High winds that caused damage across central Iowa last week have prompted NextEra Energy to close the Duane Arnold nuclear power plant about two months earlier than originally planned. The plant’s 622-MWe boiling water reactor has been off line since August 10, when a line of intense, fast-moving windstorms, called derechos, caused a loss of off-site power and damaged the plant’s cooling towers. NextEra had planned to permanently shut down Duane Arnold, Iowa’s only nuclear power reactor, on October 30.