Browns Ferry Nuclear Power Plant

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Browns Ferry Nuclear Plant
Browns ferry NPP.jpg
Browns Ferry Nuclear Power Plant (NRC image).
Browns Ferry Nuclear Power Plant is located in Alabama
Browns Ferry Nuclear Power Plant
Location of Browns Ferry Nuclear Plant
Country United States
Location Athens, Alabama
Coordinates 34°42′14″N 87°7′7″W / 34.70389°N 87.11861°W / 34.70389; -87.11861Coordinates: 34°42′14″N 87°7′7″W / 34.70389°N 87.11861°W / 34.70389; -87.11861
Status Operational
Construction began 1966–77
Commission date Unit 1: Dec. 20, 1973
Unit 2: Aug. 2, 1974
Unit 3: Aug. 18, 1976
Operator(s) Tennessee Valley Authority
Nuclear power station
Reactor type boiling water reactor
Reactor supplier General Electric
Power generation
Units operational 3,297 MW
(3 reactors)
Annual generation 21,227 GWh
Website
www.tva.gov/power/nuclear/brownsferry

The Browns Ferry Nuclear Plant is located on the Tennessee River near Decatur and Athens, Alabama, on the north side (right bank) of Wheeler Lake. The nuclear power plant is named after a ferry that operated at the site until the middle of the 20th century. The site has three General Electric boiling water reactor (BWR) nuclear generating units and is owned entirely by the Tennessee Valley Authority. Browns Ferry was TVA's first nuclear power plant; its approval occurred on June 17, 1966 and construction began in September 1966.[1] In 1974, the time of its initial operation, it was the largest nuclear plant in the world. It was the first nuclear plant in the world to generate more than 1 gigawatt of power.[2]

In 2006, the Nuclear Regulatory Commission (NRC) renewed the licenses for all three reactors, extending them for an additional twenty years.

Surrounding population[edit]

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.[3]

The 2010 U.S. population within 10 miles (16 km) of Browns Ferry was 39,930, an increase of 12.3 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 977,942, an increase of 11.0 percent since 2000. Cities within 50 miles include Huntsville (28 miles to city center).[4]

Tornado of April 27, 2011[edit]

Crumpled towers

At 5:01 PM on April 27, 2011, all three reactors scrammed due to loss of external power caused by a tornado in the vicinity of the plant. Control rod insertion and cooling procedures operated as designed with no physical damage or release of radiation. Diesel backup generators provided power after a brief period of outage. An NRC Unusual Event, the lowest level of emergency classification, was declared due to loss of power exceeding 15 minutes. Additionally, a small oil leak was found on one generator. Due to widespread transmission grid damage from the storms, Browns Ferry was unable to produce power for the grid and significant blackouts occurred throughout the Southeastern United States.[5][6]

Unit One[edit]

Unit One under construction

Unit One is a 1,065 MWe BWR built by General Electric. Construction started on Unit One September 12, 1966[1] and originally came online on December 20, 1973. It is licensed to operate through December 20, 2033. However, Unit One was shut down for a year after a fire in 1975 damaged the unit. The unit was subsequently repaired and operated from 1976 through 1985, when all three Browns Ferry units were shut down for operational and management issues. Units Two and Three were restarted in 1991 and 1995, respectively.

Starting in 2002, TVA undertook an effort to restore Unit One to operational status, spending $1.8 billion to do so. The United States Nuclear Regulatory Commission (NRC) approved the restart of Unit 1 on May 15, 2007 and the reactor was brought up to criticality on May 22 for the first time since March 3, 1985.[7] During initial testing after restart, on May 24, 2007, a leaky hydraulic control pipe in the turbine hall burst, spilling about 600 gallons of non-radioactive fluid, and the newly restarted reactor was temporarily powered down. Reactor power-up and tests resumed on May 27 and the unit started supplying power to the electricity supply grid on June 2, 2007, reaching full power on June 8. The Browns Ferry restart is expected to pay for itself in five years.[8]

Unit One can generate 1,155 MW of electricity, and TVA plans an uprate to 1,280 MWe for this and the other two reactors.

Unit One fire[edit]

Polyurethane foam used to fill a cable tray penetration at a power plant in Nova Scotia (subsequently removed and replaced with firestop mortar).

The March 22, 1975 fire started when a worker using a candle to search for air leaks accidentally set a temporary cable seal on fire. At Browns Ferry, foamed plastic, covered on both sides with two coats of a flame retardant paint, was used as a firestop. The fire spread from the temporary seal into the foamed plastic, causing significant damage to the reactor control cabling in the station.[9]

A U.S. Nuclear Regulatory Commission bulletin explained the circumstances of the fire.

