Mercury-free dissolution of aluminum fuels in nitric acid

Since the 1950s, most chemical flow sheets for the dissolution of aluminum-clad nuclear fuels have utilized mercury-catalyzed nitric acid dissolvent to dissolve aluminum. Apparently the mercury, as dissolved mercuric nitrate, reacts with the aluminum oxide surface layers on the aluminum alloy to form a Hg-Al amalgam that dissolves readily in nitric acid. The reaction is rapid, efficient, and highly exothermic. Fuel dissolution rates are limited primarily by the ability to remove excess heat and to control foam. Unfortunately, however, mercury is an Environmental Protection Agency listed Resource Conservation and Recovery Act hazardous waste, and its presence in the resulting high-level waste is sufficient to render it into open-quotes mixed hazardous waste.close quotes This paper discusses the results of a series of bench-scale tests conducted in search of alternatives to mercury catalysis of nitric acid dissolvent