Spent fuel vertical

The CANDU bundle verifier for stacks (CBVS) moves vertically along the space between columns of trays (10 cm gap) of spent fuel and uses a CdZnTe detector for bundle identification (Ahmed et al. 2001). It employs thick lead shielding to protect the electronics and detector. The CBVS is unable to verify the spent fuel at the bottom layer of a stack due to limited accessibility of a large-size detector part through the funnel structure. During inspection, the tray must be moved. In addition, the large size of the scanning part is both heavy and difficult to handle. 

In the vertical and horizontal storage configurations, an internal canister stores the spent fuel assemblies in a safe subcritical configuration. The internal canister is a welded stainless steel pressure vessel that provides for criticality control, an inert helium environment, structural support of the fuel assemblies, and confinement of the highly radioactive... 

Thermal decomposition of spent acids, eg, sulfuric acid, is required as an intermediate step at temperatures sufficientiy high to completely consume the organic contaminants by combustion temperatures above 1000°C are required. Concentrated acid can be made from the sulfur oxides. Spent acid is sprayed into a vertical combustion chamber, where the energy required to heat and vaporize the feed and support these endothermic reactions is suppHed by complete combustion of fuel oil plus added sulfur, if further acid production is desired. High feed rates of up to 30 t/d of uniform spent acid droplets are attained with a single rotary atomizer and decomposition rates of ca 400 t/d are possible (98). 

Spent acids are atomized in very small droplets to achieve good thermal decomposition. Energy is provided by the organics from the spent acids and by additional energy from natural gas, fuel oil, or coke. Preheating the combustion air reduces the amount of fuel needed. Furnaces can be horizontal (fixed or rotating) or vertical. 

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