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Timeline of the Fukushima nuclear accident

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File:2011-03-12 1800 NHK Sōgō channel news program screen shot.jpg
Reactor building #1 at Fukushima I, wrecked by explosion

This is a timeline of events surrounding the explosions and partial meltdowns at the Fukushima nuclear power stations in Japan.

On March 11, 2011, a 9.0 magnitude earthquake struck off the coast of Japan, off the island of Honshu. This earthquake produced a large tsunami in Japan, and a tsunami warning for over 20 countries. The earthquake triggered the shut down of three of the Fukushima I (Dai-Ichi) Power Plant's six Reactors and of the Fukushima II (Dai-Ni) Power Station's four reactor units. The subsequent tsunami stopped Fukushima I station's backup diesel generators. The earthquake and tsunami caused the damage that led to the explosions and partial meltdowns at the Fukushima I facility.

Times are given in Japan Standard Time (JST), unless noted, which is UTC plus nine hours.

Timeline

Friday, 11 March

File:Japanese officials check for radioactive material on residents living near the Fukushima station.jpg
Japanese officials check for radioactive material on residents living near the Fukushima station
14:46
A 9.0 magnitude earthquake strikes off the coast of Honshu Island at a depth of about 24 kilometres (15 mi). Fukushima I power plant's nuclear reactors 1, 2, and 3 are automatically shut down by the shake. Nuclear reactors 4, 5, and 6 were undergoing routine maintenance and were not operating, (reactor 4 was defueled Nov 2010). The tremor has the additional effect of causing the power plant to be cut off from the Japanese electricity grid, however, backup diesel generators kick in to continue cooling. Tokyo Electric Power Company (TEPCO), the plant's operator, finds that units 1 and 2 are not operating correctly and notifies the proper officials.
15:01 (approximate)
The tsunami unleashed by the earthquake strikes the Fukushima facility damaging the backup generators required to cool the reactors. With the loss of power from the grid and the damage to the generators, the plant has become "dark". Later, reports indicate that only the generator for unit number 6 remained working in full operational capacity.
According to a report in the New York Times, "t the start of the crisis Friday, immediately after the shattering earthquake, Fukushima plant officials focused their attention on a damaged storage pool for spent nuclear fuel at the No. 2 reactor at Fukushima I, said a nuclear executive who requested anonymity.... The damage prompted the plant’s management to divert much of the attention and pumping capacity to that pool, the executive added. The shutdown of the other reactors then proceeded badly, and problems began to cascade."
16:00
The Nuclear and Industrial Safety Agency of Japan initiates an emergency headquarters in an attempt to gather information on the 55 nuclear reactors in Japan. There is no report that radiation was detected outside plant borders.
19:03
Prime Minister Naoto Kan declares a nuclear emergency status. This is announced by Yukio Edano, Chief Cabinet officer in Japan. Japanese government officials try to comfort the people of Japan by telling them that the proper procedures are being undertaken. They also announce that no radioactive leaks have been detected.
21:00
An evacuation order is issued by the government to persons within a 3 kilometres (1.9 mi) radius of the Fukushima I station. Those within a 10 kilometres (6.2 mi) radius are told that they can remain in their homes and carry on with regular activities until told otherwise.
At Fukushima I, the ongoing lack of electricity is causing the cooling system to fail, and the pressure within the nuclear units build up. This pressure buildup is the result of residual decay heat causing the coolant, which is not being circulated, to evaporate. There is no confirmation of radiation leaking from the reactor. TEPCO announces that pressure inside reactor unit 1 of Fukushima I is more than twice normal levels.

