Drought conditions across the country are causing fairly obvious problems, but some of the not so obvious issues are also appearing as power output at Vermont Yankee nuclear power plant in Vernon, VT, had to decrease because of low water conditions in the river the plant uses to help cool the reactors.
Vermont Yankee decreased its power to 83 percent early Tuesday due to low flow and higher temperatures in the Connecticut River. By Tuesday afternoon, power output was back up to 92.6 percent.
Because of river conditions, the plant switched over to closed-cycle cooling utilizing the plant’s cooling towers to cool the water necessary to prevent the plant’s reactor from overheating.
“In this kind of hot and humid weather with low river flows, we reduce power to insure the plant’s systems remain within administrative limits,” said Rob Williams, spokesman for Vermont Yankee.
While the plant can operate at 100 percent while the cooling towers are in use, its output to the grid reduces because some of the power run the fans in the towers.
“Sometimes in the summer, the weather dictates how much electricity we can supply to the grid,” said Williams. “That’s the nature of doing business on a river with variable flow and variable temperature.”
In addition, Vermont Yankee works under conditions of a state discharge permit where it can’t increase the river’s water temperature when the ambient temperature reaches a certain point.