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Wednesday, 10 September 2014
The Yomiuri Shimbun learned on Aug. 29 the full details of remarks made by the late Masao Yoshida, former plant manager for Tokyo Electric Power Co.’s Fukushima No. 1 nuclear power plant, to the government’s investigation committee on the nuclear accident at the plant. The following is a summary of Yoshida’s account of what happened at the plant for the five days immediately after the March 11, 2011, disaster.
March 11: Wrong impression about reactor water level
After the tsunami struck, Yoshida was shocked to face the unprecedented situation of a total power outage. The personal handy-phone system (PHS) at the plant had stopped working, and reports he received from within the plant were too confusing to grasp exactly what was happening. Yoshida regretted immensely not realizing that the isolation condenser (IC) at the No. 1 reactor had stopped working.
Total power outage
Investigation committee : What did you think to do after receiving a report that the plant had lost all AC power sources?
Masao Yoshida : “To be honest, I was stunned. I thought the situation was grave. There was a strong possibility of this escalating into a severe accident, so we would have to start making preparations, I thought. My first thought was, “It’s a calamity.” I didn’t know if the plant had been submerged under water at that point, so I first considered if we could power up the emergency diesel generators. If we still had access to the IC or reactor core isolation cooling (RCIC) pump, we could cool the reactor core for several hours, but thoughts about what to do next were going around in my head.”
Q : What did you decide to do after finding that the emergency diesel generators were not operational?
A : I was in despair. As we were not able to use the emergency reactor coolant [pumps], I told [my subordinates] to find a way to cool the core. I myself thought about it, but I didn’t know the clear answer. I knew, according to the accident management manuals, that we could engage the diesel-powered extinguisher pump, but we soon learned we didn’t seem to have enough filtrate, so this solution seemed very unlikely. We were talking about how, in any event, we still had to think about how to supply water to the reactor and that we’d better investigate whether there was a pump we could bring online by using a power panel from the No. 2 reactor.
Q : In terms of preventing core meltdowns, how long did you estimate the RCIC, IC, etc., would last?
A : I figured we had 8 hours before they shut down.
Awareness of the state of the IC system
Q : At 6:18 p.m., the person on shift opened and then closed the IC valve. Had you received any specific information on what was being done to the valve?
A : We had no such information. At the very least, I did not hear anything about it.
Q : This means the IC may not have been operational. Did you not receive any report to that effect?
A : We did not. The person on shift had the understanding that the IC system was online the whole time.
Q : You were under the impression that the system was online and operational?
A : That was my understanding. We had confirmed that the IC had a sufficient water level, so I thought it was working. We hadn’t received any specific information about valves being open or closed. We assumed it was working.
Q : Putting the particulars aside, were you aware of any information indicating that the IC was not working properly?
A : We were not. One of the things I now regret is that we got no information from the reactor group leader, nor did we know if the manager on duty was in communication with the reactor group leader. Information of that sort was primarily shared via the reactor group leader, and there was no protocol in place whereby the manager on duty would call me to provide that information. I should have personally confirmed at several stages whether the IC was truly OK. Partly, I was operating under a false apprehension, assuming that the IC was working because the water level was, to a certain extent, regular. At the very least, I received no emergency SOS call. If an SOS had come in, I would have moved to dispatch people, but since I was watching all of the plant operations and data as a whole, and not just the No. 1 reactor, giving specific instructions to my subordinates was not easy. I was under the mistaken impression that the reactor had sufficient water levels; I am racked with regret that I did not ask for specific confirmation of this fact.
March 12: No intention of halting the seawater injection
As the three nuclear reactors were entering a state of crisis, Yoshida decided to begin cooling them with seawater even at an early stage in the situation. However, TEPCO headquarters in Tokyo remained unable to make necessary decisions on its own, and urged Yoshida to stop cooling the reactors with seawater, citing the lack of permission from top government officials at the Prime Minister’s Office. But he decided to continue the process, saying, “I’ll go ahead at my own discretion.”
Explosion at the No.1 reactor
Investigation committee : How did you come to know of an explosion at the No.1 reactor?
