Watts Bar Nuclear Plant

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Watts Bar Nuclear Plant
Watts Bar-6.jpg
Watts Bar Nuclear Power Plant Units 1 & 2 cooling towers and containment buildings.
Country United States
Location Rhea County, near Spring City, Tennessee
Coordinates 35°36′10″N 84°47′22″W / 35.60278°N 84.78944°W / 35.60278; -84.78944Coordinates: 35°36′10″N 84°47′22″W / 35.60278°N 84.78944°W / 35.60278; -84.78944
Status Operational
Construction began Unit 1: July 20, 1973
Unit 2: September 1, 1973[a]
Commission date Unit 1: May 27, 1996
Unit 2: October 19, 2016[a]
Construction cost More than $12 billion
Owner(s) Tennessee Valley Authority
Operator(s) Tennessee Valley Authority
Nuclear power station
Reactor type PWR
Reactor supplier Westinghouse
Cooling source Tennessee River
Cooling towers 2 × Natural Draft
Power generation
Units operational 1 × 1167 MW
1 × 1165 MW
Make and model WH 4-loop (ICECND)
Thermal capacity 1 × 3459 MWth
1 × 3411 MWth
Nameplate capacity 2332 MW
Capacity factor 68.10% (2017)
73.45% (lifetime)
Annual net output 13,650 GWh (2017)
Website
Watts Bar Nuclear Plant

The Watts Bar Nuclear Plant is a Tennessee Valley Authority (TVA) nuclear reactor pair used for electric power generation. It is located on a 1,770-acre (7.2 km²) site in Rhea County, Tennessee, near Spring City, between the cities of Chattanooga and Knoxville. Watts Bar supplies enough electricity for about 1,200,000 households in the Tennessee Valley.

The plant, construction of which began in 1973, has two Westinghouse pressurized water reactor units: Unit 1, completed in 1996, and Unit 2, completed in 2015. Unit 1 has a winter net dependable generating capacity of 1,167 megawatts. Unit 2 has a capacity of 1,165 megawatts. Unit 2 is the most recent civilian reactor to come on-line in the United States and the first new reactor to enter service in the United States after a 20-year hiatus.

Unit 1[edit]

The construction began on 23rd January 1973, and suffered from many delays. First criticality was achieved on 1st January 1996 and commercial operation was resumed on 5th May 1996.[1]

Unit 2[edit]

Unit 2 was 80% complete when construction on both units was stopped in the 1980s due in part to a projected decrease in power demand.[2] In 2007, the Tennessee Valley Authority (TVA) Board approved completion of Unit 2 on August 1, and construction resumed on October 15.[3] The project was expected to cost $2.5 billion, and employ around 2,300 contractor workers. Once finished, it was expected to employ 250 people in permanent jobs.[4] The final cost of the plant is estimated at $6.1 billion.[5]

A year after the 2011 Tōhoku earthquake and tsunami and subsequent Fukushima Daiichi nuclear disaster, the Nuclear Regulatory Commission (NRC) issued 9 orders to improve safety at domestic plants. Two applied to Watts Bar Unit 2 and required design modifications: "Mitigation Strategies Order"[6] and "Spent Fuel Pool Instrumentation Order".[7] In February 2012, TVA said the design modifications to Watts Bar 2 were partially responsible for the project running over budget and behind schedule.[2] The second unit cost a total of $4.7 billion bringing the total cost of the plant to more than $12 billion.[8]

TVA declared construction substantially complete in August 2015 and requested that NRC staff proceed with the final licensing review; on October 22, the NRC approved a forty-year operating license for Unit 2, marking the formal end of construction and allowing for the installation of nuclear fuel and subsequent testing.[9] On December 15, 2015, TVA announced that the reactor was fully loaded with fuel and ready for criticality and power ascension tests. In March 2016, the Nuclear Regulatory Commission described the project as a "chilled work environment," where employees are reluctant to raise safety concerns for fear of retribution.[5]

On May 23, 2016, initial criticality was achieved.[10] As of August 31, 2016, a transformer fire had delayed the start of commercial operation past the late summer goal.[11] Commercial operation started in October 2016, once the affected transformer was replaced, operators completed the inspection on the switchyard affected equipment and the final full power testing was completed.[12] On October 19, 2016 the Watts Bar 2 was the first United States reactor to enter commercial operation since 1996.[13] Due to failures in its condenser, TVA took it offline on March 23, 2017; as of May 2017, the cause of the problem had not been determined. The condenser, which was installed during the original construction phase of the plant in the 1970s, suffered a structural failure in one of its sections. On August 1, 2017 the unit was restarted after four months of repairs to the condenser.[5]

It will likely be the last Generation II reactor to be completed in the US.[14]

Tritium production[edit]

The NRC operating license for Watts Bar was modified in September 2002 to allow TVA to irradiate tritium-producing burnable absorber rods at Watts Bar to produce tritium for the U.S. Department of Energy's (DOE's) National Nuclear Security Administration. The Watts Bar license amendment currently permits TVA to install up to 240 tritium-producing rods in Watts Bar Unit 1. Planned future license amendments would allow TVA to irradiate up to approximately 2,000 tritium-producing rods in the Watts Bar reactor.

