Actions Taken to Address Risks Related to Coal Plant DuctWork

Along with steam, the coal combustion process produces hot gases (called flue gases), including sulfur dioxide, nitrogen oxides, and ash particles. Flue gas moves through ductwork to various air pollution control devices prior to being emitted through the stack. The objective of our evaluation was to determine if TVA is taking actions to address environmental and safety risks related to flue gas ductwork at coal plants. Since scrubbers increase the risk of corrosion within flue gas ductwork, our evaluation included plants with operational scrubbers. We found TVA has completed repairs to address environmental risks associated with flue gas ductwork at coal plants. However, TVA's framework for repairing and reporting ductwork leaks could be improved by (1) clarifying thresholds to repair and report cumulative leaks, (2) establishing realistic repair timelines, and (3) prioritizing the most environmentally damaging leaks for repair. We also found TVA has completed some repairs designed to address safety risks associated with ductwork, but TVA site management indicated long-term capital projects are needed and planned for remediation at Bull Run Fossil Plant and Cumberland where the worst material conditions were present. In addition, we found weakness in the identification of safety concerns related to ductwork at the sites. Additionally, we determined TVA is incurring risk by adopting a strategy to apply internal thermal coatings to ductwork at Cumberland to resist corrosion. Thermal coatings have not previously been used for this application nor have they been through a technical review involving Generation Engineering. This could result in TVA spending several million dollars on a solution that may not work.