Yoshida : We had just finished making preparations for boric acid injection [to suppress nuclear fission] at the No. 1 reactor. We were just a button push away from completing the cooling injection from the central control room. But then, there was a sudden, very short vibration, as though [the floor] had been thrust up from below. First, we presumed there was probably another earthquake. However, we received a report from the accident site that there was probably an explosion at the roof of the No. 1 reactor building.
Q : When were you informed of the possibility of it being a hydrogen explosion first discussed?
A : By the end of that day, at least, we came close to concluding that the blast had most likely been an explosion of hydrogen from the reactor’s containment vessel.
Q : Were you aware that its reactor core had been exposed and damaged?
A : Yes, we were aware of that.
Q : When did you issue your first order for seawater injection?
A : On the afternoon of March 12, I started telling the workers to begin making preparations for seawater injection, as our supplies of freshwater were drying up. My final decision [on the seawater injection] was made at 2:54 p.m., but it came after we had given it a lot of consideration.
Q : Had you heard of any case involving seawater injection into a nuclear reactor before then?
A : There had been no such case anywhere in the world, but we had no other choice but to use seawater when it came to securing an unlimited supply of water. I had only two things in mind at that time. First, I wanted to lower the pressure inside the containment vessel at all costs. Second, we had to continue pouring water into the reactor.
Q : Injecting seawater meant the reactor would be disabled. Did you ever feel that you had to do the best you could to deal with the situation while using only freshwater to cool the reactor?
A : Not in the slightest. The fuel rods had already been damaged, so we were certain the reactor had already been rendered useless. Our highest priority was to control the reactor. I never thought about the idea of putting the plant back in service.
Q : The seawater injection was recorded as beginning at 8:20 p.m., but TEPCO’s announcement put the time at 7:04 p.m. What is the source of this gap?
A : Immediately after the injection started at 7:04 p.m., Ichiro Takekuro [of TEPCO], who was stationed at the Prime Minister’s Office at that time, telephoned us to order the halt of seawater injection, citing the lack of permission from the Prime Minister’s Office for seawater injection. “Stop it without arguing,” he told us. We had consultations with TEPCO’s head office, and told them the ongoing seawater injection was being conducted on a trial basis. And it was decided that the seawater injection would be suspended.
However, I didn’t have the slightest intention of halting the process. I told myself that since there was no guarantee about when the seawater injection would be resumed, I would do it at my own discretion. Therefore, I told people at the TEPCO head office’s roundtable that the process would be suspended, but I said to a disaster management group leader at the site, “I’ll tell them the seawater injection will be halted, but we must not stop it at any cost.” Then I told the headquarters that the injection had been stopped.
Prime Minister Naoto Kan’s visit
Q : At what point were you informed [then] Prime Minister Kan would visit [the crippled facility]?
A : I hardly remember at what time it was, but probably about one hour before he arrived, I believe we were notified that he was en route by helicopter. So I think we received information [about his visit] at around 6 a.m.
Q : What were you told was the reason for his visit?
A : I had no idea.
Q : Who dealt with him at the Fukushima No. 1 plant?
A : I was the only one to do so. At the time, I had issued instructions [for the workers] to continue venting the reactor. Our mobile phones and PHS didn’t work, so I told them to come to me in person if they had anything to report to me.
Q : What did the prime minister talk to you about?
A : In an extremely stern tone, he asked, “What’s the situation like?” I responded by saying: “Nearly all power supplies are dead. The situation is uncontrollable.” I explained why, and he raised questions for [then] Nuclear Safety Commission Chairman Haruki Madarame. I was also asked what had become of the venting procedure. But that is all I remember. I told [Kan] the workers were going through extreme difficulties, though we were doing everything we could. But we didn’t talk for too long.
Q : Did you explain [to Kan] about the extent to which the situation was critical?
A : The atmosphere was so tense I was unable to talk sufficiently. I don’t think I was able to explain fully enough. The atmosphere was such that I never felt free to speak. All I could do was answer questions from the prime minister.
