KIEV -- Radioactive water leaked from a holding basin for spent nuclear fuel at Ukraine's Chernobyl nuclear power plant, officials said Thursday. The incident, which occurred Tuesday, ranked zero or one on a seven-point international scale of nuclear accidents, said Boris Yukhymenko, duty officer at the state committee on nuclear safety."The exact location and reason for the leak are still being investigated. We are still waiting to receive a report on this from plant officials," Yukhymenko said. The Chernobyl station was the site of the world's worst nuclear disaster in 1986.