ASN Report 2020

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 the coordination of the various operations which involve numerous specialist companies. Decommissioning is effectively characterised by a succession of operations rather than a production state, and therefore by changing risks. Some risks, particularly the risk of significant off-site discharges, decrease because the quantity of radioactive substances gets smaller. But the work carried out, sometimes in close contact with the radioactive substances, presents serious 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, 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 if possible) 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 availability of the final waste disposal outlets on the stated dates is called into question, the licensees must, with due caution, organise the facilities necessary for the interim storage of their 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 2016-2018 (PNGMDR) (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 decom­ missioning 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 first- generation 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. 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, an administrative operation which consists in removing the installation 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. The licensee then proceeds with Post-Operational Clean-Out (POCO) of the premises, remediation of the soils, and possibly the destruction of civil engineering structures. The aim of the decommissioning and POCO operations is to achieve a predetermined final state in which all the hazardous substances, non-radioactive substances included, have been removed from the nuclear installation. The decommissioning of a nuclear installation is prescribed by Decree issued after consulting ASN, the French Nuclear Safety Authority. This phase in the life cycle of the installations is characterised by a succession of operations which are often long and costly, and produce massive amounts of waste. In the course of decommissioning, the installations undergo continuous changes which alter the nature of the risks and represent challenges for the licensees in terms of project management. In 2020 in France, 36 nuclear facilities 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 one quarter of the BNIs in operation. As at 31 December 2020, ASN was examining 18 decommissioning files for definitively shut down facilities whose decommissioning has not yet been prescribed or whose decommissioning conditions have been substantially changed. The year 2020 was marked in particular by the shutdown of the two reactors of the EDF’s Fessenheim Nuclear Power Plant (NPP) in February and June 2020, followed by the submission of the BNI decommissioning file. Decommissioning of Basic Nuclear Installations 13 340 ASN Report on the state of nuclear safety and radiation protection in France in 2020