Fukushima (Japan)

Map of Fukushima

Map Loading...

10 BWR units:
Unit 1/2: 440 MW and 760 MW constructed by General Electric; grid connection in 1970 and 1973
Unit-6:1100 MW; constructed by General Electric; grid connection in 1979

Facilities in Fukushima

plantreactor typconstruction startoperation startshut down
Fukushima-I-1 (Daiichi)BWR196719702011
Fukushima-I-2 (Daiichi)BWR196919732011
Fukushima-I-3 (Daiichi)BWR197019742011
Fukushima-I-4 (Daiichi)BWR197319782011
Fukushima-I-5 (Daiichi)BWR19721977
Fukushima-I-6 (Daiichi)BWR19731979
Fukushima-II-1 (Daini)BWR19761981
Fukushima-II-2 (Daini)BWR19791983
Fukushima-II-3 (Daini)BWR19801984
Fukushima-II-4 (Daini)BWR19811986
2011-03-18

Core damage by loss of all cooling function due to the big tsunami.

More information see on the "Nuclear accident in Japan" under countries/Japan

Here is what the IAEA officially states:

"Fukushima Dai-ichi Nuclear Power Station Unit 1, 2 and 3, which is in rated power operation, have automatically shut down around 14:46 (JST) in March 11, 2011 because of the Tohoku regional Pacific Ocean Offshore Earthquake.
After that, the power station was attacked by tsunami.
Electricity rooms and seawater pump rooms were flooded, and the cooling function became only the coolant injection of the turbine driven pump. The turbine driven pump operation increased the pressure of the suppression chamber, and it became impossible to continue the operation.
It means loss of all cooling function, and the declaration of a state of emergency was done.
The release valve was opened several times and injections of the sea water into the reactor vessel were carried out with fire extinguishing pumps. The gas in the containment vessel was also vented.
Then, the radioactive dose rate at site boundary had exceeded the limit value of 0.5 mSv/h.
This value is thought smaller than the value resulting in the release of a few per cent of core inventory of a power reactor from the fuel assemblies.
But the radioactive dose rate at the suppression chamber was high. And it is thought that hydrogen gas was generated enough to damage the reactor building.
The behavior of the pressure of the reactor vessel and the containment vessel, and the behavior of the water level of the reactor vessel were complicated. Some measurements were not possible because of failures of measurement equipment. As a result, the detailed estimate can not be done.
But these values are thought the values resulting in the release of more than a few per cent of core inventory of a power reactor from the fuel assemblies.
The inhabitants of the range of 20 km took refuge. At least, one worker received a dose (about 106 mSv) in excess of the annual limit (100 mSv). But we can not rate on impact on people and the environment because the correspondence work still continues."

On April 11 2011 the INES level was finally raised to 7:
"In March 18, rating of the INES on the events in Fukushima Dai-ichi Nuclear Power Station, by the Tohoku Regional Pacific Ocean Offshore Earthquake is temporary estimated Rating 5. However, Nuclear and Industrial Safety Agency (NISA) estimated total amount of discharge from Fukushima Dai-ichi NPS, using the analytical result of the state of nuclear reactor under the cooperation of Japan Nuclear Energy Safety Organization (JNES). As a result of re-evaluation, total amount of discharged I131 is estimated at 1.3*10^17Bq, and Cs137 is estimated at 6.1*10^15 Bq. Hence NISA concluded that the rating of the accident would be equivalent of Rating 7.
This result is present status of discharge from Fukushima Dai-ichi NPS. Because discharge is on going and the amount of discharge from each reactor is unspecified, NISA will continuously be gathering information and evaluate them."

source (http://www-news.iaea.org/news/)

2011-03-18

"Fukushima Dai-ichi Nuclear Power Station Unit 4, which was in shutdown mode, was attacked by the Tohoku regional Pacific Ocean Offshore Earthquake around 14:46 (JST) in March 11, 2011.
After that, the power station was attacked by a tsunami.
Electricity rooms and seawater pump rooms were flooded, and the cooling function and water supplying function on the spent fuel pool became inoperable. The temperature of the spent fuel pool has been increasing, and the water level of the spent fuel pool was thought to be decreasing.
The water in the spent fuel pool boiled by residual heat of spent fuels, and the reactor building was damaged by an explosion which seems to be a hydrogen explosion.
It is carrying out to pour the sea water for cooling spent fuels."

(source: http://www-news.iaea.org/news/)

2011-03-18
Loss of cooling function and water supplying function on the spent fuel pool due to the big tsunami.

