ASN Report 2018

1 —  The fuel cycle 1. Transuranic elements are chemical elements heavier than uranium. 2. Storage is temporary, while disposal is final. The uranium ore is extracted, then purified and concentrated into “yellow cake” on the mining sites. The solid concentrate is then transformed into uranium hexafluoride (UF 6 ) through a series of conversion operations. These operations are performed in the Orano Cycle plants in Malvési and Tricastin. These plants, which are regulated under the legislation for Installations Classified for Protection of the Environment (ICPE), use natural uranium in which the uranium-235 content is around 0.7%. Most of the world’s NPPs use uranium which is slightly enriched in uranium-235. For example, the Pressurised Water Reactors (PWR) require uranium enriched with the U-235 isotope. In France, uranium hexafluoride (UF 6 ) enrichment between 3% and 6% is carried out using an ultra-centrifuge process in the GB II plant at Tricastin. This enriched UF 6 is then transformed into uranium oxide powder in the Framatome plant in Romans-sur-Isère. The fuel pellets manufactured with this oxide are introduced into cladding to make fuel rods, which are then combined to form fuel assemblies. These assemblies are then placed in the reactor core where they release energy, notably through the fission of uranium-235 nuclei. Before it is used in the reactors, new nuclear fuel can be stored in one of the two Inter-Regional fuel Stores (MIR) operated by EDF in Bugey and Chinon. After a period of use of about three to four years, the spent fuel assemblies are removed from the reactor and cooled in a pool, firstly on the site of the plant in which they were used and then in the Orano Cycle reprocessing plant at La Hague. In this plant, the uranium and plutonium from the spent fuels are separated from the fission products and other transuranic elements (1) . The uranium and plutonium are packaged and then stored for subsequent re-use. However, at present, the uranium obtained from this reprocessing is no longer used to produce new fuels. The radioactive waste produced by these operations is disposed of in a surface repository if it is low-level waste, otherwise it is placed in storage pending a final disposal solution (2) . The plutonium resulting from the reprocessing of uranium oxide fuels is used in the Orano Cycle plant in Marcoule, called “Melox”, to fabricate MOX fuel (mixture of uranium and plutonium oxides) which is used in certain 900 MWe nuclear power reactors in France. The MOX nuclear fuels are not reprocessed after being used in the reactors. Pending reprocessing or disposal, the spent MOX fuels are stored at the La Hague plant. The main material flows for the fuel cycle are presented in Table 1. Other facilities are needed for the operation of the Basic Nuclear Installations (BNI) mentioned above, more particularly the ex-Socatri facility, which is responsible for the maintenance and decommissioning of nuclear equipment, as well as the treatment of nuclear and industrial effluents from the Orano Cycle platform in Tricastin. CHAPTER 11 Nuclear fuel cycle installations T he nuclear fuel cycle begins with the extraction of uranium ore and ends with packaging of the various radioactive wastes from the spent fuels so that they can be sent for disposal. In France, the last uraniummines were closed in 2000, so the fuel cycle concerns the fabrication of the fuel and then its reprocessing once it has been used in the nuclear reactors. The licensees of the cycle plants are part of the Orano Cycle (formerly Areva NC) or EDF (Framatome, formerly Areva NP)groups: Orano Cycle operates Melox in Marcoule, the La Hague plants, all the Tricastin plants since 31 December 2018, as well as the Malvési facilities. Framatome operates the facilities on the Romans-sur-Isère site. ASN monitors the safety of these industrial facilities, which handle radioactive substances such as uranium or plutonium and constitute specific safety risks, notably radiological risks associated with toxic risks. ASN monitors the overall consistency of the industrial choices made with regard to fuel management and which could have consequences for safety. In this context, ASN periodically asks EDF to submit a “Cycle Impact” file prepared jointly with the fuel cycle stakeholders and presenting the consequences - for each step of the nuclear fuel cycle - of EDF’s strategy for using the different types of fuel in its reactors. 318  ASN report on the state of nuclear safety and radiation protection in France in 2018