Radioactive water leaked at a South Korean nuclear power plant last night, exposing at least 22 people to radiation. The government says the radiation was contained within the facility and would not affect the outside environment. The incident follows an accident last week at a uranium-processing plant in Japan, which exposed at least 49 people to radiation and was thought to be the most serious nuclear incident after the Chernobyl meltdown in 1986. Ironically, before last night’s incident took place, South Korea officials yesterday were assuring the public that the nation’s nuclear plants were safe and in no danger of an accident like the one that took place in Japan. Environmental groups had warned of the danger of nuclear accidents in South Korea, which has 14 nuclear power plants that supply 40 percent of the nation’s electricity.