Lessons Learned From Fukushima Dai-ichi (2. BWR & Interim Report. 2011. 10. 28)


Uploaded by H2OProjectBBT on 21.03.2012

Transcript:
Good evening everybody.
Good evening.
I am Business Breakthrough University President Kenichi Ohmae.
Today I have just had a joint press conference with Nuclear Power Plant Administrating Minister Hosono regarding our research report,
what should we learn from the severe accident at Fukushima Dai-ichi Nuclear Power Plant.
In the conference, I explained the summary of the report.
Minister Hosono also explained the background of the research.
Tonight I would like to present the whole report to you all.
Also, this broadcast is being recorded at Business Breakthrough's studio,
but it is being simultaneously distributed on Ustream, and will be uploaded to YouTube afterwards.
Then regarding the summary and whole interim report,
we will upload them onto a web site that will be introduced later so that you all can download the PDF files.
Although those who visited Business Breakthrough website may already know,
I uploaded 'The Ohmae Live News', a weekly live broadcast, after the severe accident on March 11th, on March 12th and 19th onto YouTube.
Over 2.5 million people have visited.
At the time, I believe that there were quite a few people who were very concerned about "what is really going on?", or about whether
what the government had announced was correct or not.
After that, I started doubting whether the government was telling the truth to the public.
So I tried to distribute my thoughts, by publishing the book "Japan: The Road To Recovery" and so on.
Amidst all of this, I had the opportunity to meet Mr. Hosono, an Assistant to the Prime Minister at that time.
He was in charge of recurrence prevention of the power plant accident. I asked questions like the following;
if the situation continues to be as it has been by next spring, all nuclear power plants will be stopped,
and re-activation of the plants would become more difficult. Also, even if the stress test is performed,
it will be hard to gain the public acceptance.
If "what actually happened at Fukushima" is disclosed,
and if "what needs to be done to prevent a reoccurrence of such a serious accident" is logically explained,
then the understanding of the people could possibly be gained. How many people would agree with reactivation of
the plants, just by performing a stress test with a computer simulation and just by saying "it's safe according to the stress test" without explaining
the details of the Fukushima accident? Is the government addressing this issue in a responsible way?
I also told Mr. Hosono that though I know those who are related to nuclear power plants, it would be appropriate to introduce me to those
who know very well about this accident first-hand, specifically the front liners such as specialists at TEPCO, Hitachi, Toshiba, and those companies
making boiling-water reactors (BWR), also those who are processing and analyzing the actual data of Fukushima Dai-ichi.
"If we can communicate with these people,
we will gather information directly from them,
and summarize the accident report in about three months.
Also, I will do this research not by a request from the government, but as a volunteer.
From my point of view, if the current situation continues as the way it is,
conditions will become even harder not only for Japan, but also for industrial society as well.
So I would like to analyze the facts in my way that makes sense to me."
Later Mr. Hosono became the Minister in charge of Nuclear Power.
A request came directly from him with the words, "Please conduct the research and analysis".
So, I started this research by telling the Minister that I would like to make and deliver an analysis that I could be satisfied with.
Therefore, I did this research completely voluntarily, without receiving any money from the government.
For information resources, I could get an access to the specialists and senior engineers on the front lines at TEPCO, Hitachi-GE Nuclear Energy and Toshiba.
I have worked on this research and analysis during the whole summer for 3 months.
The interim report was finalized today,
and I have explained and submitted the reports to Minister Hosono.
I gave the Minister several midterm reports until now,
and it has been done completely under my general overview and within my responsibility as the project manager.
That is to say that the report has been created including the perspective and analysis of Kenichi Ohmae.
However, I have other work to do as well,
so I asked Mr. Iwao Shibata, whom I will introduce today,
to be in charge of the day-to-day management of this project, as a project management expert.
In total, including two fulltime members, eleven staff gathered for this team,
and we had asked all sorts of questions to collect data. Based on that, we analyzed and asked more questions.
We continued this process until today to finalize this report.
This is, as Mr. Hosono said, a second opinion. Basically this is not something that the government has officially ordered.
So it is absolutely a second opinion, but I am fine with that.
Of course, I am doing this because I was requested by the government, but my true intention is not to write a report that follows
the government's expectations. This report was finalized completely from my standpoint as a third party. In this way, I have conducted this work.
Also, I requested Minister Hosono to keep this project confidential,
because I would like to avoid any pressure or resistance from other organizations or companies.
So I made this request.
That is the way this project had started.
Fortunately, the research has completed safely without publicity
and I was able to present the interim report to the Minister this evening.
So, even in today's press conference, there may be people and press who may be asking why I had not disclosed anything about this report earlier.
But it would have made the work harder to complete if it had been opened to the public.
Therefore, we asked to keep this project confidential until the end.
However, this research has been completed today, and it is no longer confidential.
So I would like to introduce and explain the entire final report which is in your handout.
And once this broadcast is finished, it will be uploaded on YouTube.
All the resources and handouts we have distributed today,
in other words the entire report and summary, will all be available directly on the Business Breakthrough (BBT) site,
which you will be guided to later on.
Therefore, by midnight tonight, all of this information will be available to the public.
This is all that I have mentioned in today's press conference.
So now, I would like to present the result in this report, its summary, and conclusion.
Now, Mr. Iwao Shibata will explain the report of this research project.
Please go ahead, Mr. Shibata.
Thank you very much.
I am Iwao Shibata, the administrative manager of this project. I thank you in advance for your attention.
On the contents of this project, I would like to begin right away.
Our research result includes an approximately 200 page interim report,
a report little less than 40 pages which is the main summary,
and backup data showing the chronology and situations of each reactor in each nuclear power plant.
Also, there is a spreadsheet describing the loss of power supplies in each plant.
I would like to take about 60 minutes to explain what had happened in Fukushima Dai-ichi, Dai-ni, Onagawa, and Tokai Dai-ni
and explain the facts regarding the accidents at these nuclear power plants as much as possible.
First of all, I will explain the purpose of this project. As Mr. Ohmae outlined earlier, there are three major purposes.
The first is to diligently investigate the facts regarding what had occurred at the Nuclear Plant during the earthquake, tsunami, and afterwards.
We extracted the facts, the challenges, and the lessons learned that should be shared with the public.
This is the first purpose.
The second is related to the issue, whether nuclear power plants should be re-activated or not. Since we have been given little information on
the facts of this severe accident, we can discuss this issue only as emotional opinions, or in an all-or-nothing approach. The second purpose is
to provide a more scientific, technical, and logical framework necessary to discuss whether we should re-activate the nuclear power plants or not.
The third purpose is to create a report which can gain a consensus from internationally neutral and
reliable organizations such as IAEA,
by analyzing the facts of the accident objectively from a neutral point of view, as civilians.
Regarding the project schedule,
we structured three phases of three months each,
and at this time, phase one has been completed.
As the first phase, we aimed to create a different guideline for the stress test which is accountable to the international standards.
This should be different from the stress test of the Nuclear and Industrial Safety Agency (NISA) and EU which have been already publicized.
This is the yellow part at bottom left on this sheet.
This has just been completed.
After phase 1, we have designed phase 2 and 3,
phase 2 for conducting the stress test, and phase 3 for implementation of safety measures,
so that the plants which could be reactivated can be activated by next spring or summer.
Regarding the procedure of operation,
the outline is on the lower half of this screen.
We began with gathering information in order to conduct fact-based analysis.
Then, we accumulated the information on the accident in time-line format in each reactor and plant in Fukushima Dai-ichi, Dai-ni, plus the other plants.
That is what we organized the information chronologically.
Then, we organized the lessons learned and potential countermeasures gained by these information.
After that, we examined the various existing stress tests which governmental and official institutions have been trying to implement.
This is the research and analysis that we have done.
After that, we analyzed why such a big accident had occurred and the reasons behind.
We then analyzed the cause-and-effect, so that we can better develop the stress test framework to discuss on the same basis
as to the plant safety, reoccurrence prevention, and re-activation more logically. These are the procedures for this project.
The project structure is as introduced by Mr. Ohmae previously.
I was in charge of administration such as presenting the questions and collecting the information through interviews and hearings
from electric power groups, Toshiba, Hitachi as introduced earlier.
The scope of the research focused on designing countermeasures for both plant and local safety,
so it can be said that this research mainly focused on the technical aspects of the Fukushima accident.
The main issues were: facts of the earthquake and tsunami,
what occurred at the Fukushima Dai-ichi power plant,
the differences of facts between Fukushima Dai-ichi and other plants,
the power loss of each plant,
the condition of the high pressure cooling system, vent function,
low pressure cooling function, and hydrogen explosion.
These were all included in our scope and analysis.
These were the project procedures and definitions.
From here, I would like to explain what happened at the Fukushima Dai-ichi Power Plant,
and its implications.
