The Aqueous Corrosion Behavior of Plutonium Metal and Plutonium-Gallium Alloys Exposed to Aqueous Nitrate and Chloride Solutions

Previous work in this laboratory examined the polarization behavior of high-purity plutonium metal exposed to various solutions, however, the polarization behavior of plutonium-gallium alloys has not been studied. The objective of this work is to establish the effect of gallium on the electrochemical behavior of plutonium metal exposed to nitric acid, sodium nitrate, and sodium chloride solutions. Results indicated that plutonium-gallium alloys were not passive in HNO3 solutions, unlike unalloyed plutonium. The dissolution of 0.5 and 1 wt % Ga alloys exposed to HNO3, and all materials exposed to NaCl, was found to be controlled by the presence of a corrosion product film. Relative oxide thickness measurements of unalloyed Pu exposed to HNO3 were obtained. Chloride was found to aggressively attack Pu and its alloys with increasing chloride concentration resulting in increased corrosion. Nitrate ions were shown to have a weak effect on the corrosion behavior of Pu, as compared to protons and chloride ions.