Q : Did the prime minister go to a room that had a round table [at a special quake-resistant building] and give a word of encouragement to the workers?
A : No. He just came, sat down, and left.
Q : Did time tick away at the site in a situation in which the RCIC system could go down at any time?
A : The No. 1 reactor fell into a state of crisis first, and then the No. 3 reactor. A crisis [like an explosion] could have erupted at any time then. We were short of workers, and, honestly, I was panicking. All we could do in dealing with any of the reactors was to keep injecting water into them and venting them. Under such circumstances, the No. 1 reactor exploded, and I struggled to gather information about it. At the same time, I tried to check any changes in the state of the Nos. 2 and 3 reactors, and issued necessary instructions. Everything was in turmoil, and I could not afford to logically think about what should be done and with what timing. Whatever idea crossed my mind, I immediately issued instructions [to try it].
March 13: Seawater injected ‘at my discretion’
On March 13, radiation levels sharply rose around the No. 3 reactor. This made Yoshida aware that there was an increasing possibility of a hydrogen explosion at the reactor, which was apparently losing its cooling water — an incident that had already struck the No. 1 reactor. Adding to the sense of anxiety felt by Yoshida and his personnel was the fact that large quantities of spent fuel in the pools of the Nos. 1 to 4 reactors were far from adequately cooled.
Changing sources of water
Investigation committee : At 2:42 a.m., the No. 3 reactor’s high-pressure coolant injection (HPCI) system was halted, and preparations were being made for the injection of seawater as a coolant. What happened by the time the source of water was switched to freshwater from fire trucks at 9:25 a.m.?
Yoshida : I have no memory of having received stern instructions from TEPCO’s head office not to use seawater. Therefore, I decided all we had to do was inject whatever water was available at that time, freshwater or seawater. That means whichever method was easier would suffice.
Q : Did your authority as manager of the plant include making a decision about whether to inject water?
A : If you carry out ordinary procedures for using [equipment at the facility], you only have to follow the protocol stipulated in our operational manuals. But injecting seawater into a reactor was an unprecedented experience for us. Adopting a procedure of that nature was beyond the bounds of our manuals. I was convinced that the procedure should be completed at my sole discretion.
Crisis at the No. 3 reactor
Q : TEPCO’s records show radiation levels registered 300 millisieverts within the consecutive doors leading into the reactor building, and also that there was whitish smoke nearby. Do you recall conditions like that?
A : Yes.
Q : Was it before the No. 3 reactor exploded?
A : Yes, before an explosion took place there.
Q : When you received that report, what did you think had happened at the No. 3 reactor?
A : I assumed that the No. 3 reactor’s fuel had been damaged just as in the No. 1 reactor, and that steam and other leaks from its container were starting to fill its building.
Q : A series of problems occurred at the No. 1 reactor, and all this led to a hydrogen explosion there. You said that, at the time, you thought hydrogen was filling the upper part of the structure, though it was unknown what was causing this. Did you think the No. 3 reactor was in the same condition?
A : Naturally, I thought as much.
Q : Did you go so far as to predict when [it would explode]?
A : I wasn’t sure, but I had an idea that there was a growing possibility of an explosion.
Q : Does that mean people at TEPCO, including those at its head office, remained unable to find a workable way [to defuse the crisis] despite studying how to respond to the situation?
A : Exactly.
About spent fuel pools
Q : Did you feel you would have to come up with a means of dealing with the fuel pools?
A : I guessed so from the beginning.
Q : From the beginning?
A : Naturally, the loss of water meant the fuel pools were not being cooled, so I presumed that the temperature would climb and cause the water to evaporate. I knew something must be done to deal with the situation.
Q : Does all this mean there was the need to monitor the state of the fuel pools at all reactors?
A : Yes. However, the No. 4 reactor had just gone offline to undergo a periodic inspection, so all of its fuel was in the pool. All of its 548 fuel rods, used continuously during the course of a year, had been returned to the pool, meaning the fuel pool at the No. 4 reactor was the hottest. This means it had been left in the most difficult state.