First, we examined the situation during the earthquake and tsunami on March 11th,
the scale and scope of damage caused, and its implications to the safety of the plant.
About its basic features, the Fukushima Dai-ichi Power Plant has a total of six nuclear reactors,
and it is one of the oldest and earliest power plants that were established in Japan about forty years ago.
Reactors one, two, and three were in operation at the time of the earthquake
and they are the oldest reactors in Fukushima Dai-ichi.
The altitude of buildings of those reactors was the lowest among all reactors.
The overview of Fukushima Dai-ichi is shown on this screen now.
The bottom part highlighted in blue is Reactors
1, 2, and 3 that were in regular operation with full power at the time of earthquake.
These reactors originally started operations in 1971, 1974, and 1976 respectively.
On the type of the primary containment vessels,
these plants were equipped with Mark I and Mark II vessels.
Now on the screen, you can see the overview of each reactor, from the left, the Mark I-BWR 3, Mark I-BWR 4, and Mark II-BWR 5.
On Friday, March 11th, at 14:46, a large earthquake occurred,
with an intensity of a little larger than 6 around the Fukushima Dai-ichi.
Following the earthquake, as you are all aware,
an overwhelming tsunami was generated and approached the coasts of Miyagi and Fukushima.
About forty minutes after the earthquake, around 15:27, the first wave of the tsunami attacked the Fukushima Dai-ichi.
Eight minutes later, at 15:35,
an even higher second wave hit the plant.
As to the scale of the earthquake and tsunami, as on this screen,
both were the 4th largest in the recorded history, globally.
The earthquake's magnitude was 9.0. It was fourth largest in recorded history.
Looking at the tsunami, its magnitude was 9.1,
and it means that the fourth largest earthquake as well as tsunami in our recorded history slammed into the nuclear plant.
From now I would like to explain the damage caused by this earthquake at Fukushima Dai-ichi.
Countless of liquefaction and subsidiary fractures of infrastructure resulted from the earthquake.
It can be said that the damage incurred at Fukushima Dai-ichi was larger than that at Fukushima Dai-ni.
The liquefaction of infrastructure disabled to transport necessary equipments, people, and other supplies.
This made a huge difference in accident management afterwards.
Now you can see three pictures of the Fukushima Dai-ichi and its damage.
If you look at the upper middle photo, you can see the road is completely destroyed,
and there is no way to transport batteries or cables, and people and vehicles have no access in and out of the plant.
Now if you look at the upper right photo, you can find that the guardrail has fallen on to sideways,
and the road has cracked or fractured. And there are countless cracks on the road.
You can see the disastrous situation clearly.
The two photos at the bottom are of the damage situation in Fukushima Dai-ni.
Compared to Fukushima Dai-ichi, damage at Fukushima Dai-ni is relatively minor.
Now, shifting topic to the tsunami,
Fukushima Dai-ichi and Dai-ni had strengthened their safety measures based on the tsunami evaluation by the Civil Engineering Society in 1998.
However, the tsunami on March 11 had greatly exceeded those presumptions, by over 10 meters.
Especially at Fukushima Dai-ichi, a tsunami 3 times taller than the assumptions hit the plant.
Now on the screen, you can see the comparison between the design assumptions of Fukushima Dai-ichi and Dai-ni as 5.7m height,
and the actual height of the Tsunami on March 11th.
In actuality, tsunami with a run height of 11.5-15.5 meters was generated on that day.
Therefore, it means that a little less than 3 times, or in actual numbers, 5.8-9.8 meters of difference existed between
the supposed tsunami and the actual tsunami.
As a result, the tsunami struck not only the seaside of the Fukushima Dai-ichi Plant, but also the whole area including the mountain-side.
It completely submerged the most important nuclear reactor buildings and turbine buildings.
Obviously, it can be said in hindsight that the safety allowance in its design against tsunami had been low.
The image on the screen is a cross section of Fukushima Dai-ichi reactor 1 to 4 at ground level and an image of the tsunami.
As mentioned, the maximum tsunami height assumed was 5.7 meters, but, in reality, a tsunami of 15 meters height hit the plant.
So as you can see, everything was completely submerged.
At the bottom, you can see various photographs of different spots after the tsunami.
Two photographs on the lower left are of the sea side,
where important pumps for cooling, and the emergency diesel generators were located,
but rubble and many other random objects have flooded in.
You can see the situation later,
and here, important equipment were damaged or washed away.
And this is the turbine building.
This is the building for running generators.
As you can see in the photograph, the second from the right on the bottom,
several cars are drifting.
These are cars that were carried by the tsunami.
And the photo on the bottom right is the mountain side.
It may be a little hard to see, but there is a five meter-tall tank.
This photo shows the top of that tank is almost completely submerged.
It shows just how strong and powerful this tsunami was.
The next photo was taken
at the moment the tsunami arrived. It shows the initial crest of the wave that reached Fukushima Dai-ichi.
The focus is a little off and may be a little blurry, but this is a 120 meter-tall air exhaust stack.
This photo shows the wave rising close to halfway up the stack.
Therefore, rather than saying the tsunami was about 15 meters high,
you can clearly see that the water has risen up to several dozen meters.
Looking at the traces of the tsunami, this is an aerial photo.
The top left shows the land before the tsunami, and the bottom right photo shows the view after the tsunami.
You can see that the forestation on the sea side has been pulled up from the roots.
And next, this is an aerial photo of Fukushima Dai-ichi.
Reactors 1 to 4 are built together in one place, and Reactors 5 and 6 are in a separate location.
Reactors No 1, 2, and 3 were in operation,
and reactor No 4, 5, and 6 were not due to periodic examination.
As an important data, this photo shows the altitude of each plant.
This 'OP four meters' means four meters above sea level.
The main buildings of reactors No 1 to 4 were located at the altitude of 10 meters, and the altitude of sea side area of those reactors was 4 meters.
That means that reactors 1 to 4 were built on the ground ten meters above sea level.
Now if you look at the left side of the screen, you can see that the sea side area of reactors No 5 and 6 was four meters above sea level.
And reactors 5 and 6 were located thirteen meters above the sea level.
Therefore reactors 5 and 6 were located three meters higher than reactors 1 to 4.
Among these, when you look at reactors No 1, 2, 3, and 4,
you see that 1, 2, and 3 were in operation, and were brought to emergency shutdown due to the earthquake, which is called "scram".
And, because the fuel rods of reactor No 4 had been removed and moved into the spent fuel pool, its reactor core was empty.
In reactors No 5 and 6, the fuel rods were in the reactor core.
However, because these plants were undergoing periodic inspection, these reactors were not in operation.
Therefore, they were to say in 'scram' condition, in other words, the control rods had already been inserted in these reactors.
So, in reactor 4, the fuel rods were removed and moved into the cooling pool.
So cooling function of this spent fuel pool should have been performed properly.
Situation had been different in each reactor,
and there's a little more that needs to be explained. Let me just recap.
The operation of reactors No 1, 2, and 3 had been stopped due to the earthquake.
And the fuel rods for reactor four had been moved into the cooling pool.
Furthermore, reactors 5 and 6 were stopped due to periodic tests.
However, these fuel rods also needed continuous cooling, or they would reach tremendously high temperatures.
Mr. Shibata, please continue.
Yes, thank you very much.
Next, I would like to describe exactly how much the tsunami submerged the Fukushima Dai-ichi Power Plant.
Here is the screen that explains, or more accurately, shows the situation.
Due to the 15.5 meter tsunami,
the whole areas of the main facilities of reactors 1 to 6 were submerged.
The parts colored in blue are the places that have been directly submerged.
As you can see, areas of both the reactor buildings No 1 to 4, and No 5 to 6, and the areas
surrounding the turbine buildings of those six plants have been submerged.
Secondly, I would like to explain especially two places with a red border with photographs taken at a closer position.
First of all, please look at this red frame on the right side of the screen.
This is a picture of the area near the exhaust stack of reactor four.
These are sequential photos of the moment when the tsunami exactly hit.
They are in chronological order from the top left to the bottom right, and you can see the top left photo which shows two heavy fuel tanks.
Their height is approximately 5.5 meters.
Following the order,
you can clearly see that the 5.5 meter heavy fuel tank is submerged rapidly in the tsunami,
and in the lower middle photo, it has been completely hidden from the surface of the water, and the water is rushing in at a furious pace.
In the last picture on the bottom left, cars are carried away.
If you look at the top right photo, you can see some white and red cars on the bottom left side,
but the white car in this photo has been stuck into the wall of the building in the bottom right photo.
It is a shot that demonstrates how strong the force of this tsunami was.
Next, after the water receded, from a broader shot, in the last picture in the middle of the lower half, you can see that several cars that were actually
on the left side in the previous page have all been washed away, and one of them has drifted and stuck into the wall of the building.
