ASN issues its opinion on the management of High Level Waste (HLW) and Intermediate Level, Long-lived Waste (ILW-LL)

In response to a request from the Minister in charge of energy, as required by the French National Radioactive Materials and Waste Management Plan (PNGMDR), ASN issued its opinion on the management of high-level waste (HLW) and intermediate-level long-lived waste (ILW-LL), contributing to the orientations of the 5^th edition of this plan.

HL waste mainly consists of vitrified packages containing waste produced by the reprocessing of spent fuels. For its part, IL-LL waste to a large extent consists of the metal structures of spent fuel assemblies after reprocessing, or resulting from the operation and maintenance of fuel reprocessing plants. The volume of these two categories of waste, once conditioned in primary packages, is estimated at 85,000 m³. In France, the law requires that ultimate radioactive waste which, for nuclear safety or radiation protection reasons, cannot be disposed of in above-ground or near-surface facilities, shall require deep geological disposal. It is the duty of Andra to design a deep geological disposal facility project. It is currently developing a project for such a repository, called Cigéo, which will be a basic nuclear installation (BNI) and, as such, will be subject to regulation by ASN.

For the 4^th edition of the PNGMDR, studies were more specifically conducted on:

- the acceptability of the various HL or IL-LL wastes in Cigéo,

- a more detailed examination of safety implications relating to bituminous waste packages management,

- characterisation studies of IL-LL waste produced before 2015 so that the retrieval and conditioning of this waste could begin before the 2030 deadline set by law,

- the repercussions on storage needs of any delay in the Cigéo project.

The public debate held in 2019, with a view to drafting the 5^th edition of the PNGMDR, underlined the need for clarification concerning, on the one hand, the essential preconditions for the implementation of deep geological disposal, which are reversibility, safety guarantees or the design of the pilot industrial phase and, on the other, the prospects for research on the transmutation of certain radionuclides.

Management of HL and IL-LL wastes prior to disposal

After analysis of the studies submitted to it, and with regard to the IL-LL waste produced before 2015, ASN considers that the waste producers must take all steps to meet the 2030 deadline set by law for the conditioning of this waste and to prioritise it according to the safety and radiation protection implications.

The law states that the operation of Cigéo begins with "a pilot industrial phase” to confirm reversibility and the facility’s safety case, in particular by means of an in-situ test programme. ASN considers that the waste producers must demonstrate their capacity to produce, condition and transport the waste packages, a necessary precondition for the safety case and for the ramp-up to an industrial rate of disposal during this pilot industrial phase.

 Disposal of HL and IL-LL wastes

Concerning the management of bituminous waste, an external review ordered by the Minister in charge of energy and ASN was held in 2018 and 2019. The review report, issued on 28 June 2019, considered that “technical  provisions allowing the disposal of bituminous waste packages in Cigéo in acceptable conditions of safety may be defined on the basis of the engineering techniques today available”, that “the studies carried out by Andra are pertinent and should in the short term be able to reach a design for which safety could be convincingly demonstrated” and that, however, “the possibility that some packages may not be able to meet the acceptance specifications to be defined and would thus require particular processing, cannot be ruled out”.

On the basis of these conclusions, which highlight new technical aspects since the publication of the opinion on 11 January 2018, ASN considers that the waste producers must implement an ambitious programme to characterise the bituminous waste packages, with this being an essential precondition for developing the demonstration that some or all of the bituminous waste packages could be disposed of in the Cigéo facility without prior processing and with a high level of safety. ASN also considered that given the safety implications, it is necessary to explore all conceivable processing avenues for the packages of bituminous waste, for which safe disposal could not be demonstrated.

The Cigéo disposal facility is developed to receive waste from a “reference” inventory. The law also requires that this disposal facility be subsequently adaptable so that it could receive other waste, identified in a “reserve inventory”. ASN considers that, in order to allow Cigéo adaptability studies to be conducted, the waste producers must define the conditioning procedures and consolidate the disposal volumes of all the waste in the reserve inventory.

Storage in addition to disposal

With regard to the storage of waste prior to disposal, ASN recalls the position it adopted in 2006: “long-term storage cannot constitute a permanent solution […]. It implies maintaining oversight on the part of society and the retrieval of waste by future generations, which it would appear to be hard to guarantee over a time-frame of several centuries”.

In the light of the studies conducted in the successive editions of the PNGMDR, ASN confirms that near-surface storage offers no decisive advantage over surface storage, in terms of nuclear safety and radiation protection.

ASN notes that the saturation deadlines for existing waste storage facilities and the future storage needs for the coming 20 years were on the whole well identified by the producers. However, in order to plan ahead, the storage capacity estimates must be consolidated. The producers shall more specifically regularly demonstrate that the maximum storage capacity of their facilities and the operational rate of shipment from their respective sites are compatible with the updated Cigéo delivery time-lines, in order to avoid saturation of the storage sites.

Transmutation

ASN recalls that the prospects for transmutation on an industrial scale of the waste already conditioned in the Cigéo reference inventory are not credible. It considers that, although transmutation studies should be continued, they should concern radioactive substances currently qualified as materials or the waste produced by a future fleet of reactors and that they be carried out with a view to developing complete solutions, including the disposal of the waste resulting from transmutation and offering a high level of safety.