Gérald Ouzounian

Role of colloids and humic substances in the transport of radio-elements through the geosphere

Abstract Migration phenomena of radionuclides in geological systems are of great interest for the safety assessment of nuclear waste disposal. The mobility of trace radio-elements in natural groundwater is governed by complex physico-chemical interactions which depend largely on the properties and characteristics of the radio-elements, the aquifer and the solid surface. Among others, the presence of colloids (particles with size of 1–1000 nm) and natural organic substances such as humic and fulvic acids in most aquifer systems may affect the behaviour of radio-elements by different processes such as sorption, complexation and dissolution/precipitation. These geochemical phenomena are discussed and reviewed as well as the occurrence of these colloidal entities in environmental systems, with emphasis to the French programme in these fields.

Actinide Speciation in the Presence of Humic Substances in Natural Water Conditions

A review of literature data concerning complex properties of humic substances with actinides (Th, U, Np, Pu, Am) and with cations largely present in natural waters is presented. From data which have been selected according to criteria discussed in the present paper, speciation diagrams of actinides have been calculated in the most representative conditions for natural systems (pH range 4—9; [humic substances] 0.1 to lOppm). Humic substances dominate actinide (Th, U, Am) speciation up to pH 7 (or even 8). Above these pH, inorganic complexes regulate actinide speciation. The presence of competing cations (Ca or Al) modifies actinide speciation in the pH range 4—6.

Actinide sorption at oxide-water interfaces: application to α alumina and amorphous silica

Abstract The experimental investigation and modelling of radionuclide sorption processes is an essential part of safety analysis of an underground repository for radioactive wastes. Interactions at solid/liquid interfaces play a significant role in the speciation and transport of radionuclides in aquifer systems. The retention behaviour of Am (III) at trace concentration (10 −8 M) onto a alumina and amorphous silica has been studied at two ionic strengths in the pH range 4–9. In both systems the Am uptake increases with increasing pH. The ionic strength seems to have a minor effect on this sorption. A surface complexation model has been applied to the results and surface complexation constants have been determined in both systems.

The Management of Radioactive Waste in France: What Is the Threat?

Radioactive waste is a potentially valuable material for a terrorist organization that could use it against the population with malicious intent. This article addresses the key aspects of this issue through the prism the radioactive waste management, and illustrates how this security challenge has been considered in the French electro-nuclear field. Indeed, with 58 nuclear power reactors each producing yearly a significant amount of various types of radioactive materials, the management of the final waste product is of paramount importance in regard to the long-term safety of the population and the protection of the environment, as well as in terms of security threat mitigation.

Site Selection for a Geological Disposal in France: An Approach of Convergence

On December 1991, the French National Assembly passed the French Waste Management Research Act, authorizing a 15 year research program of three options for HLW: separation and/or transmutation, long-term storage, and geologic disposal. On June 2006, the “Planning Act on the sustainable management of radioactive materials and waste” sets a new framework and new aims to the above mentioned options. This paper deals only with the geologic disposal research program. In a step by step approach, this program has been broken down into three phases having intermediate goals (objectives): site selection for an Underground research Laboratory (URL), potential disposal feasibility, potential reversible disposal design. The first step of the research program aimed at URL site selection. From 1994 to 1996, Andra carried out geological-characterization work in four districts. This enabled to make the Request for Licensing and Operation of the laboratory facility on three sites. During this phase, wells, 2D seismic campaigns and land studies of geologic outcrops were the essential activities. The result was the selection of the most suitable site for the implementation of an underground laboratory. Main results on Bure URL will be presented in the paper. In the second phase the research program targeted the safety and technical feasibility of a potential reversible disposal somewhere in Meuse and Haute Marne districts site, chosen by the government in 1998. Andra conducted geologic survey during the URL shaft construction and experiments in drifts at depths of 445 and 490 m. This program allowed consolidating the knowledge already acquired: geological environment, stability of the rock, containment properties and it confirms that the rock will maintain its qualities. The 2005 Progress Report presents the results of this phase. The main conclusion is that a potential disposal facility may be safely constructed over a zone around the URL, called transposition zone (about 250 km2 ). The paper will present the most important results in this phase. From 2006, the third phase of the program, the activities were oriented, inside the transposition zone, to determine a smaller zone in which a potential disposal facility could be designed. In 2009, Andra issued a proposal describing such a zone to the French authorities. In this paper, the main results of this phase will be presented. Finally, the next steps towards a final implementation will be given.Copyright

