Fukushima Daini Nuclear Power Plant


Fukushima Daini Nuclear Power Plant
Daini Offshore.jpg
The Fukushima II NPP
Coordinates37°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
Construction beganMarch 16, 1976 (1976-03-16)
Commission dateApril 20, 1982 (1982-04-20)
Decommission dateSeptember 30, 2019 (2019-09-30)
Operator(s)Tokyo Electric Power Company
Nuclear power station
Reactor typeBWR
Reactor supplierToshiba
Power generation
Units operational4 × 1,100 MW
Nameplate capacity4,400 MW
Capacity factor0%
Annual net output0 GW·h
External links
WebsiteHome page
CommonsRelated media on Commons

The Fukushima Daini Nuclear Power Plant (福島第二原子力発電所, Fukushima Daini (audio speaker iconpronunciation) 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 Daini automatically shut down.[2] While the sister plant Fukushima Daiichi Nuclear Power Plant, approximately 12 km (7.5 mi) to the north, suffered extensive damage, the Daini Plant was back under control within two days, reaching cold shutdown.[3] The plant has not been operating since, and in July 2019 a decision to decommission the plant was made.[4]


All reactors in the Fukushima II Nuclear Power Plant are BWR-5 type[5] with electric power of 1,100 MW each (net output: 1,067 MW each).[6]

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.[6]

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


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

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.[11][12] 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.[11] All four units were automatically shut down immediately after the earthquake,[2] and the diesel engines were started to power the reactor cooling.[13] A worker died of injuries from the earthquake when he was trapped in the crane operating console of the exhaust stack.[14][15][16][17][18]

The tsunami that followed the earthquake and inundated the plant was initially estimated by TEPCO to be 14 meters high, which would have been more than twice the designed height.[11] Other sources give the tsunami height at Fukushima Daini plant at 9-meter-high, while the Fukushima Daiichi plant was hit by a 13-meter-high tsunami. The tsunami caused the plant's seawater pumps, used to cool reactors, to fail. Of the plant's four reactors, three were in danger of meltdown.[19] 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 plant worked to stabilize the reactors. Some employees connected over 9 kilometers of cabling using 200-meter sections of cable, each weighing more than a ton from their Rad Waste Building to other locations onsite.

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, one seawater pump remained operational and the residual heat removal system (RHR) was started to cool the suppression pool and later brought the reactor to cold shutdown on March 12. 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 reached 100 °C between 05:30 and 06:10 JST,[20][21][22] removing the ability to remove pressure from the reactor and drywell.[13]

Operators had to also 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 the reactor pressure drops below a certain level, the RCIC shuts down automatically. The normal electrically driven Emergency Core Cooling Systems (ECCS) were for the most part unavailable due to the loss of the 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 (MUWC) system to maintain water level which was an accident mitigation method TEPCO put in place at all its nuclear plants.[citation needed] 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.[when?][citation needed] The MUWC and the makeup water purification and filtering (MUPF) systems were also used 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 ECCS 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.[clarification needed] Unit 1 was prioritized as it had the highest drywell pressure.[23]

Cold shutdown

The ultimate heat sink was restored on March 13 when the service seawater system pumps in the pump room were repaired in units 1, 2 and 4. This allowed to restore 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 °C, the RHR was switched to the shutdown cooling mode and brought the reactors to a cold shutdown.[20]

Coolant temperatures below 100 °C (cold shutdown) were reached in reactor 2 about 34 hours after the emergency shut down (scram).[20] Reactors 1 and 3 followed at 1:24 and 3:52 on March 14 and Reactor 4 at 7:00 on March 15.[24] By March 15, all four reactors of Fukushima II reached cold shutdown, which remained non-threatening.[25]

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.[26][27][28]

Officials made preparations for release of pressure from the plant on March 12,[29][30] but no pressure release was necessary.[20][31] An evacuation order was issued to the people living within 3 kilometres (1.9 mi) of the plant,[32] subsequently expanded to 10 km (6.2 mi).[14][33] Air traffic was restricted in a 10 km (6.2 mi) radius around the plant, according to a NOTAM.[34] These zones were later superseded by the 20 km evacuation and 30 km no-fly zones around Fukushima Daiichi on March 12 and 15, respectively.[35]

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.[36]


On December 26, 2011, the Prime Minister officially cancelled the nuclear emergency declaration for the Fukushima Daini plant officially ending the incident. On February 8, 2012, the plant was opened to news media for the first time since the 2011 Tōhoku earthquake and tsunami.