Saturday, 12 March

04:30
Officials declare a heightened state of alert for Fukushima II (Dai-ni). Officials declare a state of nuclear emergency for Fukushima I (Dai-ichi).
05:30
Despite the high risk of the hydrogen ignited after combining with oxygen in water or the atmosphere, in order to release some of the pressure inside the reactor at Fukushima I unit 1, the decision is taken to vent some of the steam (which contained a small amount of radioactive material) into the air in the concrete container building surrounding the unit.
10:09
TEPCO confirms that a small amount of vapor has been released into the air to release pressure in reactor unit 1 (Fukushima I).
10:58
Pressure still remains too high inside reactor unit 2 at Fukushima I. In order to alleviate some of this pressure, a consensus is reached to, once more, vent radioactive vapor into the air.
15:30
Evacuation of residents within 3 km of Fukushima II underway. Evacuation of residents within 10 km of Fukushima I underway.
15:36
Unit 1 at Fukushima I: cameras document a massive hydrogen explosion on the outer structure of one of four buildings at the plant. It also documents the outer structure collapsing. TEPCO 3 hrs later announces that four persons who are employed at the power plant have been injured.
18:36 (approximately)
TEPCO announces that four persons who are employed at the power plant have been injured in the unit one explosion.
20:00
Uncertainty surrounds the actual cause of the blast at Fukushima I (later identified as a hydrogen explosion) and the damage caused.
Yukio Edano announces that the concrete building surrounding the steel reactor container at unit 1 in Fukushima I has collapsed as a result of the explosion; however no damage has been inflicted on the reactor itself.
21:40
Evacuation zone around Fukushima I extended to 20 km. Evacuation zone around Fukushima II extended to 10 km.
To release pressure within the reactor unit 1 at Fukushima I, steam is released out of the unit into the air. This steam contains water vapor, Hydrogen, Oxygen and some radioactive material, mostly tritium and N.

Sunday, 13 March

05:10
Fukushima I Unit 1 declared as an INES Level-4 "accident with local consequences" event.
10:35
Fukushima II Unit 3 confirmed as shutdown cold and safe.
At Fukushima II, one worker is confirmed to have died in a crane accident, four other injured.
Fukushima II Units 1, 2, and 4 are being powered by offsite power.

Monday, 14 March

11:15
The outer building surrounding Unit 3 of Fukushima I explodes, presumably due to the ignition of built up hydrogen gas. No health risk reported, though 600 people have been ordered to stay indoors. Chief Cabinet Secretary Yukio Edano reported that "The vessel containing the No. 3 reactor’s radioactive core is intact after yesterday’s blast", and while that the outer reactor building of Unit 3 at Fukushima I was blown apart, the inner containment vessel was not breached. TEPCO also stated that one worker was injured and seven missing. TEPCO later said at least four employees and two contractors were injured in the blast.
11:44
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 20 μSv/hour.
12:30
Status of the Fukushima I station at 12:30 March 14 1 2 3 4 5 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity Damaged Not damaged Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Not damaged Not damaged Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional RCIC working Not functional Not necessary Not necessary Not necessary
Building integrity Damaged Not damaged Damaged Not damaged Not damaged Not damaged
Environmental effect (NPS border) 20 μSv/hour at 11:44
Pressure vessel, water level Unknown Above core Unknown Safe Safe Safe
Pressure vessel, pressure Stable Stable Stable Safe Safe Safe
Containment pressure Stable Stable Stable Safe Safe Safe
Seawater injection Suspended To be decided Performed Not necessary Not necessary Not necessary
Containment venting Performed Preparing Performed Not necessary Not necessary Not necessary
Evacuation radius 20 km
INES Level 4 (estimated by NISA)
13:15
Fukushima II Unit 1 cooling system has been restored, work continues on units 2 and 4.
13:55
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 15 μSv/hour.
20:30
Status of the Fukushima I station at 20:30 March 14 1 2 3 4 5 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity Damaged Unknown Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Not damaged Not damaged Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Building integrity Damaged Not damaged Damaged Not damaged Not damaged Not damaged
Environmental effect (NPS border) 15 μSv/hour at 13:55
Pressure vessel, water level Unknown Low (recovering) Unknown Safe Safe Safe
Pressure vessel, pressure Low Unknown Stable Safe Safe Safe
Containment pressure Stable Increasing Stable Safe Safe Safe
Seawater injection Suspended Performed Performed Not necessary Not necessary Not necessary
Containment venting Performed Preparing Performed Not necessary Not necessary Not necessary
Evacuation radius 20 km
INES Level 4 (estimated by NISA)
21:00 (approximate)
Fuel rods within Reactor #2 of the Fukushima I nuclear plant were fully exposed to air (but were still within the intact containment vessel and therefore not exposed to the outer atmosphere). TEPCO earlier said the cooling system had been lost and began injecting seawater into the reactor to cool it down.
21:16
Yukio Edano affirms that Reactor number 2 of Fukushima I is unlikely to explode. In addition, he stated that there is ongoing work to cool down the reactor.
23:20 (approximate)
Fuel rods at Reactor #2 of Fukushima I became fully exposed once again. TEPCO says that pressure inside the reactor rose again because the unit's air flow gauge was accidentally turned off. With the gauge turned off, flow of water into the reactor was blocked, leading to full exposure of the rods.

