Monticello uprate postponed

07 September 2011

US utility Xcel Energy has announced a delay of about one year in the implementation of a power uprate at its single-unit Monticello nuclear power plant in Minnesota. In early 2008, the company announced plans to increase the generating capacity of the 600 MWe boiling water reactor by 10% - some 71 MWe - through an 'extended power uprate'. This involves significant modifications to major plant equipment, such as replacing steam turbines. Xcel has now said that the uprate has been postponed due to a delay in a subsidiary's ability to submit data to the Nuclear Regulatory Commission "regarding the uncertainty associated with the hydraulic margins of the pumps that supply cooling water to the reactor in the unlikely event of an emergency." Xcel also noted that new pumps that need to be fitted as part of the uprate "failed to meet performance specifications during testing and will require additional rework or rebuilding prior to installation." The uprate project - originally planned to take place later this year - is now expected to be completed during a refuelling outage in late 2012.