March 14: I thought I might have to commit suicide
After the hydrogen explosion at the No. 1 reactor, Yoshida felt an impending sense of crisis concerning the Nos. 2 and 3 reactors. With high levels of radiation being produced, and lacking materials, he was unable to take the measures he intended, and his frustration with the Prime Minister’s Office and with TEPCO headquarters, which did not understand the situation on the ground, was mounting.
Confirming the No. 3 reactor’s status
Investigation committee : We assume preparations were being constantly made as dawn was breaking. There was a certain period of time between the HPCI system going offline and the water injection beginning. As plant manager, what was your understanding of the condition of the No. 3 reactor’s core?
Yoshida : I figured this was the end of the plant. That is to say, I wanted to inject water sooner, but in the end, a range of circumstances piled up and conspired against us.
Q : At the time were you aware that a considerable portion of the fuel rods was exposed?
A : I focused only on getting water to the reactors and venting pressure on the containment vessels, but the situation was not yet ready to get us where we needed to be. Other people have made all sorts of criticisms, like saying we were “slow,” but from my point of view, if they can say that with such ease, I’d like to say, “Then, you should try to fix it under the circumstances.” I get pretty riled up when this comes up. Three reactors were on the blink right before my eyes, and we were working with an understaffed crew. I will never forgive anyone who calls us “slow” under those circumstances.
Q : So, after the hydrogen explosion and until you realized there was radiation leaking, it did not occur to you that you must secure water for the reactor?
A : To the contrary, I feel paranoid about this. No one came to help us in the end. Let me vent my feelings: We were doing all that [work] with such a limited crew, and yet nobody, not from headquarters, not from anywhere, came up with a substantial, effective rescue. I have a ton of pent-up resentment about the way no one helped us in our hour of need.
Explosion at the No. 3 reactor
Q : Did you discuss the issue about [radiation] leaks during videoconferences with TEPCO headquarters?
A : As far as I was concerned, I did. I explained that the No. 3 reactor also had its fuel rod damaged and that, based on the pressure in the containment vessel, it was approaching the same condition the No. 1 reactor had been in. There was a risk of another explosion at 9:30 a.m. or 10 a.m. on March 14, so I called for an evacuation of all personnel at that time.
Q : Where would personnel take refuge?
A : In the special quake-resistant building [on the plant grounds]. I realized there was a risk of a hydrogen explosion, so I called for us to decamp. However, when discussing this with headquarters, I was told, “Just how long are you evacuating?” I told them that there was a risk of an explosion, and there was no way we could put personnel on the ground. They [headquarters] said to me, ‘Can you get back to handling the site soon?’ The pressure on the containment vessel had dropped a bit. But, when we sent personnel back, it exploded.
Q : After you dispatched personnel, how much time elapsed before the explosion?
A : It was quite short. I issued the order to go back, and almost as we were doing so, it exploded. They said there were about 40-plus people missing from the initial site. That was the first report, and I thought I should kill myself at that point. If that report were true, and some 40-plus people were really dead, I thought I should commit harakiri.
Q : After evacuating from the site, what was the rationale for resuming work?
A : The water injection [at the No. 3 reactor] had been halted, and we also had to make preparations for the injection at the No. 2 reactor. If we left things unattended, conditions would worsen still further. However, there was a pile of debris said to be at the site, so I asked personnel to take immediate measures in advance of the injection — getting clear readings on radiation levels, removing debris and switching out hoses for the bare minimum water injection needed. What really moved me was that, after issuing this plan, everyone moved into action to go back. In fact, I had to tell them not to go based only on their own judgment. At that time, the majority of personnel had already been exposed to excessive radiation. By going back, however, we were able to restart the seawater injection at 4:30 p.m.
Handling the No. 2 reactor
Q : Following the explosion, where did you think to prioritize the limited personnel and materials on-site?
A : The water injection, of course. The Nos. 1 and 3 reactors had their fuel rods exposed, so the only option available was, after all, adding more water. I wanted to start cooling the No. 2 reactor quickly, if possible. Making the preparations as soon as possible was a key point here.
