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SynopsisWe highlight below our results from the title project. The project is a coordinated effort of the three Co-PIS to assist the Safety Programs at the Hanford and other DOE Environmental Management Sites. We present in the report our observations and interactively discuss their implications for safety concerns, We focus on three issues: a. Reducing radicals in the NOx systemWe show that the only reducing radical that lasts longer than a few ns in typical waste solutions, and is capable of generating hydrogen, is NOS2-. We measured the lifetime of this species across the whole pH range (3 5 pH I 14) and found it to be shorter than -15 ps, before it dissociates to give the strongly oxidizing NO, radicals. We found that it reacts with many proton donors (H+, phosphate, borate, W4+, amines) in a reaction that is not merely an acid-base equilibrium reaction but is probably a dissociative proton transfer. We estimate the redox potential from theoretical considerations and obtain an experimental verification. We conclude that it is highly unlikely, although thennodynamically possible, that this radical will generate hydrogen in waste solutions. b. Aging of organic chelators and their degradation products by NO,Methodologies to study the degradation of organic substrates (including the important waste components, formate and oxalate) to CO,, or On the other hand, the same mechanism may also provide a pathway for oxidative aging of organics by holes even when the organic is dissolved in the liquid or adsorbed on the solid surface.We have started to study reactions of NOz. Methodology and instrumentation to measure reactions of relevant organic radicals with NO, and with its parent NO; were developed. Because of low extinction coefficients, conductivity will be the method of choice.