Tuesday 15 March

06:00 (approximate)
A fire in unit 4 reportedly breaks out around 6AM
06:14 (approximate)
A third explosion occurred at Fukushima I, unit 2 and damage of the containment building was feared. Reactor unit 2's pressure-suppression system was feared damaged, and the radiation level exceeded the legal limit to reach 965.5 µSv/hour. The radiation level later fluctuated up to 8217 µSv/hour, two hours after the explosion. The level went down to 2400 µSv/hour shortly later. Workers at the plant started evacuation, with a select few remaining to keep the reactors cooled. The plant's operator said the nuclear fuel rods could be melting. Additionally, it was confirmed that the 4th floor rooftop area of the Unit 4 Nuclear Reactor Building had sustained damage, likely caused by the earlier blast of Unit 3.
07:00
Status of the Fukushima I station at 07:00 March 15 1 2 3 4 5 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity Damaged Damaged Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Partly damaged Not damaged Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not functional Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not functional Not necessary Not necessary
Building integrity Damaged Partly damaged Damaged Not damaged Not damaged Not damaged
Environmental effect (NPS border and onsite) 8217 µSv/hour at 08:30, and between 100 and 400 mSv/hour at times.
Pressure vessel, water level Unknown Low (recovering) Unknown Safe Safe Safe
Pressure vessel, pressure Low Leaked Stable Safe Safe Safe
Containment pressure Stable Increasing Stable Safe Safe Safe
Seawater injection Suspended Performed Performed Not necessary Not necessary Not necessary
Containment venting Performed Preparing Performed Not necessary Not necessary Not necessary
Evacuation radius 20 km
INES Level 4 (estimated by NISA); Level 6 (estimated by France's nuclear watchdog agency, ASN)
08:30
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 8217 µSv/hour.
08:54
A fourth explosion and resulting fire is reported at unit 4. IAEA Reports that initial fire at unit 4 started at 2354 UTC on March 14th.
09:14 (approximate)
MSNBC reported that radiation measurements spiked at 11,900 µSv/hour around 0914 as measured at the front gate of the facility and speculated it was caused by the third explosion at unit 2.
09:40
The Fukushima I Unit 4 building caught fire around 6AM, likely releasing radioactive contamination from the spent fuel stored there. TEPCO said workers extinguished the fire by 12:00. As radiation levels rose, some of the fifty employees still at the plant were evacuated.
10:22
The Fukushima I radiation monitor readings outside of the buildings were 30 mSv/hour between Unit 2 and Unit 3, 400 mSv/hour beside Unit 3, and 100 mSv/hour beside Unit 4.
11:00 (approximate)
IAEA Reports that initial fire at unit 4 was extinguished at 200 UTC on March 15th.
11:35
At Fukushima II (Dai-Ni), Units 1, 2, and 3 are in cold shutdown. For Unit 4, work is in progress to restore cooling and bring it to cold shutdown.
13:35
No fly zone declared for 30 km around the Fukushima I plant. Prime Minister warns of radiation hazard and further radiation leaks.
16:09
There is a fire at a spent fuel pond of a reactor and radioactivity has been released into the atmosphere, says the IAEA according to AFP news agency.
16:30
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 489.8 µSv/hour.
16:38
The AFP reports that the fire previously reported at unit 4's spent fuel pond had released "radioactivity... directly into the atmosphere" according to the IAEA .
17:00
The fire at the spent fuel pond has been put out by Japanese authorities according to the IAEA they state "Japanese authorities have confirmed that the fire at the spent fuel storage pond at the Unit 4 reactor of Fukushima I nuclear power plant was extinguished on 15 March at 17:00 JST."
17:03
There has been a slight rise in temperature of two more reactors at Fukushima I nuclear plant, the chief government spokesman says according to AFP.
18:00
Japanese nuclear safety official has confirmed reports that the water inside the waste fuel storage pool for the Unit 4 Fukushima reactor may be boiling, AP reports.
19:00
Status of the Fukushima I station at 19:00 March 15 1 2 3 4 5 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity Damaged Unknown Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Damage suspected Not damaged Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Building integrity Severely Damaged Slightly damaged Severely Damaged Partially Damaged Not damaged Not damaged
Environmental effect (NPS border) 489.8 µSv/hour at 16:30
Pressure vessel, water level Around half of the fuel Recovering after dried-up Around half of the fuel Safe Safe Safe
Pressure vessel, pressure Stable Fluctuating Stable Safe Safe Safe
Containment pressure Stable D/W: Unknown, S/P: Atmosphere Stable Safe Safe Safe
Seawater injection into core Continuing Continuing Continuing Not necessary Not necessary Not necessary
Seawater injection into containment building Continuing To be decided To be decided Not necessary Not necessary Not necessary
Containment venting Continuing Preparing Continuing Not necessary Not necessary Not necessary
Spent fuel integrity (no data) (no data) (no data) SFP level low, injecting water SFP temperature increasing SFP temperature increasing
Evacuation radius 20 km
INES Level 4 (estimated by NISA); Level 6 (estimated by France's nuclear watchdog agency, ASN)
21:00
The water level in Fukushima I Unit 5 has been decreasing. Workers plan to use Unit 6's diesel generator to help pump water into Unit 5. Japanese authorities have also informed the IAEA that at 12:00 UTC of 15 March the water level in Unit 5 had decreased to 201 cm above the top of the fuel. This was a 40 cm decrease since 07:00 UTC of 15 March. Officials at the plant were planning to use an operational diesel generator in Unit 6 to supply water to Unit 5.
23:35
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 6308 µSv/hour.

