Cement-Organic-Radionuclide interactions (CORI)

‘What’

This WP aims to develop an in-depth understanding of the interaction of cementitious materials with omnipresent organic matter and with radionuclides. Organic materials are present in some nuclear waste and as admixtures in cement-based materials and can potentially influence the performance of a geological disposal system, especially in the context of low and intermediate level waste disposal. The potential accelerating effect of organic molecules on radionuclide migration is related to the formation of complexes in solution with some radionuclides of interest (actinides and lanthanides) which can (i) increase the radionuclide solubility and (ii) decrease the radionuclide sorption. The WP’s raison d’être is to quantify the organic release issues which can accelerate the radionuclide migration in the context of the post closure phase of geological repositories for ILW and LLW/VLLW, including surface/shallow disposal.

‘Why’

The thematic represented by the WP Cori has been selected for the first phase of the EJP as “improved understanding of the role of organics (either naturally occurring or introduced by the wastes) and their influence on radionuclide migration” was identified as an important subject in theme 4 (Geoscience to understand rock properties, radionuclide transport and long-term geological evolution) phase 1 and 2 of the roadmap. Due to the potential degradation of organic matter, this subject is particularly challenging in cementitious environments. Due to the importance of this subject in national programs, various mandated actors are working already since long time on the issues addressed by this WP (see for instance the meetings of the former TSWG in May 2013, Ghent, Belgium, leading to CEBAMA, or the latter extended discussion on CORI at the IGD-TP EF 6 (2015) in London, UK). Over this entire period, partners were eager to join forces for a strong improvement in scientific understanding allowing assessing long term radionuclide mobility in organic rich cementitious waste disposal environments.

Major highlights (June - Nov 2022) and forward look 

The technical progress in CORI focused on continuing the studies performed within the three R&D tasks. New data and results were reported regarding organics degradation and retention processes in the binary organics-cement and ternary radionuclide-organics-cement systems. Related peer-reviewed publication were focusing on (i) uptake of selected organic ligands by hardened cement paste (detailed studies on proxy ligands for the degradation of polyacrylonitrile and general considerations on the role of different functionalities in the uptake process) (ii) study on radium behaviour in contact with calcium-silicate-hydrates, and (iii) solubility of Ca(II), Ni(II), Nd(III) and Pu(IV) in the presence of proxy ligands for the degradation of polyacrylonitrile in cementitious systems. 
The contributions to the Proceedings document from the last Annual CORI Workshop is currently under completion. In total, from the 6 KPIs for Year 4 in EURAD, 5 have so far been positively addressed already in the first 6 months, i.e. the present reporting period.
A highlight was the presentation of CORI at the EURADWASTE conference (held end of May until early June 2022) and the preparation of a related peer-reviewed paper together with CONCORD, FUTURE and MODATS (https://doi.org/10.1051/epjn/2022022). Apart from the presentation of technical progress in CORI, this event allowed specific focus on the networking in EURAD performed on several levels, i.e. between different WPs and between different actors.
Within the trilateral exchange between CORI, UMAN and ICS, several meetings were held and the path forward for the upcoming period, in which additional exchange meetings will take place, defined. 
With a look forward into the second half of Year 4, continued output from the experimental programme in CORI can be expected, together with a more dynamic dissemination and especially an increasing publication output. This is also relevant with respect to young and PhD researcher involved in CORI who in several cases shall finalize the PhD studies in the next half year. The interaction with other EURAD partners will likewise be continued, especially regarding the interactions between CORI, UMAN and the ICS group, or within exchanges at the Annual EURAD event.