ASN Report 2020

1.2  Fuel fabrication The fabrication of fuel for electricity generating reactors involves the transformation of UF 6 into uranium oxide powder. The pellets fabricated from this powder in the Framatome “FBFC” plant in Romans-sur-Isère (BNI 98) are placed in zirconium metal cladding to constitute the fuel rods, which are then grouped together to form the fuel assemblies. The fuels used in the experimental reactors are more varied and, for example, some of them for example use highly-enriched uranium in metal form. These fuels are fabricated in the Framatome plant at Romans-sur-Isère usually called Cerca (BNI 63). The MOX fuel is fabricated in BNI 151 Melox, operated by Orano and located on the Marcoule nuclear site. 1.3  The back-end fuel cycle – reprocessing The Orano reprocessing plants in operation at La Hague The La Hague plants, intended for reprocessing of spent fuel assemblies from nuclear reactors, are operated by Orano. The various facilities of the UP3-A (BNI 116) and UP2-800 (BNI 117) plants and of the STE3 (BNI 118) Effluent Treatment Station were commissioned from 1986 (reception and storage of spent fuel assemblies) to 2002 (R4 plutonium reprocessing facility), with most of the process facilities entering service in 1989-1990. The Decrees of 10 January 2003 set the individual reprocessing capacity of each of the two plants at 1,000 tonnes per year (t/year), in terms of the quantities of uranium and plutonium contained in the fuel assemblies before burn-up (in the reactor), and limit the total capacity of the two plants to 1,700 t/year. The limits and conditions for discharges and water intake by the site are defined by two ASN resolutions of 22 December 2015 (resolu­ tion 2015‑DC‑0535 and resolution 2015-DC-0536). Operations carried out in the plants The reprocessing plants comprise several industrial units, each of which performs a specific operation. Consequently there are facilities for the reception and storage of spent fuel assemblies, for their shearing and dissolution, for the chemical separation of fission products, uranium and plutonium, for the purification of uranium and plutonium, for treating the effluents and for packaging the waste. When the spent fuel assemblies arrive at the plants in their transport casks, they are unloaded either “under water” in the spent fuel pool, or dry in a leaktight shielded cell. The fuel assemblies are then stored in pools for cooling. The fuel assemblies are then sheared and dissolved in nitric acid to separate the pieces of metal cladding from the spent nuclear fuel. The pieces of cladding, which are insoluble in nitric acid, are removed from the dissolver, rinsed in acid and then water, and transferred to a compacting and packaging unit. The nitric acid solution comprising the dissolved radioactive substances is then processed in order to extract the uranium and plutonium and leave the fission products and other transuranic elements. After purification, the uranium is concentrated and stored as uranyl nitrate UO 2 (NO 3 ) 2 . It will then be converted into a solid compound (U 3 O 8 ) called “reprocessed uranium” in the TU5 facility on the Tricastin site. After purification and concentration, the plutonium is precipit­ ated by oxalic acid, dried, calcined into plutonium oxide, packaged in sealed containers and stored. It is then intended for the fabrication of MOX fuels in the Orano plant in Marcoule (Melox). The effluents and waste produced by the operation of the plants The fission products and other transuranic elements resulting from reprocessing are concentrated, vitrified and packaged in standard vitrified waste packages (CSD-V). The pieces of metal cladding are compacted and packaged in standard compacted waste packages (CSD-C). These reprocessing operations also use chemical and mechanical processes, the operation of which generates gaseous and liquid effluents as well as solid waste. The gaseous effluents are are given off mainly when the fuel assemblies are sheared and during the dissolution process. These gaseous effluents are treated by washing in a gas treatment unit. The residual radioactive gases, particularly krypton and tritium, are checked before being discharged into the atmosphere. The liquid effluents are processed and generally recycled. After verification and in accordance with the discharge limits, certain radionuclides, such as iodine and tritium, are sent to the marine outfall pipe. The other effluents are routed to on-site packaging units (solid glass or bitumen matrix). The solid waste is packaged on-site, either by compacting, or by encapsulation in cement, or by vitrification. The solid radioactive waste from the reprocessing of spent fuel assemblies from French reactors is, depending on its composition, either sent to the low level and intermediate-level, short-lived waste (LLW/ILW-SL) repository at Soulaines (see chapter 14) or stored on the Orano site at La Hague, pending a final disposal solution (in particular the CSD-V and CSD-C). In accordance with Article L. 542-2 of the Environment Code, radioactive waste from the reprocessing of spent fuels of foreign origin is shipped back to its owners. It is however impossible to physically separate the waste according to the fuel from which it originates. In order to guarantee an equitable distribution of the waste resulting from the reprocessing of the fuels of its various customers, the licensee has proposed an accounting system that tracks the entries into and exits from the La Hague plant. This system, called Exper system, was Tricastin site Philippe Coste plant GB II TU5 and W ex-Socatri Tricastin uranium storage areas P35 Atlas Romans-sur-Isère facility FBFC Cerca Malvési site ex-Comurhex Marcoule site Melox La Hague facility UP3 UP2-800 STE3 Installations of the fuel cycle in operation or undergoing decommissioning ASN Report on the state of nuclear safety and radiation protection in France in 2020 325 11 – “NUCLEAR FUEL CYCLE” INSTALLATIONS 11