Vogtle Electric Generating Plant - Power Uprate

Power Uprate

In 2008, both reactors were increased in power by 1.7% by an "Appendix K" uprate, also called a Measurement Uncertainty Recapture uprate. "Measurement uncertainty recapture power uprates are less than 2 percent and are achieved by implementing enhanced techniques for calculating reactor power. This involves the use of state-of-the-art feedwater flow measurement devices to more precisely measure feedwater flow, which is used to calculate reactor power. More precise measurements reduce the degree of uncertainty in the power level, which is used by analysts to predict the ability of the reactor to be safely shutdown under postulated accident conditions." Because the reactor power can be calculated with much greater accuracy now than with the old venturi type measurement, the plant can safely run within a tighter margin of error to their limit. The new flow meter works by comparing the time it takes ultrasonic sound pulses to travel upstream versus downstream inside the pipe, and uses that time difference to figure the flow rate of the water in the pipe.

The NRC approved Vogtle's License Amendment Request (LAR) in March 2008. "The NRC staff determined that Southern Nuclear could safely increase the reactor’s output primarily through more accurate means of measuring feedwater flow. NRC staff also reviewed Southern Nuclear’s evaluations showing the plant’s design can handle the increased power level." Unit 1 was uprated during its spring 2008 defueling outage, and Unit 2 was uprated in the fall outage of the same year.