Next is a photo of a tank, called the "solid waste storage tank" on the sea side, southeast of reactor five,
which is in this photo of the east side.
You can see very clearly that the wave easily came over a ten meter breakwater,
causing many cars to drift around,
and this giant tank was covered by water almost completely.
Picture No 2 shows the moment the tsunami crossed over the ten meter breakwater.
And picture No 4 shows the large surge tank, the same tank shown in Picture No 3.
This was submerged approximately two-thirds to eighty percent,
and the right side of the middle of picture No 4 shows many cars that have been washed away and are carried in from elsewhere.
Following is the moment the water begins to retreat,
and in picture 5, the large heavy fuel tank, and the smaller heavy fuel tanks have been washed away,
and driven onto the road.
In picture No 6,
you can see that the largest surge tank has been twisted as if someone had wrung a PET bottle.
These are some portions of the on-site investigation
to demonstrate just how large the tsunami that hit the Fukushima Dai-ichi Power Plant was.
Following this, regarding the damage of the tsunami,
I would like to explain the situation regarding the driftage of facilities and buildings.
After enormous tsunami hit those plants, after power loss, scram, and the emergency shutdown of the nuclear plant,
it was necessary to carry out the various actions for accident management.
But, in order to do that, it's necessary to transport equipment like power sources, electrical panels,
cables and fire trucksfrom the outside. But it was hardly possible as you can see.
Also, there was a need to secure an emergency water source.
For these operations, the infrastructure needs to be solid or these operations cannot be performed. Again it was almost impossible.
So in that respect this is a very important point.
On the screen, for example,
on the left side of the road near reactor 1, the heavy fuel tank had drifted in, and it has blocked the road.
And at the sea side of the turbine building of reactors 3 and 4, here a large crane truck has moved, and drifted in.
These scenes were observed all over.
This is the photograph showing the road being completely blocked by the heavy fuel tank.
It is on the upper left.
The crane weighs 45 tons,
and it has blocked the access to the buildings along with the rubble.
Now in the center bottom photo,
it shows a car drifted up and over the pipelines and is now stuck between buildings and pipelines.
The pileup from these events is a major factor in the worsening difficulties of operation
by on-site personnel to supply and transport necessary items after the tsunami.
Explaining the situation of the mountain side, the accordion covers of containers have drifted
for several hundred meters due to submergence, and multiple containers are discarded throughout the area.
On the picture, this is the area that is enclosed by the yellow dotted line.
Now if we take a look at the sea side of reactors five and six where the altitudes of the buildings were higher,
the breakwater has been destroyed and countless of tetra pods have been driven up, making transportation in the bank protection area impossible.
The tsunami also entered through the mountain side, which bathed the electrical systems of reactors one to four in salt and sea water.
Along with the liquefaction of the surrounding roads,
landslides and rubble were piled up, and it made transportation of personnel and supplies extremely difficult.
This is a photo of the oil fence stabbed into a building,
and if you look at the ground, along with severe liquefaction of the road and scattering of rubble,
it is a far cry from being able to transport even during the day.
At night, it is impossible and dangerous to walk without lights.
So even though this is a different place,
it is the same situation.
Now this is the inside of the turbine building of reactor four. It is where the electrical board is located,
but so many tires, vacuum lines, and hoses have drifted in and covered everything.
The electrical board to connect batteries or power sources after power outages to restore power is here, but as you can see it cannot be accessed.
So, taking the above into account, we believe that liquefaction, large quantities of rubble,
and subsidiary fractures in the roads made transportation of personnel and supplies extremely difficult.
Furthermore, the darkness at night due to power loss made situations worse, making the work environment at night even more brutal.
Also, after the first earthquake,
aftershocks occurred frequently making the halt of operations and the recovery operations from power loss even more difficult.
The red line is the total numbers of aftershocks in the ocean area at this time.
And the lines below show the numbers of aftershocks of each major earthquake in the past.
For example, at the earthquake off the coast of Sanriku and Tokachi,
only the aftershocks with a magnitude of 5 and over have been selected, but there have been quite a few.
It became more and more difficult to monitor the conditions of the plants due to darkness
as well as malfunctioning of the monitoring devices both because of power loss. And the rubble strewn around was a tremendous obstacle
to the on-site work to recover this situation.
Now, some of these situations are shown on the screen.
For example
the photo on the upper left. This shows where the inside of a building is completely dark.
If you look closely, there are many objects scattered around.
Following, in the photo in the upper right, is a picture of a makeshift battery being used
for monitoring instruments because normal power has been completely shut down.
And the two on the bottom, this shows instructions being given or monitoring being conducted in pitch darkness
with just handheld lights to guide, as the nuclear reactor performed scram in the dark.
And, another condition that added to the difficulty of the operations was the radiation dosage.
For example, in the area around the reactor one turbine building,
on March 11th and 12th it was 1.20 micro Sv per hour.
And 0.9, 0.9 mSv of radiation
was recorded every hour.
This level of radiation constrained their operations and recovery work.
These are excerpts of interviews and comments from those on-site,
and if you read them one by one, the extremity and severity of on-site work at the time are described more directly.
For example, while performing recovery operations near the torus,
when stepping on the torus, his boots melted due to the heat,
or that another person ran back for his life due to an aftershock,
or that a cable that was usually connected with machinery was connected by manpower,
we can see an extreme environment from their comments.
In this way, the earthquake and tsunami that hit Fukushima Dai-ichi
brought many layers of extensive obstacles to the on-site work environment.
And these factors caused the delay of the countermeasures taken against the core damage, and the hydrogen explosion that occurred later.
They were the underlying factors of the overall failure.
The main condition was, as mentioned previously, the darkness.
Due to loss of AC/DC power, all lights were out, so the site was plunged into darkness.
Another issue was the loss of the command center functions.
The central control room performs all sorts of operations, but due to power loss,
almost all of the data comprehension, including important data such as nuclear reactor temperature, pressure, and water level
became impossible to monitor.
There was also loss of communication which caused difficulty in passing on verbal instructions.
There are also difficulties in logistics and movement of personnel and supplies.
This is due to the infrastructure liquefaction, rubble, and the frequent aftershocks.
The others are the extremely hard work environment due to radiation levels that exceeded the standards,
and the lack of protective gear, masks and dosimeters, which limited movement and the time that people could work on the site.
Additionally, there was isolation, and the destruction of supplies. These can all be given as factors to delay operations.
The above was the reality of the earthquake and tsunami around Fukushima Dai-ichi.
Following this, I would like to simply explain what happened at Fukushima Dai-ni.
First, could you please project the slide?
For a summary of the Fukushima Dai-ni Power Plant, it has a total of four nuclear reactors,
which were activated, approximately twelve years after Fukushima Dai-ichi, in 1982.
At the time of the earthquake, all four reactors were in operation.
As an overview,
the oldest, reactor one, had been in operation from 1982,
and the newest one since 1987.
All plants were in rated output operation.
The type of the containment vessels was Mark II as are shown here.
The estimated height of safety design for tsunamis was 5.2 meters.
That means that it was prepared for a tsunami with a height of 5.2 meters.
In comparison to that, a 6.5 to 7 meters high tsunami hit.
Compared to Dai-ichi, the difference between estimated value and actual value was small.
Like shown before, here is a cross section view from the side.
Compared to Dai-ichi, the damage from the tsunami is limited.
In Dai-ni's case, the grounds were separated into two sections, four meters and twelve meters above sea level,
and the nuclear reactors and turbine buildings were located at twelve meters above sea level.
Compared to a wave height of seven meters, there was an elevation in land,
and this was one of the reasons that damage from the tsunami was relatively small.
This is the aerial photo of the Dai-ni before the tsunami, and sea level like the previous slide.
Sea side was at altitude four meters,
and the plant was at twelve meters.
The submerged conditions were as below.
The parts in blue are those that were submerged, the parts in yellow are where the tsunami ran up, and went around.
So looking at this photo, the tsunami hit from the upper right angle.
The tsunami hit against reactor one,
and the water that has run along the right side of reactor one and vertically up,
to the important control center called the anti-seismic important wing.
Here it is.
The rushing water entered this anti-seismic important wing, and its power was lost.
After that, it flowed around to the back of each nuclear reactor, around this area here.
If you look at the tsunami damage, you see that Fukushima Dai-ni's damage is mainly
around the south side of reactor 1 where the tsunami ran up, and the sea side where the ground level is lower.
This, photo No 1 is the tsunami that I described previously, that continued to rise.
In the same way as at Fukushima Dai-ichi, the water is rising up with a furious force and speed.
Now this is No 2 and is at the sea side. This is the area that was colored in blue previously,
and rubble has been scattered here as well.
However, as the turbine buildings for reactors No 3 and 4
were located at twelve meters above sea level,
you can see almost no tsunami damage.
Regarding reactor one where the tsunami raced up the south side road,
the wind intake duct of the reactor's annex area has been submerged.
