Fukushima Daini Nuclear Power Plant

Not to be confused with Fukushima Daiichi Nuclear Power Plant.
Fukushima Daini Nuclear Power Plant

The Fukushima II NPP
Location of Fukushima Daini Nuclear Power Plant in Fukushima Prefecture
Country Japan
Location Naraha
Coordinates 37°18′59″N 141°1′32″E / 37.31639°N 141.02556°E / 37.31639; 141.02556Coordinates: 37°18′59″N 141°1′32″E / 37.31639°N 141.02556°E / 37.31639; 141.02556
Status Out of service
Construction began March 16, 1976 (1976-03-16)
Commission date April 20, 1982 (1982-04-20)
Operator(s) Tokyo Electric Power Company
Nuclear power station
Reactor type BWR
Reactor supplier Toshiba
Hitachi
Power generation
Units operational 4 x 1,100 MW
Nameplate capacity 4,400 MW
Website
Home page, Real time monitoring

The Fukushima Daini Nuclear Power Plant (福島第二原子力発電所 Fukushima Daini ( pronunciation) Genshiryoku Hatsudensho, Fukushima II NPP, 2F), is a nuclear power plant located on a 150 ha (370-acre) site[1] in the town of Naraha and Tomioka in the Futaba District of Fukushima Prefecture, Japan. The Tokyo Electric Power Company (TEPCO) runs the plant.

After the 2011 Tōhoku earthquake and tsunami, the four reactors at Fukushima II automatically shut down.[2]

Japan's worst nuclear accident occurred at TEPCO's Fukushima Daiichi Nuclear Power Plant (approximately 12 km (7.5 mi) to the north[3]) after the same March 11 earthquake.

Description

All reactors in the Fukushima II Nuclear Power Plant are BWR-5 type[4] with electric power of 1,100 MW each (net output: 1,067 MW each).[5]

The reactors for units 1 and 3 were supplied by Toshiba, and for units 2 and 4 by Hitachi. Units 1–3 were built by Kajima while the unit 4 was built by Shimizu and Takenaka.[5] The design basis accident for an earthquake was between 0.42 g (4.15 m/s2) and 0.52 g (5.12 m/s2) and for a tsunami was 5.2 m.[6]

Unit First criticality Installation costs (yen/MW) Reactor supplier Architecture Construction Containment[7]
1 31/07/1981 250,000,000 Toshiba Toshiba Kajima Mark 2
2 23/06/1983 230,000,000 Hitachi Hitachi Kajima Mark 2 advanced
3 14/12/1984 290,000,000 Toshiba Toshiba Kajima Mark 2 advanced
4 17/12/1986 250,000,000[8] Hitachi Hitachi Shimizu
Takenaka		 Mark 2 advanced

Electrical connections

The Fukushima Daini plant is connected to the rest of the power grid by the Tomioka Line (富岡線) to the Shin-Fukushima (New Fukushima) substation.[9]

Events

1989 incident

In January 1989, an impeller blade on one of the reactor coolant pumps in Unit 3 broke at a weld, causing a large amount of metal debris to flow throughout the primary loop. As a result, the reactor was shut down for a considerable length of time.[10]

2011 earthquake and tsunami

On March 11, 2011, a 9-meter-high tsunami struck the No. 2 plant, while the No. 1 plant was hit by a 13-meter-high tsunami. The tsunami caused the No. 2 plant's seawater pumps, used to cool reactors, to fail. Of the plant's four reactors, three were in danger of meltdown. One external high-voltage power line still functioned, allowing plant staff in the central control room to monitor data on internal reactor temperatures and water levels. 2,000 employees of the No. 2 plant worked to stabilize the reactors. Some employees connected 200-meter sections of cable, each weighing more than a ton, over a distance of 9 kilometres. It is pointed out only 40 employees would have been at the plant if the earthquake had occurred in the evening or on a weekend. According to the head of the plant, the plant was near meltdown.[11]

