Hydrogen explosion occurred at Fukushima Daiichi nuclear power plant Unit 3, residents within 20 km radius evacuated indoors

On March 12Explosion occurred at Unit 1 of Fukushima Daiichi Nuclear Power PlantFollowed by an explosion at Unit 3 of Fukushima Daiichi Nuclear Power Plant.

Indoor shelter is called for residents around the house.

Details are as below.
Initial report of explosion


A state of explosion. It occurred at 11:01.


Suddenly exploding. It is said that the explosion has taken place twice.



Smoke is rising.










Asahi.com (Asahi Shimbun): Explosion Hydrogen Explosion Potential at Fukushima Daiichi nuclear power plant 3 - Society

A big explosion occurred around 11 am at 14 am on Fukushima Daiichi nuclear power plant 3 damaged by the Great East Japan Earthquake. Although details are unknown, there is a possibility that if the reactor containment vessel is damaged, it may develop into the worst situation where a large amount of radioactive substance diffuses into the atmosphere. According to the Ministry of Economy, Trade and Industry's Nuclear and Industrial Safety Agency, there is a possibility that a hydrogen explosion has occurred.

The nuclear reactor is protected from the inside by three "walls" of pressure vessel, containment vessel, reactor building. In the explosion that occurred on Fukushima Daiichi nuclear power plant No. 1 on the 12th, the damage remained in the reactor building, and no abnormality was found in the containment vessel and the pressure vessel. If the pressure vessel or containment vessel which becomes the "last strike" to protect the nuclear reactor is broken, it will be a serious accident comparable to the Chernobyl accident.

Hydrogen explosion of Fukushima Daiichi nuclear power plant Unit 3 NHK News

According to NISA, at 11:01 am on the Unit 3 of the Fukushima Daiichi Nuclear Power Station, a hydrogen explosion has occurred. NISA calls on residents to enter the building if they are outdoors.

2011/03/14 11:38
The wind direction is from south to north. As of 11:05, the director of the site reports that the containment vessel is healthy, around 11:30.

2011/03/14 11: 40
Unit 3 after the explosion. The skeleton is exposed.


Asahi.com (Asahi Shimbun): Explosion of Unit 3, Plume of a few hundred meters Fukushima Daiichi Nuclear Power - Society

The explosion of Unit 3 of TEPCO Fukushima Daiichi Nuclear Power Station, according to the relay video of the television, flames came out from the top of the building, and the next moment the gray smoke went up several hundred meters. I saw a lot of large masses blown off, falling.

According to NHK helicopter picture, the framework of the reactor building is visible.

2011/03/14 11: 44
Since radiation leakage is expected to be about the same level as at the time of explosion of Unit 1, inhabitants within the radius of 20 km are called for indoor escape.

2011/03/14 11: 46
Chief Cabinet Secretariat Edano, commented at a press conference that it is unlikely that a large amount of radioactive material appears.

2011/03/14 11: 49
Received the explosion report, the Nikkei futures average is lower than 9500 yen.

Asahi.com (Asahi Shimbun): Unit 3 exploded, TSE 9500 yen cracked Nikkei futures also plummeted - Business · economy

"Nikkei average futures" trading the future trading price of the Nikkei Average is plunged after 11:15 am on 14th, after receiving reports that an explosion occurred at Unit 3 of the Fukushima Daiichi Nuclear Power Station. The stock price, which was 9670 yen in 12 minutes, fell by 190 yen in 10 minutes, setting 9480 yen.

2011/03/14 12: 05
Graph of radiation dose. The radiation dose leaked at the time of the explosion of Fukushima Daiichi nuclear power plant Unit 1 is worth the limit to which ordinary people can be exposed in one year.


2011/03/14 12: 06
A meeting of the Nuclear and Industrial Safety Agency. According to the report from TEPCO, the containment is confirmed to be healthy by the parameters. The vicinity of the containment vessel is 20 micro sievert. Also, workers at Fukushima Daiichi Nuclear Power Plant were injured and they are arranging an ambulance at the moment.

2011/03/14 12: 10
Tokyo Electric Power Company's press conference. We confirmed bruises by two employees and one employee of a cooperating company. There are seven missing people, of which one is a cooperating company and six are SDF personnel. There is no injured person in the personnel in the central control room.

