remains very low. 2.3.2 Type A packages and industrial packages containing non-fissile substances Type A packages can, for example, be used to transport radioisotopes for medical purposes commonly used in nuclear medicine departments, such as technetium generators. The total activity which can be contained in a type A package is limited by the regulations. Type A packages must be designed to withstand incidents which could be encountered during transportation or during handling or storage operations (small impacts, package stacking, falling of a sharp object onto the packages, exposure to rain). These situations are simulated by the following tests: ཛྷ ཛྷ exposure to a severe storm (rainfall reaching 5 cm/hour for at least 1 hour); ཛྷ ཛྷ drop test onto an unyielding surface from a height varying according to the mass of the package (maximum 1.20 m); ཛྷ ཛྷ compression equivalent to 5 times the weight of the package; ཛྷ ཛྷ penetration by dropping a standard bar onto the package from a height of 1m. Additional tests are required if the content of the package is in liquid or gaseous form. Industrial packages allow the transportation of material with a low specific activity, or objects with limited surface contamination. Uranium-bearing materials extracted from foreign uranium mines are, for example, carried in France in industrial drums with a capacity of 200 litres loaded into