PNNL

Abstract

Complexants containing hydroxyl functionality such as glycolic acid (GA) and hydroxyethylethylenediaminetriacetic acid (HEDTA), undergo thermally activated oxidation by nitrite ion in alkaline high level wastes (HLW) leading to the production of H2 and nitrogenous gases, as well as oxalate, formate and carbonate ions. Aluminate ion catalyzes the oxidation of GA and HEDTA. It has been postulated that nitrite esters (RONO) are important intermediates leading to the observed products. To eludicate the reaction mechanism and kinetics, we are measuring and deriving thermochemical kinetic parameters for pathways involving RONO, both with and without aluminate ion. We will present recent results telling of the possible role of RONO and other relevant species important to the development of kinetic models for predicting rates of thermal degradation and gas generation from HLW.