Fukushima Daiichi nuclear power plant Unit 2, loss of pressure suppression room (suppression pool), explosion sound observed

It was revealed that at the TEPCO Fukushima Daiichi Nuclear Power Station Unit No.2, a defect was found in a place called suppression pool. Also, there was an explosion sound at Unit 2.

At the present time, it is announced that the measured value of peripheral radiation concentration does not show a sharp rise and it will not lead to health damage or the like.

Details are as below.
According to Secretary Chief Cabinet Secretary Shigeo Edano which took place at 6:40 am, it became clear that there is a defect in the place where water vapor is converted to water vapor called suppression pool connected to containment vessel at Unit 2 of Fukushima Daiichi Nuclear Power Plant .

Previously, TEPCOReleases upon inspection of the nuclear power plant No. 2Based on the suppression pool, "a suppression pool" is located in the lower part of the reactor containment vessel, and when the pressure inside the reactor containment vessel rises with steam or the like, the steam is guided into the pressure suppression chamber and cooled, It is said that it has the role of storing water as a source of water for an emergency core cooling system at the time of a reactor coolant loss accident. "

The place called "pressure suppression room" by coverage is the same as this "suppression pool".

At the present time, the measurement value of the peripheral radiation concentration did not show a sharp rise and the Chief Cabinet Secretary indicated that he would not lead to health damage or the like.

The reporter asked if TEPCO had concealed information, but I do not know if this was hiding the information that was known before or whether it was confirmed again about.

2011/03/15 7:14
Unit 2 "Some defects found" NHK News

Asahi.com (Asahi Newspaper): Fukushima nuclear power plant Unit 2 defective in cooling water equipment leading to containment vessel - politics

2011/03/15 8: 00
According to NISA, there was an explosion sound at Fukushima No. 1 nuclear power plant at 6:10.


2011/03/15 8: 16
Immediately after the explosion sound, 965.5 μSv (micro sievert) is observed.

2011/03/15 8: 30
TEPCO judged that some abnormality occurred in the pressure suppression room (suppression pool). We continue water injection work, but we are evacuating from the Fukushima Daiichi nuclear power plant to a safe place for the cooperating company workers and our employees who are directly involved in the work by the director's decision.

2011/03/15 8: 43
TEPCO started a press conference.

As a matter of fact, "Since there was a sound in the vicinity of the pressure suppression room of Unit 2, we confirmed the parameters, the pressure inside the room decreased and it was judged that there was an abnormality here. With this fact movement of staff members It started. " In addition, the water level has risen to -2700 mm instead of downscale, indicating the water level around the sound after the sound.

At Fukushima Daii Nuclear Power Plant, cold shutdown of Unit 4 also occurred at 7:15. This means that all of Units 1 to 4 have been cold stopped.

2011/03/15 8: 51
Nuclear power safety and NISA announced that radioactive material in the nuclear reactor could be leaked outside.

【Nuclear Explosion】 Explosion of Unit 2, Possibility of Radiation External Leakage Nuclear Safety · NISA Announced - MSN Sankei News

The Nuclear and Industrial Safety Agency announced that the reactor building of Unit 2 was damaged and the radioactive material in the nuclear reactor could be leaked to the outside through the reactor building.
According to the Nuclear and Industrial Safety Agency NISA, the pressure suppression pool is usually 3 atm, but it was said that it was damaged because it fell to 1 atm after the explosion. The pressure suppression pool is the part where water was left at the bottom of the reactor pressure vessel.

2011/03/15 8: 59
TEPCO announced that it measured 8127 micro sievert around the main gate of Fukushima nuclear power plant at 8:31.

Asahi.com (Asahi Shimbun): Fukushima Daiichi nuclear power plant 2 Unit 2 radiation sharp rise near explosive sounds - Society

At 7:00 am in the main gate of the Fukushima Daiichi Nuclear Power Plant, it said that it observed 965 microsieverts of radiation every hour. This amount explains "It is an amount to be bathed in one hour, about half of the radiation exposed in the natural world in one year." However, at 8:31 am it is rising to 8217 microsievert per hour in the same place.

2011/03/15 9:12
It is contents of the interview by NISA.

NISA:
For radiation workers it is limited to 20 mSv. It is said that it is very good that the times of emergency work are collectively one year and the numerical values ​​of international institutions are adopted. In case of emergency it will tolerate up to 100 mSv, but people taking up to 100 mSv should not work on radiation for 5 years.

Reporter:
If you enter inside 100 mSv, 12 hours is the limit?

NISA:
Simply calculating it will be that way. When going inside it will put protective equipment but if you do simple calculations it will.

Reporter:
How much is reduced by protection?

