Assessment of Economic Risk in the Repair and Replacement of Prestressed Concrete Cylinder Pipe Used in the Circulating Water System at Great River Energy's Coal Creek Station

Risk is commonly defined as the product of the likelihood of an event and the consequences should that event occur. The economic risk that must be weighed by electric utilities in evaluating repair and replacement options for circulating water system piping is significantly different from other industries. Energy generation facilities depend on circulating water as a critical component of plant operations. Circulating water piping systems for existing generation facilities were generally constructed without redundancy, so evaluation or repair of the pipelines likely requires a costly generation outage. Additionally, the failure of a pipe section may result in an unplanned generation outage. Although the likelihood of a system failure is low for generation facilities, the consequences of disrupting plant operations are substantial. This paper describes the unique factors that affect the circulating water pipe repair/replacement decision process for the energy generation industry, with an emphasis on the evaluation of economic risk. A case history of Great River Energy's (GRE) decision to replace a portion of a 96-inch- to 120-inch-diameter prestressed concrete cylinder pipe (PCCP) circulating water pipeline at Coal Creek Station is also presented.