About 200 gallons of oil has leaked out of the Monticello Nuclear Generating Plant in southern Minnesota, according to Minneapolis-based Xcel Energy. The leak was discovered Tuesday morning while crews were testing a motor that helps circulate water through the plant for cooling. Plant officials say no oil has reached the Mississippi River. The spill comes more than three years after 400,000 gallons of water containing the radioactive isotope tritium leaked into groundwater underneath the facili