TVA began irradiating tritium-producing rods at Watts Bar Unit 1 in the fall of 2003. TVA removed these rods from the reactor in the spring of 2005. DOE successfully shipped them to its tritium-extraction facility at Savannah River Site in South Carolina. DOE reimburses TVA for the cost of providing the irradiation services, and also pays TVA a fee for each tritium-producing rod that is irradiated. As the tritium is used for military purposes, Watts Bar unit 1 is fuelled by uranium which does not have peaceful only use non-proliferation restrictions as is normal for commercial reactors.[15]

Surrounding population[edit]

Watts Bar's cooling towers, with the Tennessee River in the foreground

The NRC 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.[16]

The 2010 U.S. population within 10 miles (16 km) of Watts Bar was 18,452, an increase of 4.1 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 1,186,648, an increase of 12.8 percent since 2000.[17]

Seismic risk[edit]

The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Watts Bar was 1 in 27,778, according to an NRC study published in August 2010.[18][19]

See also[edit]

Notes[edit]

  1. ^ a b Although Unit 2 originally began construction on September 1, 1973, construction was halted on September 17, 1985 due to regulatory and economic factors. Construction was subsequently resumed on October 15, 2007, and the plant was completed on October 19, 2016, 43 years after construction first started (although the plant was only under active construction for 21 of those years).

References[edit]

  1. ^ "WATTS BAR-1: Reactor Details". Power Reactor Information System. International Atomic Energy Agency. Retrieved July 14, 2018.
  2. ^ a b DiSavino, Scott (March 16, 2012). "TVA cuts contractors at Alabama Bellefonte nuclear site". Reuters.
  3. ^ "WATTS BAR-2". PRIS. International Atomic Energy Agency. June 29, 2013. Retrieved June 29, 2013.
  4. ^ "TVA: Watts Bar Nuclear Plant". Tennessee Valley Authority. February 10, 2008. Archived from the original on February 12, 2012. Retrieved March 14, 2012.
  5. ^ a b c Hiltzik, Michael (2017-05-08). "America's first '21st century nuclear plant' already has been shut down for repairs". Los Angeles Times. ISSN 0458-3035. Retrieved 2017-05-09.
  6. ^ "Mitigation Strategies". nrc.gov. Retrieved 2015-11-09.
  7. ^ "Spent Fuel Pool Instrumentation Order". nrc.gov. Retrieved 2015-11-09.
  8. ^ "TVA Awards Watts Bar, Sequoyah Outage Contract To Westinghouse". nuclearstreet.com. 2016-02-22. Retrieved 2017-03-05.
  9. ^ "Watts Bar nuclear reactor granted operating license - first new U.S. reactor in 19 years". timesfreepress.com. Retrieved 2015-10-22.
  10. ^ Today — Initial Criticality. www.tva.com. Retrieved 23 May 2016.
  11. ^ "Transformer Fire Will Delay Watts Bar Unit 2 Commercial Operation". 31 August 2016.
  12. ^ "Watts Bar power ascension tests completed". www.timesfreepress.com. Time Free Press. 3 October 2016. Archived from the original on 4 October 2016. Retrieved 4 October 2016. The newest unit at the Watts Bar plant near Spring City, Tenn. is now producing more than 1,150 megawatts of electricity ...
  13. ^ Blau, Max (2016-10-20). "First new US nuclear reactor in 20 years goes live". CNN.com. Cable News Network. Turner Broadcasting System, Inc. Retrieved 2016-10-20.
  14. ^ Mintz Testa, Bridget (27 May 2012). "Three Generations of Nuclear Power Plants in the U.S." About.com. Archived from the original on 1 April 2016. Retrieved 7 March 2017.
  15. ^ "USA awards HEU downblending contract". World Nuclear News. 1 October 2018. Retrieved 3 October 2018.
  16. ^ "NRC: Backgrounder on Emergency Preparedness at Nuclear Power Plants". Fact Sheets. Nuclear Regulatory Commission. January 2009. Retrieved March 14, 2012.
  17. ^ Dedman, Bill (April 14, 2011). "Nuclear neighbors: Population rises near US reactors". NBCNews.com. Retrieved May 1, 2011.
  18. ^ Dedman, Bill (March 17, 2011). "What are the odds? US nuke plants ranked by quake risk". NBCNews.com. Retrieved April 19, 2011.
  19. ^ Hiland, Patrick (2010-09-02). "Implications of Updated Probabilistic Seismic Hazard Estimates in Central and Eastern United States on Existing Plants" (PDF). MSNBC Media. Retrieved 2016-10-05.

External links[edit]