1.2 The ASN decommissioning doctrine At the international scale, 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 and qualified personnel, knowledge of the operating history, 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 The principle of decommissioning “in the shortest time frame possible under economically acceptable conditions” figures 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 BNI decommissioning and delicensing, has been enshrined in legislation by Act 2015-992 of 17 August 2015 relative to Energy Transition for Green Growth. This approach aims to avoid 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 strategy adopted in France aims to ensure that: ∙ The licensee prepares the decommissioning of its installation as of the design stage and updates this preparation throughout the life of the installation. ∙ The licensee anticipates decommissioning and sends ASN the decommissioning application file before it stops operating the installation. ∙ The licensee has financial resources to finance decommissioning, 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 nevertheless vary from a few years to a few decades, depending on the type of installation and the decommissioning complexity. The decommissioning plan, which describes the operations the licensee intends implementing to decommission its facility, aims to prepare and plan ahead for decommissioning as best possible. Since 2007, this document has been required as from commissioning of the facility, and is then updated regularly during its lifetime. It capitalises on the operating experience feedback by identifying any impacts on the future decommissioning operations, and must enable the licensee to justify the chosen decommissioning strategy on the basis of technical and economic criteria. 1.2.2 Post operational clean out and achieving the final state The decommissioning and POCO operations of a nuclear facility must lead to the gradual removal of the radioactive or hazardous substances from the structures and soils, with a view to delicensing the facility with its subsequent withdrawal from the list of BNI. The radioactive substances can result from activation or deposition phenomena caused by the activities of the BNI or the incidents it has experienced. Hazardous chemical substances can also be present in the facility due to the use of certain processes or products (hydrocarbons, hydrofluoric acid, sodium, etc.). In some cases, the radioactive or hazardous substances migrate into the structures of the BNI buildings, or even into the soils of the site and its surroundings, in which case they must be cleaned out. POCO corresponds to the operations to reduce or eliminate radioactivity or any other hazardous substances remaining in the structures or soils alike. ASN asks the licensees to deploy POCO practices that integrate the best available scientific and technical knowledge under economically acceptable conditions. The complete POCO scenario must always be envisaged as the reference scenario. This scenario, which leads to unconditional release of the buildings and sites, effectively enables the protection of people and the environment to be guaranteed over time with no reservations. In the event of identified technical, economic or financial difficulties, the licensee can submit one or more appropriate POCO scenarios compatible with the site’s futures usages (confirmed, planned and practicable) to ASN. Whatever the case, the licensee must provide elements proving that the reference scenario cannot be applied under acceptable technical and economic conditions and that the planned POCO operations constitute a technical and economic optimum. In such cases ASN examines the scenarios proposed by the licensee and ensures that the POCO will be taken as far as reasonably possible. Whatever the case, the regulations stipulate that the POCO strategy implemented by the licensee must lead to a final state of the BNI and its site that is compatible with administrative delicensing. DELICENSING OF THE ULYSSE REACTOR BNI 18, named “Ulysse”, was commissioned in 1961. This research reactor with a nominal power of 100 kilowatts thermal (kWth) was operated by the CEA on its Saclay site for 47 years for the purpose of training and experimental activities. The reactor was definitively shut down in 2007. Following decommissioning preparation operations, including in particular removal of the spent fuel, the decommissioning operations began in 2014 after publication of the decommissioning decree. Decommissioning was organised in three stages spanning five years, with a first phase of conventional work, followed by a second phase of nuclear work and finally a clean-out phase. In February 2021, the CEA filed a BNI delicensing application, including a presentation of the postdecommissioning state of the site and the prospects for its future use. After analysing the file and the conclusions of the consultations, ASN considered that BNI 18 could be delicensed without active institutional controls. The CEA was able to demonstrate that it had performed a complete post-operational clean-out in accordance with the ASN doctrine and the clean-out methodology approved by ASN in 2017. After conducting all the decommissioning operations, the land on which the facility was located is now compatible with all the potential future uses. Consequently, ASN delicensed the Ulysse reactor through a resolution of 24 June 2022. BNI 18 has thus been removed from the list of BNIs. ASN Report on the state of nuclear safety and radiation protection in France in 2022 337 • 13 • Decommissioning of Basic Nuclear Installations 13 01 07 08 AP 04 10 06 12 14 03 09 05 11 02
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