NISA:If you attach something like a lead armor, attach a shielding device and attach an apron or the like, it is considerably reduced, but we do not know any specific numerical values
According to TEPCO at 8:31 at the main gate 8217 micro sievert per hour was detected. It fell to 2400 microsievert at 8: 45. I'd like to think that I need follow-up and correspondence.

Reporter:
How much influence usually?

NISA:
It is the same content as when I first explained 900 numerical values ​​earlier, but the radiation hit by human beings in the natural world is 2400 micro sievert. It is supposed to take three times as much as one taking nature in an hour.
I think that this will be a large number, but to what extent the human body is affected ... ... Because there is no acute impact value, even if you are exposed to radiation, there will be no immediate health problems, but dehumidification treatment Is required.

2011/03/15 9:24
Unit 3 nuclear fuel pool without covering NHK News

Pool at the Fukushima Daiichi Nuclear Power Station Unit 3, where used nuclear fuel stored in the containment vessel is stored, because the roof of the containment was blown off by hydrogen explosion on the morning of 14th, It is also in a state that there is no one that covers.
This pool is a facility provided to move and cool spent nuclear fuels that have been burned in nuclear reactors and used up. Under normal conditions, the pool water is circulated to cool nuclear fuel, but at the Fukushima Daiichi nuclear power plant, there is a possibility that the cooling function is lost because of power outage. TEPCO says at the press conference, "There is no clear answer at this moment" on the relation with the fact that there is something like steam on the top of the building containing Unit 3 's reactor.

2011/03/15 9:34
It is the question-and-answer contents of TEPCO's interview that had been held until recently.

TEPCO:
First of all, there is no other way than dipping fuel into water, except to inject water. Later information has not been entered so far.
In an emergency situation, working with human tactic tactics with an upper limit of 100 mSv.

Reporter:
I can not work for one year if I take 100 millimeters, but are the personnel sufficient?

TEPCO:
It is enough for now.

Reporter:
8217 (micro) Se Belt has been confirmed, but how can you do the work and how much will it stop

TEPCO:
I can still do the work. Specific value of the upper limit is not set.

Reporter:
We should ask for support including overseas

TEPCO:
In that sense, the SDF is also helping. Request other if necessary.

Reporter:
Does the official residence understand by continuing water injection

TEPCO:
I keep working in keeping in touch with the country.

Reporter:
Was it possible to assume until the building was broken?

TEPCO:
It is not supposed to have assumed it to that extent.

Reporter:
What will happen if the water level does not rise

TEPCO:
Rather than what kind of situation it is, we are now focusing on raising the water level.

Reporter:
What is the possibility of meltdown?

TEPCO:
I believe there is.

Reporter:
Are there residents in the possibility of meltdown?

TEPCO:
Continue evacuation in the 20 km range. I believe there is no further urgency in the rising width.

Reporter:
Can you see confusion at the site?

TEPCO:
I am doing a video conference and I am coping with it calmly.

Reporter:
What is the option of closing the furnace?

TEPCO:
There are options like that (decommissioning furnace), but I can not do it right away.

Reporter:
What is the assumed temperature inside the furnace?

TEPCO:
Specifically, I do not know. Since it is usually saturated water temperature, it can be seen by monitoring pressure and water vapor, but now the fuel is not immersed in water and the temperature there is not understood.

Reporter:
The explosion time is 6:14, is it? (As it was said at 6:10 in the beginning)

TEPCO:
We report at 6:14.

Reporter:
Do you know the specific location where the pressure suppression room exploded?

TEPCO:
I do not know. I think there is a seam, but it is very strict whether I can go there to see it.

Reporter:
How many people were there before evacuating

TEPCO:
I do not know. Check. It seems that there were no SDF personnel among the remaining people. I have not heard the fact that I asked for the withdrawal of SDF personnel. Also, as of yesterday this situation could not be assumed.

Reporter:
Should the appropriate person open a meeting

TEPCO:
I will bring it back.

Reporter:
Can not tell the latest information in real time

TEPCO:
Certainly.

Reporter:
Is it okay for a person remaining within 20 km to retire from home?

TEPCO:
I will promptly evacuate to a range outside 20 km.

Reporter:
What about neutron beams?

TEPCO:
No sound has been detected

Reporter:
The story that cesium is out

TEPCO:
It is not said that it was new in the previous story

Reporter:
At the stage where the people who are announcing here are able to speak responsibly about what to do as TEPCO at a press conference?

TEPCO:
Certainly. I would like to respond promptly as to the points I pointed out.

· Continued
Even in Tokai-mura, Ibaraki prefecture, "10 report", 5 micro sievert observed