"I think the situation is equivalent to a severe accident (severe accident)", the contents of the Tokyo Electric Power Interview at the 20 o'clock conclusion summary

Nuclear safety and NISA interviewIn parallel,Tokyo Electric Power CompanyA meeting was also held.

The current state of Fukushima Daiichi Nuclear Power Plant seems to correspond to "severe accident (severe accident)" assuming failure of high pressure and low pressure water injection and power loss, and it seems that management based on this is done is.

The contents of the interview are as follows.
TEPCO:
The current state of Fukushima Daiichi Nuclear Power Plant corresponds to severe situation, severe accident. Based on this, we are managing to prevent the impact of accidents by making full use of current capacity. In response to Fukushima Daiichi, venting of containment containers, seawater injection, etc. are done, but based on the results of consideration for accident management. We are making efforts to suppress harsh accidents based on information such as dry well pressure etc. in correspondence including containment damage etc. after fuel loss.

Regarding the effect of sprinkling by the helicopter, it is necessary to implement measures such as water spraying and water discharge in order to fully cool the spent fuel. I would like to continue implementing cooperation in the future. Sprinkling water itself was requested from the beginning from the beginning, the dose change due to watering was reduced to 3786 μSv / h (microsieverted hour) at 9:30 and to 3500 μSv / h at 10: 30. Units 1 to 3 are continuing to inject water through the fire extinguishing system (?) Line, the figures are unknown. I think that the problem that drywell pressure of No. 2 drops around 0 o'clock on March 17 is not damaged, but I would like to investigate accuracy including accuracy.

Pool temperature change can only be measured at Units 5 and 6 at the moment. The rest can not be measured. Unit 4 of Fukushima Daiichi Nuclear Power Plant can not be measured after building damage. The time to drain water from the ground is from 19:55. Regarding water source and water discharge related to water discharge, we are discharging seawater. With a water discharge capacity of 2,900 liters per minute, a pump car is put in order to pump seawater into pits, but water is discharged by one unit. The dose of the seismic isolation important building is 110 μSv / h as of 18:55. The execution dose of the work vehicle is measured when working near the plant, but it is not known at the present time.

Today's work on the power supply construction work still continues, but I do not know how long it will be.

(About disconnection of communication line between TEPCO head office and Fukushima Daiichi nuclear plant yesterday) The communication was cut off from around 17:20, the communication only returned at around 00:30, the video line returned to 05: 30. Meanwhile, we secured communication means by satellite phone. For switching, we will promptly contact permanent satellite mobile phones as a means of communication. The cause of shutoff is around 17:20, cutting the optical fiber in the ground wire while working near the first transmission tower that went outside from the Fukushima Daiichi nuclear plant during the transmission line restoration work. Due to the risk of collapse, the steel tower was incorrectly disconnected from there during work to remove (communication line?).

Reporter:
What time did you check that water remained in the pool of Unit 4?

TEPCO:
It was around 16 o'clock yesterday.

Reporter:
Did you confirm it with pictures?

TEPCO:
I prepared this. Currently increasing printing.

Reporter:
Regarding the effect of watering today, was this effective, what kind of evaluation are you doing?

TEPCO:
It is necessary to continue ongoing and wave-like in the future, but it seems that there was an effect when looking at the dose value.

Reporter:
In the afternoon it seems to be high at 4100 (μSv / h) level or so?

TEPCO:
There are places depending on the location, but I want to scrutinize this stuff.

Reporter:
It was 4100 in the afternoon that I said that I went down earlier.

TEPCO:
It decreased as compared with 9:30 and 10:30, but there was no significant change as to whether it was a significant change if it was a significant change. Also in the afternoon when looking at the main building north, it rises slightly, then it is the same figure as in the morning. Although it is high in absolute value, it seems that it is not in a condition that there is a big change.

Reporter:
Still it can be said that there was a certain effect?

TEPCO:
The main purpose of water spray is to ensure cooling in the spent fuel pool. Today's watering was done in the morning and after the evening, but it is related to the amount of water spray, but I think that concrete evaluation will be in the future. In the morning's watering, I thought that steam went up from the building from the 5th floor of the reactor building of Unit 3 after sprinkling to the place considered as a pool. Although there is a talk about the cooling effect by the water spray, to what extent, I think that it was effective

Reporter:
Are you confirming that watering has definitely entered the pool?

TEPCO:
Although not so far, we have confirmed the situation that after the watering, the white smoke from the vicinity of the pool was not so much but it got up.

Reporter:
Is there information that the amount of water spray is 1/3?

