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 in 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, therefore the risk levels evolve. The work carried out, sometimes in close contact with the radioactive substances, nevertheless presents significant radiation exposure risks for the workers. Other risks increase, such as the risks of dispersion of radioactive substances into the environment or certain conventional risks, such as the risks of falling loads when handling large components on worksites situated at height, fires or burns during hot work in the presence of combustible materials, anoxia when working in confined areas, 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 very large volumes of waste produced compared with the operational waste. The scale and the difficulty of the work must be assessed as early as possible in the life of the installation (as of the design stage for new facilities), in order to ensure completely safe decommissioning in 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, with due caution, organise the facilities necessary for the safe interim storage of this waste pending opening of the corresponding disposal route. This point is the subject of provisions in the Decree of 23 February 2017 establishing the provisions of the French National Radioactive Material and Waste Management Plan (PNGMDR) 2016-2018 (see chapter 14). ASN also believes that management of the waste resulting from decommissioning operations is crucial for the smooth running of the decommissioning programmes (availability of disposal routes, management of waste streams). This subject is addressed with particular attention during the assessment of the decommissioning and waste management strategies established by the Alternative Energies and Atomic Energy Commission (CEA), EDF and Orano (see point 4). Decommissioning of CEA’s old installations and Orano’s firstgeneration plants (especially the plants that played a role in the French deterrence policy, such as the gaseous diffusion plants of the Pierrelatte Defence Basic Nuclear Installation –DBNI) at Tricastin and the UP1 plant of the Marcoule DBNI is going to produce extremely large quantities of very-low level (VLL) waste. This massive production of waste in the decades to come, which DECOMMISSIONING OF BASIC NUCLEAR INSTALLATIONS The term decommissioning covers all the technical and administrative activities carried out after the final shutdown of a nuclear installation, on completion of which the installation can be delicensed, that is to say it can be removed from the list of Basic Nuclear Installations (BNIs). These activities include removal of the radioactive materials and waste still present in the installation and disassembly of the equipment, components and facilities used during operation, and the clean-up of the premises, remediation of the soils, and possibly the destruction of civil engineering structures. The aim of the decommissioning and Post Operational Clean Out (POCO) operations is to achieve a predetermined final state that prevents the risks or drawbacks the site can present for the protected interests. 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 often long and costly, which produce massive amounts of waste, and which must be optimally planned for –especially given that the regulatory framework require them to be carried out in the shortest time frame possible. 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 2021 in France, 35 nuclear installations of all types (power and research reactors, laboratories, fuel reprocessing plants, waste treatment facilities, etc.) were either shut down or undergoing decommissioning, which represents more than a quarter of the BNIs in operation. 13 328 ASN Report on the state of nuclear safety and radiation protection in France in 2021
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