Structural Modification of a Power Plant’s River Water Intake to Minimize Ice Blockage

Ice blockage of a power plant’s water intake is of paramount importance since it can lead to an unplanned shutdown of the intake compromising water supply and plant operation. American Electric Power’s (AEP) Conesville Power Plant historically controlled ice accumulation at the river intake by routing to the intake a portion of the warm water return from the condenser on the only operating “once-through” unit’s circulating water system. The unit operating with this once-through cooling system was retired at the end of 2012; thus, the plant lost the use of the condenser outlet/warm water return deicing flow at the river intake. A numerical study was conducted to evaluate design alternatives to alleviate ice accumulation at the river intake. A numerical model to predict the ice transport and accumulation at the river intake was developed and used to understand the main phenomenon leading to intake blockage. The effectiveness of mitigation measures was evaluated with the model. A mitigation plan consisting of intake modifications to be implemented during several phases is presented. In the first phase, large pipe openings are cut in the walls separating intake pump wells of previously retired units at the facility. In the second phase, a number of sediment control vanes previously placed in front of the intake are removed to facilitate downstream ice transport. A third phase, if needed to be implemented, involves removing additional sedimentation control vanes and cutting holes in the pump wells on the operating units. The paper describes the model, discusses numerical results and presents the field experience after implementation of phase one.