ASN Report 2020

This massive production of waste in the decades to come, which was not anticipated and which is incompatible with the current capacities of Cires (1) , was addressed by a PNGMDR working group resulting in several lines of reflection, including the creation of a new centralised repository, the possible recycling of some of the waste or its disposal on site. ASN issued a position statement in 2020 on the studies submitted by the licensees on this subject (see chapter 14). 1.2  The ASN decommissioning doctrine Many factors can influence the choice of one decommissioning strategy rather than another: national regulations, social and economic factors, financing of the operations, availability of waste disposal routes, decommissioning techniques, qualified personnel, personnel present during the operating phase, exposure of the personnel and the public to ionising radiation resulting from the decommissioning operations, etc. Consequently, practices and regulations differ from one country to another. 1.2.1 Immediate dismantling Decommissioning in the shortest time-frame possible is a core principle in the regulations applicable to BNIs (Order of 7 February 2012 setting the general rules relative to BNIs). This principle, which ASN has affirmed since 2009 as regards decommissioning and delicensing, has been enshrined in legislation by Act 2015-992 of 17 August 2015 relative to Energy Transition for Green Growth. This strategy moreover avoids placing the technical and financial burden of decommissioning on future generations. It also provides the benefit of retaining the knowledge and skills of the personnel present during operation of the installation, which are vital during the first decommissioning operations. The aim of the strategy adopted in France is that: ∙ The licensee prepares the decommissioning of its installation as of the design stage. ∙ The licensee anticipates decommissioning and sends the decommissioning application file before it stops operating the installation. ∙ The licensee has financial resources to finance decommission­ ing, covering its anticipated expenses by dedicated assets. ∙ The decommissioning operations are carried out “in as short a time as possible” after shutting down the installation, a time which can vary from a few years to a few decades, depending on the complexity of the installation. 1.2.2 Complete clean-out The decommissioning and post-operational clean-out operations for a nuclear facility must lead to the gradual elimination of any hazardous substances, in particular radioactive substances, resulting from the activation or deposition phenomena, as well as any migration of contamination in the structures of the facility’s premises or the soil of the site, with a view to delicensing the facility. The ASN reference approach, as stated in its doctrine, requires that the licensees deploy decommissioning and clean-out practices taking into account the best scientific and technical knowledge available at the time and in economically acceptable conditions, with the aim of achieving a final state in which all the hazardous and radioactive substances have been removed from the BNI. Should it be difficult to apply this approach due to the nature of the contamination, ASN considers that the 1. French acronym standing for “Industrial centre for grouping, storage and disposal”. Located in Morvilliers (Aube département ) and renamed Cires in October 2012, it was originally commissioned in 2003 under the name CSTFA, standing for “Very low level waste disposal facility”. 2. ALARA principle (As Low As Reasonably Achievable). licensee must go as far as reasonably possible in the clean-out process. Whatever the case, the licensee must provide technical or economic justification that this reference management approach cannot be applied and that the clean-out operations cannot be taken further under acceptable economic conditions using the best technical clean-out and decommissioning methods available. In accordance with the general principles of radiation protection, the dosimetric impact of the site on the workers and public after delicensing must be as low as reasonably possible (ALARA principle (2) ). ASN is not in favour of introducing general thresholds and considers that it is preferable to adopt a case- by-case approach according to the intended subsequent use of the site. More specifically, reaching a threshold with exposure leading to an effective annual dose of 300 microsieverts (μSv) – i.e. one third of the annual dose limit of 1 millisievert (mSv) for the public – in all the envisaged and envisageable situations is only acceptable after demonstrating the integration of an optimisation process, in accordance with the International Atomic Energy Agency (IAEA) texts on the unconditional release of a site contaminated by radioactive substances. In 2016, ASN thus updated and published a guide on structure clean-out operations (Guide No. 14, available on asn.fr ) . The provi- sions of this Guide have already been implemented on numerous installations with varied characteristics, such as research reactors, laboratories, fuel manufacturing plants, etc. In 2016, ASN also published a guide relative to the management of polluted soils at nuclear installations (Guide No. 24, available on asn.fr ) . 1.3  Decommissioning regulatory framework Once a BNI is definitively shut down, it must be decommissioned. Its purpose therefore has to change as it is no longer that for which its creation was authorised, as the Creation Authorisation Decree notably specifies the operating conditions of the installation. Furthermore, the decommissioning operations imply a change in the risks presented by the installation. Consequently, these operations cannot be carried out within the framework set by the Creation Authorisation Decree. The decommissioning of a nuclear installation is prescribed by a new decree issued on the basis of an opinion from ASN. This decree sets out, among other things, the main decommissioning steps, the decommissioning end date and the final state. As part of its oversight duties, ASN monitors the implementation of the decommissioning operations as directed by the Decommissioning Decree. In order to avoid fragmentation of the decommissioning projects and improve their overall consistency, the decommissioning file must explicitly describe all the planned operations, from final shutdown to attainment of the targeted final state and, for each step, describe the nature and scale of the risks presented by the facility as well as the envisaged means of managing them. This file is subject to a public inquiry. Given that installation decommissioning operations are often very long, the Decommissioning Decree can stipulate that some steps will be subject to prior approval by ASN on the basis of specific safety analysis files. The Diagram below describes the corresponding regulatory procedure. The licensee must demonstrate in its decommissioning file that the decommissioning operations will be carried out in as short a time-frame as possible. ASN Report on the state of nuclear safety and radiation protection in France in 2020 341 13 – DECOMMISSIONING OF BASIC NUCLEAR INSTALLATIONS 13