Fukushima II Nuclear Power Plant
Encyclopedia
The , or Fukushima Dai-ni (dai-ni means "number two"), is a nuclear power plant
located on a 1500000 square metres (370.7 acre) site 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
.
Japan's worst nuclear incident occurred at TEPCO's Fukushima Daiichi Nuclear Power Plant, a 11.5 kilometres (7.1 mi) boundary to boundary road journey to the north, after the same March 11 earthquake.
type with electric power of 1,100 MW each (net output: 1,067 MW each).
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
. 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.
substation.
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. All four units were automatically shut down
immediately after the earthquake, according to Nuclear Engineering International, and the diesel engines were started to power the reactor cooling. 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. This flooded the pump rooms used for the essential service water system transferring heat to the sea, the ultimate heat sink
of the reactors.
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.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
, removing the ability to remove pressure from the reactor and drywell. Also, operators had to prepare an alternate injection line for each unit as the RCIC cannot 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. Operators prepared for this and setup 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. Water injection into unit 4 was later switched from the MUWC to the High Pressure Core Spray (HPCS) system, part of the Emergency Core Cooling System. While the water level was maintained in the three units using emergency water injection, pressures in the containment vessel continued to rise 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.
The service seawater system pumps in the pump room were repaired in units 1, 2 and 4 starting March 13th and cooling was switched to the Residual Heat Removal System (RHR). The RHR systems were first activated to cool down the suppression pools (torus) and drywells, 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. 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. Reactors 1 and 3 followed at 1:24 and 3:52 on March 14 and Reactor 4 at 7:00 on March 15. 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.
Officials made preparations for release of pressure from the plant on March 12. As of March 20, however, no pressure release had been reported.
An evacuation order was issued to people living within 3 kilometres (1.9 mi) of the plant, subsequently expanded to 10 km (6.2 mi). Air traffic was restricted in a 10 km (6.2 mi) radius around the plant, according to a NOTAM
. These zones were superseded by the 20 km evacuation and 30 km no-fly zones around Fukushima I on March 12 and 15, respectively.
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 p.m. and confirmed dead at 5:17 p.m.
Smoke was escaping from one of the buildings on 30 March 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.
By March 15, all four reactors of Fukushima II reached cold shutdown which remained non-threatening through April.
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.
}
Nuclear power plant
A nuclear power plant is a thermal power station in which the heat source is one or more nuclear reactors. As in a conventional thermal power station the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.Nuclear power plants are usually...
located on a 1500000 square metres (370.7 acre) site in the town of Naraha
Naraha, Fukushima
is a town located in Futaba District, Fukushima, Japan.As of 2003, the town has an estimated population of 8,230 and a density of 79.56 persons per km². The total area is 103.45 km²....
and Tomioka
Tomioka, Fukushima
is a town located in Futaba District, Fukushima, Japan.As of 2003, the town has an estimated population of 16,078 and a population density of 234.82 persons per km². The total area is 68.47 km². The town is famous for having one of the longest cherry blossom tunnels in Japan...
in the Futaba District
Futaba District, Fukushima
is a district located in Fukushima, Japan.As of 2003, the district has an estimated population of 75,220 and a density of 86.95 persons per km². The total area is 865.12 km².-Towns and villages:*Futaba*Hirono*Katsurao*Kawauchi*Namie*Naraha*Ōkuma...
of Fukushima Prefecture
Fukushima Prefecture
is a prefecture of Japan located in the Tōhoku region on the island of Honshu. The capital is the city of Fukushima.-History:Until the Meiji Restoration, the area of Fukushima prefecture was known as Mutsu Province....
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. The Tokyo Electric Power Company (TEPCO) runs the plant.
After the 2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...
, the four reactors at Fukushima II automatically shut down
Scram
A scram or SCRAM is an emergency shutdown of a nuclear reactor – though the term has been extended to cover shutdowns of other complex operations, such as server farms and even large model railroads...
.
Japan's worst nuclear incident occurred at TEPCO's Fukushima Daiichi Nuclear Power Plant, a 11.5 kilometres (7.1 mi) boundary to boundary road journey to the north, after the same March 11 earthquake.
Description
All reactors in the Fukushima II Nuclear Power Plant are BWR-5Boiling water reactor
The boiling water reactor is a type of light water nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor , also a type of light water nuclear reactor...
type with electric power of 1,100 MW each (net output: 1,067 MW each).
The reactors for units 1 and 3 were supplied by Toshiba
Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
, and for units 2 and 4 by Hitachi
Hitachi
Hitachi is a multinational corporation specializing in high-technology.Hitachi may also refer to:*Hitachi, Ibaraki, Japan*Hitachi province, former province of Japan*Prince Hitachi and Princess Hitachi, members of the Japanese imperial family...
. Units 1–3 were built by Kajima while the unit 4 was built by Shimizu
Shimizu Corporation
is a leading architectural, engineering and general contracting firm, offering an integrated, comprehensive planning, design and build solutions for a broad range of construction and engineering projects worldwide...
and Takenaka
Takenaka Corporation
is the biggest architecture, engineering, and construction firm in Japan. Its headquarters is in Chūō-ku, Osaka, Osaka Prefecture.The company's website also claims it to be the oldest firm of that type anywhere in the world, since the demise of Kongō Gumi which was substantially older...
