Title: Evaluation of radionuclide migration in the homogeneous system of a geological repository

Authors: S. Prvakova, J. Duran, V. Necas

Addresses: Nuclear Power Plants Research Institute, Department of Accident Management and Risk Assessment, Okruzna 5, Trnava 918 64, Slovak Republic. ' Nuclear Power Plants Research Institute, Department of Accident Management and Risk Assessment, Okruzna 5, Trnava 918 64, Slovak Republic. ' Faculty of Electrical Engineering and Information Technology, Department of Nuclear Physics and Technology, Slovak University of Technology, Ilkovičova 3, Bratislava 812 19, Slovak Republic

Abstract: The aim of this paper is to study radionuclide migration and release from a deep underground repository situated in a clay formation. An insight into the processes influencing the radionuclide transport in the near field and far field will be presented. For the calculation, a set of radionuclides has been chosen, considering the half-life, decay chains, capacity of the sorption, solubility limits and diffusion coefficients. The migration of radionuclides is dependent on transport properties of the particular nuclide. Due to the low hydraulic conductivity of the backfill material and clay geological formation, the transport in the repository occurs mainly by diffusion. The migration rate will be influenced by the water chemistry, solubility, retardation and diffusive properties of the nuclides, and the water flow rate in the clay. The release rates of radionuclides from the geosphere to the biosphere will be converted into the indicative dose rates using dose conversion factors for ingestion. The impact of the critical group is considered via consumption of meat, root vegetables and drinking water from wells.

Keywords: spent fuel; nuclear fuel; nuclear waste; deep geological repository; carbon-steel canisters; bentonite buffer; biosphere; radionuclide migration; radionuclide release; clay; underground repository; radionuclide transport; half-life; decay chains; sorption capacity; solubility limits; diffusion coefficients; water flow rate; water chemistry; release rates; dose rates.

DOI: 10.1504/IJNEST.2005.008552

International Journal of Nuclear Energy Science and Technology, 2005 Vol.1 No.4, pp.265 - 273

Published online: 30 Dec 2005 *

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