2011/03/14 12: 22
Asahi.com (Asahi Shimbun): Fukushima Daiichi Nuclear Explosion, 7 people missing Present TEPCO Presentation - Society

TEPCO announced that "there are seven people missing" about the explosion of Unit 3 of Fukushima Daiichi nuclear power plant.

2011/03/14 12: 23
The location of seven people who were missing was confirmed. Three of them are injured.

2011/03/14 12: 43
Chief Cabinet Secretary 's interview. Explosion is thought to be the same kind as the explosion of Unit 1 and explanation that the soundness of containment vessel is maintained at present. It is unlikely that large amounts of radioactive material will be released. The internal pressure of the containment vessel is stable.

The radiation dose was monitored, 57 microsieverts at 11:37 in the power station. In the vicinity of the main gate is 20 micro sievert as of 11:44. Even at the off-site center about 5 km away, it recorded the same 1 microsiever as yesterday as of 12:36. There is no problem with neutron beams, and the central control room is maintained. The water injection work for Unit 3 is continued, and the workers are evacuating. About 500 people are retreating from within a 20 km radius.

2011/03/14 12: 52
TEPCO announced the hydrogen explosion.

About the occurrence of white smoke near Unit 3 of Fukushima Daiichi Nuclear Power Station | Press Release 2011 | TEPCO News | Tokyo Electric Power Company

On the occurrence of white smoke near Fukushima Daiichi Nuclear Power Station Unit 3 (2nd report) | Press Release 2011 | TEPCO News | Tokyo Electric Power Company

2011/03/14 13: 10
The Asahi Shimbun reported on the opinions of experts.
Asahi.com (Asahi Shimbun): Explosion of Unit 3, voices of concern from experts - Society

Experts who saw television images telling the state of explosion of Unit 3 of Fukushima Daiichi nuclear power plant are experiencing severe views on the seriousness of accidents.

Kobayashi Keiji · Former Kyoto University Institute for Nuclear Engineering Instructor (Nuclear Engineering) said, "It seemed different from the explosion of Unit 1. The red flame was rising at a high place of the building and the containment vessel itself was not destroyed "I am worried about the scope of influence.Is not being able to cool due to breakage of piping, deformation or crack in containment containers, etc. Whether it is a crack or a partial breakage , There is a possibility that a large amount of radioactive substance leaks out. "

Atsushi Sakurai, a technical critic, said, "The situation is not very good.I am afraid that if the cooling water can not be injected into Unit 3 and the cladding falls to the bottom of the pressure vessel and it falls to the bottom of the pressure vessel, It may be broken, it may rupture to the containment so that a large amount of radioactivity will be released into the environment, so it will be worse than Three Miles. "

Meanwhile, Kazuo Sato, Former Nuclear Safety Engineering Chairperson (Reactor Safety Engineering) said, "It is about the surface that heat caused by explosion affects containment containers, I think that there is no long heat transfer and there is no big influence. There is a reinforced concrete of 1 meter or more around the container, depending on its degree, if it explodes outside, it will not echo inside the containment vessel. "

2011/03/14 13:11
There was a report that the number of injured people due to the explosion occurred in Unit 3 was eleven.

2011/03/14 14:50
TEPCO announces press release. As of 13:30 minutes, four employees of the company and three workers including cooperating enterprises were injured. Based on the events of Unit 1 and Unit 3, it was decided to consider the treatment for removing hydrogen gas on the reactor building wall surface in advance for Unit 2 .

On the occurrence of white smoke near Unit 3 of Fukushima Daiichi Nuclear Power Plant (Part 3) | Press Release 2011 | TEPCO News | Tokyo Electric Power Company

2011/03/14 18: 21
Confirmation of the adhesion of radioactive substances to 6 out of 7 injured people. About 5 of them were decontaminated and 4 Self-Defense Force personnel who were cooperating in supplying cooling water were also injured, but it is said that details are being confirmed.

On the occurrence of white smoke near Unit 3 of Fukushima Daiichi Nuclear Power Station (4th report) | Press Release 2011 | TEPCO News | Tokyo Electric Power Company