Probabilistic safety assessment model for near surface radioactive waste disposal facilities

A Methodology for Simulating Radionuclide Diffusion in Unsaturated Soils

“…In the due course of time, these disposal modules and immobilized waste forms (i.e., cement waste form and polymer waste form) may loose their structural integrity and create path for ingress of water, which may actuate leaching of radionuclides (Hideo and Suzuki 1989;Nair and Krishnamoorthy 1999;Yim and Simonson 2000;Zhaorong 2005). Subsequently, these radionuclides migrate through the backfills, disposal modules, unsaturated soil mass and ultimately through saturated porous media to the far field (geo-environment) (Yim and Simonson 2000).…”

A reliability engineering study for a near surface radioactive waste repository using genetic algorithm

“…The amount of activity released per year (Bq/y) is therefore the product between the probability density function, pdf (1/y), and the activity (Bq) [1,25]. The pdf related to the release of Tc-99 caused by the barriers failure, due to rain water infiltration, is given by eqn.…”

“…As starting point for optimization, the following set of geometric and structural parameters of the repository is used, as shown in reference [1] (reference repository): A -top cover (0.40m high); B -upper layer (0.32m high); C -packages (1.20m x 4 high, 1.40m x 17 depth and 1.40m x 51 width); D -base (0.80m high); E -repository walls (0.60m thick); and F -geosphere (40m thick). The number of packages is equal to 3,468 (n o pack proj ) and the total volume of concrete used to build the repository is equal to 3,314.06m 3 (Vol total,proj ).…”

“…The deposition system safety is determined by the performance of its individual components, by shape and containment of the wastes, engineering barriers and natural barriers (host environment). Previously, multiple barriers systems were regarded as groups of independent individual barriers that worked in sequence [1,2]. However, this concept is currently seen in a more integrated and synergic way, as complementary barriers that operate simultaneously and together [3].…”

Modeling the release and transport of 90Sr radionuclides from a superficial nuclear storage facility

“…The problem of modeling the contamination of a superficial aquifer due to contaminant release is a classical groundwater quality problem (Bear 1979;Bear and Cheng 2010) and several analytical and/or numerical approaches have been proposed in the literature for addressing problems which bear some similarities with ours (Nair and Krishnamoorthy 1999;Ho 2008;Troldborg 2010;Simunek et al 2007;Pacific Northwest National Laboratory 2004). Many of these resolution methods, indeed, allow very detailed analyses, but the computational effort that they require is often so large that the uncertainty and sensitivity analyses needed within risk assessment become almost impractical (Pacific Northwest National Laboratory 2004), and it significantly increases as the amount and the complexity of the modeled physical processes increase.…”