Wednesday, 16 March

05:45
A location in the building of reactor 4 has been reported to be on fire at the Fukushima I (by NHK TV). According to one of the worker's testimony, flames were present at the location of Tuesday's fire. The fire was verified by satellite imagery showing smoke rising from the reactor 4 building. The fire disappeared later. IAEA confirms reports that a fire was visually observed in unit 4, in a similar area as the original fire. This new fire cast into doubt the earlier hope that the Tuesday blaze in the Unit 4 housing was caused by lubricating oil pumps; instead TEPCO officials acknowledge it is possible the spent fuel rods are uncovered and overheating, remarking that "the possibility of a re-criticality is not zero." Iouli Andreev, former director of the Soviet Spetsatom clean-up agency involved in Chernobyl clean-up, as well as Laurence Williams, professor of nuclear safety at the University of Central Lancashire, speculate that the Fukushima management had engaged in an unsafe practice of re-racking spent rods in the pool well beyond its rated capacity, in effect heightening danger of melting and pool boil-off.
06:15
IAEA Reports that the fire previously observed in unit 4 is no longer visible.
07:30
Evacuation of the 20km zone around Fukushima I has been completed.
08:00
Status of the Fukushima I station at 08:00 March 16 1 2 3 4 5 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity 70% damaged 33% damaged Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Damage suspected Not damaged Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Building integrity Severely damaged Slightly damaged Severely damaged Partially damaged Not damaged Not damaged
Environmental effect (NPS border and onsite) 6308 μSv/hour at 23:35, March 15, with increases to 1,000 mSv/hour early March 16 and then decreasing to 800-600 mSv/hour
Pressure vessel, water level Around half of the fuel Recovering after dried-up Around half of the fuel Safe Safe Safe
Pressure vessel, pressure Stable Fluctuating Stable Safe Safe Safe
Containment pressure Stable D/W: Unknown, S/P: Atmosphere Stable Safe Safe Safe
Seawater injection into core Continuing Continuing Continuing Not necessary Not necessary Not necessary
Seawater injection into containment building Continuing To be decided To be decided Not necessary Not necessary Not necessary
Containment venting Continuing Preparing Continuing Not necessary Not necessary Not necessary
Spent fuel integrity (no data) (no data) (no data) SFP level low SFP level decreasing SFP level decreasing
Evacuation radius 20 km
INES Level 4 (estimated by NISA); Level 6 (estimated by France's nuclear watchdog agency, ASN)
08:30
White smoke was seen rising from the vicinity of Fukushima I Unit 3. Damage to the containment vessel of the unit was suspected. Later TEPCO reported that failing to cool the Spent Fuel Pool resulted in evaporation of pool water, which caused steam.
09:00
The fire that broke out inside the building of Fukushima I reactor 4 appears to be extinguished. According to Kyodo News, TEPCO is considering spraying boric acid by helicopter to prevent the spent nuclear fuel rods from reaching criticality again and starting a nuclear chain reaction. However, TEPCO said that readings showed high levels of radiation, making the building inaccessible, and therefore making the spraying "extremely difficult".
10:01 (estimated)
Reactor 3 at Fukushima I nuclear power plant begins emitting white smoke.
10:46
TEPCO says the reactor 3 at Fukushima I nuclear power plant has been emitting white smoke for about 45 minutes.
11:00
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 3391 µSv/hour
11:36
The remaining 50 workers located in the Fukushima I nuclear power plant have evacuated after radiation levels there have surged.
11:40
Chief cabinet secretary Edano announces that the white fumes emerging from the plant may constitute radioactive steam that has breached Fukushima I Unit 3's containment.
12:30
Status of the Fukushima I station at 12:30 March 16 1 2 3 4 5 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity 70% damaged 33% damaged Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Damage suspected Damage suspected Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Building integrity Severely damaged Slightly damaged Severely damaged Severely damaged Not damaged Not damaged