. The design basis accident
Design Basis Accident
A design basis accident or maximum credible accident is a postulated accident that a nuclear facility must be designed and built to withstand without loss to the systems, structures, and components necessary to assure public health and safety....
for an earthquake was between 0.42 g
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
(4.15 m/s2) and 0.52 g (5.12 m/s2) and for a tsunami was 5.2 m.
| Unit | First criticality | Installation costs (yen/MW) | Reactor supplier | Architecture | Construction | Containment |
|---|---|---|---|---|---|---|
| 1 | 31/07/1981 | 250,000,000 | Toshiba Toshiba is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and... |
Toshiba | Kajima | Mark 2 |
| 2 | 23/06/1983 | 230,000,000 | Hitachi Hitachi Hitachi is a multinational corporation specializing in high-technology.Hitachi may also refer to:*Hitachi, Ibaraki, Japan*Hitachi province, former province of Japan*Prince Hitachi and Princess Hitachi, members of the Japanese imperial family... |
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 | Hitachi | Hitachi | Shimizu Shimizu Corporation is a leading architectural, engineering and general contracting firm, offering an integrated, comprehensive planning, design and build solutions for a broad range of construction and engineering projects worldwide... Takenaka Takenaka Corporation is the biggest architecture, engineering, and construction firm in Japan. Its headquarters is in Chūō-ku, Osaka, Osaka Prefecture.The company's website also claims it to be the oldest firm of that type anywhere in the world, since the demise of Kongō Gumi which was substantially older... |
Mark 2 advanced |
Electrical connections
The Fukushima Daini plant is connected to the rest of the power grid by the Tomioka Line to the Shin-Fukushima (New Fukushima)substation.
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 considerably long time.2011 earthquake and tsunami
The March 11, 2011 Tōhoku earthquake2011 Tōhoku earthquake and tsunami
The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...
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. All four units were automatically shut down
Scram
A scram or SCRAM is an emergency shutdown of a nuclear reactor – though the term has been extended to cover shutdowns of other complex operations, such as server farms and even large model railroads...
immediately after the earthquake, according to Nuclear Engineering International, and the diesel engines were started to power the reactor cooling. TEPCO estimated that the tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
that followed the earthquake and inundated the plant was 14 meters high which is more than twice the designed height. This flooded the pump rooms used for the essential service water system transferring heat to the sea, the ultimate heat sink
Heat sink
A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...
of the reactors.
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.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
Japan Standard Time
Japan Standard Time or JST is the standard timezone of Japan, and is 9 hours ahead of UTC. For example, when it is midnight in UTC, it is 09:00 in Japan Standard Time. There is no daylight saving time, though its introduction has been debated several times. Japan Standard Time is the same as...
, removing the ability to remove pressure from the reactor and drywell. Also, operators had to prepare an alternate injection line for each unit as the RCIC cannot 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. Operators prepared for this and setup 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. Water injection into unit 4 was later switched from the MUWC to the High Pressure Core Spray (HPCS) system, part of the Emergency Core Cooling System. While the water level was maintained in the three units using emergency water injection, pressures in the containment vessel continued to rise 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.
The service seawater system pumps in the pump room were repaired in units 1, 2 and 4 starting March 13th and cooling was switched to the Residual Heat Removal System (RHR). The RHR systems were first activated to cool down the suppression pools (torus) and drywells, 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. Coolant temperatures below 100 °C (cold shutdown) were reached in reactor 2 about 34 hours after the emergency shut down (SCRAM
Scram
A scram or SCRAM is an emergency shutdown of a nuclear reactor – though the term has been extended to cover shutdowns of other complex operations, such as server farms and even large model railroads...
) restoring the ability to lower the pressure of the reactor via the torus. Reactors 1 and 3 followed at 1:24 and 3:52 on March 14 and Reactor 4 at 7:00 on March 15. The loss of cooling water at reactors 1, 2 and 4 was classified a level 3 on the International Nuclear Event Scale
International Nuclear Event Scale
The International Nuclear and Radiological Event Scale was introduced in 1990 by the International Atomic Energy Agency in order to enable prompt communication of safety significance information in case of nuclear accidents....
(serious incident) by Japanese authorities as of March 18.
Officials made preparations for release of pressure from the plant on March 12. As of March 20, however, no pressure release had been reported.
An evacuation order was issued to people living within 3 kilometres (1.9 mi) of the plant, subsequently expanded to 10 km (6.2 mi). Air traffic was restricted in a 10 km (6.2 mi) radius around the plant, according to a NOTAM
NOTAM
NOTAM or NoTAM is the quasi-acronym for a "Notice To Airmen". NOTAMs are created and transmitted by government agencies and airport operators under guidelines specified by Annex 15: Aeronautical Information Services of the Convention on International Civil Aviation...
. These zones were superseded by the 20 km evacuation and 30 km no-fly zones around Fukushima I on March 12 and 15, respectively.
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 p.m. and confirmed dead at 5:17 p.m.
Smoke was escaping from one of the buildings on 30 March 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.
By March 15, all four reactors of Fukushima II reached cold shutdown which remained non-threatening through April.
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.
See also
- Nuclear power in JapanNuclear power in JapanNuclear energy was a national strategic priority in Japan, but there has been concern about the ability of Japan's nuclear plants to withstand seismic activity...
- 2011 Japanese nuclear accidents2011 Japanese nuclear accidentsThis is a list of articles describing aspects of the nuclear shut-downs, failures, and nuclear meltdowns triggered by the 2011 Tōhoku earthquake and tsunami.-Fukushima nuclear power plants:* Fukushima I Nuclear Power Plant...
- List of boiling water reactors
- Lists of nuclear disasters and radioactive incidents
- List of civilian nuclear accidents
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
}