The March 11, 2011 Tōhoku earthquake resulted in maximum horizontal ground accelerations of 0.21 g (2.10 m/s2) to 0.28 (2.77 m/s2) at the plant site, which is well below the design basis.[6][12] All four units were automatically shut down immediately after the earthquake, according to Nuclear Engineering International,[2] and the diesel engines were started to power the reactor cooling.[13] TEPCO estimated that the tsunami that followed the earthquake and inundated the plant was 14 meters high which is more than twice the designed height.[6] This flooded the pump rooms used for the essential service water system transferring heat to the sea, the ultimate heat sink of the reactors.[13] In unit 3, one seawater pump remained operational. The steam powered reactor core isolation cooling system (RCIC) in all 4 units was activated and ran as needed to maintain water level. At the same time, operators utilized the safety relief valve systems to keep the reactor pressures from getting too high by dumping the heat to the suppression pools.[13] In unit 3, the residual heat removal system (RHR) was started to cool the suppression pool and later brought the reactor to cold shutdown on March 12, but in units 1, 2, and 4 heat removal was unavailable, so the suppression pools began heating up and on March 12, the water temperature in the pools of units 1, 2, and 4 topped 100 °C between 05:30 and 06:10 JST,[14][15][16] removing the ability to remove pressure from the reactor and drywell.[13] Also, operators had to prepare an alternate injection line for each unit, as the RCIC can run indefinitely only while there is sufficient pressure and steam in the reactor to drive its turbine; once reactor pressure drops below a certain level, the RCIC shuts down automatically. The normal AC driven ECCS systems were for the most part unavailable due to the loss of ultimate heat sink and damage to some of the electrical infrastructure. Operators prepared for this and set up an alternate injection line using a non-emergency system known as the Makeup Water Condensate System to maintain water level which was an accident mitigation method TEPCO put in place at all its nuclear plants. The system was started and stopped in all 4 units, including unit 3, as needed to maintain the water level. The RCICs in each unit later shut down due to low reactor pressure. Operators had to also use the MUWC and the makeup water purification and filtering (MUPF) system to try to cool the suppression pool and drywell in addition to the reactor to prevent the drywell pressure from getting too high. Operators were later able to restore the High Pressure Core Spray portion of the Emergency Core Cooling system in unit 4 and switched emergency water injection for unit 4 from the MUWC system to the HPCS. While the water level was maintained in the three cores using emergency water injection, pressures in the containment vessel continued to rise due to lack of suppression pool cooling and the operators prepared to vent the containments making restoration of heat removal urgent. Unit 1 was prioritized as it had the highest drywell pressure.[17]

The ultimate heat sink was restored when the service seawater system pumps in the pump room were repaired in units 1, 2 and 4 starting March 13 restoring the normal ECCS and heat removal systems to operable status and cooling was switched to the Residual Heat Removal System (RHR) portion of the ECCS. The RHR systems were first activated to cool down the suppression pools (torus) and drywells to operable status, and water injections were made to the reactors using the Low Pressure Coolant Injection (LPCI) mode as needed. When the suppression pool was cooled down to below 100 degrees, the RHR was switched to the shutdown cooling mode and brought the reactors to a cold shutdown.[14] Coolant temperatures below 100 °C (cold shutdown) were reached in reactor 2 about 34 hours after the emergency shut down (SCRAM) restoring the ability to lower the pressure of the reactor via the torus.[14] Reactors 1 and 3 followed at 1:24 and 3:52 on March 14 and Reactor 4 at 7:00 on March 15.[18] The loss of cooling water at reactors 1, 2 and 4 was classified a level 3 on the International Nuclear Event Scale (serious incident) by Japanese authorities as of March 18.[19][20][21]

Officials made preparations for release of pressure from the plant on March 12.[22][23] As of March 20, however, no pressure release had been reported.[14][24]

An evacuation order was issued to the people living within 3 kilometres (1.9 mi) of the plant,[25] subsequently expanded to 10 km (6.2 mi).[26][27] Air traffic was restricted in a 10 km (6.2 mi) radius around the plant, according to a NOTAM.[28] These zones were later superseded by the 20 km evacuation and 30 km no-fly zones around Fukushima I on March 12 and 15, respectively.[29]

TEPCO announced that a worker who had been seriously injured by the earthquake and trapped in the crane operating console of the exhaust stack was transported to the ground at 5:13 pm and confirmed dead at 5:17 pm.[26][30][31][32][33]

By March 15, all four reactors of Fukushima II reached cold shutdown, which remained non-threatening.[34]

Smoke was escaping from one of the buildings on March 30, 2011. It was emitted from equipment which supplies electrical power to a motor pump that collects outdoor water. The smoke stopped after workers disconnected the motor.[27]

As of June 2011, 7,000 tons of seawater from the tsunami remained in the plant. The plant planned to release it all back into the ocean, as the tanks and structures holding the water were beginning to corrode. Approximately 3,000 tons of the water was found to contain radioactive substances, and Japan's Fisheries Agency refused permission to release that water back into the ocean.[35]

On December 26, 2011, the Prime Minister officially cancelled the nuclear emergency declaration for the Fukushima Daini plant officially ending the incident. However, the emergency situation continues at the much more heavily damaged Fukushima Daiichi plant. On February 8, 2012, the plant was opened to news media for the first time since the 2011 Tōhoku earthquake and tsunami.