"Fukushima Dai-ichi Nuclear Power Station Unit 4, which was in shutdown mode, was attacked by the Tohoku regional Pacific Ocean Offshore Earthquake around 14:46 (JST) in March 11, 2011.
After that, the power station was attacked by a tsunami.
Electricity rooms and seawater pump rooms were flooded, and the cooling function and water supplying function on the spent fuel pool became inoperable. The temperature of the spent fuel pool has been increasing, and the water level of the spent fuel pool was thought to be decreasing.
The water in the spent fuel pool boiled by residual heat of spent fuels, and the reactor building was damaged by an explosion which seems to be a hydrogen explosion.
It is carrying out to pour the sea water for cooling spent fuels."

(source: http://www-news.iaea.org/news/)

2011-03-18
Loss of the cooling function to the ultimate heat sink due to the big tsunami - Daini-1

Fukushima Dai-ni Nuclear Power Station Units 1, 2 and 4, which is in rated power operation, have automatically shut down around 14:46(JST) on March 11, 2011, because of the Tohoku regional Pacific Ocean Offshore Earthquake. Following the earthquake, the big tsunami attacked the power station and the seawater pump rooms were flooded. The licensee lost the function operability of sea water pumps for last heat removal. The turbine driven pump started operation and the exhausted steam increased the pressure of the suppression pool. The turbine driven pump became inoperable.
As a result of the efforts by the people on site, some seawater pumps were recovered and restarted. The suppression pools were cooled and the pressure was decreased. And the sea water pumps became to discharge the heat to the ultimate heat sink through the residual heat removal system.
Finally, the temperature of the reactors was decreased below 100 degree C and the reactors became cold shut down condition.

(source: http://www-news.iaea.org/news/)

2011-03-18
Loss of the cooling function to the ultimate heat sink due to the big tsunami (Daini-2)

"Fukushima Dai-ni Nuclear Power Station Units 1, 2 and 4, which is in rated power operation, have automatically shut down around 14:46(JST) on March 11, 2011, because of the Tohoku regional Pacific Ocean Offshore Earthquake. Following the earthquake, the big tsunami attacked the power station and the seawater pump rooms were flooded. The licensee lost the function operability of sea water pumps for last heat removal. The turbine driven pump started operation and the exhausted steam increased the pressure of the suppression pool. The turbine driven pump became inoperable.
As a result of the efforts by the people on site, some seawater pumps were recovered and restarted. The suppression pools were cooled and the pressure was decreased. And the sea water pumps became to discharge the heat to the ultimate heat sink through the residual heat removal system.
Finally, the temperature of the reactors was decreased below 100 degree C and the reactors became cold shut down condition."

(http://www-news.iaea.org/news/)

2011-03-18
Loss of the cooling function to the ultimate heat sink due to the big tsunami (Daini-4

"Fukushima Dai-ni Nuclear Power Station Units 1, 2 and 4, which is in rated power operation, have automatically shut down around 14:46(JST) on March 11, 2011, because of the Tohoku regional Pacific Ocean Offshore Earthquake. Following the earthquake, the big tsunami attacked the power station and the seawater pump rooms were flooded. The licensee lost the function operability of sea water pumps for last heat removal. The turbine driven pump started operation and the exhausted steam increased the pressure of the suppression pool. The turbine driven pump became inoperable.
As a result of the efforts by the people on site, some seawater pumps were recovered and restarted. The suppression pools were cooled and the pressure was decreased. And the sea water pumps became to discharge the heat to the ultimate heat sink through the residual heat removal system.
Finally, the temperature of the reactors was decreased below 100 degree C and the reactors became cold shut down condition."

(source: http://www-news.iaea.org/news/)

2011-03-12
Effect to the Nuclear Facilities from the earthquake on east area of Japan

More information see on the "Nuclear accident in Japan" under countries/Japan

Here is what the IAEA officially states:

"14:46 (UTC 5:46) March 11, an earthquake hit east area of Japan. Summary of earthquake and current status of each nuclear facility is as follows;

1. Summary of Earthquake

(1) Time of Occurrence: 14:46 (UTC 5:46) March 11, 2011, Friday
(2) Epicenter: Off-Coast of Sanriku (North Latitude: 38; East Longitude: 142.9), 10km deep, M8.8

