Obiettivo Among natural analogue objectives. the Oklo site. in Gabon. represents a unique geological environment whcre nuclear reaction products have been naturally introduced and can still be detected in fossil reaction zones. Previous studies have shown good chemical analogies of reaction zone materials to a spent fucl repository. Although the site geology is different from that of a deep repository, Oklo is an ideal location to test predictions relating to rates of movement of various radionuclides. including fission products. However, as for most natural analogue projects. the Oklo data actually used for Performance Assessment only represent a small part of the project's scientific results. More results could be transferred to PA provided uncertainties in the geological evolution of the Oklo environment are solved. The Oklo-Natural Analogue Phase II project will thus focus on a quantitative assessment of processes Or radionuclide migration/retention within the Oklo basin. Several main questions need to be addressed at Oklo. regardless of which part of the repositor system is under investigation to eventually provide suitable data t'or performance assessement model: Which fission products and end-products are still present '? Where have they been retained and in which form'? What are the confinement mechanisms and for how long have they been active'? What were the effects of geological or geochemical disturbances on the confinement'.' What is the transport mechanism and for how long has it been active'? The Oklo-Natural Analogue Phase II project is planned as a large scale multiobjective project which has to rulfill several research requirements: to build conceptual models of processes related to radionuclide migration/retention of importance to the evaluation of the performance of disposal systems: processes regarding the repository material (item C.3.7. 1 of thc EU work programme) and processes regarding the radionuclide groundwater transport (item C.3.7.2 of the EU work programme): to test these models against data from a well characterized natural system on a relevant framwork of space and time, to improve the knowledge on the confinement capacity and mechanisms of natural material; to improve data bases to be used in justifying performance assessment results and to identify specific slow transport processes during characteristic time scales of thousands of years. Based on repository performance assessment criteria. the Oklo system will be subdivided into: -The near-field (source term) which includes the reactor zone and the altered clay halo surrounding it. The rclcvant processes to be studied are fuel dissolution, element solubility. the behaviour of radionuclides at redox Ironts the e.xtent and effects of radiolysis and the diffusion of radionuclides throug clay and solid graphitic carbonaceous matter. -The far-field (geosphere) which includes the geological. hydrological and hydrochemical environment around the near-field. The relevant processes to be studied in understanding radionuclide mobility and retardation are advective and dispersive transport. fracture flow. matrix diffusion, flow channeling, complexation, sorption dissolution and precipitation. Also total system behaviour. including heterogeneity effects. can be studied to unterstand flow and transport of fission products. One of the central objectives in the project is the involvement of performance assessment specialists in addition to field and laboratory scientific groups, in transferring the experimental scientific work into suitable data for PA modelling. Programma(i) EAEC-NFS 2 - Specific research and training programme in the field of nuclear safety and safeguards, 1994-1998 Argomento(i) 030307 - Natural analogue/system studies Invito a presentare proposte Data not available Meccanismo di finanziamento CSC - Cost-sharing contracts Coordinatore Commissariat à l'Energie Atomique Contributo UE Nessun dato Indirizzo Ctr Etudes de Cadarache - CE-CA 13108 Saint-Paul-lez-Durance Francia Mostra sulla mappa Costo totale Nessun dato Partecipanti (12) Classifica in ordine alfabetico Classifica per Contributo UE Espandi tutto Riduci tutto ASSOCIATION POUR LA RECHERCHE ET LE DEVELOPPEMENT DES METHODES ET PROCESSUS INDUSTRIELS Francia Contributo UE Nessun dato Indirizzo 35,Rue Saint-Honore 35, CNRS UMR 7619 77305 FONTAINEBLEAU Mostra sulla mappa Costo totale Nessun dato Agence Nationale pour la Gestion des Déchets Radioactifs Francia Contributo UE Nessun dato Indirizzo 1-7,Rue Jean Monnet 1-7 92298 Chantenay-Malabry Mostra sulla mappa Costo totale Nessun dato CONTERRA AB Svezia Contributo UE Nessun dato Indirizzo Fridhemsgatan 66 B 11246 STOCKHOLM Mostra sulla mappa Costo totale Nessun dato Centre National de la Recherche Scientifique Francia Contributo UE Nessun dato Indirizzo 1 rue Blessig 67084 Strasbourg Mostra sulla mappa Costo totale Nessun dato Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas Spagna Contributo UE Nessun dato Indirizzo 22,Avenida Complutense 22 28040 Madrid Mostra sulla mappa Costo totale Nessun dato EMPRESA NACIONAL DE RESIDUOS RADIOACTIVOS S.A. 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