Q : What was your thinking about injecting water into the No. 2 reactor?
A : The crucial thing was — well, venting was irrelevant — it was strange to say that was an afterthought, but our first and foremost mission was the water injection. Venting would suffice so long as it reduced pressure on the vessel enough for us to be able to inject water. A call came in from the Prime Minister’s Office and Mr. Madarame came on the line: “Vent it immediately, lower the pressure and start pouring water.” No ifs, ands, or buts. Lower the pressure and get water in. At the time, [then] TEPCO President Masataka Shimizu was holding a teleconference, and he was screaming that we should follow Mr. Madarame’s orders. “Easy for you to say, without knowing the situation on the ground,” I thought.
Q : Perhaps their instructions sounded irrational?
A : Everyone thought that way. Even I wanted, more than anybody else, to inject more water into the reactors. But there were appropriate procedures in place. Everyone thought that the personnel on-site could just do what needed to be done, and then everything would go smoothly from there — but it’s hard for them to understand. Everyone thought we hesitated. There was no hesitation on our part. The same goes for venting the No. 1 reactor on the first day. I’d like to beat up those who say we hesitated. I wanted to lower the pressure and start injecting water immediately, no matter the consequences, even if it ran afoul of Prime Minister Kan. That was the only thing on my mind, achieving that objective. Yet, in spite of that, these guys have the nerve to say things that suggest we somehow hesitated. I will get even with every one of them in one way or another.
March 15: Bigwigs patched in by videoconference
Regarding the uproar over the “full-scale retreat,” Yoshida explained that on the morning of March 15, personnel not involved in the disaster response had decamped to the Fukushima No. 2 nuclear power plant, leaving only key personnel behind, and that there was no truth to the notion that everyone had abandoned the site. He indicated that, although there had been some confusion around the evacuation order, it was an appropriate measure to have taken.
On the retreat issue
Investigation committee : At the time, you were wondering whether you would survive the accident when, at around 5 a.m., Mr. Kan arrived.
Yoshida : At headquarters, you mean.
Q : Correct, at headquarters. He arrived at the main division at TEPCO headquarters and was patched in via the teleconference room.
A : I don’t quite know whether that was a teleconference room or not. I don’t know what conditions were like at headquarters, but we got word that Mr. Kan was coming, and there was a seat set up for him, and on this side there were seats set up like where the chairman and company executives might sit. How should I say, it was like a video or teleconference set up from headquarters. So that was set up and we waited until 5 a.m. It wasn’t exactly 5 a.m. — I think a bit later — when Mr. Kan showed up. At first it was Mr. Shimizu, and [then Chairman] Tsunehisa Katsumata and executives below them but above the level of managing director. There might have been some department directors there, but I don’t know. I wasn’t watching that, so asking TEPCO headquarters would get you the most accurate response. So Mr. Kan asked why so many people were gathered for the meeting. I don’t remember the specifics, but I do remember that he was very upset and ranting and raving.
Q : And you told Goshi Hosono, then special advisor to the prime minister, and the others that a retreat was necessary amidst the dangerous circumstances.
A : We never said everyone should retreat and that we would abandon the site. I would stay behind, as would personnel manning the operation. I feared the worst, so I asked them to start preparing the necessary policy measures, and I told them I would be having nonessential personnel evacuated from the site. Those were the only two things I said.
Q : I understand that at 10 a.m. on March 15, or some time that morning, staff at the general manager level began returning. Personnel evacuated to 2F [the Fukushima No. 2 nuclear power plant] were to return, and I spoke to them, and they said that certain personnel were instructed to come back first.
A : As a matter of fact, I never told anyone to go to 2F [in the first place]. This, again, was like “whisper down the lane.” We talked about if, in the event that we were to evacuate, 2F would be a good possibility, so we talked about decamping and preparing vehicles. The person transmitting the message told the driver to go to 2F. What I said was to find a place, whether on-site or not, near the Fukushima No. 1 plant, that had low radiation levels, and temporarily decamp there and await further instructions. Somehow this got misconstrued and they went to 2F, so we had to just leave it at that. After they arrived there and contacted me, I told general manager class personnel to return first, so that’s how it turned out.
