ASN issues its opinion on the radioactive waste legacy repositories within the framework of the 5th PNGMDR

At the request of the Ministry responsible for energy (MTE), and within the framework of the French National Radioactive Material and Waste Management Plan (PNGMDR), ASN has issued its opinion on the management of legacy repositories of radioactive waste, in order to contribute to the guidelines for the 5^th edition of this plan.

In successive editions of the PNGMDR, the licensees carried out studies and work to identify legacy repositories of radioactive waste and to explain the management methods adopted for each of them. Certain radioactive wastes were managed in the past in ways that have since changed. This is particularly the case with waste repositories on or near to the production sites.

These wastes, resulting from the decommissioning or post-operational clean-up of former plants or nuclear site earthworks, were also in some cases used as backfill on the land of the sites concerned, or were managed in conventional routes. The Environment Code defines legacy repositories as “prior to the year 2000, places for the disposal of radioactive wastes which are not under the responsibility of the National Radioactive Waste Management Agency [...] and for which the producers of the waste or those in possession of it did not, at the time it was placed there, envisage management in existing or planned external disposal routes dedicated to radioactive waste management, with the exception of disposal sites for mine tailings and waste rock”.

After analysis of the studies received by the licensees concerning the legacy repositories placed under their responsibility, ASN expressed its positions concerning the investigation programmes implemented and the management principles for these repositories.

The investigation programmes

ASN considers that the principle of the approach adopted by the licensees to identify legacy repositories is pertinent.

However, the way this approach is implemented by EDF needs to be improved and the status of certain legacy waste repositories needs to be clarified.

Guidelines for the management of legacy repositories

The public debate held in 2019, with a view to the drafting of the 5^th edition of the PNGMDR, underlined that the local impacts of the management choices made in the plan need to be incorporated early on into all the decision-making processes.

ASN considers that the licensees studied an insufficient number of management scenarios for the waste present in the legacy repositories.

ASN recommends that the licensees give priority to scenarios entailing full retrieval of the waste from these repositories and transfer to existing or planned disposal routes. If the in-depth study of this scenario demonstrates that this is impossible, owing to the nature or the quantity of the waste, ASN recommends that the licensee examine other scenarios to allow management - in these routes – of the largest possible amount of waste contained in these repositories. It would therefore be useful to examine local disposal solutions.

ASN considers that pluralistic multi-criteria analyses are a pertinent decision-making tool for the long-term management of this type of site and that these methods should be applied consistently to the various waste management disposal routes. ASN thus recommends that a common analysis methodology be developed, ensuring that the approach adopted is proportionate to the issues involved in each route.

ASN also considers that the licensees should present the appropriate surveillance programme implemented on each legacy repository that would continue to hold waste. ASN also considers that the results of this surveillance programme should be regularly communicated to the public, taking account of the regulatory frameworks for the installations concerned.

ASN recommends that a pluralistic working group be set up, incorporating all the stakeholders, including the representatives of the regions involved, or liable to be involved. This working group will take part in improving the methodological approach, in prioritising the work in the light of the issues, and will guarantee its completely objective implementation.

The licensees shall provide the competent local authority with a long-term management plan, taking into account the scenario chosen, at a date to be defined by the next PNGMDR, and considering the prioritisation work mentioned above.

Finally, ASN recalls the importance of setting up and preserving a trace and a record of these legacy repositories.