ASN Report 2017

415 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 15  - Decommissioning of Basic Nuclear Installations of the EDF strategy in 2015 and after the change of strategy announced by EDF in 2016, ASN asked the company to provide justifications for this change (see point 2.1.4). The files submitted by Areva and the CEA in 2016 are currently being assessed and ASN will give its opinions on them in 2018. Furthermore, the decommissioning of the old installations of the CEA and the first-generation plants of Areva (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, which was not anticipated during the installation operating phases and which is incompatible with the current capacities of the VLL disposal route, was addressed by a PNGMDR working group resulting in several lines of reflection relative to the possible recycling or on-site storage of this waste (see chapter 16). The French policy for the management of very low level radioactive waste does not provide for release thresholds, but requires that it be managed via a specific route to guarantee its isolation and traceability. This policy is based on the waste zoning of the installations, which has often been established conservatively by the licensees for operational reasons and has been partly responsible for the difficulties mentioned during the work of the abovementioned working group. Nevertheless, this work conducted in collaboration with the licensees and stakeholders, shows that the French waste management policy with no release threshold remains appropriate for the decommissioning needs, even if some aspects could be further improved. More specifically, the operations that generate very large volumes of VLL waste are now examined at a very early stage (this is the case for BNI 93 Eurodif, see point 2.3.3). Furthermore, points of application have been detailed in ASN Guides No. 6, 14 and  24 published in 2016, enabling the particular situations of certain installations to be taken into account (massive objects, for example). 1.2 The ASN doctrine concerning decommissioning 1.2.1 Immediate dismantling 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. In 2014, the International Atomic Energy Agency (IAEA) defined two possible decommissioning strategies for nuclear facilities following final shutdown: ཛྷ ཛྷ Deferred dismantling: the parts of the installation containing radioactive materials are maintained or placed in a safe state for several decades before actual decommissioning operations begin (the “conventional” parts of the installation can be decommissioned as soon as the installation is shut down). ཛྷ ཛྷ Immediate dismantling: decommissioning is started as soon as the installation is shut down, without a waiting period, although the decommissioning operations can extend over a long period of time. The IAEA considers that safe enclosure (or entombment), which consists in placing the parts of the installation containing radioactive substances in a reinforced containment structure for a period that enables a sufficiently low level of radiological activity to be reached with a view to releasing the site, is no longer a possible decommissioning strategy, but may be justified in exceptional circumstances. Today, in accordance with IAEA recommendations, French policy aims to ensure that BNI licensees adopt an immediate dismantling strategy. This principle now figures in the regulations applicable to BNIs (Order of 7th February 2012 setting the general rules relative to basic nuclear installations). It has been included in the doctrine established by ASN for BNI decommissioning and delicensing since 2009 and has been taken up at legislative level in Act 2015-992 of 17th 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 having the knowledge and skills of the teams present during operation of the installation, which are vital during the first decommissioning operations. The aim of the strategy adopted in France is that: ཛྷ ཛྷ The licensee prepares the decommissioning of its installation from the design stage. ཛྷ ཛྷ The licensee anticipates decommissioning and sends the decommissioning application file before it stops operating the installation. ཛྷ ཛྷ The decommissioning operations are carried out “in as short a time as possible” after shutting down the installation, a time frame 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 installation must progressively lead to elimination of the radioactive substances resulting from the activation or deposition phenomena, and any migrations of contamination in the structures of the installation premises or even the ground of the site. The structure clean-out operations are defined on the basis of the prior updating of the facility’s waste zoning plan which identifies the areas in which the waste produced is, or could be, contaminated or activated. As work progresses (for example after cleaning the surfaces of a room using appropriate products), the “possible nuclear waste production areas” are downgraded to “conventional waste areas”. Pursuant to the provisions of Article 8.3.2 of the BNI Order, “the final state reached on completion of decommissioning must be such that it prevents the risks or inconveniences that the site may represent for the interests mentioned in Article L. 7-2012 of the Environment Code, in view more particularly of the projections for reuse of the site or buildings and the best post-operational cleanout and