Vogtle Electric Generating Plant
|Official name||Alvin W. Vogtle Electric Generating Plant|
|Location||Burke County, Georgia,|
|Commission date||Unit 1: June 1, 1987
Unit 2: May 20, 1989
|Construction cost||$8.87 billion (Units 1 & 2)|
|Owner(s)||Georgia Power (45.7%)
City of Dalton (1.6%)
|Nuclear power station|
|Reactor type||4-loop PWR (active), AP1000 (planned)|
|Units operational||2 × 1215 MW|
|Units under const.||2 × 1117 MW|
The Alvin W. Vogtle Electric Generating Plant, also known as Plant Vogtle, is a 2-unit nuclear power plant located in Burke County, near Waynesboro, Georgia in the southeastern United States. It is named after the Alabama Power and Southern Company board chairman, Alvin Vogtle.
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 unit 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. The twin natural-draft cooling towers are 548 ft (167 m) tall and provide cooling to the plant's main condensers. Four smaller mechanical draft cooling towers provide service water cooling to auxiliary safety and non safety components and remove the decay heat from the reactor when the plant is offline. One natural-draft tower and two service water towers serve each unit. Natural-draft type cooling towers were also selected for the new units 3 and 4 and are currently under construction. The two new cooling towers will also be nearly 550 feet tall.
During Vogtle's construction, capital investment required jumped from an estimated $660 million to $8.87 billion. This huge increase in cost was typical of the time due to new regulations mandating increased safety precautions and more robust designs, a result of the Three Mile Island accident.
The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity.
The 2010 U.S. population within 10 miles (16 km) of Vogtle was 5,845, a decrease of 16.3 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within 50 miles (80 km) was 726,640, an increase of 8.8 percent since 2000. Cities within 50 miles include Augusta (26 miles to city center).
The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Vogtle was 1 in 140,845, according to an NRC study published in August 2010.
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.
Site area emergency
On March 20, 1990 at 9:20 a.m., a truck carrying fuel and lubricants in the plant's 230kv low voltage switchyard backed into a support column for the feeder line supplying power to the Unit 1-A reserve auxiliary transformer (RAT). At the time, the 1-B RAT was de-energized for maintenance and RAT 1-A was powering both trains of emergency electrical power, and the non-emergency electrical trains were being powered by back-feeding from the 500kv switchyard through the main step-up transformer to the 1-A and 1-B unit auxiliary transformers (UAT.) Additionally, Emergency Diesel Generator (EDG) 1-B was out of service for planned maintenance. After the power loss, EDG 1-A failed to start due to a protective safety trip. 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 offline at the time, residual heat from the natural decay of the radioactive fuel needed to be removed to prevent a dangerous rise in core temperature. While the non safety power was not interrupted, there was no physical connection between the vital and non-vital electrical trains which prevented the vital trains from receiving power from the unaffected 500kv switchyard.
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., after trying multiple times to start the "A" EDG normally, plant operators performed an emergency startup of the EDG by activating the generator's "emergency start" break-glass which bypassed most of the EDG's safeties and forced it to start. The startup was successful. 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. At 11:40 a.m., crews energized RAT 1-B which had been shut down for maintenance and restored power to the "B" safety electrical train. As 12:57 p.m., the "A" safety train was switched from the EDG to RAT 1-B and the EDG was shut down. With both trains receiving offsite power, the alert was terminated at 1:47 p.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. 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 busses to non-vital power or to the Unit 2 electrical busses. Since this incident, Plant Vogtle has implemented changes to the plant that allow the non-vital electrical buses to transfer power to the vital buses in this type of scenario.
