Since 1977, power uprates at US nuclear power plants have added around 20,600 MWt or 6862 MW of electric capacity to the grid.

This accounts for more than 6% of the presently installed capacity (108.7 GW), and is equivalent to adding five or six new nuclear reactors to the grid.

However, figures recently released by the US Nuclear Regulatory Commission show that it expects to review fewer power uprate applications for US nuclear power plants over the next four years, because of commercial reasons. Just three power uprate applications adding around 180 MWe to the grid are expected by the end of September 2017 (one application is expected this year, with two more in 2016). A year ago, the NRC had reported expectations of ten such applications between October 2013 and September 2016, which would have added more than 1 GWe of capacity to the grid. These included five extended power uprates (EPU) and five measurement uncertainty recapture (MUR) projects. EPUs can be approved for increases as high as 20% and include significant modifications to balance-of-plant equipment, and thus have high costs. By contrast, MUR projects are typically achieved by implementing advanced techniques for calculating reactor power, and are typically for less than 2%.

There are currently 14 uprate applications under review, which could add around 3000 MWt or 1 GWe to US generating capacity, if approved.

As plants age, uprates will become less and less economic. The mean age of a US NPP is 33.4 years, which is above the worldwide average of 28 years. And while the industry aims to operate reactors for 50 or even 60 years, it is important to remember that less than 10% of the reactors listed in these tables have achieved more than 40 years of operation to date.

Photo:In August, Nebraska Public Power Distric decided not to proceed with an 18% EPU at the Cooper Nuclear Station (Source: NPPD)