Regulator approves US plant uprates

Tuesday, 11 February 2014

The US Nuclear Regulatory Commission (NRC) has given its blessing to uprates at five nuclear reactors that will add nearly 100 MWe of capacity to the US grid.

Byron (Image: Exelon)

The uprates at Exelon's Braidwood and Byron plants and DTE Electric's Fermi power station are all to be achieved through more accurate measurements of feedwater flow, which will enable the reactors to each increase their capacity by 1.6%.

Uprates achieved by implementing enhanced techniques for calculating reactor power are referred to as measurement uncertainty recapture power uprates. Such uprates involve the use of devices to perform more precise measurements of feedwater flow, which is in turn used to calculate reactor power, typically allowing capacity increases of up to 2%.

Power uprates

Uprates of up to 7%, known as stretch uprates, can sometimes be achieved within the design capacity of the plant without involving major modifications, while extended power uprates can be achieved through modifications to major balance-of-plant equipment such as the high pressure turbines, condensate pumps and motors, main generators, and transformers. These can add on anything up to 20% of a plant's capacity.

Fermi is a single-unit boiling water reactor, located in the state of Michigan. DTE intends to implement the uprate, which will increase the unit's generating capacity from 1179 to 1198 MWe, during the unit's current refuelling outage.

Exelon intends to implement the uprates to the Byron and Braidwood plants during February. Both plants comprise two pressurised water reactors, and the NRC says the uprates will increase each station's total generating capacity from 2350 to 2390 MWe. The plants are both located in the state of Illinois.

Including the uprates at Byron, Braidwood and Fermi, the NRC has approved uprates totalling some 7036 MWe since 1977. Applications for uprates totalling some 825 MWe are pending and the NRC anticipates receiving two further applications for measurement uncertainty recapture power uprates this year, which would add a further 39 MWe of capacity.

Researched and written
by World Nuclear News