The review group issues its opinion on the evaluation of the management of bituminous nuclear waste packages requested by the Minister responsible for Energy and the ASN Chairman

Bituminous waste

Nearly 80,000 packages of nuclear waste have been processed by bituminisation since 1966. 50,000 of these bituminous waste packages are in principle to be disposed of in the Cigéo project facility.

In its 11 January 2018 opinion on the safety options dossier (DOS) submitted by Andra for the Cigéo project, ASN expressed reservations concerning the disposal of these bituminous waste. ASN considered that priority should be given to “efforts to neutralise the chemical reactivity of bituminous waste packages. At the same time, studies to modify the design in order to rule out the risk of runaway exothermal reactions should be carried out. In any case, characterisation of these packages of bituminous waste by their producers as rapidly as possible is an essential precondition.”

An expert assessment was thus ordered by the Minister responsible for Energy and ASN in June 2018, in order to evaluate:

• the scientific knowledge relating to the characterisation and behaviour of bituminous waste,
• the pertinence of ongoing research into the neutralisation of the chemical reactivity of the bituminous waste packages,
• the pertinence of Andra’s studies aimed at modifying the design of Cigéo in order to preclude the risk of runaway exothermal reactions.

The review team is chaired by Christophe Fournier, an expert independent of the organisations concerned by these subjects, and consists of national and international experts, both academic and non-academic.

The conclusions of the review

The review report on the management of bituminous waste was submitted to the authorities on 28 June 2019 and then presented to the radioactive waste producers, to the Andra, to the IRSN and to the National plan for management of radioactive material and waste (PNGMDR) Working Group in September 2019.

These conclusions offer a fresh perspective and open up new prospects with regard to the potential conditions for acceptance of bituminous waste in Cigéo. They concern:

• the characterisation and behaviour of bituminous waste: the review group considers that additional experiments would be able to confirm the conclusions of the prior work done by CEA regarding the temperatures as of which energetic reactions can occur;
• the neutralisation of the chemical reactivity of the packages: its industrial feasibility has yet to be proven. The group believes it unlikely that such a facility could be commissioned before 2040, but considers that studies should be continued and that it would be worthwhile re-examining the benefits of chemical dissolution of the bitumen before finally choosing which process is to be industrialised, if any;
• the changes to the design of Cigéo, with the group considering that the studies carried out by Andra should in the short-term lead to a design whose safety could be convincingly demonstrated. Moreover, the cost of this direct disposal solution would be far lower than prior neutralisation of the reactivity of the waste.

Within the framework of the fifth edition of the PNGMDR, ASN and the General Directorate for Energy and the Climate (DGEC) will clarify the conclusions they draw from this review and the additional work to be done by the producers and by Andra in the coming years.