The fire started in the cable spreading room at a cable penetration through the wall between the cable spreading room and the reactor building for Unit 1. A slight differential pressure is maintained (by design) across this wall, with the higher pressure being on the cable spreading room side. The penetration seal originally present had been breached to install additional cables required by a design modification. Site personnel were resealing the penetration after cable installation and were checking the airflow through a temporary seal with a candle flame prior to installing the permanent sealing material. The temporary sealing material was highly combustible, and caught fire. Efforts were made by the workers to extinguish the fire at its origin, but they apparently did not recognize that the fire, under the influence of the draft through the penetration, was spreading on the reactor building side of the wall. The extent of the fire in the cable spreading room was limited to a few feet from the penetration; however, the presence of the fire on the other side of the wall from the point of ignition was not recognized until significant damage to cables related to the control of Units 1 and 2 had occurred.[10]

This later resulted in the Nuclear Regulatory Commission making significant additions to the standards for fire protection through the publication of 10CFR50.48 and Appendix R. According to the Nuclear Information and Resource Service, the newly restarted Unit One does not comply with these standards. Unit Three was not affected by the accident. This event was pivotal not just for firestopping in the nuclear field, but also in commercial and industrial construction. While the nuclear field went to installations of silicone foam, a wider array of firestops became prevalent in non-nuclear construction.

In a 2005 analysis of significant nuclear safety occurrences in the US, the NRC concluded that the fire at Browns Ferry was the most likely (excluding the actual Three Mile Island accident) "precursor" incident to have led to a nuclear accident in the event of a subsequent failure.[11]

Unit Two[edit]

Unit Two is a 1,113 MWe BWR built by General Electric which originally came online on August 2, 1974, and is licensed to operate through June 28, 2034. Unit Two generated 8.911261 TW-h of electricity in 2003, achieving a capacity factor of 94.1%.

During a drought in August 2007, Unit Two was shut down for one day because water temperature in the Tennessee River rose too high for the water to be used for cooling and then discharged back into the river.[12]

Beginning in 2005 Unit 2 was loaded with BLEU (Blended Low Enriched Uranium) recovered by the DOE from weapons programs. This fuel contains quantities of U-236 and other contaminants because it was made from reprocessed fuel from weapons program reactors and therefore has slightly different characteristics when used in a reactor as compared to fresh uranium fuel. By making use of this fuel which would otherwise have been disposed of as waste the TVA is saving millions of dollars in fuel costs and accumulating a database of recycled uranium reactions in LWR use.[13]

Unit Three[edit]

Unit Three is a 1,113 MWe BWR built by General Electric which originally came online on August 18, 1976, and is licensed to operate through July 2, 2036. Unit Three generated 9.260078 TW·h, achieving a capacity factor of 99% [over what time period?].

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 Browns Ferry was: Reactor 1: 1 in 270,270; Reactors 2 and 3: 1 in 185,185, according to an NRC study published in August 2010.[14][15]

References[edit]

  1. ^ a b "TVA timeline by year". Tennessee Valley Authority. Retrieved 5 August 2009. 
  2. ^ "Browns Ferry Nuclear Plant". Tennessee Valley Authority (TVA). Retrieved 2008-11-18. 
  3. ^ http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/emerg-plan-prep-nuc-power-bg.html
  4. ^ Bill Dedman, Nuclear neighbors: Population rises near US reactors, msnbc.com, April 14, 2011 http://www.msnbc.msn.com/id/42555888/ns/us_news-life/ Accessed May 1, 2011.
  5. ^ NRC: Event Notification Report for April 28, 2011
  6. ^ TVA: Power Restoration Updates
  7. ^ [1][dead link]
  8. ^ Blair, Elliot (2007-07-09). "New Reactor Costs Daunt U.S. Utilities as TVA Restarts Old Unit". Bloomberg. Retrieved 2011-03-28. 
  9. ^ Fisher, Brad (April 4, 1979). "Nuclear risk-benefit ratio needs a much closer look". The Tuscaloosa News. 
  10. ^ "IE Bulletin No. - 75-04A: Cable Fire at Browns Ferry Nuclear Plant". United States Nuclear Regulatory Commission. April 3, 1975. 
  11. ^ Nuclear Regulatory Commission. "NRC Commission Document SECY-05-0192 Attachment 2" (PDF). Retrieved 2008-01-28. 
  12. ^ Mitch Weiss, Drought Could Force Nuclear Plants to Shut Down, Associated Press, January 23, 2008, retrieved from WRAL-TV website, April 7, 2009
  13. ^ TVA press release[dead link]
  14. ^ Bill Dedman, "What are the odds? US nuke plants ranked by quake risk," msnbc.com, March 17, 2011 http://www.msnbc.msn.com/id/42103936/ Accessed April 19, 2011.
  15. ^ http://msnbcmedia.msn.com/i/msnbc/Sections/NEWS/quake%20nrc%20risk%20estimates.pdf

External links[edit]

Media related to Browns Ferry Nuclear Power Plant at Wikimedia Commons