The Alvin W. Vogtle Electric Generating Plant is a 2-unit nuclear power plant located in Burke County, near Augusta and Waynesboro, Georgia.
Each unit has a Westinghouse pressurized water reactor (PWR), with a General Electric turbine and electric generator. Units 1 and 2 were completed in 1987 and 1989, respectively. Each of Vogtle's units is capable of producing approximately 1,200 MW of electricity when online, for a combined capacity of 2,400 MW. Southern Nuclear lists the capacity as 1,215 MW each, for a combined output of 2,430 MW.[1] The twin cooling towers are 548 ft (167 m) tall.
During Vogtle's construction, costs skyrocketed from an estimated $660 million to $8.87 billion.[2][3] This was typical of the time due to increased regulations after the Three Mile Island accident.
Contents [hide]
1 Ownership
2 Power Uprate 2008
3 Site area emergency
4 Units 3 and 4
5 References
6 External links
[edit] Ownership
The plant is jointly owned by Georgia Power (45.7%), Oglethorpe Power Corporation (30%), Municipal Electric Authority of Georgia (22.7%) and the City of Dalton (1.6%). The Southern Nuclear Operating Company operates the plant.
[edit] Power Uprate 2008
In 2008, both reactors were increased in power by 1.7% by an "Appendix K" uprate, (ref NRC Regulations (10CFR) Appendix K to Part 50) 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." (ref NRC Power Uprates) 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." (ref NRC News Release 08-043) Unit 1 was uprated during its spring 2008 defueling outage, and unit 2 was uprated in the fall outage of the same year.
[edit] Site area emergency
On March 20, 1990 at 9:20 a.m. a truck carrying fuel and lubricants in the plant's low voltage switchyard backed into a support column for the feeder line supplying power to the Unit 1-A reserve auxiliary transformer (RAT). This set off a complicated chain of events that was exacerbated both by planned maintenance (in which some back-up systems were off-line) and by equipment failures in some back-up systems. The resulting loss of electrical power in the plant's "vital circuits" shut down the residual heat removal (RHR) pump that was cooling Unit 1 (which was nearing the end of a refueling outage) and prevented the back-up RHR from activating. Even though Unit 1 was not operating at full-power, residual heat from the natural decay of the radioactive fuel needed to be removed to prevent a dangerous rise in core temperature. At 9:40 a.m. the plant operators declared a site area emergency (SAE) per existing procedures which called for an SAE whenever "vital" power is lost for more than 15 minutes. At 9:56 a.m., plant operators performed a manual start of the A-train emergency diesel generator (EDG), which bypassed most of the EDG's protective trips that had prevented it from coming on-line. RHR-A was then started using power from EDG-A. With core cooling restored the SAE was downgraded to an alert at 10:15 a.m. The temperature of the Unit 1 core coolant increased from 90 °F to 136 °F during the 36 minutes required to re-energize the A-side bus. Ironically, throughout the event, non-vital power was continuously available to Unit 1 from off-site sources. However, the Vogtle electrical system was not designed to permit easy interconnection of the Unit 1 vital buses to non-vital power or to the Unit 2 electrical buses.(ref NRC Information Notice No. 90-25) Since this incident, Plant Vogtle has implemented changes to the plant that allow power to be transferred from one side to the other from an off-site source.
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