Lessons Learned From Fukushima Dai-ichi (1. Press Conference. 2011. 10. 28)




Uploaded by H2OProjectBBT on 21.03.2012

Transcript:
Minister Hosono will now begin the press conference.
Regarding the flow of this conference,
the reception of the second opinion report will be conducted first, then following the opening address from the Minister,
Mr. Ohmae will introduce a brief summary of his report, and finally there will be a Q&A session.
We would like to begin now.
At first for the presentation of the reports, Mr. Ohmae, please step forward.
Please use this report for the prevention of accident recurrence.
Thank you very much.
And now, here are some words from Minister Hosono.
I have just accepted the opinions regarding what can be learned from the Fukushima Daiichi Nuclear Reactor accident from Mr. Kenichi Ohmae.
I would like to explain how I came to receive these opinions.
As you are all aware, following March 11th, I have been serving for the restoration of the accident site.
However, I have continued to consider questions such as why this terribly serious accident had occurred, and whether we could have prevented it or not.
I also have had the thought that
it is important to implement the lessons learned for the future safety of nuclear energy as well as to prevent actual accidents.
Of course the Nuclear and Industrial Safety Agency and Nuclear Safety Commission have been presently engaged in the prevention of a reoccurrence.
However, future measures must be taken by considering the opinions of field specialists.
That is what I have been thinking as I have been taking measures.
Around June, when I was still an aide,
I had the opportunity of being introduced to Mr. Kenichi Ohmae. At that time, Mr. Kenichi Ohmae offered his services to me to analyze the accident
in a responsible way, collect information from specialists, and submita proposal regarding methods for measures that can be taken.
I personally had been also thinking that it is important for the government to take such second opinions into account
and if those were to be based on opinions of a specialist such as Mr. Ohmae, I would be extremely grateful.
After that, around the end of June, I became the Minister responsible for the nuclear accident oversight,
and had the opportunity to meet Mr. Ohmae again.
At that time, I “officially”, though this might be too strong of a word, requested Mr. Ohmae to conduct research on this issue.
As he kindly suggested to do it voluntarily, I humbly requested him to create a report.
Of course, this is not done only on my own decision, and I have also consulted
Mr. Kaieda, who was the Minister of Economy, Trade and Industry at the time and I explained to him that these secondary opinions would be necessary.
The contents will be explained by Mr. Ohmae afterwards, but through the preliminary exchanges,
I recognize that this is a very detailed analysis regarding this accident.
Also regarding countermeasures, especially those measures corresponding to severe accidents such as this,
I believe that this report is rich in suggestions.
Therefore, the Nuclear Power Safety Agency that I am responsible for will be newly created next April,
and I am hoping to take these points into consideration for those areas and deliberate over each of the suggested countermeasures.
Also, the Nuclear and Industrial Safety Agency is currently responsible for the regulations regarding nuclear safety.
The Minister responsible is Mr. Edano, so I hope to share the information with him, and implement any of the proposals that are feasible.
In either case, as we are tackling with the serious problems of nuclear power station safety,
and furthermore, as the reliability of the governmental administration of nuclear power safety is faltering from their roots,
I feel extremely grateful to refer to this second opinion,
so I felt it would be beneficial not only to receive this report, but to listen to the explanation with all of you in the form of a press conference.
That is the background of this conference.
Next we will have an introduction of the summary from Dr. Kenichi Ohmae.
Good Evening. I am Kenichi Ohmae.
As part of what can be learned from the Fukushima Dai-ichi Nuclear Plant,
I uploaded the television show for members of "Business Breakthrough" that was broadcasted on March 12th and 19th, onto YouTube,
and received 2.5 million view accesses.
In it, I stated my opinions such as "Regarding this situation, things might have happened this way.", "In 10 years, we should do things this way." and so on.
At the same time, though I put my thoughts and opinions in my book "Japan; The Road To Recovery" regarding those developments and
issues such as re-activation of nuclear plants and the accident itself, I was concerned that information has not been shared sufficiently to the public.
As Minister Hosono mentioned,
I made the following proposal to him who was the aid to the Prime Minister in charge of Nuclear Accident Recurrence Prevention at the time;
It would be necessary for us to kick off a project that investigates the severe accidents at Fukushima Dai-ichi
and the appropriateness of government's stress tests as second opinions from private and neutral points of view and complete in three months.
Otherwise, all the Japan's nuclear reactors will practically stop functioning from March to May of next year.
I suspected that such a serious situation for Japan would come to pass.