The electrical fault described above also affected unit 2 by causing breakers in the 230kv switchyard to trip cutting off power to RAT 2-B and vital bus B on unit 2. EDG 2-B subsequently started and restored power to the vital bus. At the same time, the electrical disturbance from the falling line striking the ground was detected by protective safeties on unit 2's main step-up transformer and a protective relay actuated and opened the transformer's output breaker causing a full load rejection to unit 2 which led to a turbine trip and reactor scram. After the unit tripped, the B non-vital electrical train lost power as it attempted to transfer from UAT 2-B (which is powered by the turbine generator) to the failed RAT 2-B causing two of the reactor coolant pumps and one of the main feedwater pumps to trip, though the plant cool down proceeded safely. At 9:03 p.m., the RAT 2-B breakers in the switchyard were reset and offsite power was restored to the vital and non-vital B electrical trains allowing reactor coolant pumps 2 and 4 to be restarted. EDG 2-B was shutdown. It was later determined that the fault disturbance caused by the line falling was not of significant magnitude to trip the protective relay per design and should not have caused unit 2 to shut down. Further investigation found that current transformers on the main transformer were improperly set. The controls were adjusted to the proper setting. Had the CTs been properly set initially, the unit would have remained online.
Units 3 and 4
|Wikinews has related news: US regulators approve new nuclear reactors for first time in 34 years|
On August 15, 2006, Southern Nuclear formally applied for an Early Site Permit (ESP) for two additional units. The ESP will determine whether the site is appropriate for additional reactors, and this process is separate from the Combined Construction and Operating License (COL) application process. On March 31, 2008, Southern Nuclear announced that it had submitted an application for a COL, a process which will take at least 3 to 4 years. On April 9, 2008, Georgia Power Company reached a contract agreement for two AP1000 reactors designed by Westinghouse (owned by Toshiba) and the Shaw Group (Baton Rouge, LA). The contract represents the first agreement for new nuclear development in the United States since the Three Mile Island accident in 1979, and received approval from the Georgia Public Service Commission (PSC) on March 17, 2009. As stated by a Georgia Power spokesperson Carol Boatright: "If the PSC approves, we are going forward with the new units."
On August 26, 2009, the U.S. Nuclear Regulatory Commission (NRC) issued an Early Site Permit and a Limited Work Authorization. Limited construction at the new reactor sites has begun, with Unit 3 expected to be operational in 2016, followed by Unit 4 in 2017, pending final issuance of the Combined Construction and Operating License by the NRC.
On February 16, 2010, President Obama announced $8.33 billion in federal loan guarantees toward the construction cost, although as of December 2013 Georgia Power had not availed itself of those guarantees. The cost of building the two reactors is expected to be $14 billion.
In February 2012, the US Nuclear Regulatory Commission approved the construction license of the two proposed reactors at the Vogtle plant. NRC Chairman Gregory Jaczko cast the lone dissenting vote on plans to build and operate the two new nuclear power reactors, citing safety concerns stemming from Japan's 2011 Fukushima nuclear disaster, and saying "I cannot support issuing this license as if Fukushima never happened".
One week after Southern received the license to begin major construction on the two new reactors, a dozen environmental and anti-nuclear groups sued to stop the Plant Vogtle expansion project, saying "public safety and environmental problems since Japan's Fukushima Daiichi nuclear reactor accident have not been taken into account". On July 11, 2012, the lawsuit was rejected by the Washington D.C. Circuit Court of Appeals.
On March 12, 2013 construction on unit 3 officially began with the pour of the basemat concrete for the nuclear island. This operation was complete on March 14. During the weekend of June 1–2, 2013, assembly of the containment vessel began with the bottom head of the vessel being lifted into place on the nuclear island. By June 2013, construction schedule has slipped by at least 14 months.
On November 21, 2013, the basemat pour for Unit 4 was completed.
The Vogtle Electric Generating Plant consists of two operational reactors; two additional units are under construction.
|Reactor unit||Reactor type||Capacity||Nuclear Construction started||Electricity grid connection||Commercial operation||Shutdown|
|Vogtle-1 ||Westinghouse 4-loop||1150 MW||1203 MW||August 1, 1976||March 27, 1987||June 1, 1987|
|Vogtle-2 ||Westinghouse 4-loop||1152 MW||1202 MW||August 1, 1976||April 10, 1989||May 20, 1989|
|Vogtle-3 ||AP1000||1117 MW||1250 MW||March 12, 2013|
|Vogtle-4||AP1000||1117 MW||1250 MW||November 19, 2013|
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- Southern Nuclear: Plant Vogtle Homepage
- U.S. Department of Energy: Vogtle
- NRC: Vogtle Electric Generating Plant, Unit 1
- NRC: Vogtle Electric Generating Plant, Unit 2
- NRC: Vogtle, Units 3 & 4 Application