Q : Is that so? That being the case, it would mean that you were considering remaining at a location near the Fukushima No. 1 plant with low levels. For example, inside a bus, if that location had low readings.
A : At the time, the No. 2 reactor was the most dangerous in terms of radioactivity or radiation levels. The quake-resistant building was also nearby, so my intent was to have personnel leave the dangerous vicinity of the No. 2 reactor and temporarily decamp to somewhere with lower levels, be it the north or south side or somewhere else. However, now that I consider, everyone was wearing full face masks. Decamping nearby for long hours would probably mean facing death, so, putting it into perspective, it made sense to go to 2F as a far safer alternative, to go there and remove the masks and recuperate, so that is what we went ahead with.
Q : Sometime between 6 a.m. and 6:10 a.m. on March 15, the pressure in the pressure suppression chamber suddenly dropped dramatically and hit zero. What happened around that time?
A : There was the sound of an explosion.
Q : So there was a sound. Was this audible from the quake-resistant building, or could it be felt? Was there an impact or noise?
A : That morning, Prime Minister Kan was slated to visit TEPCO headquarters, so we were patched in to headquarters via teleconference. We were in the quake-resistant building and watching the teleconference feed, when we got word that the measurement had reached zero, along with a report that there had been a popping sound. In the worst possible event ... the pressure reaching zero in the pressure suppression chamber [located on the bottom of the containment vessel] could mean that the containment vessel might have broken. Thinking conservatively, this meant the vessel might have been destroyed, and that popping sound would suggest some sort of breakage. This was not fully confirmed, but, using that as a premise, I decided to treat this as an emergency and issued an evacuation order, leaving only core maintenance management personnel and those related to the operation to stay. I gave an order for all other personnel to temporarily evacuate from the site.
Q : At around that time, something happened at No. 4 reactor.
A : Next, personnel who went to the central operating rooms for the Nos. 3 and 4 reactors came back with a report that the No. 4 reactor was in a dire state. So we still had no idea if that popping sound had come from the No. 4 reactor, or from the pressure suppression chamber at the No. 2 reactor, or if something else had broken. All of these events took place at approximately the same time, so we had no leads.
Q : What did the prime minister and others initially come to do?
A : I don’t know whether they came to give a rebuke, pep talk, or what, but in essence, the president, chairman and all the directors below were seen on the teleconference. Without haste, and a bit later than them (TEPCO executives), the prime minister came at, I think, a bit after 5 a.m., though I don’t recall exactly, and he seemed extremely angry for some reason. That is to say, I don’t really recall what he said, but he seemed to be furious at the way things were being handled. I do recall him being angry. He eventually said he hadn’t come to have a discussion with so many people present, and while he was ranting about changing the location, events were unfolding on-site.
Q : So those events happened when they were over there at the other end of the teleconference.
A : Correct. And it was at that time that I gave the evacuation order.
Q : Such that the other participants in the teleconference could have heard you.
A : At the time, the prime minister was in a different room from the one the conference was being held in. I don’t remember the exact order in which things happened, but when we got word that he was coming, the first thing onscreen was a room other than the usual conference room. It was somewhere at headquarters. Midway through, he started demanding on changing the venue, and then there was the issue on-site at the reactor. The next feed was with the main office at headquarters and the teleconference room, and I stated that I was evacuating personnel. There was pushback that the containment vessel would surely not explode because there was still pressure, but I countered that the pressure gauges could not be trusted. So, thinking in terms of safety, or the lack thereof — in other words, things were in an extreme state at the site — I stated my intent to prepare buses and evacuate.
Q : So there were people at headquarters who expressed the opinion that the containment vessels still had some pressure left?
A : Thinking in terms of safety, the evidence up to that point could suggest some sort of breakage, which meant there was a strong possibility of radiation leakage, so I said we would do a temporary evacuation, and we arranged buses to go to 2F.
Source: Yomiuri Shimbun