This photo No 1 is the air duct.
Water has come in through here, and it was submerged in this way, along with large quantities of rubble.
Although it was submerged, in comparison to Fukushima Dai-ichi, the damage is extremely minimal.
That was the summary of the damage of the Fukushima Dai-ichi and Dai-ni Power Plants from both the earthquake and tsunami.
Now, I would like to continue to explain what happened at Fukushima Dai-ichi.
First of all, at the Fukushima Dai-ichi Power Plant, all external power was lost due to the earthquake.
The reasons for that are the damage to the switching station and the steel tower on-site, and the transformer station located off-site.
Furthermore due to the tsunami, some parts of the electrical board were submerged, which worsened the situation.
This is a schematic view of the external power in the Fukushima Dai-ichi Power Plant,
and there are transmission lines in several systems, but they were all lost due to the earthquake.
And, along with all external power sources,
internal power sources, specifically emergency diesel generators were lost.
All except one of reactor six, emergency diesel generators were lost due to submergence by the tsunami.
There were thirteen emergency diesel generators at Fukushima Dai-ichi. All of them were lost except for one air cooling type.
Especially, important equipments for the water cooling function for these DG's, installed at sea side, were all damaged.
The result was that those cooling systems by the sea were taken out and damaged by the tsunami.
This chart is an overview on the loss of the main electrical systems of Fukushima Dai-ichi after the tsunami.
The areas colored pink or orange are generally where functions were lost or became unusable.
The white colored area is where equipment survived.
The electrical systems included emergency diesel generators, or DG.
This is machinery that activates diesel engines when external power is lost, and generates power.
But all were lost except for the one at reactor six, the air cooling type, as I mentioned before.
And this is the metal-crud switchgear that connects electricity, but almost all functionality was also lost due to the tsunami.
And now these are the same electrical boards, power-center, but for example, reactorone and reactor three have lost all of them.
And this is a DC battery, but all batteries except those of reactors three, five, and six were submerged and lost.
Regarding the above situation,
even after these power losses, the 'scrummed' nuclear reactor must be continuously cooled down.
But, of course, most of the cooling functions require electricity, and a situation where it could not be secured was unfolding.
Next, I would like to explain how the loss of power and sea water cooling systems
had accelerated the progression of core damage and events.
This chart shows an outline of the different events as they unfolded.
First, the earthquake occurred.
Then, the nuclear reactors were automatically shut down due to the earthquake.
After that all external power sources were lost due to the earthquake.
After the earthquake, the emergency diesel generators should have automatically activated,
but as the tsunami arrived afterwards,
most of the emergency generators were submerged. So, all power sources were lost.
And then there was the loss of important plant functions such as water injection and venting.
After that, the pressure in the reactor pressure vessel rose,
and of course as cooling could not be performed, the water level in the reactors dropped, then the fuel rods were exposed.
When the fuel rods were exposed, and later boil-dried, coupled with the large scale damage to the fuel rods, large quantities of hydrogen were produced.
Since the vent function was lost, functions to release hydrogen, or decrease pressure in the reactor pressure vessel were also lost.
Then hydrogen and radioactive material leaked from the reactor pressure vessels and containment vessels into the building.
This led to the hydrogen explosions.
This is the general flow.
As a result, at the Fukushima Dai-ichi Power Plant, reactors one to four reached a condition of meltdown, or something very close,
and all reactors except reactor two, experienced hydrogen explosions.
The organized timeline is on the chart on the screen.
This is the chronology of Reactor one in Fukushima Dai-ichi.
I will omit the detailed explanation here,
but regarding the Fukushima Dai-ichi Power Plant,
from the time the earthquake occurred at 14:46 of March 11th,
by 18:46 of the same day, it is assumed that core damage had already begun.
After that, at 15:36 of March 12th, a hydrogen explosion occurred in the building.
That was the situation.
If you look at this chart,
it is obvious that core meltdown has occurred.
What needs to be explained here is
that the core temperature rose to such an extreme level that the fuel rods and cladding tube began to melt.
In terms of degrees, it's around 2300-2500 degrees Celsius.
With those temperatures, the fuel rods and cladding tube began melting.
When the cladding tube begins to melt and the water level in the core drops, then the moisture from the water contacts to the cladding tube.
As the cladding tube is made from zirconium, an alloy called zircaloy-2, it produces hydrogen and oxidized zirconium.
As the meltdown of the core progresses, more and more hydrogen is produced.
Then the melted materials drop and accumulate at the bottom.
The accumulated materials have reached 2500 degrees Celsius by that time.
So when this happens, and sufficient cooling cannot be performed, the reactor pressure vessel, with about 16 cm thick steel, starts melt-through.
Once it is melted through, it starts dripping onto the bottom of the primary containment vessel.
This vessel is covered by a 2cm thick steel and another thick layer of concrete, called 'man-made rock'.
Yet these extremely hot drips could open holes into the vessel.
In addition, since the torus of the vessel, which is shaped like a donut,
is not made to withstand those pressures or temperatures,
it could begin to break in the weak parts such as flange or other pipeline sections that are not sufficiently sealed.
From there, the radioactive gas and fission products escape. Of course hydrogen escapes too.
This was the situation, and once again,
please explain where the meltdown began, and the timing for when the melt through occurred, with the previous graph.
Here it is.
Umm, the next one. This graph.
This one.
Yes.
First, on March 11th,
all the power sources were lost, then cooling functions were lost as well.
Then, around 18:46 of the same day, about 3 hours after tsunami,
we assume that the cooling water came down to just about the top of the fuel rods, and damage to the rods began.
We presume that several hours later meltdown started then developed to the melt-through.
This generated and accumulated a large volume of hydrogen.
By 15:36 of the next day, the hydrogen explosion occurred.
The hydrogen that came out of the containment vessel accumulated in the building and exploded.
It is said that if hydrogen is mixed with the air with its concentration over 4% or 4.3%, an explosion could take place.
When core meltdown occurs, then a large quantity of hydrogen would be generated. If the hydrogen, dense enough to explode,
seeps out into the reactor building, then it would be most likely that the melt-throughhad occurred.
The melt-down produces both gas and solid fission products.
All of those melt together and drop down. Then gas is mixed in with the water and could drain out from the vessel.
Also, because hydrogen is very light, it could go up to the top, or it could also seep out from the bottom.
So, most likely, by seeing this chronology, the melt down started within a day of March 11th,
in other words, on the day the earthquake and tsunami occurred.
And the melt-through occurred by the next day.
Then a large quantity of hydrogen was generated and accumulated in the reactor No 1 building.
And by three o'clock in the afternoon, it exploded. This was the process leading to the explosion.
In other words, within one day complete meltdown and melt through occurred.
And that material fell into the containment vessel,
and started a gas leak, where gas could escape.
Water also leaks. This is extremely contaminated, and it occurred within a day.
I believe this is an extremely important point.
Even after a month had passed,
the government continued to say that meltdown, any meltdown has not occurred.
But as far as we have observed,
Fukushima Dai-ichi reactor one has experienced meltdown as well as complete melt through within a day of the earthquake.
And another important issue is the damage to the containment vessel itself.
It was seriously damaged so that radioactively contaminated water and gas came out of the vessel.
There is no way that the government did not know this.
Even in this investigation we ourselves can see that this situation occurred within a day.
If this had not occurred, a hydrogen explosion would not have happened either.
So a complete meltdown has occurred.
Although they must have known that a melt through had occurred, the Chief Cabinet Secretary at the time insisted that it had not.
So, we are concerned if this important information was fully disclosed or not. If we walk through what had happened at reactor No 1, one by one,
then what the central government said at the time seems to be much different from what we think had actually happened.
Naturally those on site knew what was occurring, so it is natural to assume that the government was also being notified.
However, both NISA and TEPCO kept saying "a meltdown has not occurred".
So somewhere in between, the correct information could be shut off and was not being disclosed, at least to the television or press.
I believe that this point is extremely important.
Melt-down and melt-through occurred extremely early on at Fukushima Dai-ichi reactor one.
And later, reactors 2 and 3 experienced the same accidents.
I would like to take the time to hear the commentary regarding this.
Yes.
Now, I would like to describe the events in reactor two chronologically.
If you take a look at the timeline, reactor two differs from reactor one
in that it is assumed that the high pressure cooling function - called emergency RCIC - had been functioning for one day.
Even though all power had been lost, for some reason the RCIC was still functioning.
Therefore, the earthquake and tsunami came at the same time as reactor 1,
but after that, at 2:55 of March 12th, there is a record that RCIC was still working.
Then, most likely on the night of the 14th, by 19:45 or 19:46 damage to the core had begun,
and by the 15th, what was said to be an explosion took place.
But upon investigation, it was not an explosion, but one of the legs of the suppression chamber at the bottom of the plant had suffered huge damage.
