The alert at the Quad Cities Nuclear Power Station has been canceled. Officials from Exelon, which owns and operates the plant, shut down one of the plant’s two reactors yesterday afternoon as a precautionary step after a valve malfunctioned. Clinton County emergency management director Wally Henry explains says it was a mechanical problem and a standard safety alarm moved ahead so they manually shut the valve down. The plant is in Cordova, Illinois, just northeast of Davenport and south of Clinton. Henry says -no- radiation leaked and no one was injured. He says there was never any danger.Two state parks were closed as part of the alert yesterday but both have reopened — the Upper Mississippi Valley Wildlife Refuge and the Princeton State Wildlife Management Area.