TEPCO:
I do not know without confirming this. We will sprinkle and drain the necessary amount in the future.

Reporter:
It is said that there are only about ⅓ of the amount prepared.

TEPCO:
I do not know this.

Reporter:
How much water would you put in to suppress heat? Do you think it is effective?

TEPCO:
Regarding the spent fuel pool of Unit 3, it is currently unknown what degree of cooling water is being grasped. Think about the situation after watering and draining.

Reporter:
If you calculate the calorific value of a day, there is a voice saying that 50 tons are necessary, and have you heard it based on that?

TEPCO:
Let me think about the heat value assumption again. I think that it will be a balance between the calorific value and the balance of how accurate the watering / discharging water enters the pool.

Reporter:
What about the suspicion of the Metropolitan Police Department?

TEPCO:
I will explain it later.

Reporter:
How about the SDF's ability to drain water?

TEPCO:
I want to explain in the information.

Reporter:
Is it throwing water in the night but reaching the pool with drainage in the dark?

TEPCO:
We recognize that we are meeting in advance such as building structure.

Reporter:
Detailed explanation about power restoration situation. What steps are needed afterwards?

TEPCO:
After the water discharge by the high pressure water discharge vehicle under execution is completed, the radiation dose at the work site is measured, after that, the work site is cleaned up. If there is no work area problem thereafter, the power restoration work will be taken today.

Reporter:
Do you put it in the restoration work if there is a place?

TEPCO:
Everything is not yet gathered in the current, but as we have all the equipment for the work to be done today. Arrangement for materials has been completed.

Reporter:
Does not the power supply recover after today's work?

TEPCO:
Although it will be possible to use an external power supply, it will not be able to be used inside the facility.

Reporter:
Is it a relay to each facility?

TEPCO:
Today, the installation to the relay version connection is scheduled to be completed from the power supply meeting place to the nearest plant. I think that it will be around the schedule of the site, but plan to do so.

Reporter:
At a previous interview, I got a power car but I heard that the power receiving equipment was useless. I think whether it is meaningless to have received electricity even if you bring a high voltage line etc.?

TEPCO:
Temporary installation of power receiving equipment and construction work to individual equipment.

Reporter:
Do you restore today? Electricity comes but does not come to equipment?

TEPCO:
It is scheduled to be completed today.

Reporter:
Is it certain that electricity comes to the premises?

TEPCO:
Although it may take from today to tomorrow, it is necessary to confirm the situation whether to go on schedule by checking the dosimetry etc on site.

Reporter:
Is it tomorrow that will be the level actually used?

TEPCO:
I think that the installation of each facility will be completed after tomorrow. Since the power supply is ready, then the connection will start, so the timing will change with progress. At the moment it is as soon as possible from tomorrow.

Reporter:
How far is (work) done now?

TEPCO:
Since there is a power source today, decide the route to be pulled towards the power supply of Units 1 to 4 to recover from that end, and connect to that point. This is the power supply to supply to Units 1 to 4.

Reporter:
How far is the water discharge from the building? Is it to say between Unit 2 and Unit 3?

TEPCO:
I would like to check again, but the situation is being carried out considerably close.

Reporter:
Approximately how much is it?

TEPCO:
Want to check.

Reporter:
What is the radiation dose?

TEPCO:
I also want to check it.

Reporter:
I think that the task of connecting to the facility will be getting much closer?

TEPCO:
We check the integrity in the part where the dose is as low as possible, and the work flow does not grasp 100% of the actual site situation, so we will proceed with consideration.

Reporter:
There is a story saying to connect from Unit 2 first?

TEPCO:
I heard that it is from Unit 2

Reporter:
Is that because the bottom of Unit 2 is not yet immersed in sea water and living?

TEPCO:
As for Unit 2, there is a survey result that the damage of electrical facilities is relatively low, so from Unit 2 that connects reliably. It is said that there is a high possibility that restoration is possible because the building is healthy.

Reporter:
What happens when the power supply is connected? The cooling pump is broken and should not be used. I do not think that ECCS (Emergency Core Cooling System) will move.

TEPCO:
For equipment, we will make pumping related, instrumental related equipment such as valves to move the system first, and move it first. Also, because it can inject water into the nuclear reactor from seawater, important equipment such as SLC, CRD pump, drive system around it. In the seawater system, we will consider to promote parts related to water supply, such as checking the health of pumps, arranging pumps if necessary, and so on.

Reporter:
Because the pump is under seawater, does not it work?

TEPCO:
It is necessary to confirm what is broken. I think whether it is necessary to check the soundness of the motor. Sort objects that can be moved, difficult items, and work properly.

