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[en] The French uranium mines are progressively closing down. After a mining division has closed down, the main objectives of the Cogema group are: ensuring the long-term safety and healthiness of the site, reducing the residual impacts, preventing any abusive intrusion, reducing the surface of land submitted to right-of-way, encouraging the reconversion of the site, and succeeding in the integration of the site in the landscape in agreement with the local authorities. This brochure presents the strategy followed by Cogema for the rehabilitation of his sites: the French mining concessions and the uranium extraction and processing techniques, the storage of tailings and processing residues, the environment protection and the respect of regulation (environmental surveillance, working groups, administrative procedures and regulatory texts, impact studies...), the backfilling and safety of underground mines, the cost studies for the rehabilitation of open cast mines, the dismantling of factories, the confinement of residues and the revegetation, the continuous monitoring of the rehabilitated sites (water, atmosphere, food..). (J.S.)
[en] When measuring gamma activity located inside a large size waste package (France's 5 m3 container for example) using a global approach method such as a spectrometric measure, large uncertainties arise from the fact that the mass and activity distribution inside the package are unknown. ONECTRA designed and validated by actual site testing a method to reduce significantly these uncertainties. This error in interpretation result mainly from the unknown attenuation undergone by the gamma rays, from the emitting point in the source to the detector. The ONECTRA method evaluates this attenuation when calculating the activity inside the package. The key to evaluating the attenuation relies on either surface ratio between two peaks emitted by the same isotope (at different energies), or on the relative importance of the degraded energies in the spectrum with respect to the raw peak. (authors)
[en] The TN 13/2 cask was designed for the transport of sept fuel from 1300 MW reactors to reprocessing plants. It is capable of carrying relatively short cooled high burn-up fuel and came into service in 1983. The TN 13/2 normally transports fuel under 'dry' conditions, the cask cavity containing an inert gas at sub-atmospheric pressure during transport. The cask is designed for fuel loading operations under water and hence it is compatible with 'wet' environments. Some casks are designed to transport fuel with a water filled cavity, so called 'wet' transports. Fuel cladding temperatures tend to be lower in 'wet' transport casks but higher temperatures are of no consequence for fuel destined for reprocessing. However, in the case of fuel movements between reactors on the same site, it is desirable to limit the cladding temperature and 'wet' transport casks are the preferred option. Transnucleaire decided to add 'wet'transport capabilities to the TN 13/2 cask and thereby give customers the option of using the cask in both wet and dry modes. This paper explains the particular challenge of applying wet transport parameters to a dry cask design and explains how this was achieved for the TN 13/2 without changing any of the cask components. (authors)
[en] This paper describes the TN 17 T shuttle cad and its operation at the Tihange spent fuel pool storage facilities in Belgium. The operational constraints and the diverse range of on-site facilities were evaluated by Transnucleaire and Transnubel to establish the cask options for both on-site and off-site transports. The selected cask concept is presented in outline terms and the main project stages are listed. (authors)
[en] Highlights: • Kinetic studies allow to take into account the dynamic mechanisms of bioavailability. • An absence of Cs and Th accumulation is evidenced showing their low bioavailability. • The uranium accumulation is not only a function of the soil contamination. - Abstract: Uranium ore waste has led to soil contamination that may affect both environmental and soil health. To analyze the risk of metal transfer, metal bioavailability must be estimated by measuring biological parameters. Kinetic studies allow taking into account the dynamic mechanisms of bioavailability, as well as the steady state concentration in organisms necessary to take into account for relevant risk assessment. In this way, this work aims to model the snail accumulation and excretion kinetics of uranium (U), cesium (Cs) and thorium (Th). Results indicate an absence of Cs and Th accumulation showing the low bioavailability of these two elements and a strong uranium accumulation in snails related to the levels of soil contamination. During the depuration phase, most of the uranium ingested was excreted by the snails. After removing the source of uranium by soil remediation, continued snails excretion of accumulated uranium would lead to the return of their initial internal concentration, thus the potential trophic transfer of this hazardous element would stop.