Restoration

The evacuation order was partly rescinded for Daini evacuees in August 2012. Some of the residents, such as the 7200 at Naraha town, were permitted to return during daylight hours only, but others were ordered to remain away. The area did not become seriously contaminated and was safe to visit without protective clothing.[36]

See also

References

  1. ↑ Tepco site (Japanese). Text and answers to the Fukushima II plant quiz. Page 8.
  2. 1 2 "Japan initiates emergency protocol after earthquake". Nuclear Engineering International. March 11, 2011. Retrieved March 11, 2011.
  3. ↑ "Fukushima II Nuclear Power Plant to Fukushima I Nuclear Power Plant". Google. Retrieved April 5, 2011.
  4. ↑ "Reactors in operation". IAEA. December 31, 2009. Retrieved March 12, 2011.
  5. 1 2 "Nuclear Reactor Maps: Fukushima-Daini". Council for Security Cooperation in the Asia Pacific. Retrieved March 14, 2011.
  6. 1 2 3 "Fukushima faced 14-metre tsunami". World Nuclear News. March 24, 2011. Retrieved March 24, 2011.
  7. ↑ 福島第二原子力発電所 設備の概要｜東京電力. Tepco.co.jp. Retrieved on 2013-09-06.
  8. ↑ "原発の発電コスト". Nuketext.org. October 28, 2008. Retrieved March 16, 2011.
  9. ↑ Tepco Annual Report 2003. Page 24. (Japanese).
  10. ↑ WISE (November 23, 1990). "Wise News Communique 342". WISE. Retrieved July 4, 2011.
  11. ↑ Yomiuri Shimbun 2012-02-09 Ver.13S page 1&2, Fukushima No. 2 plant was 'near meltdown'
  12. ↑ "The record of the earthquake intensity observed at Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power Station (Interim Report)". TEPCO. April 1, 2011.
  13. 1 2 3 4 "Insight to Fukushima engineering challenges". World Nuclear News. March 18, 2011. Retrieved March 19, 2011.
  14. 1 2 3 4 Cold shutdowns at Fukushima Daini, World Nuclear News, March 14, 2011, retrieved March 14, 2011
  15. ↑ reports for reactor 1, reactor 2, and reactor 4 of Tokyo Electric, received 11:50 JST
  16. ↑ Winter, Michael "Cooling system fails at 3 reactors at another Japanese nuclear plant" USA Today, March 11, 2011, 6:01 EST.
  17. ↑ "Chronology of Events at Fukushima Daini nuclear power station" (PDF). TEPCO.
  18. ↑ "All Fukushima No.2 plant reactors safely halted". March 15, 2011.
  19. ↑ "IAEA Update on Japan Earthquake". Retrieved March 16, 2011. Japanese authorities have assessed that the loss of cooling functions in the reactor Units 1, 2 and 4 of the Fukushima Daini nuclear power plant has also been rated as 3. All reactor Units at Fukushima Daini nuclear power plant are now in a cold shut down condition..
  20. ↑ "Japan nuclear safety agency says level 5 incident at Fukushima reactors No. 1, 2, 3, raised from level 4". The Huffington Post.
  21. ↑ Nuclear and Industry Safety Agency (March 18, 2011). "東北太平洋沖地震による福島第一原子力発電所及び福島第二原子力発電所の事故・トラブルに対するＩＮＥＳ（国際原子力・放射線事象評価尺度）の適用について" (Press release) (in Japanese). Ministry of Economy, Trade and Industry. Retrieved March 18, 2011.
  22. ↑ "RPT-TEPCO releasing pressure at one Fukushima reactor". Reuters. March 11, 2011.
  23. ↑ World Nuclear News (March 12, 2011). "Battle to stabilise earthquake reactors". World Nuclear News. Retrieved March 12, 2011.
  24. ↑ "Press release 11". TEPCO. March 13, 2011.
  25. ↑ "Battle to stabilise earthquake reactors, update 2". World Nuclear News. March 12, 2010.
  26. 1 2 "IAEA update on Japan Earthquake". March 12, 2011. Retrieved March 12, 2011.
  27. 1 2 http://www3.nhk.or.jp/daily/english/30_42.html Smoke from Fukushima Daini nuclear plant
  28. ↑ "Pilot information for Sendai Airport". March 12, 2011. Retrieved March 12, 2011.
  29. ↑ Japan invokes 30km no-fly zone around Fukushima plant; more flights to north-east - Update 4 | CAPA. Centre for Aviation. Retrieved on 2013-09-06.
  30. ↑ TEPCO (March 12, 2011). "Press Releases". TEPCO. Retrieved March 12, 2011.:"We sincerely pray for the repose of his soul."
  31. ↑ asahi.com (March 12, 2011). "福島第二原発で作業員１人死亡 第一では２人が不明". Retrieved March 20, 2011.
  32. ↑ The Sankei News (March 12, 2011). "東電、協力会社社員３人死亡　２人不明 福島と茨城". Retrieved March 20, 2011.
  33. ↑ ANN News (March 12, 2011). "【地震】第二原発　閉じ込められた従業員は死亡". Retrieved March 20, 2011.
  34. ↑ "3 Week Update on Japan's Nuclear Crisis". April 2, 2011. Retrieved April 2, 2011.
  35. ↑ Kyodo News, "Fishermen to Tepco: Don't release water", Japan Times, June 9, 2011, p. 1.
  36. ↑ Restoration plans for Fukushima area. World-nuclear-news.org (2012-09-04). Retrieved on 2013-09-06.

External links

Wikimedia Commons has media related to Fukushima II Nuclear Power Plant.
This article is issued from Wikipedia - version of the Sunday, March 27, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.