Characterization of Reaction Gases and Aerosols from Underwater Plasma Arc Cutting Demonstration Tests at Three Mile Island Unit 2

Defueling operations at Three Mile Island Unit 2 involve underwater plasma arc cutting of reactor vessel stainless steel components. Sampling and analysis of released off-gases and aerosols during steady-state plasma arc cutting tests established a conversion fraction of nitrogen-to-nitrogen oxides, off-gas composition, and aerosol concentrations for engineering evaluations of potential health and safety and corrosion issues. The sample results indicate that (a) <1 vol% of nitrogen is converted to nitrogen oxides, (b) the airborne particulate concentrations for the major steel components (chromium, iron, nickel, etc.) could exceed the threshold limit values without off-gas capability, (c) the volume percent hydrogen could exceed its lower flammability limit without off-gas capability, and (d) there is low corrosion potential for off-gas system components for the given torch operations.