Therefore, reactor one exploded in the afternoon of March 12th,
but reactor two did not experience damage of the containment vessel until early morning around 6 o'clock on 15th.
Regarding reactor three, as some batteries survived even after tsunami, the cooling systems were working until the batteries expired.
Specifically, cooling functions called the RCIC and the HPCI, a high pressure water injection system were still in operation.
So cooling continued for approximately two and a half days.
After that, it is assumed that between 8 and 9 o'clock on March 13th, two days later,
fuel rod damage had begun.
And afterwards at 11:01 of the 14th, there was an explosion in the building.
The following is for reactor four, which also experienced a hydrogen explosion.
But our project has not reached to the conclusion that the fuel rods in the spent fuel pool generated hydrogen.
As for the chronology, a large sound was generated
and an explosion occurred around six o'clock in the morning on March 14th at reactor No 4. This is almost the same timing as the reactor two.
There is also research data on reactors five and six within chronological order.
Let me summarize again here.
The isolation condenser is a device to continue cooling by self-generated steam even after all power sources have been lost.
In a way it is a fail-safe device even in a failing environment.
The steam generated is put into the exchanger or condenser where the heat is taken from.
Then it returns back to cool the core.
This is the basic mechanism of the IC.
Regarding reactor one, upon our investigation, this isolation condenser was basically not functioning at all.
The valves on the inner containment vessel were closed to protect it.
Therefore, although all efforts were made to open and close the outer valves of the vessel, it did not work as there was no power.
To be more precise, there was no way to confirm whether the valve was even opened or closed.
Though the on-site workers tried with all the methods available to open it,
there is no evidence that it was working when checking the actual steam or water level.
So, the melt through occurred extremely fast without any ventilation function.
And as Mr. Shibata mentioned, some batteries were working at reactor three
because they were on the mid-second level whereas all the other batteries were located underground and submerged.
So they were saved from submergence, and worked for about the eight hours.
Those batteries were a DC power source.
And in the case of reactor four, it is not accurately known why the explosion occurred.
But a significant amount of heat should be produced because newly spent nuclear fuels were put into the pool.
It has been said that the cooling system was not functioning, so hydrogen was produced from the spent fuel and exploded.
But even after inserting video cameras and looking at various sections of the reactor,
there is no evidence of the fuel oxidizing in that way, or being damaged.
So it is hard to imagine that hydrogen was generated from the spent fuel cooling pool.
So, for now the hypothesis is that the hydrogen came from reactor 3 and caused the explosion at reactor 4.
That is to say, there is a place in the exhaust stack where reactor 3 uses for its ventilation. And this stack is connected to reactor 4.
Somehow, the hydrogen in reactor 3 flowed back into reactor 4 through this connection.
Then the hydrogen accumulated in the building of reactor 4, reached to a certain level of concentration and temperature, and finally exploded.
There is still a debate about whether this had occurred or not.
However, there are several filters in the pipeline from the exhaust stack to the reactor 4. If we look at the level of cesium at each filter,
it is possible to think in that way. So that is the case.
The explosion at reactor 4 was caused by a flow of hydrogen from Reactor 3.
We ourselves are not fully satisfied with this conclusion.
But as other possibilities of hydrogen generation cannot be determined,
we believe that this hypothesis is most likely correct.
Then, reactor three exploded.
While it is said that reactor two exploded as well, it means that a large explosive sound was heard in reactor 2.
But in actuality hydrogen had not detonated here.
A hydrogen explosion had not occurred but a core meltdown did take place at reactor two.
Regarding why a hydrogen explosion did not occur in reactor two,
at the explosion of reactor one, the windows of reactor 2 were blown out.
Then the explosion at reactor 3 blew off the blowout panels of reactor 2.
As these two windows were opened at reactor 2, the hydrogen could escape from the building through them.
This had avoided the accumulation of the hydrogen.
Speaking reversely, it can be said that if there was a method of releasing hydrogen,
these explosions at the three nuclear reactors could have been avoided.
Regarding reactors No 5 and 6,
there was one air-cooling diesel generator at the reactor 6 that survived.
So this was activated and the cooling system was maintained.
And reactor 5 could share and use the power of this DG as well.
Both the reactor 5 and 6 were able to secure their cooling systems and maintain cold shutdown because this one diesel engine survived.
So the important lesson here is
that though there are many emergency power sources, if only one of them survives, cold-shutdown can be conducted under these extreme circumstances.
This air cooling diesel engine was not part of the original designs,
but there were instructions from the NISA to put double or triple the emergency DG's for every nuclear reactor,
so the diesel generator added most recently happened to be an air cooling type.
So even after the water intake systems lined up on the sea side were all destroyed, this one air cooling device worked as long as there was air.
For this system, they were saved.
In other words, the boundary line between the reactors that suffered explosions and the ones that survived
was whether they were equipped with systems with completely different principles such as air cooling besides sea water for cooling.
Compared to a water cooling system, air cooling is slightly cheaper.
But since it is huge, it was located outside the building.
Then, these systems functioned, and the reactors were stopped.
So the line between living and dying was the existence of equipment with different principles.
Because there just happened to have one of those at reactor No 6, the two reactors, 5 and 6, were brought to cold shutdown.
Of course, reactors five and six were undergoing regular inspection,
and did not have to be shut down so urgently.
So compared to reactors one, two, and three, it was somewhat easier to bring them to cold shutdown.
However, even in this case, if the cooling system could not be maintained, things would be brought to meltdown.
So, considering this in our analysis,
a very important point is if even one cooling method functions,
a reactor can be brought to cold shutdown.
Looking at the Onagawa or Tokai Dai-ni Plants,
where all sorts of machinery were damaged and external power sources were lost,
but because even one cooling system had survived, cooling shutdown could be performed.
So I think it is very clear that is what divided the explosion and survival of reactors.
Please continue, Mr. Shibata.
Yes.
After this, I will explain some of the details.
But as Mr. Ohmae mentioned earlier, this project was not only about the Fukushima Dai-ichi Power Plant, but all plants;
the Fukushima Dai-ni, Onagawa, and Tokai Dai-ni.
So I like to go through the chronologies of those power stations and the earthquake and tsunami, and the progression of events.
This is reactor two of
Fukushima Dai-ichi, and reactor three.
We have extracted the problems of each.
And reactor four.
Then, in the same way, we had examined the issues and chronology of the Fukushima Dai-ni.
Here also are the external power sources at Fukushima Dai-ni.
Three out of four external power sources have been disabled due to the earthquake.
As you see, the vulnerability of external power sources to earthquakes has been observed at other plants besides Fukushima Dai-ichi as well.
This is the situation of the loss of power systems.
In the same way, the emergency diesel generators.
In the Fukushima Dai-ni, three out of twelve generators had survived.
As mentioned previously, at Fukushima Dai-ichi, besides the one generator at reactor six, all others were wiped out.
So even here you can see the difference between the ones that survived, and the ones that were wiped out.
The next page shows the situation of the same electrical systems at Fukushima Dai-ni.
The left half is the situation in Dai-ichi, and the right half is the one in Dai-ni.
Looking at the color, the white colored parts are the ones secured during the accident.
And it is clear that, compared to Dai-ichi, Dai-ni had more areas which could be secured.
Looking at this chart, the inlets for the external power, framed in blue, this part here was secured,
but unfortunately the external power source itself was down.
So please show that screen again,
the inlet for the external power source was not submerged and survived.
But even though it was not broken, as the external power itself was gone,
unfortunately it was necessary to perform cooling with the diesel engine which was still functioning.
So the lesson in this case is that the external power source couldn't be relied on.
All the external power sources, of which there were many, were taken out by the earthquake and tsunami.
There are several cases
where the transformer stations were damaged as well as external power source were damaged on site because of the earthquake.
Those parts with insulators were too weak.
So, when it is time to reconstruct those parts of external power supplies, it is important to ensure that the external power source does not fall.
Over all, the reliability of external power is extremely low, as it was also the case with the
Kashiwazaki Plant, where a huge problem was caused with external power supply,
even though all external power was not completely lost then.
Then there is an issue on the diesel engines. They were installed to have three backups.
But even if they would not be submerged, it will not be always guaranteed that the diesel engines will start up.
At other plants, such as the Onagawa, there is still a little doubt on the reliability of diesel engines.
These are the results of this investigation.
Please continue.
Regarding the report, I would like to continue with Fukushima Dai-ni Power Plant reactor one.
Would you please show the screen?
I would like to pursue the situation with this timeline for reactors one, two, three and four.
Besides Fukushima Dai-ichi and Dai-ni,
we also investigated the Onagawa and Tokai Dai-ni Power Plants.
Four out of five of external power lines were lost at Onagawa as well.
This screen shows the chronology of
the Onagawa Power Plant, reactors one, two and three.
And now is the case for Tokai Dai-ni.