TEPCO:
In the present stage the situation has not changed significantly, situations where water injection in the nuclear reactor is carried out. In order to advance this quickly in a good direction, it is important to restore power supply and to operate the cooling system. Proceed with work aiming for cooling.

Reporter:
Do you know whether the pump moves before supplying external power?

TEPCO:
I think that I can not confirm it, but I choose the facility that it will be okay.

Reporter:
Does it mean that Unit 2 is the easiest to move and is considered to be less damaged?

TEPCO:
In fact, it has been confirmed to some extent that the electrical system is sound and tested. There is a high possibility that it is a healthy situation.

Reporter:
What is the latest recovery start time?

TEPCO:
Confirmation of the end condition of the water discharge, field confirmation has not reached yet, so it can be confirmed.

Reporter:
Although it was a water discharge work, it seems that it was not possible to drain water easily on TV and it was not possible until night, but was the dose high?

TEPCO:
It seems that the dose was high on the scene and it took two hours for the setup. It seems that various arrangements have been carried out since it arrived.

Reporter:
After restoration, will you connect to the fuel pool?

TEPCO:
I think that there will be facilities for spent fuel pool, so I think that we will also connect there, but the priority is around the nuclear reactor.

TEPCO:
I heard that as a power source, we are thinking about the common distribution boards of Unit 2 and Unit 2, Unit 3, Unit 4 are considered as separate distribution boards. Because Unit 1 Unit 2 is relatively small in plant, it is common, Unit 3 Unit 4 will be installed separately.

Reporter:
Although it is said that the degree of breakage of Unit 2 is low, can smoke be confirmed from the sea side?

TEPCO:
Although I can not confirm directly, the hole on the sea side is a blowout panel. That smoke comes out, but seems to have disappeared above the sky, so I think that it is steam coming from the fuel pool as well as elsewhere.

Reporter:
Then there is a possibility that steam is coming out from the fuel pool at Unit 2?

TEPCO:
There is a possibility.

Reporter:
Does steam come out that the temperature is quite high?

TEPCO:
As water vapor comes out, it means that there is water, so I'd like to put in water quickly.

Reporter:
I think that smoke from Unit 2 has come out since yesterday, has it been boiling since yesterday?

TEPCO:
It is unknown whether it is boiling or high temperature just before boiling.

Reporter:
Recognizing that (white smoke) is water vapor in the pool, not smoke leaking from the pressure suppression room?

TEPCO:
That's right.

Reporter:
Does the pool temperature of Unit 6 of Unit 5 have not changed?

TEPCO:
The latest data is at 17:00, Unit 5 at 64.5 ° C (12: 64.2 ° C), Unit 6 at 64 ° C (4:16 ° C, 12: 62.5 ° C).

Reporter:
The reason why it took time to finish the water discharge work and start.

TEPCO:
Organize and explain later.

Reporter:
Do you switch work one at a time?

TEPCO:
Organize and take confirmation later.

Reporter:
Why are you recognizing that there is no problem raising from 61 ° C to 64 ° C?

TEPCO:
I will show you the data from now on this.

Reporter:
Although it puts water on top of Unit 3's fuel pool from above, it is said that steam is rising, but the inside temperature can not be measured. Can you judge what had it had no effect? Is not it going to keep doing because it can not judge?

TEPCO:
I think that the amount of water is not so much in it, so if you enter a little more and the temperature of the water drops, the water vapor decreases and if the water becomes full with cold water I think that there will be almost no water vapor.

Reporter:
Is it to achieve the purpose if water vapor does not come out?

TEPCO:
By regulation (water temperature of spent fuel pool is less than 50 degrees), because it is not in a state where temperature can be measured, we would like to judge that there was an effect by not having large water vapor. It will be heated by collapse heat again in a few days, so we will calculate how much to put in regularly. I think that it will be unnecessary to discharge water if it is possible to put water in the power restoration. .

Reporter:
Suppose power schedule, schedule schedule of joining work is assumed to end in about 1 day?

TEPCO:
Today I am departing on schedule to go to the tie-in, but there are times when I was interrupted by the dose and the planned discharge. Even assuming it to that extent, it starts with that it will be able to reach the tie-in.

Reporter:
I think that the fuel pool of Unit 3 has a depth of about 15 m, but I think that it is necessary to fill a pool with a dose out, although it is necessary to inject a considerable amount of water.

TEPCO:
We are also working hard on expectation. Currently other methods are restoring the power supply, but this is the reason (helicopter from the ground) that I can do reasonably at the present time, so I will try hard at Kore.