Territorial Integration of the Geological Repository in France

In France, a framework has been drawn up by the National Assembly and implemented by the government, in order to get the best relationship between Andra, among others, and the stakeholders and the inhabitants of the towns and countries where disposal facilities or projects are or could be established. The main threads of the two Acts passed in 2006, being relevant to the relationship with inhabitants are the information exchange and the local economic development. Dealing with the information exchange and diffusion: • The Local Information Committee (CLI), for each nuclear facility, has been reinforced and a specific, Local Information and Oversight Committee (for the Underground Laboratory in Meuse-Haute-Marne) has been renewed. The CLI was in charge of a general assignment to inform and consult on nuclear safety, radioprotection and environmental topics. Now, since 2006, the nuclear facility’s CLI and the CLIS are able to order study reports, measures and analyses to experts freely selected. • Creation of the High Committee for Transparency and Information on Nuclear Safety (HCTISN). This new authority aims to inform, consult and debate about the risks relevant to nuclear activities and their impacts on people’s health, environment and nuclear safety. Andra contributes to the functioning of CLI in disposal facilities at Manche and Aube Departments, and CLIS of the underground Laboratory at Meuse and Haute-Marne departments. This paper will present these contributions and how Andra’s action helps to reach the goals of information and exchange with the people around its facilities. Concerning the local economic development, there are specific organizations or schemes, depending on the facility: • Local taxes contributions based on the disposal facilities activities as is usual in France. • A High Level Committee (CHN) and two public interest groups (GIP) in Meuse and Haute-Marne departments have been set up since 1991 and 2005. Andra is represented in these three institutions, but they are not funded at all by Andra. This paper will show the Andra’s involvement in the local economic and territorial developments. Within this general framework Andra has developed information and exchanges actions with the stakeholders and the inhabitants around its facilities. Examples of these actions will be presented also.Copyright

Radioactive Waste: Feedback of 40-Year Operations in France

France’s experience in the management of radioactive waste is supported by forty years of operational activities in the field of surface disposal. This feedback is related to three disposal facilities: Centre de la Manche disposal, not far away Cherbourg, from design to post-closure facility. Centre at Soulaines-Dhuys from site selection to design to operation during nearly 20 years. Centre at Morvilliers from site selection to operation for seven years now. During the operational period of Centre de la Manche disposal facility (1969–1994), the safety concept for low- and intermediate level short lived waste (LIL-SLW) was developed and progressively incorporated in the procedures of the facility. The facility entered its institutional control period and the experience of this facility has been useful for the operating facilities. Centre de l’Aube that took over Centre de la Manche, and Morvilliers for very low level wastes. Both facilities currently accommodate the major part of the volume of radioactive wastes that are generated in France. However disposal facilities have to be considered as rare resources. Then new waste management options are being investigated as the disposal of large components or recycling metallic wastes within the nuclear industry.Copyright

I-Graphite Waste Management in France

In France about 23,000 tons of irradiated graphite waste were generated mainly from 9 nuclear gas-cooled reactors (UNGG type). All these reactors are now shut down. In France, a final disposal route has been decided for i-graphite waste management by the French Parliament in 2006. The planning act of June 28, 2006 has provisioned that a research and investigation programme shall be established with a view to developing disposal options for graphite waste. The low specific activity of these wastes means shallow disposal facilities located in a geological layer with a low permeability. The main radionuclides that need specific attention for the long term safety are Chlorine 36 and Carbon 14. This establishes the main requirements for the graphite disposal. According to these requirements, underground disposal in a clay layer, at shallow depth, offers good performance in terms of the delay and the reduction of the radionuclide release; it also offers guarantees for the cover’s hydrodynamic and transport properties. The progress of the programme makes it now necessary for a site to be found. Based on a bibliographical study, a wide-spread call for applications took place during the second semester of 2008.Copyright

Geological repository for nuclear high level waste in France from feasibility to design within a legal framework

Over the past 15 years, the French program on deep geologic disposal of high level and long-lived radioactive waste has benefited from a clear legal framework as the result of the December 30, 1991 French Waste Act. To fulfil its obligations stipulated in this law, Andra has submitted the “Dossier 2005 Argile” (clay) and “Dossier 2005 Granite” to the French Government. The first of those reports presents a concept for the underground disposal of nuclear waste at a specific clay site and focuses on a feasibility study. Knowledge of the host rock characteristics is based on the investigations carried out at the Meuse/Haute Marne Underground Research Laboratory. The repository concept addresses various issues, the most important of which relates to the large amount of waste, the clay host rock and the reversibility requirement. This phase has ended upon review and evaluation of the “Dossier 2005” made by different organisations including the National Review Board, the National Safety Authority and the NEA International Review Team. By passing the “new”, June 28, 2006 Planning Act on the sustainable management of radioactive materials and waste, the French parliament has further defined a clear legal framework for future work. This June 28 Planning Act thus sets a schedule and defines the objectives for the next phase of repository design in requesting the submission of a construction authorization application by 2015. The law calls for the repository program to be in a position to commission disposal installations by 2025.Copyright