The US Nuclear Regulatory Commission (NRC) has granted Xcel Energy a 20 year licence extension for its Prairie Island nuclear power plant in Minnesota. Units 1 and 2 began life in 1973 and 1974 respectively with 40 year licences due to end in 2013 and 2014, but the extensions will see the dates pushed out to 2033 and 2034. Xcel will now invest at least $500m in the plant to support life extension projects, and will invest even more if an uprate request is approved by the NRC. The two units are both Westinghouse two-loop reactors currently rated at 560 MW and 554 MW respectively. The approval brings the total number of US reactors to receive licence extensions to 68 as compared to the total of 104 power reactors operating in America. The majority of the remainder are either applying or set to apply for extensions in coming years. The Prairie Island relicensing application process took three years to complete.