Environmental effect (NPS border) 3391 µSv/hour at 11:00, March 16
Pressure vessel, water level Around half of the fuel Recovering after dried-up Around half of the fuel Safe Safe Safe
Pressure vessel, pressure Stable Fluctuating Stable Safe Safe Safe
Containment pressure Stable D/W: Unknown, S/P: Atmosphere Stable Safe Safe Safe
Seawater injection into core Continuing Continuing Continuing Not necessary Not necessary Not necessary
Seawater injection into containment building Continuing To be decided To be decided Not necessary Not necessary Not necessary
Containment venting Continuing Preparing Continuing Not necessary Not necessary Not necessary
Spent fuel integrity (no data) (no data) High temperature suspected SFP level low,
Preparing water injection,
Damage to fuel rods suspected
SFP temperature increasing SFP temperature increasing
Evacuation radius 20 km from Nuclear Power Station (NPS)
INES Level 4 (estimated by Japanese NISA and accepted by the international IAEA); Level 6 (estimated by the French nuclear authority and the Finnish nuclear authorities))
12:35 (approximate)
The 50 personnel that were evacuated at 1136 returned to the facility after radiation levels subsided.
14:30
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 1937 µSv/hour.
17:26
TEPCO says that work on cooling the Fukushima I reactors is suspended due to radiation risks for the second time.
18:00
Radiation decreased to 1500 µSv/hour at Fukushima I site boundary (NHK TV). See also this map of various detectors stationed around Japan (owned by public and government).
19:00
The Fukushima I Unit 3 Spent Fuel Pool level is low, with preparations for water injection.
19:00
Status of Fukushima I at 19:00 March 16 Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity 70% damaged 33% damaged Damaged No fuel rods Not damaged Not damaged
Containment integrity Not damaged Damage suspected Damage suspected Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Building integrity Severely damaged Slightly damaged Severely damaged Severely damaged Not damaged Not damaged
Pressure vessel, water level Around half of the fuel Recovering after dried-up Around half of the fuel Safe Safe Safe
Pressure vessel, pressure Stable Fluctuating Stable Safe Safe Safe
Containment pressure Stable D/W: Unknown, S/P: Atmosphere Stable Safe Safe Safe
Seawater injection into core Continuing Continuing Continuing Not necessary Not necessary Not necessary
Seawater injection into containment building Continuing To be decided To be decided Not necessary Not necessary Not necessary
Containment venting Continuing Preparing Continuing Not necessary Not necessary Not necessary
Integrity of fuel in Spent Fuel Pool (SFP) (no data) (no data) SFP level low,
Preparing water injection
SFP level low,
Preparing water injection,
Damage to fuel rods suspected
SFP temperature increasing SFP temperature increasing
Environmental effect (NPS border) 1937 µSv/hour at 14:30, March 16
Evacuation radius 20 km from Nuclear Power Station (NPS). People who live between 20km to 30km from the Fukushima I Nuclear Power Station are to stay indoors.
INES Level 4 (estimated by Japanese NISA and accepted by the international IAEA); Level 6 (estimated by the French nuclear authority and the Finnish nuclear authorities)
19:50
Radiation level at Fukushima II reactor (10km south of Fukushima I): 28.6 µSv/hour. ref
21:05
Australian Foreign Minister Kevin Rudd advises Australians to leave Tokyo.
23:30
The workers, along with 130 additional people, are allowed back in the plant as radiation levels fall.
23:55
IAEA Web Site Reports that "Japanese authorities have reported concerns about the condition of the spent nuclear fuel pool at Fukushima I Unit 3 and Unit 4. Japanese Defense Minister Toshimi Kitazawa announced Wednesday that Special Defence Forces helicopters planned to drop water onto Unit 3, and officials are also preparing to spray water into Unit 4 from ground positions, and possibly later into Unit 3. Some debris on the ground from the 14 March explosion at Unit 3 may need to be removed before the spraying can begin."