In the case of Tokai Dai-ni, all external power sources lost their function because of the earthquake.
And this is the chronology for Tokai Dai-ni.
And,
The detailed chronology leading to the cold shutdown is uploaded in an A3 sheet on the website,
so please take a look.
The resources shown now are all available for download in PDF,
so even though some portions of this screen may be difficult to read,
please take a look at those files and make use of them.
Different from the Fukushima Dai-ichi, at the other plants the AC and DC power and sea water circulation systems functioned even minimally.
So water injection to the core and cooling functions could be performed with the degraded power that survived, and they worked normally.
Although it was only the slight difference, the fact that these power sources survived was one big difference between plants
such as Fukushima Dai-ichi that experienced a huge accident, and those that did not.
These are the facts found in our investigation on the earthquake, tsunami, subsequent power loss, accident chronology, and relations
at the Fukushima Dai-ichi Power plant, and other plants such as Fukushima Dai-ni, Onagawa, and Tokai Dai-ni.
Now, I would like to pass the baton to Mr. Ohmae, and he will explain the lessons learned, and methods for countermeasures, prevention, etc.
We have analyzed "what is necessary to stop an accident" when something like this happens again.
In order to find the solution, we have walked through each fact one by one in a chronological order.
During these investigations, we could find solutions like "if we had this, then it could have been stopped".
You can see the details such as lessons learned, countermeasures, or things needed in the report.
The extremely important lesson is that the severe accident happened due to the loss of all power sources, both alternating current and direct current.
In addition, this power loss lasted over a long period of time.
There is an extremely important point regarding this.
If you look at the Nuclear Safety Commission's Nuclear Reactor Design Guide, it says
"It is NOT necessary to consider the loss of all the AC powers over a long period of time,
because a recovery of external power supplies or a repair of emergency alternating power generators can be expected."
In case of the accident in Fukushima, both methods were lost and useless.
The electrical lines fell and did not function.
Emergency power facilities were submerged and disabled.
So, many electrical supply vehicles were brought in, but the electrical panels that connect to the external power sources were submerged and unusable.
Since this is an official guideline by the NSC, the manufacturer and TEPCO had designed the plants in line with it.
However, the loss of power continued and was never recovered. That is what happened.
Furthermore, this guideline says
"In cases where the reliability of emergency AC power facilities is high enough in terms of its system structure or operation,
such as constantly in operation, the loss of all AC power sources need NOT be considered."
This sentence does not make sense, but in other words it is saying that "Such an event would never happen".
In reality, though there were emergency electrical facilities and three diesel engines, all of them were gone.
When the electrical supply vehicles were brought from off-site, all it needs was to plug those vehicles in.
There were at least five external power sources at Dai-ichi, and there were four at Dai-ni.
These external power sources are not just one system, but are coming from all sorts of places.
So, the guideline indicates that as these backups are prepared, loss of AC does not need to be supposed.
But this time, all of the above were lost. In addition, they had not been recovered in a short period of time.
Even though the power supply vehicles were brought in, there was no place to plug in.
And IF the vehicle were plugged in, the batteries could not have been charged since they themselves were under ground and completely submerged.
So, as long as this guideline exists, accidents like this will occur.
"There is no alternating current power source.",
"So the cooling systems cannot function, and the valves cannot be opened or closed." and
"The meters cannot be read because there is no direct current power. Therefore we don't know the current pressure or temperature in the reactors".
This situation will be repeated.
So the operators took out the batteries from their automobiles,
and carried them around to use them to read the parameters, or check the temperature.
It was extremely tiring and hard work, but there was no other choice.
Actually, the NISA and the Japanese government issued a report to the IAEA.
I would like to read a little of it here.
This is the second report in the last September, which is additional to the first report.
In the 'first group of lessons learned',
it says that the accident was caused by the tsunami,
and the major reason of the accident was that the supposition of the tsunami, such as its frequency and height were too low.
There were not enough countermeasures for a large-scale tsunami, and that is why the accident in Fukushima happened.
The report also says; "The Central Disaster Prevention Council, in regards to the tsunami disaster prevention plan,
proposed basic ideas such as to pursue countermeasures against tidal waves by anticipating two categories, the maximum size and frequency.
The Nuclear and Industrial Safety Agency started
deliberating on design standards for anticipating appropriate height and taking into account the period and frequency of recurrence."
These reports have also been sent to the United Nations.
The Secretary General Ban Ki-Moon criticized that the assumptions of accidents were too low in Fukushima,
and indicated that the prediction of possible accidents was too few,
warning all Power Plants around the world to reevaluate their suppositions towards accidents.
However, this is wrong.
According to our analysis,
the problem is not that the estimations towards severe accidents were too low.
The official design guide indicates that all power loss need not be considered.
However, in actuality, power must be secured in any accident.
At the same time, cooling systems, called heat sinks, must function with either water or air.
So the sources for cooling and power,
these two must be secured under all circumstances.
When these cannot be secured, a meltdown like this one will occur.
And once a meltdown occurs, hydrogen is generated, and fissile gas is generated.
Those substances are discharged from the primary containment vessel.
So, what I am trying to say is that the lesson of this disaster is not that the predictions for tsunami were off,
but that we have to prevent extreme accidents no matter what the circumstances.
Right now, there is no such design philosophy.
In other words, no matter what the conditions are, the heat sink and power source mustbe secured in terms of multiplicity and diversity.
The NISA said that it supposed a 10 meter tsunami wave. In reality, a 20 meter wave hit.
Even though they say, "It happens once in a thousand years.
We are very sorry but we did not predict that level.
So this time we will make our assumptions higher to 20 meters".
However, what if over 20 meter wave really does come?
When it comes down to it, no one would believe that tsunami greater than 20 meters would never occur, nor 20 meters would be high enough.
Up until now, at the resident's explanatory meetings, they have been told
"Reactors have been designed to be secured up to ten meter waves, so even if a tsunami comes it will be okay." or
"We have made enough suppositions for earthquakes, and the probability greater than this is extremely low".
"Even if something like this comes, it will be alright".
We now know all of those were lies. If they are told "The 20 meter tsunami, larger than the previous supposition (10 meter), took place.
Now, we will raise it to 20 meter.",
then they would ask "what will happen if a 21 or 25 meter tsunami hits?".
Even if you say, "No, no, that will not happen. The chances of it happening are very slim",
"very few" is not good enough. It is necessary to explain how it will be stopped absolutely.
The countermeasures need to be in place no matter how high tsunami hits.
Because when it does happen, the probability is 100%.
It is not an issue of low probability.
When it does happen, the cooling systems, power sources, and heat sink must be 100% secured no matter what.
No matter what, even if an earthquake occurs, or a tsunami hits, or terrorists attack or an airplane crashes into the reactor, whatever happens,
the hot nuclear reactor will be cooled down and equipment and resources for it will be secured.
In Fukushima, because of one air cooling diesel engine that was not even in the initial design, the reactors No 5 and 6 were brought to cold-shutdown.
That means, what separated the reactor from life and death was just one power source.
It is not so difficult to understand.
If there is no heat sink and melt through occurs,
a hydrogen explosion will occur.
However, in the design philosophy, hydrogen explosion caused by melt-down and melt-through has not been supposed to happen.
So there is no detector to measure hydrogen, or device to release it when a hydrogen explosion is about to occur.
The design philosophy itself was flawed.
It is wrong to say that you don't have to consider the events with sufficiently low probability.
No matter what, the cooling systems must function.
This is not so difficult, just as reactor six in Fukushima demonstrates.
So I believe that the design philosophy was
not just inadequate, but that it was wrong.
Also, there was no philosophy for securing the reactors by any means possible.
If there is no reflection regarding this,
nuclear reactors will never be safe enough.
Now they are trying to prepare for twenty meter tsunami, and making a monstrously large seawall, saying that we are safe now.
Even though a bulwark has been designed for twenty meters,
it is not safe enough.
As far as we stand on this theoretical framework which I have just described,
there is no guarantee that a tsunami which occurs once in 10,000 years, will happen tomorrow.
If a 35 meter tsunami comes, the same mistake will be repeated.
Therefore, I believe that the government should admit that their design guidelines and instructions are fundamentally flawed.
Considering this and what happened at Fukushima Dai-ichi,
the regulatory agency, or Nuclear Safety Commission, or NISA should first admit that their design philosophy itself was wrong.
It sounds very much a like bureaucratic way of speaking. It cannot be solved with a 20 meter breakwater.
"We are sorry, but we hadn't thought of something so severe".
"The predictions in the design philosophy and design itself were inadequate. The accident suppositions were too poor".
"Next time, we will make them much more severe".
But that is not the issue.
Another issue is "the myth of the primary containment vessel".
The myth had been that no matter what happens, the containment vessels will not release radioactive materials.
Experts and engineers have believed that nuclear reactors are designed to be safe
as it takes into account even events with its probability very low, such as against this type of accident or that accident.