Reporter:
Is there a dose reduction as a side effect of water discharge?

TEPCO:
It may be possible to spread out (radioactive substances) by discharging water, or put out things in the building.

Reporter:
Kitazawa (Defense) Minister said that there was a word "today is limit"?

TEPCO:
The situation in the pool is only an imagination, but as steam is also rising, I think it is as early as possible. I think that there is no limit itself.

Reporter:
I think that photos of the pool of Unit 4 will be dealt after this, was this taken yesterday? Although I fly over the sky several times today, I think that it is possible to see the current situation in the steam, because I have targeted Unit 3 only to destroy that Unit 4 how it was today, but that report is totally Is not it in?

TEPCO:
It is not included. I think that it is difficult to see the water surface when steam is coming out. It is said that the water surface was visible when Unit 4 saw from the side. I think that there is credibility as there are some places which I do not understand in the photograph (in that information).
Although I do not know whether there is any relationship, the standard of spent fuel storage period of Fukushima nuclear power plant is 19 months.

2011/03/18 0:29
We added content (part) of the Tokyo Electric Power Company's interview that began around 0 o'clock.

TEPCO:
Among the contents you asked about, we will calculate again the amount of calorific value of the fuel in the pool and tell it. The distance from the water discharge car to the building is 10 m, the number of water discharges is 6 times in total. Quantitatively it is not possible to grasp quantitatively the amount of water discharge expected to have entered the No. 3 spent fuel pool. It is also confirmed visually that water vapor is reduced at the present time, and it is considered that there was an effect. The reason why the work was delayed is that it took time to prepare and I was asked whether it was careful. I heard that power recovery work has started preparatory work. Specific start time is undecided.

I think that it wants to restore power supply as soon as possible and I heard that the water will be emitted after lighting in the morning again, so I think that it will be work until after it gets brighter, but it will be done as soon as it gets brighter.

Reporter:
What time is it to drain water?

TEPCO:
I am considering, but I can not confirm the time.

Reporter:
Does it come when white smoke does not come up?

TEPCO:
It is thought that a certain cooling was obtained when the state where the white smoke had risen did not go up until it was discharged.

Reporter:
The fact that workers can not come close to it is because there is a possibility of steam explosion etc?

TEPCO:
Although we are not afraid of risks such as generation of hydrogen which will cause a new explosion of water vapor at this time, I think that we need to keep an eye on future.

Reporter:
Is there no new problem caused by draining water?

TEPCO:
I have not heard of so far.

Reporter:
What are the prospects of the important work after the water discharge tomorrow as a prospect?

TEPCO:
I can not answer it clearly, but I heard that we are advancing debris removal work as preparatory work at night until brightening. After that, I checked the working environment and started the actual work, but I installed three switchboards for Units 1 and 2, Unit 3 and Unit 4, but the road extension was about 1 km in the day, but I did it at night I think that the work will flow with Unit 3 and Unit 4 after the water discharge tomorrow. At least I believe that it will be possible to complete the distribution board construction work tomorrow.

Reporter:
Did you ask about 2 km?

TEPCO:
About 1.5 km is to say the correct figure.

Reporter:
Is it until the building? Up to the breaker?

TEPCO:
It will be about 1.5 km until breakers for Units 1 and 2.

Reporter:
Why did you stay in preparation?

TEPCO:
As soon as the work is over, we will check the worksite and do the installation of distribution boards as far as possible. After that, I will interrupt the work and do the water discharge work. After that, I am planning to resume work.

Reporter:
Can you think that there are various kinds of racks containing fuel rods?

TEPCO:
TEPCO has adopted several kinds of racks. There is only stainless steel and also contains boron, about Fukushima Dai 1 is a stainless steel rack.

Reporter:
(If it is stainless steel) It means that it melts at about 1500 ° C?

TEPCO:
Yes.

Reporter:
There is a possibility of rupture / explosion rather than melting, before 1500 degrees.

TEPCO:
The possibility of explosion / explosion is not specifically assumed. Because it is a rack that contains fuel, in comparison with 1500 degrees, since the clothing hall becomes fragile at the time of 1200 degrees, I think that it is necessary to manage at a lower temperature than that. Originally the rack is not intended to be used at high temperature and high pressure, so it is considered to be used in a state where water does not boil, around 40 to 50 degrees. The temperature rise varies depending on how long the spent fuel has been used since it was used.

Reporter:
There is a water discharge work from the helicopter and from the land, but what kind of thing are you supposing tomorrow?

TEPCO:
I can not confirm it at the moment. I will contact you if I know the move tomorrow.