The U.S. currently has 104 commercial nuclear reactors, and in 2011 these plants generated 768 billion kWh of electric, neatly one-fifth of the country’s total generation. Four new reactors are under construction in the U.S.; two 1,154 MWe Westinghouse AP1000 reactors at the Vogtle plant in Georgia and two AP1000 plants at the V.C. Summer site in South Carolina. But “new” nuclear generation is not coming from only newly-constructed plants.
According to information released by the U.S. Energy Information Administration (EIA) on July 17, since 1977 more than 6,500 MWe of nuclear uprates have been approved by the Nuclear Regulatory Commission (NRC) and most have been implemented. The NRC has approved a total of 144 uprates. EIA said through July 10, 2012, these cumulative uprates are roughly the equivalent of constructing six new nuclear power plants.
Three types of uprates can be implemented at nuclear power plants. Measurement uncertainty recapture (MUR) uprates generally result in an increase in electrical output of less than 2 percent and involve implementing enhanced methodologies for calculating reactor power and/or replacing old analog instrument sensors and control systems with modern sensors and digital control systems. The NRC has approved 55 MUR uprates, totaling about 829 MWe.
Stretch uprates increase electrical output by 3 percent to 7 percent and generally do not involve major plant modifications. Older components may be replaced with newer designs and modern materials. The NRC has approved 65 stretch uprates, totaling about 2,832 MWe.
And the third are extended uprates that increase electrical output by more than 7 percent and can be as large as 20 percent. Extended uprates generally involve significant plant modifications and may take years to fully implement. The NRC has approved 26 extended uprates, totaling about 2,883 MWe.
EIA said all but six of the 104 U.S. reactors have applied for an uprate, and only one reactor, Vermont Yankee, applied and was approved for a full 20 percent extended uprate. Susquehanna Units 1 and 2 and Hatch Units 1 and 2 are the only reactors to have received NRC approval for all three types of uprates.
The NRC is reviewing applications for seven extended and nine MUR uprates. If approved, these uprates would add about 1,140 MWe of nuclear capacity, in addition to the approximately 6,500 MWe already approved by the NRC. The total 7,640 MWe is roughly the equivalent of seven reactors the size of each of the Vogtle Units 3 and 4 reactors.
In the upcoming July issue of Nuclear Power International magazine, Associate Editor Lindsay Morris will provide an update on uprates currently taking place in the U.S.
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