Kiev - Ukraine's Chernobyl nuclear power plant, scene of the world's worst nuclear accident, shut down its only functioning reactor yesterday after a heavy rainstorm flooded several parts of the facility. Mr Volodymyr Shenchenko, the station's duty engineer, said that the station had been shut down in the morning and there had been no increase in radiation levels. He said the plant would be restarted on July 17th. Ukraine promised last month to close the stricken troubled plant on December 15th.