So, although it may sound funny, but as a taxpayer or from a citizen's standpoint, I would like to do this project as a volunteer.
I asked Mr. Hosono only for the access to the necessary information for the project as an intermediary.
I also told him that as I will analyze from an objective perspective,
the report may not always be as the government, or industry expects,
but I would like to take on this operation taking those points into consideration.
Regarding the existence of this project, I asked him to treat as confidential until the report is finalized.
Let me talk about the project team. I received my doctorate degree in nuclear power engineering at the Massachusetts Institute of Technology,
and was doing core design of high speed reactors at Hitachi, Ltd,
so my memory may be quite rusty on the topic,
but by remembering this knowledge,
or should I say, using that, I wanted to clarify how the nuclear reactor accident came about, and even propose a countermeasure.
The manager of this project is Mr. Iwao Shibata, whom I will introduce a little later. Mr. Shibata, who has experience in project management,
and another person have worked as our administrators,
and after gaining access to specialists from Tokyo Electric Power Company, Hitachi GE Nuclear Energy, and Toshiba,
I was able to organize this report that I am submitting today.
I have been a consultant at companies such as McKinsey, and managed projects for close to forty years,
so I strove to complete this project by the proposed deadline.
I have organized the 189 page report that was submitted today.
In regards to the investigation,
we analyzed not only Fukushima Dai-ichi, but also Fukushima Dai-ni, Onagawa, and Tokai Dai-ni as well. We compared these plants,
and analyzed plants and reactors that went to cooling and shutdown during emergencies, and those that did not, and what differed between them.
First of all, what happened?
This is called the chronology, and we pursued how the events happened in a time-line as they occurred from the time the earthquake occurred.
This is all in sheet one which is in A3 spread paper among the handouts you received.
In the sheet, all the nuclear reactors we examined are listed up:
Reactor 1 to 6 of Fukushima Dai-ichi, the four reactors of Dai-ni,
the three reactors of Onagawa,
and Tokai Dai-ni.
As you can see, chronology of what had been happening in these reactors from the time of the earthquake,
as well as from March 12th, 13th, and 14th till finally the explosion of reactor four are organized here.
It was hard work, but this is the way this report has been organized.
This is sheet two. This chart shows equipment loss of all the nuclear reactors such as power supply of AC/DC.
Therefore, there may be many people with the impression that Fukushima Dai-ichi reactor 1 to 4 are in the most severe difficulties,
but actually, other reactors are all in considerably severe condition with the external power,
or emergency power devices.
The red marked devices are broken.
Regardless of such extreme situations, though not much has been broadcast, as you will find in the sheet,
in all reactors except for one, two, three, and four of Fukushima Dai-ichi, cold shutdown occurred well until the end.
In examining this process,
the fact that managers and operators at these reactors
were able to conduct cold-shutdown procedures calmly despite the situation that these equipments were being lost,
is something we should take note of, and be proud of.
As you are aware, in the case of the Three Mile Island accident, the operators were distracted by the accident,
and continued to proceed in wrong operations one after another, finally a nuclear meltdown occurred.
But at least this did not happen in any of the Japanese reactors other than unit 1 to 4 of Fukushima Dai-ichi which experienced complete loss of power.
This is one noteworthy point in this chronology.
Also regarding the cause and effect,
what was the difference in four reactors that led to catastrophe and those that were able to carry out cold shutdown procedure?
We analyzed, or examined the differences from this viewpoint.
Also as the purpose was to find the lessons,
we tried to clarify the cause-and-effect relationship among accidents, design concepts, and design guidelines
as well as how these design concepts and design guidelines have affected the development of the severe accidents at each reactor.
Regarding the organization and its risk management capability,
the potential problems in plant operation on catastrophes have been examined.
This includes problems with radioactivity, evacuation directives, and the relationships among local government bodies.
And, regarding disclosure of information, we also investigated whether the authority disclosed gained information to the public appropriately,
and if not performed, what the issues were.
These are the main issues of our investigation.
To state our conclusions in one sentence,
the greatest lesson was not that assumptions toward tsunami were too optimistic,
but that there was no such design philosophy and guideline that "no matter what happens, we will not allow severe accidents to happen".
I believe that it was the greatest problem.
In that meaning, the severe accident at Fukushima Dai-ichi 4 reactors was not an act of God but a man-made disaster.
In your handouts,
the Nuclear Safety Commission states in their design guideline that
the AC power does not need to be guaranteed at all times,
and if a substitute power supply is installed and reliable,
a long-term loss of AC power does not need to be considered in the design of reactors.
The biggest cause of the Fukushima accident is in this one sentence.
