The US Nuclear Regulatory Commission (NRC) has approved uprates to seven nuclear reactors over the last year, adding a further 249 MWe to overall US nuclear capacity.
Beaver Valley: more potent than before (Image: First Energy)
Almost half of American reactors have undergone maintenance to boost performance, often carried out alongside work to extend the reactors' working lives.
Uprates not previously announced include a 14.6 MWe increase in capacity at Progress Energy Florida's Crystal River, which took the unit to 838 MWe in November 2007. First Energy's (Fenoc's) Beaver Valley 1 went up 43 MWe to 911 MWe, with unit 2 following suit in May 2008.
In June 2008, the capacity of PSEG Nuclear's Hope Creek was increased by 122 MWe net to 1185 MWe, while Fenoc's Davis Besse and Nebraska's Cooper were each uprated by 12 MWe in the July-August period. Southern Company's Vogtle 1 was uprated by 45 MWe to 1172 MWe net in April and the firm is expecting about 47 MWe for unit 2 this month.
The total quantified increase not previously reported is 249 MWe – about one quarter of the typical total capacity for a US reactor. The boost takes US net capacity to 100,599 MWe (based on April 2008 data from the Nuclear Energy Institute). Planned uprates to Beaver Valley 2 and Vogtle 2 will increase this further by about 19 MWe, while in 2009 Progress Energy plans the first stage of a further 180 MWe uprate of Crystal River.
A nuclear power plant's capacity can be increased after improvements are made to the reactor itself, to the supporting technology such as turbines and piping, or from changes to operating regimes following improvements in instrumentation. Equipment upgrades often become highly economic as plants grow older and can even be carried out alongside routine maintenance jobs during annual refuelling outages. Timing the work for these scheduled outages means no generating time is lost, while the relatively small cost of the upgrade can be funded many times over by the additional power generated from then on. The latest US uprates range from small improvements from flow control, to large 'extended' uprates from replacement of high pressure steam turbines.