2. The status of operation at Power Stations(Number of automatic shutdown(units): 10 (as of 00:30(UTC:11:46), March12)

a. Onagawa Nuclear Power Station (Onagawa-machi and Ishinomaki–shi, Miyagi Prefecture)
(1) The status of operation
Unit 1 (524MWe): automatic shutdown
Unit 2 (825MWe): automatic shutdown
Unit 3 (825MWe): automatic shutdown
(2) Readings of monitoring post etc.
Variation in the monitoring post readings: No
Variation in the main stack monitor readings: No
(3) Report concerning other malfunction
Report of fire: CO2 extinguishment started at 17:15

b. Fukushima Dai-ichi Nuclear Power Station, Tokyo Electric Power Co.,Inc.(TEPCO) (Okuma-machi and Futaba-machi, Futaba-gun, Fukushima Prefecture )
(1) The status of operation
Unit 1 (460MWe): automatic shutdown
Unit 2 (784MWe): automatic shutdown
Unit 3 (784MWe): automatic shutdown
Unit 4(784MW): in periodic inspection outage
Unit 5(784MW): in periodic inspection outage
Unit 6(1,100MW): in periodic inspection outage
(2) Readings at monitoring post etc.
Variation in the monitoring post readings: No
Variation in the main stack monitoring readings: No
(3) Report concerning other malfunction
Article 10* of Act on Special Measures Concerning Nuclear Emergency Preparedness (Fukushima Dai-ichi, Unit 3)
(*A heightened alert condition)
Article 15 of Act on Special Measures Concerning Nuclear Emergency Preparedness (Fukushima Dai-ichi, Units 1 and 2)
(
Nuclear emergency situation)
Situation of power source to recover water injection function at the Station.
Three or four electric power source cars are waiting in the premise. Part of cable was obtained and connecting work is under way. This work is done with paying attention to tsunami. (2:00, March 12)
Pressure in the Confinement Vessel has arisen. The pressure could have arisen to 600kPa as compared to the design pressure of 400kPa.

c. Fukushima-Daini Nuclear Power Station(TEPCO)
(Naraha-cho/Tomioka-cho, Futaba-gun, Fukushima pref.)
(1) The status of operation
Unit1(1,100MW): automatic shutdown
Unit2(1,100MW): automatic shutdown
Unit3(1,100MW): automatic shutdown
Unit4(1,100MW): automatic shutdown
(2) Readings at monitoring post etc.
Variation in the monitoring post readings: No
Variation in the main stack monitoring readings: No
(3) Report concerning other malfunction
Report of fire: No
Article 10* of Act on Special Measures Concerning Nuclear Emergency Preparedness (Fukushima Dai-ni, Units 1,2 and 4)
(*A heightened alert condition)"

(source: http://www-news.iaea.org/news/)

2011-03-12

Abnormal rise of radioactive dosage value at site boundary

More information see on the "Nuclear accident in Japan" under countries/Japan

Here is what the IAEA officially states:

"The core damage by loss of all cooling function due to the big tsunami.-Provisional 2

Fukushima Dai-ichi Nuclear Power Station Unit 1, 2 and 3, which is in rated power operation, have automatically shut down around 14:46 (JST) in March 11, 2011 because of the Tohoku regional Pacific Ocean Offshore Earthquake.
After that, the power station was attacked by tsunami.
Electricity rooms and seawater pump rooms were flooded, and the cooling function became only the coolant injection of the turbine driven pump. The turbine driven pump operation increased the pressure of the suppression chamber, and it became impossible to continue the operation.
It means loss of all cooling function, and the declaration of a state of emergency was done.
The release valve was opened several times and injections of the sea water into the reactor vessel were carried out with fire extinguishing pumps. The gas in the containment vessel was also vented.
Then, the radioactive dose rate at site boundary had exceeded the limit value of 0.5 mSv/h.
This value is thought smaller than the value resulting in the release of a few per cent of core inventory of a power reactor from the fuel assemblies.
But the radioactive dose rate at the suppression chamber was high. And it is thought that hydrogen gas was generated enough to damage the reactor building.
The behavior of the pressure of the reactor vessel and the containment vessel, and the behavior of the water level of the reactor vessel were complicated. Some measurements were not possible because of failures of measurement equipment. As a result, the detailed estimate can not be done.
But these values are thought the values resulting in the release of more than a few per cent of core inventory of a power reactor from the fuel assemblies.
The inhabitants of the range of 20 km took refuge. At least, one worker received a dose (about 106 mSv) in excess of the annual limit (100 mSv). But we can not rate on impact on people and the environment because the correspondence work still continues."

