Concerning the formation of hydrogen in nuclear waste. Quantitative generation of hydrogen via a Cannizzaro intermediate

Abstract

During the storage of certain nuclear waste, particularly mixtures containing complexing agents like EDTA and HEDTA in highly basic media, mixtures of gases containing large amounts of hydrogen are produced. In order to provide the foundation for control of this potentially dangerous situation, a fundamental understanding of the reactions responsible for the formation of hydrogen is crucial. The proposed mechanism for the formation of H[sub 2] involves the formation of a Cannizzaro intermediate, which reacts as a hydride ion donor with a water molecule, to produce hydrogen and sodium formate. Conditions are believed to be presented in nuclear waste storage tanks where small, steady-state concentrations of formaldehyde can form by radiolysis or thermal decomposition of organic complexants and other decomposition products. Formaldehyde and other aldehydes that do not possess [alpha] hydrogen atoms are very likely intermediates for the generation of H[sub 2] during the storage of alkaline nuclear waste. The data reported herein suggests that formaldehyde and water each provide one hydrogen atom in the formation of H[sub 2]. 12 refs., 4 tabs.