However, during resident briefing sessions,
they were told that "You must say it is safe for sure. Say that it is safe." or
"People may not understand complex probability theory'.
Therefore, they had explained,
"There is a container called the primary containment vessel, which is solidified with 2 meters of concrete.
No matter what happens, it will not let anything escape. Even if something not anticipated occurs, it is safe".
However, once a core meltdown occurred, hydrogen, fission byproducts, water and everything came dribbling out.
Since serious core damage was not assumed, melt-down and melt-through were also out of the assumption.
This was what happened in Fukushima and all these materials come flowing out.
Therefore, the myth of the containment vessel was dispelled in just one day.
"Even though an unaccountable event occurs, the containment vessel will protect everything".
"For example, look at the accidents at Chernobyl"
"In the case of Chernobyl, the nuclear reactor in operation had a nuclear burst, a recriticality accident and exploded.
However, nuclear reactors in Western countries and Japan are surrounded by containment vessels that don't allow any substances out."
However, once a melt through occurs, these substances do escape.
We found out how easily materials inside the containment vessel really do get out this time.
So we learned that the myth of the containment vessel had been a fiction.
We must prevent melt through, or meltdown no matter what.
And to do so, the heat sink and power sources must be secured no matter what.
This is the solution.
So, the explanations given to the local residents were also erroneous as well.
Melt-down's have occurred in reactors one, two and three.
These things had happened in an extremely short period of time.
Therefore,
in the case of Fukushima Dai-ichi, it is clear that the containment vessel was NOT the last bulwark.
This must be taken very seriously.
So, melt-down and melt-through must not occur even given any mistakes.
We must prepare for this.
The safety of both power and the ultimate heat sink were designed only in terms of multiplicity.
This was the only safe design.
It means that they were told to install three emergency diesel generators,
but all three generators were located along the same sea side.
By doing this, all three were damaged at the same moment as the main cooling system was blown away.
It is no way to secure safety by placing them
in the same location, with the same specifications and facilities, and having them work from the same power source at multiple plants.
If you place the normal and emergency measures in the same place, they could be damaged by the same cause.
Now it is clear that safety is not secured by just increasing the multiplicity.
So, like reactors six and five, where one air cooling system survived,
not only multiplicity but also diversity is important.
Safety measures with different principles must be prepared as back-up.
And when all of those fail, alternatives must be brought in from off-site.
It means that countermeasures from off-site must be considered as well as ones at on-site in order to strengthen its diversity and multiplicity.
For example, it can be carried in by helicopter.
If such things are not considered, it cannot be said that it is safe.
The concept for safety itself, safety would be secured by multiplicity, had been wrong. It was wrong because
every device was lined up in the same location, relied on the same external power which was lost simultaneously,
then all devices tried to intake sea water from the same place,
as a result, both the regular cooling systems and emergency systems failed at the same time.
In designing nuclear reactors, more than enough reconsideration and reflection must be made,
and back-up with different fundamentals must be prepared multiply and diversely.
It is very regretful that it hasn't been considered even once before,
but in reality, this is the biggest reason leading to the accident.
Another issue is the power source and cooling systems for nuclear reactors.
For the water source for the cooling system, this does not have to be sea water,
but fresh water, such as a reservoir if a river flows nearby, or a lake, to obtain fresh water, these can be prepared.
Not only that, equipment or systems for normal operations, for emergencies,
and for extreme emergencies, must be prepared.
These sorts of things need to be created with completely separate and safe fundamentals.
Thinking of these things, the computer may be able to simulate for normal and emergency use,
but when it comes to emergency plus extreme emergency and extremely severe accidents,
stress tests and simulations can not be applied reliably.
These sorts of things must be assumed properly so the facilities can be built correctly.
Does it have facilities with various differing fundamentals or not?
The concept of multiplicity and diversity is extremely important.
The stress tests currently conducted are computer simulation based on the European forms.
Even if the test results show that it can withstand sufficient pressure,
as long as it does not fulfill the principle that I mentioned earlier,
securing the cooling systems no matter what,
and securing the power sources to keep the cooling system running,
safety cannot be ensured.
At least it cannot be said that the lesson learned from the extreme accident at Fukushima is being considered.
Most likely the workers on-site already understand the methods that I have been speaking of,
and they have begun to work towards it in each plant.
But I believe that it is clear from this report
that passing a stress test does not secure the safety of the plant and we cannot feel completely secure because of it.
Also at the time of the tsunami, everything lined up along the coast was washed away.
But there are some methods to avoid it.
This is just an example, but as is shown here, a giant seamless pipe, such as used for transporting petroleum, gas, or LNG gas, can be used.
If a 100 meter seamless pipe is prepared,
with its intake on this mountain side,
even if a tsunami hits this sea side, the other mountain side would be unaffected.
It could function as a damper.
So this is another method to pump water up from someplace like this.
Of course, it is preferable that there is a completely separate water source nearby,
or even more ideal to have a reservoir with a considerable amount of water.
On the other hand, if preparing these is challenging,
power sources and pump equipment sets can be brought in from off site.
Such countermeasures for extremely severe accidents are needed.
So, I believe it is necessary to prepare safety measures for normal operations, emergency situations, and extreme emergencies.
This time,
many electric supply vehicles were brought in, and according to one source, 50 cars were brought in,
but since the electrical board was submerged, connecting these was impossible.
There needs to be places where those boards can not be submerged, or are at a height that won't be submerged.
This is another important issue.
As shown in earlier pictures, there were places that were hard to access after the earthquake.
With that in mind, it will be necessary to find a solution for the connection problem such as
putting the inlet in more distant location, or bringing it in with underground cables.
For countermeasures, security of power as an example,
it has come up a lot here, from securing alternating current power to emergency diesel.
Regarding the new items shown here in red,
we have written up these measures in the report that was submitted to the Minister. Each of these countermeasures must be counted one at a time.
We separated the safety measures that the NISA has already considered and ordered to electric power companies and has not, for review of the policies.
Furthermore, regarding security of cooling functions,
control room functions,
and vent functions,
we have written the safety measures that might make it safer from the lessons learned.
We have also summarized the prevention of hydrogen explosions, and the severe accident manuals as well.
We have learned that the accident management manual is well constructed,
but to prevent confusion at a time like this, it must be easy to comprehend.
For example, in the case of Fukushima Dai-ichi, there are six reactors.
At Kashiwazaki Kariwa, there are seven reactors.
At Fukushima Dai-ni there are four.
Not all are operating under the same condition when it comes to accident mode.
So to see each situation, such as
"This valve is opened or closed",
"This power source can be used right now or not",
"This water supply can be used right now or not",
"This pump is working right now or not"
without easy comprehensibility, it becomes extremely difficult to make decisions.
When the number of electric supply vehicles,
or fire pumps, or high pressure water cannon trucks are limited, dilemmas such as
"Which place should be prioritized?" arose.
So I believe that in places with multiple nuclear reactors,
it is necessary to be able to comprehend, and view the most urgent need at once.
Niigata Governor, Mr. Izumida has commented that
"They are talking about stress tests,
but the examination of Fukushima Dai-ichi accident is essential.
Computer simulations without any consideration of it do not have intrinsic value."
He reiterated that point in the representative assembly on September 14th.
We believe that this is definitely true.
In regards to the countermeasures in the future,
the issue is not only the technical aspects,
but also the accident management that the local citizens can participate in for making decisions together.
As a stakeholder, the locals should be a part of the accident management scheme and trainings under predicted emergency conditions,
If they are told to evacuate ten or twenty kilometers while they do not understand what is really happening,
at that moment the locals become casualties or victims.
This is a big problem as well.
In America's case,
there is the regulatory authority called the NRC, Nuclear Regulatory Commission which is comparable to the NISA.
Based on the information from NRC, the State Governor determines how to implement evacuations.
In the time of the nuclear accident in Three Mile Island,
pregnant women and infants were asked to evacuate ten miles first.
As for the rest of the residents,
they were told that there was no need to evacuate until the condition worsened.
They called for a voluntary evacuation, where residents were asked to determine on their own whether or not to evacuate.
It will be very important that the local government and community make those decisions for themselves.
And the information necessary for those decisions must be shared in real time at the time of the accident.
People will not accept the situation if information has been hidden,
and are suddenly told that "It's dangerous, so please leave this place".
Therefore, information must be shared.
When an accident occurs and the accident management mode, called AM mode, is on,
100% of the information must be shared
with the locals, not everybody but at least the local governor and vice-governor who oversees the nuclear reactor.
Decisions should be made together if necessary.
So a network should be constructed in which safety of local community is prioritized and information is shared in real time.
With local participation, a transparent and speedy decision can be made.
Preparation and training for that should also be repeated periodically.
We have written in the report that training to secure safety is necessary.