As cold-shutdown was performed successfully at all the reactors where "at least" one power source was available,
the existence of such an official guideline is a big, big problem.
There was also an error in the design philosophy.
As I recall when I was involved in designing reactors,
there was a fundamental design concept that the primary containment vessel will stand as the last bastion.
There is also another one, called probability theory, where the design conditions are evaluated based on the probability.
For example, "possibilities for those events to happen is such and such" or "an over 20 meter high tsunami will only come once in a thousand years
and 10 meter high one is such. So we need to consider events with up to this probability".
This is a method of Professor Rasmussen in MIT, but it was the mistake.
In other words, to bring about cold shutdown no matter what happens,
the heat sink and cooling system are needed. No matter what happens, water, air, or some method of cooling system and electricity must not be lost.
It cannot be based on probability. Because when it happens, it is 100%.
Once the plant is activated, then it must be stopped by any method. This has to be the essential mindset.
But in reality it was thought that when the worst accident happens, the containment vessel will protect it.
In actuality, the reactor pressurized vessel was melted through, and hydrogen and fission products seeped out of the containment vessel,
so believing the mythology of the containment vessel is a very large mistake.
This mythology was also used at a resident's orientation session, but I believe we should admit that this was a mistake.
As I mentioned earlier,
there is a huge mistake in the design guide indicating that it is unnecessary to consider the long-term loss of all AC power supplies.
Another problem is the distinction between normal use and emergency use.
This time, as the emergency diesel engine's inlet for water is next to the one for regular use, they were both swept away.
They were all lost simultaneously.
So, when thinking on it now, it lacks common sense to place the power supplies of both custom and emergency systems in the same fashion,
but it was designed in that way.
Also as the melt-down was not assumed,
such an accident was not assumed that large quantities of hydrogen were accumulated simultaneously.
Therefore, the method of releasing hydrogen as well as handling fission product was not considered in the design.
The occurrence and dispersion of hydrogen were not foreseen. No detectors and no way to release it.
Important to say, there were a few random things that prevented a major catastrophe though they were not in the original design.
One of these is that there was an air cooling diesel generator in Fukushima Dai-ichi's 6th reactor.
Even when all the other (water cooling) diesel engines and batteries were sunk,
because this air cooling device existed, and because its heat sink was the air,
the diesel generator functioned and reactor six, as well as reactor five that shared the power supply with reactor six, was cooled and shutdown.
This was not in the original design.
It was added later and happened to be water cooling type, and could function as a cooling system by using air as its heat sink, eventually.
Regarding recommendations,
if we discuss about the re-activation of the nuclear power plant, and in order to prevent such a severe accident from ever happening again,
it would be imperative to clarify responsibility of those mistakes and problems stated in our report.
For example, who was responsible for the official design guideline in the regulatory authorities?
Why had such an erroneous guide been made, and has been left alone as it was for a long time? Many other issues are included in the report.
In spite of the fact that it is a man-made disaster, no one has taken responsibility for the accident yet. Should it be allowed?
Also, it has been said, "next time we will set the tsunami assumption of 20 meter" and so on.
But it is necessary to consider the possibility that a much more severe accident can occur.
So we must change the design concept to "no matter what happens, power supply, cooling source, and ultimate heat sink have to be secured".
Any nuclear reactor that cannot meet this requirement must not be re-activated.
This is our second recommendation.
On the third recommendation,
even though three emergency power sources were lined up at each reactor of Fukushima Dai-ichi, they were all washed away.
In other words, what was needed is not the multiplexing of the same mechanism,
but multiplexing of different mechanisms with different fundamentals.
Also, three independent systems of accident management such as the one for normal, emergency, and extreme emergency are necessary.
And when a situation goes into catastrophe mode,
plants must share information in real time with local authorities, and decide together on the procedure of evacuation, refuge, or so on.
It is necessary to create offsite facilities or platforms which are available to stakeholders
including local and central governments even under a grave accident. In the future, the command of the self-defense force would also be deliberated.
Nearly all of the world's nuclear reactors are built with the same design concepts as the ones in Fukushima,
so there is a possibility that the same problems can be precipitated.
We have to secure an ultimate heat sink and power supply to the reactor, no matter how severe the accident would be
such as an airplane crash or a terrorist attack. The cooling system must continue functioning.
I hope that this point will be shared over the world.
Regarding loss of "external" power supply, the earthquake had caused much damage.
At Fukushima Dai-ichi, from line one to six, all six external power lines have been lost by the earthquake. This is too weak.
So, securing the power onsite is the key.