(source: http://www-news.iaea.org/news/)

2011-03-12
Effect to the Nuclear Facilities from the earthquake on east area of Japan
2011-03-12
Effect to the Nuclear Facilities from the earthquake on east area of Japan
2007-06-19

During periodic inspection of emergency Diesel generator 1A, smoke was emitted from the generator and its power panel. Excess current flowed through the part, because part of the circular breaker components had been assembled in reverse due to an assembling error.
(source: http://cnic.jp/english)

2007-06-08

When conducting blast work for recoating of the suppression pool wall, metal powder used for intensive blasting hit a small area of the wall due to incorrect operatijon. Part of the wall was eroded to less than the required thickness. Due to the poor work environment, communication between the workers was insufficient. The damaged section will be built up by overlay welding."
(source: http://cnic.jp/english)

2006-03-14

"A recirculation pump of F. I-2 stopped automatically causing a power reduction. The reactor was shut down for inspection when damage was discovered in the electric circuit in the inverter."
(source: http://cnic.jp/english/)

2006-03-11

"During periodic inspectiono f Fukushima-I-3 cracks were found in sheaths and tie rods of 5 hafnium blade type control rods. The sheath of one of the control rods was significantly damaged. Cause: The cracks were initiated by neutron irradiation."
(source: http://cnic.jp/english/)

2006-01-09

"During periodic inspection in F. I-6, cracks were found in sheaths and tie rods of 9 hafnium blade type control rods. The sheath of one of the control rods was significantly damaged. The cracks were induced by neutron irradiation. One control rod had failed to insert when the reactor was shut down on 21 December 2005."
(source: http://cnic.jp/english/)

2005-10-09

"The recirculation pump of Fukishima I-2 stopped automatically following an alarm related to problems with control of the pump. The reactor was operated at reduced power until it was shut down manually on October 10th. The inverter stopped automatically due to a bad connection in the fuse holder."
(source: http://cnic.jp/english/)

2005-08-22

"During periodic inspection, it was discovered that the necessary flow rate for the reactor core spray system was not secured. The reactor was shut down manually in order to check the flow rate control valve. Cause: It was discovered that the flow rate control valve stem was broken."
(source: http://cnic.jp/english/)

2001-11-01

Reactor automatically shutdown due to high signal of reactor neutron flux during reactor start up operation.
(source: http://cnic.jp/english/)

2001-07-06

Cracks found on core shroud lower ring during periodic inspection at Fukushima II-3.
(source: http://cnic.jp/english/)

2001-05-24

Radioactivity leak found at Fukushima I-6's fuel assembly during intermediate periodic inspection.
(source: http://cnic.jp/english/)

2001-05-07

Reactor F. II-2 manually shutdown due to failure of shutting check valve during residual heat removal system inpection.
(source: http://cnic.jp/english/)

2001-03-12
Effect to the Nuclear Facilities from the earthquake on east area of Japan
2001-01-15

Reactor F. II-1 manually shutdown due to rupture of coolant flow measurement housing tube at jet pump.
(source: http://cnic.jp/english/)

1997-07-06

The operators, the Power Reactor and Nuclear Fuel Development Corporation (PNC), were ordered on April 14th to shut down the reactor and make improvements to their incident reporting system. PNC had delayed reporting leaks of radioactive tritium.
Fugen, situated on Japan's western coast, has a net capacity of 148 megawatts, and has been in commercial operation since 1979. The advanced thermal reactor (ATR) uses heavy water as a moderator and light water as the coolant. The ATR has been supported in Japan as part of a policy of using plutonium-based fuels to meet national energy needs in the mid-21st century and beyond. However, two years ago Japan's major power utilities came out against plans to build a demonstration version of the ATR because of its high cost in comparison with standard light water reactors.

1997-06-09

Fukushima leaked radioactive coolant :
The leak was found at one of the two back-up pumps at the reactor which send coolant back to the reactor pressure vessel.

1997-03-26

TEPCO opts to replace shrouds:
The Tokyo Electric Power Co. (TEPCO) announced on 26 March that it intends to replace shrouds (the partitions around the cores of nuclear reactors) on several reactors at Fukushima I.
During the last tow or three years, checks have turned up aging-induced damage in the equipment and structural elements inside reactor pressure vessels at Fukushima I. TEPCO may believe that replacing the shrouds and all the equipment around them will solve all the problems caused by the aging of core structural elements, but the situation is probably not that simple.
Slated for replacement are the type SUS304 stainless steel shrouds of reactors 1, 2, 3 and 5 of the six reactors the shrouds of reactors 4 and 6. This is perhaps because TEPCO and the manufacturers decided that as these two shrouds are made of type SUS304L, a kind of stainless steel with a lower carbon content than type SUS304, they are less susceptible to damage.
TEPCO says that once the technical requirements have been cleared up, it will begin replacing the shroud of Fukushima I-3 as part of the soon-to-begin periodic inspection for FY 1997. The replacement plan then calls for the replacing of the shrouds of reactors 2, 1 and 5 in that order, with all four to be finished by FY2000. This is a very tight schedule, but it is probably an indication of the seriousness of the situation.

