4SIGHT Manual: A Computer Program for Modelling Degradation of Underground Low Level Waste Concrete Vaults/System

by Kenneth A. Snyder and James R. Clifton

6System

Although each LLW facility may be unique, most underground facilities can be represented schematically as in Figure 1. Below the ground surface there will be an engineered barrier to deflect surface water away form the concrete vault below. The entire facility is sited on a geologically suitable location.

Wikisource Note: This figure has been redacted for public release and is therefore not available in the original text.

Figure 1: Schematic of underground LLW facility

From the schematic in Figure 1 it appears as though the roof is the most critical element because it is most likely to have a moist environment, especially upon the failure of the engineered barrier. Because of this, the analysis of the entire concrete vault can concentrate on the roof. If the roof is treated as a simple slab, the analysis simplifies further. Since the flow through the roof slab will be approximately uniform over the surface of the slab, a one-dimensional analysis of transport vertically through the slab should serve as a sufficiently accurate model for transport through the roof of the vault.