The evacuation order was partly rescinded for Daini evacuees in August 2012. Some of the residents, such as the 7200 at Naraha, 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.[37] In 2015, the evacuation order for Naraha was completely lifted, allowing residents to return and reconstruction efforts to begin. Naraha is the first of a number of towns in the area to have had its evacuation order removed.

2016 earthquake

On Tuesday, November 22, 2016, a magnitude 6.9 earthquake struck Japan 37 km (23 mi) east southeast of Namie, Fukushima Prefecture at a depth of 11.3 km (7.0 mi). The shock had a maximum intensity of VII (Very strong).[38] 14 people were injured and more than 1,900 homes briefly lost electricity.[39] Though a warning of a possible tsunami of 3 m (9.8 ft) in height was issued,[40] a 60 cm (24 in) wave was reported by NHK in the port of Onahama of Iwaki, Fukushima; a 90 cm (35 in) wave hit Soma, Fukushima; and another wave 1 m (3 ft 3 in) in height struck the Fukushima Daiichi Nuclear Power Plant site after the 6.9 shock.[41] Chief Cabinet Secretary Yoshihide Suga said that the third reactor's spent fuel cooling systems at Fukushima Daini had stopped as a result of the earthquake; TEPCO later reported the restart of the spent fuel cooling system after only 100 minutes of stoppage.[40][41][42][43]


On 31 July 2019, the TEPCO board of directors decided to decommission the plant, in response to local demands for a decision. Decommissioning is expected to take more than 40 years to complete, and will include moving spent nuclear fuel from spent fuel pools to on-site dry cask storage.[4]