"Band-Aid" Solution too Inadequate to Ensure Safety:
Shrouds are cylindrical enclosures that totally envelope reactor cores, and measure 4,5 - 5,5 meter in diameter and 6-7 meter in height and with walls about 5 cm thick.
In Japan, an inspection in 1994 revealed a large crack around the total circumference of the shroud of Fukushima I-2, along the weld of its center ring. Although this reactor is still operating, TEPCE has merely jury-rigged the shroud to keep it together by fitting a bracket around it.

1996-11-26

Aging reactors pose serious safety problems
Cracks on in-core pipes of Fukushima I-1:
On 26 November 1996, during a regular inspection at Tokyo Electric's Fukushima I-1 reactor, inspectors discovered cracks in the pipes inside the reactor pressure vessel. Having been in operation for 25 years, this is the second-oldest boiling water reactor after Tsuruga 1. The cracks are perhaps manifestations of the reactor's old age.
The cracks appeared near the welds in two neighboring pipes out of a total of 10 pipes (SUS304steel, 27 cm outside diameter, 9,3 mm thickness) that carry coolant from the recirculation pump to the pressure vessel jet pump, and it appears that the direct cause is stress corrosion. In all, five cracks of lengths varying from 2 to 19 cm were discovered in almost identical places on the pipes, very close to the inside wall of the pressure vessel.
TEPCO has decided to deal with the cracks by simply clamping on steel supports and bolts and not by replacing the pipes. This is, however, obviously a stopgap measure providing no long-term guarantee of safety.

1995-11-25

Reactor trip due to high sump water level in containment.

1995-11-10

Detector found detached from power range monitor during periodic inspection.

1995-09-17

Circ. water pump flow rate dropped.

1995-07-31

Drop in water flow rate in circ. water pump

1995-03-24

Circulating water pump axis vibration

1995-01-31

Fire in front of administration building, caused by welding work.

1994-01-02

7,5 months maintenance outage: cracked core shroud was repaired by bracketing, parts of instruments, sea water pipes and LP turbine rotor were replaced. cracks in core shroud were the first found in a japanese BWR - cracks went up to half of the wall's thickness.

1993-02-22

190 °C high pressure steam gushing out of an auxiliary boiler in waste treatment facility killed one worker and injured 2 more

1992-11-09

reactor manually stopped during ECCS start-up test due to failure of steam line inlet valve for HPI pump

1992-09-29

scram due to failure of all high pressure condensate pumps-> complete loss of FW, ECCS actuated by low reactor water levelectrical ( the level fell 2.4 m, but there was no uncovering of the core, says the untility)

1991-11-26

Cable fire in turbine building

1990-05-28

damage to emerg. diesel generator

1989-11-08

cracks found on inner surface of recirc pump casing

1989-11-08

Cracks found on inner surface of recirc pump casing

1989-09-18

3 cracks found at welds of steam dryer drain channels

1989-07-03

39 cracks found on surface of heat exchanger of coolant purification system.

1989-06-22

feed water pump tripped due to rotary shaft deformation

1989-06-03

Primary coolant leaked from heat exchanger piping of coolant purification system, reactor manually shut down

1989-02-26

Failure of a recirculation pump, reactor manually stopped, cracks in shafts of 2 recirc pumps found

1989-01-06

Rupture of inner stuctures of a recirculation pump. More than 30 kg of broken metal pieces penetrated into reactor core. First vibrations occured on 1.1.89, on 6.1. One pump developed wild vibrations -> manual shutdown, Examination discovered that a 100 kg bearing in the pump was dislocated and damaged and part of turbine components were destroyed. Metallic bebris was found on 61 of 764 fuel assemblies. The recirculation pump had not been inspected for cracks prior to the failure despite the discovery over 4 years ago of weld failures in a similar pump in a BWR. Weld failures in a recirc pump in a BWR in Japan were first discovered in 1984. A bearing problem was found on Fukushima II-4 in June 1988. Bearings were changed also on Fukushima II-2.

1988-12-11

Damage to main steam valve found on restarting, reactor manually stropped

1988-10-10

Damage to the bearings of a recirculation pump found during inspection. Cracking discovered in the bearing ring. This one had been replaced after an incident in Nov. 1983; when part of the bearing ring separated and landed on the impeller of the pump. Both incidents were precursors of the pump accident at Fukushima II-3.

1988-07-24

Primary coolant leakage due to crack in recirculation pipe. reactor manually stopped

1988-01-13

Filter fire in turbine building