As mentioned, the long-term loss of power caused the fatal damage.
All of the emergency power devices excluding the previously mentioned reactor six are submerged.
The cooling pumps and motors that have been placed on the sea side have been damaged.
All the DC batteries are submerged except for the one at the reactor 3 at Dai-ichi.
There were power panels for intake of external power, but all three were submerged.
So the situation is much more severe than had been previously reported.
This is a damage that was caused by a giant tsunami that surpassed any assumption,
but the true reason of the Fukushima accident was not the optimistic assumptions of Tsunami height.
Because the inlets for coolant to emergency power supply that are lined up on the sea side
could be washed out by even much smaller Tsunami, say five meter high,
and also because existence of air cooling emergency power that was not submerged became the boundary line between life-or-death.
So, as far as considering design concepts,
if it was focused on just this one point "secure power and a cooling source under any circumstance", the accident should have been avoided,
and could possibly be avoided in the future.
I also believe that the design policy, that is represented by one sentence of "it is unnecessary to consider loss of all AC power over
a long period of time" stated by the Nuclear Safety Commission, disregards this extremely important point.
This is the direct causes of the major catastrophe at Fukushima.
Let me talk about a message to the public.
If you see sheet one, Fukushima Dai-ichi's meltdown had already begun on the night of March 11th.
Then the hydrogen explosion took place on the next day, implying that the reactor went into complete meltdown sometime during midnight of 11th.
In other words, there was too much of a disassociation with the public announcement stating that a meltdown had not occurred,
and not admitting the core meltdown even after a month had passed.
I believe as our research has disclosed with these facts very clearly, and the real information existed there.
Therefore, the question, whether disclosure of information to the public and international society was appropriate or not, still remains.
On the other hand, at that time much rumor and speculation was generated, but as far as we have found,
there is no data to support those rumors.
For example, one of the rumors is that events and meltdown of Fukushima Dai-ichi was accelerated because infusion of sea water
or implementation of vents was delayed. As far as we have examined, there are no data supporting this assumption.
Another rumor is that because large-scale pipe rupture occurred due to the earthquake, event development at reactor one was accelerated.
We have not found any evidence supporting this theory during the research.
Another rumor is that because the containment vessel in reactor one was a Mark I type, the accident in this reactor was significantly accelerated.
In Fukushima, reactors one to five contain Mark I types and only reactor six contains a Mark II.
As far as seeing the cause of the accident in all six reactors, there is no difference between Mark I and Mark II.
Also there is a speculation that there was extreme operational error at Fukushima Dai-ichi, which accelerated the event progression.
However, as far as we have examined, this is also false.
Of course, in the pitch dark where the meters could not be read, I would not say that there were completely no errors.
Also there are some saying that
the main reason for the hydrogen explosion was the meltdown of used fuel,
but evidence supporting this idea has not been found, either.
The main cause, as I have mentioned previously again and again,
is in the fact that the safety concept and design philosophy was flawed.
It has to be that power and cooling source to the plant have to be secured regardless of the circumstances.
And regarding future recurrence prevention, I strongly recommend we discuss this point more specifically.
At last, even in this major earthquake, all nuclear reactors have scrammed normally.
It has been a major pending question at the time of design
whether it would really scram during an earthquake, in other words, whether inserting the control rods would really stop the reactor or not.
However, following the Kashiwazaki Kariwa nuclear power plant case,
Higashi-dori, Onagawa, Fukushima Dai-ni, Dai-ichi, and Tokai, all reactors have scrammed so far.
It is a notable fact, and that even large-scale pipe rupture has not occurred.
Also the operation team at Dai-ichi, who were handling such catastrophic problems onsite amidst the extreme danger right after March 11th,
had no choice but to use their ingenuity above the manual, in conditions with no power.
We believe this is not something to be blamed, but that they should be commended for their efforts.
Regarding the contents of the report, all 189 pages will be made public on a web site.
And this press conference, my explanation, and detailed explanation of the report will be in viewable format by this evening.
Live video of this debriefing will be covered on YouTube and Ustream after six o'clock today.
In other words, this report in its entirety will be available for the public tonight.
On the other hand, regarding the PWRs,
the deliberation has not been concluded, but with all of your cooperation, I would like to continue.
We will not accept media coverage, regarding related questions.
But if there are thoughts regarding the fact such as "Is this a mistake or not?", I would be glad to receive e-mails and answer them.
This is the end of my explanation.
Special thanks to: Ms Jewel Naruse Ms Seiko Toyama Mr. Curtis Hoffmann Ms Keiko Sato