ASN Report 2018

1 —  Research facilities, laboratories and other facilities in France 1.1  ̶  Research reactors The purpose of research reactors is to contribute to scientific and technological research and to improve the operation of the nuclear power plants. Some of these facilities also produce radionuclides for medical uses. They are facilities in which a chain reaction is created and sustained, to produce a neutron flux of varying density, used primarily for scientific experimentation purposes. Unlike in nuclear power plants, the energy produced by research reactors is not recovered and is in fact a “by-product” removed by cooling. The quantities of radioactive substances used are smaller than in nuclear power reactors. Each research reactor is a specific facility, for which ASN adapts its regulation and oversight to the particular risks and detrimental effects. An overview of the various types of research reactors present in France and the main corresponding risks is presented below. In their design, these reactors take account of reference core melt under water (failure of the cooling system) and core melt in air (after uncovering of the core or during handling) accidents. They also take account of accidents specific to certain research reactors. • Neutron beam reactors Neutron beam reactors are pool type. They are mainly designed for fundamental research (solid physics, molecular physico- chemistry, biochemistry, etc.), using the neutron diffraction method to study matter. The neutrons are produced in the reactor, at different energy levels and are captured by channels (thimbles) in the reactor before being routed to experimentation areas. In France, there are two neutron beam reactors in service: the Orphée reactor (BNI 101) operated by CEA in Saclay (rated power limited to 14 MWth), and the High-Flux Reactor – RHF (BNI 67) operated by the Max von Laue-Langevin Institute (ILL) in Grenoble (rated power limited to 58 MWth). These reactors operate in cycles of about 50 to 100 days. The main safety issues are reactivity control, cooling and containment. CEA will be shutting down the Orphée reactor permanently at the end of 2019. It will then be decommissioned. • “Test” reactors “Test” reactors are pool type. They are designed to study accident situations. They are able to reproduce certain accidents postulated in the safety case of nuclear power reactors in a controlled manner and on a small scale and gain a clearer understanding of the evolution of physical parameters during accidents. In France, there is one “test” type reactor in service, Cabri (BNI 24), operated by CEA in Cadarache. The reactor, whose power is limited to 25 MWth, can produce the neutron flux needed for the experiments. The safety issues are similar to those of the other reactors: Controlling the reactivity of the driver core, cooling to remove heat and containment of the radioactive substances in the fuel rods making up the core. Modifications were made to the facility so that it could run new research programmes to study the behaviour of high burn-up fraction fuel during reactivity insertion accident situations. Reactor divergence in its new configuration was authorised in 2015. On 30 January 2018, after major renovation work, ASN authorised the first active experimental test of the facility’s pressurised water loop. • Irradiation reactors Irradiation reactors are pool type. They are used to study the physical phenomena linked to the irradiation of materials and fuels, as well as their behaviour. As the neutron fluxes obtained by these facilities are more powerful than those in a PWR type nuclear power reactor, the experiments enable ageing studies to be performed on the materials and components subjected to a high neutron flux. After irradiation, the samples undergo destructive examination, notably in the research laboratories, in order to fully characterise the effects of irradiation. They are thus an important tool for the qualification of materials subjected to a neutron flux. These research reactors are also significant sources for the production of certain radionuclides for medical uses. The power of these reactors varies from a few tens to a hundred MWth. These reactors operate in cycles of about 20 to 30 days. In France, no technological irradiation reactors are still in service: the Osiris reactor (BNI 40), in Saclay, was permanently shut down in 2015. The Jules Horowitz Reactor (RJH, BNI 172), which is to replace it, is currently under construction. • Critical mock-ups Critical mock-ups are very low power reactors (from a hundred watts to a few kilowatts). They are simple in design and their purpose is to gain more in-depth knowledge of the neutron characteristics of materials and study reactor core neutronics to validate scientific computing tools. Critical mock-ups can be adapted to the experimental programme. The cores are extensively instrumented in order to be able to exploit the results of the experiments carried out. CHAPTER 12 Nuclear research and miscellaneous industrial facilities N uclear research or industrial facilities differ from the BNIs involved directly in the generation of electricity (nuclear power reactors and fuel cycle facilities) or waste management. Traditionally, most of these BNIs are operated by the Alternative Energies and Atomic Energy Commission (CEA), but also by other research organisations (for example the Laue-Langevin Institute (ILL), the ITER international organisation and the Ganil) or by industrial firms (for instance CIS bio international, Steris and Ionisos, which operate facilities producing radiopharmaceuticals, or industrial irradiators). The variety and the past history of the activities covered by these BNIs explains the wide diversity of facilities concerned. 328  ASN report on the state of nuclear safety and radiation protection in France in 2018