Fears mount as Japan races against time to cool reactors

Linda Sieg and Chisa Fujioka, ReutersMarch 17, 2011TOKYO (Reuters) - Operators of a quake-crippled nuclear plant in Japan dumped water on overheating reactors on Thursday while the United States expressed growing alarm about leaking radiation and said it was chartering aircraft to help Americans leave the country.Engineers were rushing against time to run in a power line off the main grid to fire