1 Technical and legal framework for decommissioning 1.1 DECOMMISSIONING CHALLENGES Accomplishing the decommissioning operations – which are often long and costly – within the set time frames is a challenge for the licensees in terms of project management, skills maintenance and coordination of the various operations which involve numerous specialist companies. Despite this, the choice of immediate dismantling in France obliges the licensees to carry out their decommissioning operations within the shortest time frame possible under economically acceptable conditions (see point 1.2). Decommissioning is characterised by a succession of operations which tend to gradually reduce the quantity of radioactive substances present in the facility, and therefore by evolving risk levels. Although the reduction in the quantities of substances present in the facility tends to reduce the risks, the decommissioning work, which sometimes takes place very close to the radioactive substances, nevertheless presents significant radiation protection risks for the workers. Other risks also increase as the work proceeds, such as the risk of dispersion of radioactive substances into the environment or certain conventional risks, such as risks of falling loads when handling large components, or of fires during hot work in the presence of combustible materials, instability of partially dismantled structures, or chemical risks during decontamination operations. One of the major challenges in the decommissioning of an installation is linked to the large volumes of waste produced, which are usually very much greater than the volumes produced during its operation. The decommissioning of the former facilities of the Alternative Energies and Atomic Energy Agency (CEA) and Orano’s first generation plants (in particular the plants which were involved in France’s deterrence policy, such as the gaseous diffusion facilities of the Pierrelatte Defence Basic Nuclear Installation (DBNI – defence sector) in Tricastin, and the UP1 facility at the Marcoule DBNI, will thus lead to the production of a very large quantity of very low level (VLL) waste. The scale and the difficulty of the work must be assessed as early as possible in the life of the installation, and as of the design stage for new facilities, in order to ensure that they can be decommissioned safely within as short a time frame as possible. Correct performance of the decommissioning operations is also dependent on the availability of the decommissioning support facilities (waste storage, processing and conditioning facilities, effluent treatment facilities) and of appropriate management routes for all the types of waste likely to be produced. When the final waste disposal outlets are likely not to be available at the time the decommissioning waste is produced, the licensees must make prudent provision for the facilities necessary for the safe interim storage of this waste pending opening of the corresponding disposal route. The adequacy of the available interim storage capacities for the waste resulting from BNI operation and decommissioning, and the progress of the studies concerning the various definitive radioactive waste management options, are regularly examined in this respect under the French National Radioactive Material and Waste Management Plan (PNGMDR – see chapter 15). The term decommissioning covers all the technical and administrative activities carried out after the final shutdown of a nuclear facility, following which it can be delicensed, in other words removed from the list of Basic Nuclear installations (BNIs). These activities comprise the removal of radioactive materials and waste still present in the facility and operations to dismantle the equipment and components used during operation, as well as clean-out of the premises and soils plus civil engineering structures demolition work as necessary. The aim of the decommissioning and clean-out operations is to achieve a predetermined final state that allows prevention of the risks and impacts that the site may present for the environment and people, taking into account its possible future uses. The decommissioning of a nuclear installation is prescribed by Decree issued after consulting the French Nuclear Safety Authority (ASN). This phase in the life cycle of the installations is characterised by a succession of operations which are sometimes highly complex, are lengthy, produce large amounts of waste, and are costly; optimum forward planning is essential – especially given that they must be carried out within the shortest time frame possible, as stipulated in the regulations. The continuous changes that installations undergo in the course of decommissioning alter the nature of the risks and represent challenges for the licensees in terms of project management. In 2023, 36 nuclear installations of all types (power and research reactors, laboratories, fuel reprocessing plants, waste treatment facilities, etc.) were shut down or are undergoing decommissioning in France, representing more than one quarter of the BNIs in operation. 14 346 ASN Report on the state of nuclear safety and radiation protection in France in 2023 • 14 • Decommissioning of Basic Nuclear Installations
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