The Consequences of Poor Human Factors at a Super Critical Coal Power Plant, A Case Study

Abstract: This case study will provide an overview of the impact that a lack of human factors integrated into the operation of a super critical coal fired power plant (CPP). The CPP was of modern design, with a digital control system; however, the plant lacked human core human factors considerations, such as: human factored procedures; sufficient operator training; adequate supervision of the workforce; poor to nonexistent labeling; and operating staff frequently operating outside of procedures and standard practices. The significant consequences of this absence were that the plant’s turbine was destroyed twice, and the generator was destroyed once. The cost of the damage was in the tens of millions of dollars. The CPP was owned by a major utility and supplied power to several smaller, local utilities. The following is a specific example of how the lack of human factors led to the costly damage at this CPP, in this case turbine damage. The plant was in a startup phase and an operator heard some chatter on his radio and left his duty station to discuss what he heard with a fellow operator. The operator then proceeded to the turbine lube oil (TLO) skid. The TLO supplies lubrication and coolant to the turbine. It also provides the seal for the generator’s hydrogen coolant. The operator, unsatisfied with his understanding of the situation, decided to adjust the TLO valve. The TLO valve is a 6-way valve. The 6-way valve was manipulated inappropriately by the operator and turbine lube oil was shutoff to the turbine and generator hydrogen seal. Communications did not occur between the control room personnel and the operator prior to position changes; plan of action was not validated with other operators prior to taking the action. The mental model of the worker did not align with the potential consequences of operating a valve for oil flow to the turbine running at 3600 RPM. The consequences of turbine damage were caused by a failed mechanical stop in the valve, which allowed the valve to fully isolate turbine lube oil. Further, human factors was not considered with regard to the operation of the valve. There was no clear way to ensure proper valve lineup, e.g., no markings, no immediate feedback that desired end-state was achieved. At the time there were no procedures for operating the valve and training on operating the valve was lacking. In fact, the valve had only been operating a few times in the life of the CPP, despite the the original equipment manufacturer recommending regular manipulation to ensure working order. The turbine was severely damaged and a small explosion occurred in the TLO filter due to hydrogen back up into the tube oil. The generator was not affected in this incident. Animations of the TLO valve incident and a detailed description of this incident will be provided during the presentation.

Keywords: Human Factors, Safety, Accident Analysis

DOI: 10.54941/ahfe1005791

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