ASN Report 2017

414 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 15  - Decommissioning of Basic Nuclear Installations 1. Technical and legal framework for decommissioning 1.1 Decommissioning risks 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. The nuclear risks generally decrease as decommissioning proceeds, but the work involved, sometimes carried out very close to the radioactive substances, present serious radiation protection implications for the workers. Other risks increase such as the risks of dispersion of radioactive substances into the environment or certain more “conventional” risks such as falling objects 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, etc. T he 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 (BNI). 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 can then proceed with post-operational clean-out 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 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 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 2017 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, representing more than a quarter of the BNIs in operation. The periodic safety review conclusion reports for the majority of these installations were filed in 2017. Four decommissioning files underwent a public inquiry and were the subject of an opinion issued by the Environmental Authority of the CGEDD (General Council for the Environment and Sustainable Development), namely BNI 93 Eurodif and BNI 105 Comurhex on the Tricastin site (Areva), BNI 94 AMI Chinon (EDF) and BNI 52 ATUe at Cadarache (CEA). The examination of the decommissioning and waste management strategy files of CEA and Areva were launched jointly with ASND, the Defence Nuclear Safety Authority. EDF submitted to ASN the files supporting its change of decommissioning strategy for its Gas-Cooled Reactors (GCR) announced in 2016, and was heard by ASN on this subject. Lastly, 2017 saw the delicensing of BNI 61 LAMA (Active Materials Analysis Laboratory) in Grenoble (CEA). One of the major challenges in the decommissioning of an installation lies in the very large volumes of waste produced comparedwith the operational waste, and the scale and associated difficulties must be assessed as early as possible in the life of the installation (from the design stage if possible) in order to ensure safe decommissioning in as short a time frame as possible. Smooth running of the decommissioning operations is thus governed by the availability 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 moreover forms the subject of provisions in the Decree of 23rd February 2017 establishing the provisions of the French National Radioactive Material and Waste Management Plan (PNGMDR) 2016-2018 (see chapter 16). 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 receives particular attention when evaluating the decommissioning strategies and the waste management strategies established by EDF, Areva and CEA. ASN conducted an overall assessment