SEOUL, South Korea (AP) - Radioactive water leaked inside a South Korean nuclear power plant during repair work, exposing 22 workers to small amounts of radiation, the government said Tuesday. About 12 gallons of so-called "heavy water" was leaked during the accident Monday evening at a nuclear plant in Wolsung, 190 miles southeast of the capital Seoul, the Science and Technology Ministry said. It said the radioactive water was contained inside the plant and did not escape into the environment. The mishap followed neighboring Japan's worst nuclear accident, in which at least 49 people were exposed to radiation last week. The town of Tokaimura was temporarily closed down amid heightened fears about the safety of Japan's nuclear plants.