1 The “fuel cycle” 1. Transuranic elements are chemical elements heavier than uranium (atomic number 92). The main ones are neptunium (93), plutonium (94), americium (95), curium (96). In a reactor, they are derived from uranium during secondary reactions other than fission. 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 (UF6) following conversion operations. These operations are performed in the Orano plants in Malvési and Tricastin. These plants, which are regulated under the legislation for Installations Classified for Protection of the Environment (ICPEs) use natural uranium in which the uranium-235 content is around 0.7%. Most of the world’s nuclear power reactors use uranium slightly enriched with uranium-235. The Pressurised Water Reactor (PWR) series for example requires uranium enriched with isotope-235. In France, UF6 enrichment between 3% and 6% is carried out by ultracentrifuges in the Georges Besse II (GB II) plant in Tricastin. This enriched UF6 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. Irradiation of these assemblies in the core leads to the creation of plutonium. 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. In 2023, Framatome also took over the fabrication of fuel assemblies based on Enriched Reprocessed Uranium (URE) intended for the Cruas-Meysse Nuclear Power Plant (NPP). After a period of use of about 3 to 4 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 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. The plutonium resulting from the reprocessing of uranium oxide fuels is used in the Melox plant operated by Orano in Marcoule, to fabricate MOX (Mixed OXides) fuel which is used in certain 900 MWe NPPs reactors in France. The MOX nuclear fuels are not currently reprocessed after being used in the reactors. Pending their reprocessing or disposal, the spent MOX fuels are stored in the pools of the La Hague plant. The main material flows for the “fuel cycle” are presented in Table 1 (see next page). Other facilities are needed for the operation of the Basic Nuclear Installations (BNIs) mentioned below, more particularly the IARU facility (formerly Socatri), which is responsible for the maintenance and decommissioning of nuclear equipment, as well as the treatment of nuclear and industrial effluents from the Orano platform in Tricastin. 1.1 The front-end “fuel cyle” Before fuels are fabricated for use in the reactors, the uranium ore must undergo a number of chemical transformations, from the preparation of the Yellow Cake through to conversion into UF6, the form in which it is enriched. These operations take place primarily on the Orano sites of Malvési, in the Aude département, and Tricastin in the Drôme and Vaucluse départements (also known as the Pierrelatte site). On the Tricastin site, Orano operates: ∙the TU5 facility (BNI 155) for conversion of uranyl nitrate, produced by reprocessing spent fuel at La Hague into triuranium octoxide (U3O8); ∙the W plant (ICPE within the perimeter of BNI 155) for converting depleted UF6 into U3O8; ∙the former Comurhex facility (BNI 105) for converting uranium tetrafluoride (UF4) into UF6, which contains the Philippe Coste plant; ∙the GB II (BNI 168) UF6 ultra-centrifuge enrichment facility; ∙the Atlas analysis laboratory (BNI 176); ∙areas for the storage of uranium and thorium in various forms (BNI 93, 178, 179 and 180); ∙the IARU facility (BNI 138 – formerly Socatri) which manages waste from the Tricastin site and carries out nuclear equipment maintenance and decommissioning; ∙a Defence Basic Nuclear Installation (DBNI) which more particularly operates the radioactive substances storage areas, virtually all of which are for civil uses. The TU5 facility and the Orano W plant – BNI 155 BNI 155, called “TU5”, can handle up to 2,000 tonnes (t) of uranium per year, enabling it to reprocess all the uranyl nitrate produced by the Orano plant at La Hague, converting it into U3O8 (a stable solid compound able to guarantee safer uranium storage conditions than in liquid or gaseous form). Once converted, the reprocessed uranium is placed in storage on the Tricastin site. The Orano uranium conversion plants – BNI 105 BNI 105, which notably transformed reprocessed uranyl nitrate into UF4 or U3O8, is being decommissioned (see chapter 14). The Philippe Coste plant is located inside its perimeter and is devoted to the fluorination of UF4 into UF6, to allow its subsequent enrichment in the GB II plant. It has a production capacity of about 14,000 t of UF6 from the UF4 coming from the Orano facility in Malvési. It has ICPE status subject to authorisation with institutional controls (“Seveso” class installation) and is monitored by ASN accordingly. The Georges Besse II ultra-centrifuge enrichment plant – BNI 168 BNI 168, called “GB II”, for which creation was authorised in 2007, is a plant enriching uranium by means of gas ultra-centrifugation. This process involves injecting UF6 into a cylindrical vessel rotating at very high speed. Under the effect of the centrifugal force, the heavier molecules (containing uranium-238) are separated from the lighter ones (containing uranium-235). By combining several centrifuges, creating a cascade, it is then possible to recover a stream of uranium enriched with fissile 235 isotope and a depleted stream. The GB II plant comprises two enrichment units (South and North units) and a support unit, REC II. On 19 June 2023, Orano sent the Minister in charge of nuclear safety a substantial modification authorisation application, with the aim of increasing the nominal production capacity of the GB II plant by 30%. Enrichment of the uranium resulting from reprocessing, which would require prior authorisation from ASN, is not currently carried out in this plant. The Atlas facility – BNI 176 The purpose of the Atlas facility is: ∙to carry out industrial physico-chemical and radio-chemical analyses; ∙to monitor liquid and atmospheric discharges and monitor the environment of the Tricastin facilities. The Atlas facility, commissioned in 2017, meets the most recent safety requirements. 336 ASN Report on the state of nuclear safety and radiation protection in France in 2024 “Nuclear fuel cycle” facilities
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