Thursday, 17 March

01:37
The Australian Department of Foreign Affairs and Trade issued a Travel Advice Bulletin advising Australian travellers to reconsider the need to travel to Tokyo, the surrounding earthquake-affected districts, Chiba, Fukushima, Aomori, Iwate, Nagano, Niigata and Ibaraki prefectures and not to travel to the Fukushima Nuclear Power Plant exclusion zone and Miyagi Prefecture.
02:35 (approximately)
The US Embassy in Japan is recommending that all personnel to adhere to the Japanese safety measures, including their recommended 20 km radius for evacuation and additional shelter-in-place recommendations out to 30 km.
03:50
IAEA Director announces he will travel to Japan to "see the situation for himself".
05:15 (approximately)
The US Embassy, on advice from the Nuclear Regulatory Commission, told Americans to evacuate a radius of approximately 50 miles (80 km) from the Fukushima plant.
05:25 (approximately)
The head of the U.S. Nuclear Regulatory Commission said that the fuel pool at unit 4 had run dry and as a result, radiation levels at the plant were "extremely high". TEPCO denied that the pool had run dry and said "the condition is stable" at unit 4.
09:00
Table of status
09:19 (approximate)
Naoki Tsunoda, a TEPCO spokesman, indicates that the new power lines to the plant were almost finished and that officials planned to try it "as soon as possible." Kyodo said that could be as early as Thursday afternoon.
09:48
Japan's Self Defense Force used a CH-47 helicopters to perform water spraying operations on reactor unit 3. JAIF reported that the helicopter had been specially modified with lead shielding to protect the personnel onboard. However, much of the water appeared to be dispersed in the wind before reaching its target.
10:15
The IAEA releases a summary of all injuries and contaminations due to the situation at the Fukushima I nuclear plant. It indicates that 23 people were injured, more than 20 were contaminated, and 2 are missing.
10:25
Helicopter based spraying operations have stopped and helicopters have left the site. Spraying operations will continue from the ground. Personnel are monitoring the radiation levels around the base.
11:05
The Japanese nuclear safety agency says external power to the plant should partially resume later in the day.
12:07
Cabinet Secretary Edano says Unit 3 is the top priority for cooling efforts
16:00
Status of Fukushima I at 16:00 March 17 Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity 70% damaged 33% damaged Damaged No fuel rods Not damaged Not damaged
Containment integrity Not damaged Damage suspected Damage suspected Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Building integrity Severely damaged Slightly damaged Severely damaged Severely damaged Not damaged Not damaged
Pressure vessel, water level Around half of the fuel Recovering after dried-up Around half of the fuel Safe Safe Safe
Pressure vessel, pressure Stable Unknown Stable Safe Safe Safe
Containment pressure Stable D/W: Unknown, S/P: Atmosphere Stable Safe Safe Safe
Seawater injection into core Continuing Continuing Continuing Not necessary Not necessary Not necessary
Seawater injection into containment building Continuing To be decided To be decided Not necessary Not necessary Not necessary
Containment venting Continuing Preparing Continuing Not necessary Not necessary Not necessary
Integrity of fuel in Spent Fuel Pool (SFP) (no data) (no data) SFP level low,
Preparing water injection
SFP level low,
Preparing water injection,
Damage to fuel rods suspected
SFP temperature increasing SFP temperature increasing
Environmental effect (NPS border) 646 µSv/hour at 11:10, March 17
Evacuation radius 20 km from Nuclear Power Station (NPS). People who live between 20km to 30km from the Fukushima I Nuclear Power Station are to stay indoors.
INES Level 4 (estimated by Japanese NISA and accepted by the international IAEA); Level 6 (estimated by the French nuclear authority and the Finnish nuclear authorities)
17:00
South Korean foreign minister asked South Koreans in Japan to stay 80 kilometers outside the earthquake-stricken nuclear complex in Fukushima.

See also

References

  1. http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0001xgp/
  2. Josef Oehmen (March 15, 2011). "Fukushima Nuclear Accident – a simple and accurate explanation". theenergycollective.com. Retrieved March 15, 2011.
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