Evaluation of the Retention Capability of Backfill Materials in the Presence of Cement Waste form
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EVALUATION OF THE RETENTION CAPABILITY OF BACKFILL MATERIALS IN THE PRESENCE OF CEMENT WASTE FORM N.K.Ghattas, K.A.El Adham, S.B.Eskander, N.S.Mahmoud, Atomic Energy Authority, Egypt.
ABSTRACT The present study focused on the retention capability of the different local backfill materials and on horizontal and vertical radionuclide migration in simulated repository conditions of a saturated static humid environment, using single or combined components of the near-field. The results obtained from semi-field experiment show that no migration of cesium radionuclide was detected outside the backfill zone within the time interval of the experiment. This reflects the possible efficiency, of the backfill materials used, for the confinement of radioactivity to the disposal site. On the other hand laboratory experiments show the effect of simulated repository condition on the sorption and desorption properties of backfill materials.
It is clear from the results obtained that the presence of cement waste forms in equilibrium with underground water affect the retention capability of the backfill materials. The motivation of the work was a desire to provide a basis for minimizing radioactive waste processing by improving nonradioactive engineering barriers. 1. INTRODUCTION Most evaluations give some measure of the importance of various parameters affecting the retention capability of a given barrier but only very limited data are provided concerning their interaction. The essential topic of research priority in radioactive waste management has been
waste forms [1]. However, the influence of sorption properties of materials on the release of radionuclides from the near-field was studied in various ways [2]. The Atomic Energy
Authority in the United Kingdom (AEA-UK) have supported an extensive program of research to investigate the phenomena of radioelement behavior in a cementitious environment [3]. In situ migration experiments in the Boom clay at Mol were performed [4]. The chemistry and geochemistry of the buffer backfill was studied by Johnson [5] and a number of potential
additives to the backfill materials have been suggested to maintain the sorption properties [6]. Interesting data were obtained recently by comparing the retention capability of the different
cement barriers used in a waste repository [7]. A near surface facility was the chosen option for the disposal of low- and intermediate-level radioactive wastes arising from Inshas Reactor Site (Egypt) and from uses of radionuclides in various fields. The present study focused on the behavior of released radionuclides from waste forms in a simulated disposal environment. Soil materials at the disposal site available for use as backfill materials are sand, sand-clay, and clay. It is of interest to study the sorption behavior of these materials under disposal environment using underground water obtained from the well nearest to the disposal site and in the presence of cement waste forms. The work reported is part of a comprehensive research program that includes c
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