Performance improvement

Monticello marvel

29 May 2009



Improvements at Monticello have led to a marvellous increase in performance


The Monticello Nuclear Generating Plant (MNGP) near Minneapolis, Minnesota is a General Electric boiling water reactor. MNGP entered commercial operation in 1971, uprated reactor thermal power from 1670MWt to 1775MWt (578MWe) in 1998 and had its operating licence extended in 2006. It has had a refuelling outage every two years since 2001. From 2000 to 2008, the plant’s lifetime load factor has increased 148 basis points to 76.7% (as of September 2008), which takes it well above the BWR industry lifetime average of 70.1%.

Operator Xcel Energy says, “Since January of 2002, the site has operated very reliably with only three automatic reactor scrams. Non-refuelling outage related capacity factor losses have averaged 2.3% per year. Almost two-thirds of the capacity factor losses occurred in two of the scrams. One scram was an age-related electrical fault in a buried power cable that supplied power to the site. The other was due to a structural failure caused by original design flaws that resulted in the turbine control valves failing to open.

“For many years MNGP has performed modifications aimed at enhancing plant reliability and efficiency. MNGP has performed maintenance activities and changes to address age-related issues effectively to ensure minimal losses in thermal performance. Procedure and training enhancements have contributed to reliable plant operation. Human performance initiatives have also helped to ensure site performance meets management expectations.”


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