To study the phenomena and mechanisms of radionuclide transfer in soils, sub-soils and to ecosystems.
The CNRS and the IRSN has led a national research grouping TRASSE on the study of Transfer of Radionuclides in Soils, Sub-soils and to Ecosystems. This GNR is integrated into the CNRS's PACEN programme which focuses on the downstream aspects of the nuclear cycle and energy.
Officially over since the 31st December 2011, the grouping has led to the writing of many scientific publications. 15 of them has been gathered in a special issue of Applied Geochemistry coming on 6th June 2012. Discussions are in progress with some others partners to extend the fruitful collaboration between the IRSN, the CNRS in the frame of "Nucléaire, énergie, environnement, déchet, société" (NEEDS) challenge.
The TRASSE GNR hinges around 2 lines of research, each based on one of the two experimental platforms available at the IRSN.
Line 1: Study of transfers of natural and artificial radionuclides in the soil and water tables, and to plants.
This research subject uses the T 22 experimental platform on the site of Chernobyl (Ukraine), set up by the IRSN in collaboration with the UIAR (Ukrainian Institute of Radioecology) and the IGS (Institute of Geosciences). Situated in the exclusion area near the reactor No.4 that suffered the nuclear accident in 1986, and thanks to appropriate instrumentation, this platform allows the study of the transfer of radionuclides in the soil, the water table and plants, around a trench filled with radioactive waste and materials from the nuclear catastrophe of April 1986. The lessons drawn from the experiments conducted on this site offer various fields of application related to the management of polluted sites and old uraniferous mining sites, or the dismantling of nuclear facilities.
Line 2: Study of the containment capacities of an argilaceous geological formation and the induced transfers to ecosystems
The research conducted along this line uses the underground experimental station of Tournemire (Aveyron), situated in an old railway tunnel dug in an argilaceous sedimentary formation. The ease of access to the IRSN experimental station simplifies the logistics and allows in situ research into rocks that have similarities with the argillite studied by the ANDRA on the Meuse/Haute-Marne site. The experiments conducted at Tournemire aim more specifically at exploring the key parameters that can guarantee the operation of the containment barriers and study the impact of degraded conditions on their overall performance. The projects envisaged in the framework of the TRASSE GNR focus more particularly on:
- the qualification of innovative geophysical methods for identifying subvertical discontinuities (faults) with low throw affecting this formation, from the surface or from the wall of an underground gallery,
- the disturbances induced by the digging of the galleries (damaged zones, denoted EDZ) and by the concrete linings of varied ages (120 years for the tunnel, 12 years for the West and East galleries, 5 years for the main and secondary galleries).
Objectives and organization
The creation of TRASSE is fully in line with the IRSN's mandate for research into nuclear and radiological risks and strengthens the position of the CNRS in its research into the downstream end of the electronuclear cycle, pursuant to the law of 28 August 2006 relative to the sustainable management of radioactive substances and waste.
TRASSE favours the development of the scientific knowledge and skills of the IRSN and CNRS research teams regarding the phenomena and mechanisms involved in the transfer of radionuclides present in geological environments. This knowledge is important for assessing the possible impact of such transfers on ecosystems, and ultimately the exposure of man, in the assessment of radioactive waste storage performance or in the study of radiocontaminated sites. It is also useful for evaluating the factors that can alter the containment properties of geological environments. TRASSE also helps valorise the experimental tools already at the IRSN's disposal (the Tournemire experimental station and the T22 experimental platform in Chernobyl) by opening them more widely to scientific collaboration with the teams of the CNRS, in a federating and communicating structure.
Based on a principle of cofinancing, the GNR has a budget of 250,000 euros per year, financed in equal shares by the two partners. This cofinancing covers part of the operating expenses or the acquisition of equipment specific to the chosen research projects. The GNR has governing authorities (grouping council and scientific council) that allow the continuous evaluation of the research and scientific production activities, and ensure the relevance of the chosen scientific orientations.
La direction du GNR TRASSE est assurée par Joel Lancelot, enseignant-chercheur au CNRS, en tant que directeur du groupement, et Jean-Michel Matray, chef du Laboratoire de recherche sur le stockage géologique des déchets et les transferts dans les sols (LR2S) de l'IRSN, en tant que correspondant IRSN. L’organisation et le fonctionnement du GNR TRASSE ont vocation à favoriser :
The TRASSE GNR is managed by Joel Lancelot, a lecturer-researcher at the CNRS, who is the director of the grouping, and Jean-Michel Matray, Head of the IRSN Laboratory of Research into the Geological Storage of Waste and Transfers to Soils (LR2S), as representative of the IRSN. The organization and functioning of the TRASSE GNR are designed to encourage:
high-level discovery research into themes not yet covered by the PACEN programme and therefore complementary to those of the other structures (GNR and PCR) existing within this programme,
flexible governance favouring responsiveness and ensuring transparency for the teams participating in the GNR and for the 2 partner entities,
a policy of publication in A+ ranking reviews taking priority over internal reports.
The expected spin-offs from the research work conducted by the TRASSE GNR
The knowledge acquired on the radionuclide transfer processes will enhance the ability to make predictive evaluations of the impact of sites polluted by radioactive substances or storage and warehousing sites for radioactive waste and residues. The results of the studies in these areas conducted in partnership by the IRSN and the CNRS will work towards achieving the general objective of developing knowledge in an open and transparent context, and help strengthen the technical foundations of the IRSN's expertise.
They will thus allow the development of a reference expert capacity in radiological and nuclear risks. It is true that the control of risks associated with nuclear activities is first and foremost the responsibility of the operators, under the control of the public authorities. But it also implies the availability at national level of a reference public research and expertise capacity that can perform scientific and technical assessments independently of designers and operators. This has been the IRSN's prime role since its creation.
This fundamental mission, carried out on behalf of the State and more particularly to assist the ASN (French Nuclear Safety Authority), requires the IRSN to continuously develop its skills in a national and international framework. Thus the Institute's finalized research programs and scientific collaborations must enable it to assert itself in its role as a reference public expert, whose scientific, technical and operational credibility and independence in the expression of its opinions must be recognized by all the components of society. This requirement is particularly strong in the domain of high-level long-lived radioactive waste, given the scientific and societal stakes with which it is associated.