See also


  1. ^ Tepco site (Japanese). Text and answers to the Fukushima II plant quiz[permanent dead link]. Page 8.
  2. ^ a b "Japan initiates emergency protocol after earthquake". Nuclear Engineering International. March 11, 2011. Archived from the original on March 14, 2011. Retrieved March 11, 2011.
  3. ^ Gulati, Ranjay; Casto, Charles; Krontiris, Charlotte (July 2014). "How the Other Fukushima Plant Survived". Harvard Business Review. Retrieved March 16, 2017.
  4. ^ a b "Tepco declares Fukushima Daini for decommissioning". World Nuclear News. July 31, 2019. Retrieved July 31, 2019.
  5. ^ "Reactors in operation". IAEA. December 31, 2009. Retrieved March 12, 2011.
  6. ^ a b "Nuclear Reactor Maps: Fukushima-Daini". Council for Security Cooperation in the Asia Pacific. Archived from the original on February 15, 2005. Retrieved March 14, 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 Archived April 3, 2012, at the Wayback Machine. Page 24. (Japanese).
  10. ^ WISE (November 23, 1990). "Wise News Communique 342". WISE. Archived from the original on March 26, 2012. Retrieved July 4, 2011.
  11. ^ a b c "Fukushima faced 14-metre tsunami". World Nuclear News. March 24, 2011. Retrieved March 24, 2011.
  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. ^ a b c "Insight to Fukushima engineering challenges". World Nuclear News. March 18, 2011. Retrieved March 19, 2011.
  14. ^ a b "IAEA update on Japan Earthquake". March 12, 2011. Retrieved March 12, 2011.
  15. ^ TEPCO (March 12, 2011). "Press Releases". TEPCO. Retrieved March 12, 2011.:"We sincerely pray for the repose of his soul."
  16. ^ 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.
  17. ^ 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". Archived from the original on March 23, 2011. Retrieved March 20, 2011.
  18. ^ ANN News (March 12, 2011). "【地震】第二原発 閉じ込められた従業員は死亡". Archived from the original on March 15, 2011. Retrieved March 20, 2011.
  19. ^ Yomiuri Shimbun 2012-02-09 Ver.13S page 1&2, Fukushima No. 2 plant was 'near meltdown'
  20. ^ a b c d Cold shutdowns at Fukushima Daini, World Nuclear News, March 14, 2011, retrieved March 14, 2011
  21. ^ reports for reactor 1, reactor 2, and reactor 4 of Tokyo Electric, received 11:50 JST
  22. ^ Winter, Michael "Cooling system fails at 3 reactors at another Japanese nuclear plant" USA Today, March 11, 2011, 6:01 EST.
  23. ^ "Chronology of Events at Fukushima Daini nuclear power station" (PDF). TEPCO.
  24. ^ "All Fukushima No.2 plant reactors safely halted". March 15, 2011. Archived from the original on March 18, 2011.
  25. ^ "3 Week Update on Japan's Nuclear Crisis". April 2, 2011. Retrieved April 2, 2011.
  26. ^ "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..
  27. ^ "Japan nuclear safety agency says level 5 incident at Fukushima reactors No. 1, 2, 3, raised from level 4". The Huffington Post.
  28. ^ 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.
  29. ^ "RPT-TEPCO releasing pressure at one Fukushima reactor". Reuters. March 11, 2011.
  30. ^ World Nuclear News (March 12, 2011). "Battle to stabilise earthquake reactors". World Nuclear News. Retrieved March 12, 2011.
  31. ^ "Press release 11". TEPCO. March 13, 2011.
  32. ^ "Battle to stabilise earthquake reactors, update 2". World Nuclear News. March 12, 2010.
  33. ^ "Archived copy". Archived from the original on April 2, 2011. Retrieved March 30, 2011.{{cite web}}: CS1 maint: archived copy as title (link) Smoke from Fukushima Daini nuclear plant
  34. ^ "Pilot information for Sendai Airport". March 12, 2011. Retrieved March 12, 2011.
  35. ^ 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.
  36. ^ Kyodo News, "Fishermen to Tepco: Don't release water", Japan Times, June 9, 2011, p. 1.
  37. ^ Restoration plans for Fukushima area. World-nuclear-news.org (2012-09-04). Retrieved on 2013-09-06.
  38. ^ "M6.9 - 37km ESE of Namie, Japan". United States Geological Survey. November 21, 2016. Retrieved November 21, 2016.
  39. ^ Breslin, Sean (November 22, 2016). "Strong Japan Earthquake Produces Tsunami but Spares Major Damage". The Weather Channel. Retrieved November 23, 2016.
  40. ^ a b Fifield, Anna (November 22, 2016). "Tsunami warning for Japan's Fukushima coast after 6.9-magnitude earthquake". The Washington Post. Naha, Japan. ISSN 0190-8286. Retrieved November 23, 2016.
  41. ^ a b "Japan earthquake sparks tsunami at Fukushima". BBC News. November 22, 2016. Retrieved November 23, 2016.
  42. ^ "TEPCO to study cooling system stoppage". NHK World. November 22, 2016. Archived from the original on November 24, 2016. Retrieved November 23, 2016.
  43. ^ "Seismic activity continues off Fukushima". NHK World. November 23, 2016. Archived from the original on November 24, 2016. Retrieved November 23, 2016.

External links

  • Tokyo Electric Power Company 東京電力
  • Webcam showing Fukushima I Nuclear Power Plant
  • Official site c/o Tokyo Electric Company 東京電力・福島第一原子力発電所
  • "IAEA Alert Log". International Atomic Energy Agency.
  • All Things Nuclear
  • H2O-project: Extensive information about the events during and after the tsunami[permanent dead link]