Chemical durability and performance of assessment of spent fuel and high level waste forms under simulated repository co
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Chemical durability and performance of assessment of spent fuel and high level waste forms under simulated repository conditions – Spanish contribution to IAEA project Aurora Martínez-Esparza1, José Antonio Gago1, Javier Quiñones2, Eduardo Iglesias2, Esther Cera3, Juan Merino3, Joan de Pablo4, Ignasi Casas4. 1 ENRESA, C/ Emilio Vargas 7, 28043-Madrid. SPAIN 2 Ciemat. Avda. Complutense 22, 28040-Madrid. SPAIN 3 ENVIROS, Passeig de Rubi, 29 - 31, 08197 Valldoreix, Barcelona. SPAIN 4 Dept. of Chemical Engineering. ETSEIB-UPC, Diagonal 647 H-4, 08028 Barcelona. SPAIN ABSTRACT Chemical durability of spent fuel under repository conditions is one of the main topics of interest in national and international projects from the last two decades. During the last decade there have been growing the activities in Enresa related to the deep disposal concept with the aim of developing a spent fuel alteration model for the understanding of the behaviour of this nuclear waste under repository conditions. In this context, the development and utilisation of models and sub-models based on experimental work have been of great importance. Experimental studies with spent fuel(in Collaboration Agreement with ITU) and spent fuel analogues in several environmental conditions have been carried out into Enresa R+D Programmes in order to reach a better knowledge of the relevant processes and to quantify the spent fuel chemical durability under repository conditions. In this work, it is showed the utility of data provided from experiments with spent fuel analogues to test the mechanisms and the influence of relevant parameters in the spent fuel alteration under repository conditions. The evolution of irradiated fuel under interim storage conditions and in deep geologic storage and its oxygen to metal ratio (O/M) before the water access to the fuel is another factor of great influence on enhanced spent fuel leaching. This effect has been also studied by means of spent fuel analogues and by using simulated (artificially) aged fuel. INTRODUCTION Most of the OCDE countries have been performing several performance assessment studies in order to know the viability of the spent fuel storage into geologic formations[1-10]. Experimental studies with spent fuel and spent fuel analogues in several environmental conditions have been carried out in most of international research centres in order to reach a better knowledge of the main processes which should be considered to quantify the spent fuel behaviour under repository conditions. It has been showed the utility of data provided in experiments with spent fuel analogues for processes understanding. In experiments with spent fuel some parameters such as radiation fields are overestimated with respect those radiation dose rates which are expected after container failure and water access. On the other hand, experiments with spent fuel have high cost and handling limitations. Therefore, it makes useful the work with spent fuel analogues to test the mechanisms and the influence of relevant parameters in spent fu
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