It is clear that in the case of Fukushima Dai-ichi accidents
the information was not completely transparent even though it is essential.
Even though a meltdown had occurred in a day, which is obvious in the investigation,
the government told to the press and people of the public that "a meltdown has not occurred".
And, the press relays what the headquarters makes public. However, they only explain what they have been told,
and never deepen their investigation on their own.
Most likely, there are considerations so that people won't panic.
But with that way,
a large amount of data gathered on the accident was worthless and should not be applied for the future safety.
The point is what we should learn from Fukushima Dai-ichi,
and I believe this is extremely important.
For the record, I would like to direct your attention to this.
The government had said on March 12th that the Fukushima accident was level 4 of INES scale.
Regardless of the fact that a meltdown was occurring on that day, and they knew it was occurring,
they said that it was an accident of level 4.
Level 4 is very low.
Even the Three Mile Island accident was level 5.
Chernobyl was level 7.
Even considering this, they have made their announcement.
On April 12th, they had re-announced that it was level 7, which is the same as Chernobyl.
But if you look at this analysis on the timeline,
after four days following the earthquake, all the reactors one, two and three have had a meltdown and melt through,
and radioactive substances had leaked outside.
In spite of this situation,
they have not admitted a meltdown, and continued to insist it was level five.
And they finally remedied that on April 12th to level 7.
Mr. Edano, who was Chief Cabinet Secretary at the time,
continued to repeat in his announcements that "a meltdown has not occurred".
The way they made announcement,
level determination, timing of announcement, and messages are summarized here.
The more facts are revealed,
the bigger this issue becomes.
In other words, we do not know from our investigation whether the government intentionally hid the facts or not.
But since TEPCO should have reported this information to NISA in real time,
somewhere between the NISA and government, the information was not shared with.
For that reason, though it is no surprise, there is a possibility that Mr. Edano had made his announcements without knowing the facts.
We do not know even now at what stage the information was concealed.
Obviously, there is no way this should be allowed.
It is a big question of whether the Prime Minister's office knew it or not at the time.
With these questions,
there are some indications that they might not have known the facts for a quite long time.
Therefore, this point should be cleared.
The Accident Investigation Board of the government has been conducting their official investigation.
And now the Diet is selecting ten civilian intellectuals and setting up another project team
to investigate the accident with the official right given by the law.
So, these projects should clearly disclose the exact point where the information was concealed.
With our team this time, we were unable to discern this.
Regarding the message to the public,
if we look at what had happened such as the hydrogen explosion at reactor 1 on March 12th and other reactors after 13th,
we see that all the events that I explained today had been actually progressing.
It seems as if the direction of the message had been completely different.
Therefore, regarding this point, much reflection must be made.
There must be an answer as to why the information was suppressed or hidden.
We focused on the investigation of how the accident occurred,
and what can be done to prevent this accident.
So we expect the accident investigation committee to discover
what had actually happened regarding the suppression of information and the message to the public and international society.
As I mentioned in the beginning,
there is the mistake for the design philosophy regarding power loss in the Nuclear Safety Commission's guidelines, 'Safety Review Guideline 27'.
This is the whole reason of the accident that occurred this time.
The long-term loss of alternating current power does NOT need to be presumed.
It also says that the recovery of transmission lines, or the facilities of emergency alternating current power can be depended on.
However, this time, all emergency power sources were submerged,
and the transmission lines were down without being restored.
So those guidelines were wrong and the supposition was very misdirected.
I believe that it must be fixed immediately,
and more important than stress tests, this issue should be ensured.
On the long term power loss,
I believe that the power source must be secured 'on-site' at least for 24 hours.
In other words, within the grounds of the power plant.
The accident management and measures beyond 24 hours against power loss,
equipment and resources should be brought in from 'off-site'.
It can be by helicopter, or boat.
It should be brought in within 24 hours from outside of the power plant.
Multiple nuclear reactor groups share several facilities in certain areas.
When accidents happen, these can be used by all.
The equipments and devices needed within 24 hours should be installed in each reactor.
For equipments necessary after 24 hours, I think it will be fine to prepare in this way.
This differs in each country.
In the United States, they require that devices to maintain the reactor for 72 hours should be installed on-site.
After our analysis, I believe 24 hours can be one of the standards.
For education, seminars, and training,
it is necessary that the lessons learned in Fukushima be included.
The training and practice such as bringing in substitute power sources have to presume the worst extreme environments.
It must be supplied to the plants within two hours.
Water sources other than the sea must be also prepared.
And the trainings have to set numerical goals specifically by which the countermeasures be implemented or accomplished, such as within X hours.
The skill levels gained by training should be evaluated, too.
Fundamentally,
the training should not be operated only for the electric power companies, but also for the local citizens, the government, and related institutions.
All related people must join the training together as well as sharing information and making decisions.
We have to share all the information with the world
on the accident situation, our reflections, the lessons learned, and necessary training program based on the facts on March 11 at Fukushima Dai-ichi.
After all of these analyses,
the lessons learned at Fukushima should be shared not only with IAEA, but also places that have or plan to have nuclear reactors around the world
since they are all based on a similar or same design philosophy.
However, the information from Japan right now is wrong.
They are saying that the estimations for tsunami were too low.
"This time we had estimated a 10 meter tsunami and 20 meter waves came.
So now we will change it to 20 meters." "The assumptions were too low, and that was the reason of the accident."
That is what they are broadcasting to the world. People around the world believe it and are relieved.
This leads to people believing "Tsunami won't come to our country", or "First of all, we don't have earthquakes,
and the accident that happened in Fukushima was Japan-specific."
The information which Japan's government broadcasts makes people globally think
"Only places like Japan may need severe and high level predictions".
But this is wrong.
For instance in Europe, it could be a plane crash.
When a plane crashes into the nuclear reactor,
it is necessary that power and coolant must be prepared at several levels so that cooling can be maintained.
It is important that the design philosophy and guidelines be changed.
In the United States the other possibility is terrorist attack.
In case of US, this terrorist attack would be the most severe accident presumption.
If that happens,
ultimate heat sink, coolant and power sources must be secured in a place where the terrorists won't notice and can't destroy.
The fuel rods must be cooled without terrorists noticing, and in the meantime the terrorists must be captured and dealt with.
So, no matter what the situation is, cooling has to be performed. In Japan's case it may be earthquakes or tsunami.
But in other places around the world, the most severe accident will not always be the same, but terrorists, or plane crashes.
If the attitude of Japan toward reactor design is reconsidered so that the design philosophy is of securing the cooling system
in the case of all kinds of tsunami and even complete submergence of the plant
and if that is broadcast globally, then the attitude of the world society toward nuclear power plant design would be revised.
It is not a difficult operation.
I believe that it is an extremely important message learned from the accident in Fukushima. People around the world should share this as well.
This is the end of this report.
Please take your time to peruse the whole report as a reflection of the Fukushima accident.
We also recommend you to compare these reports to the announcements the government has made, or information you have gained up until now.
Our team performed this work in the limited time frame of three months.
I do not think all in these reports are perfect.
However, I do believe that there are some very important lessons that were learned.
And speaking reversely,
light was shed on the way to make nuclear reactors safer, or a direction to proceed will be somehow given to some extent.
We should avoid the severe electric loss of 34% by having all the nuclear reactors stopped.
This may cause more severe shortages of electricity or power reductions over the next summer than last summer.
An alternative energy could be found for the long-term scheme.
However, in the meantime,
nuclear energy is still necessary.
I hope the government or industry will modify the existing nuclear power plants by introducing the recommendations in this report.
Mr. Shibata, if there is anything else you would like to add, please go ahead.
Well, I took on this project without having any background knowledge regarding nuclear power.
But in that sense I was able to start drawing pictures on a blank canvas.
And through learning the situation from those on the site,
I felt an extremely wide gap between what was being broadcast at the time, and what was actually happening.
Along with that, there are so many lessons learned that can be gleaned from this report.
So it is my hope that it does not remain only in Japan, but shared around the world,
and be used for recurrence prevention and countermeasure provisions for safer nuclear power plants.
Thank you very much.
Regarding these resources, it will be downloadable from the internet.
The address will be shown in the subtitles later,
since the dialog may be hard to understand.
This video will be uploaded onto YouTube as well.
There may be other places it will be uploaded.
If you go to the URL written here,
you will find all the information
on YouTube and everything.
You will see an active window on the site,
so all you have to do is click it to see
the video, as well as the other resources.
Additionally the contents of today's press conference can also be accessed from there,
and the press release that was distributed at the conference.
So, we hope that you will be able to use this as a reference.
Thank you very much for taking the time to watch this.
This is the whole content of the report that our team spent three months to complete.
Thank you very much.
Thank you very much.
Special thanks to: Ms Jewel Naruse Ms Seiko Toyama Mr. Curtis Hoffmann Ms Keiko Sato