Читать книгу Meltdown - Yoichi Funabashi - Страница 34

When Unit 1 exploded, the cooling of the Unit 3 reactor was continuing. This was because of the high-pressure coolant injection (HPCI) system, which turns on automatically at the time of an accident. HPCI is the trump card of nuclear reactor cooling in the case of AC power failure.

However, it should not be relied on indefinitely. After lowering the reactor pressure so that it would be easier to put water in, it was necessary, at some point, to switch to alternative pumping, which uses firefighting trucks.

On the night of March 12, the duty head of Units 3 and 4 consulted with the head of the ERC in the Anti-Seismic Building concerning his wish to stop the HPCI and switch over to the next method of water injection. The head of the ERC replied, “Stopping it is unavoidable.”

At 2:24 a.m. on March 13, the operator stopped the HPCI manually. But the valve to lower the pressure of the nuclear reactor wouldn’t open. DC power supply was needed to start up the HPCI. The green light was on, showing that there was such a battery …

Ten minutes later, the operation was tried again, but it did not start up. In a flash, the reactor pressure shot up.

3:52 A.M., MARCH 13. Videoconference.

Yoshida: “Well, I am getting in touch because something has changed, it is Unit 3.”

Head Office: “Yes, Unit 3.”

Yoshida: “It is the HPCI, it was stopped momentarily at 02:44. After the HPCI was stopped, the reactor pressure has … increased fivefold.”

After close to twenty minutes had passed, the Head Office made an inquiry.

Head Office: “Erm, about Unit 3’s HPCI, did it automatically trip? Or was it stopped manually? Did you manually stop it?”

A few moments passed.

Fukushima Daiichi NPS: “The tripping of Unit 3 was an automatic trip due to the decline in rotational frequency of the turbines, as reactor pressure dropped and the driving force disappeared.”

That was not the case. In actual fact, the operator had stopped it.¹⁷ Yet this information had not reached the ERC at this point. After this, pumping was put on hold until just past nine a.m.

4:13 A.M. The head of Fukushima Daiichi NPS communicated to the Head Office that the outlook was not good for the recovery of the high-pressure pumping equipment. The only option was to proceed with pumping water into the reactor using firefighting trucks. However, pumping water in with firefighting trucks differs from high-pressure water devices in that it is pushed back by the pressure inside the reactor, because its water-spouting pressure is weak.

The head of Fukushima Daiichi announced, “If there is a battery, I think it can work.”

Yoshida asked, as if taken by surprise, “Is a battery being arranged at the moment?”

Someone at the Head Office jeered:

“That is impossible, impossible. How many impossible things will you try to pursue, you idiot, that is a waste of effort!”

Among the engineers who joined in the videoconference, there were also those who expressed their anger and shame at the sense of helplessness they felt about the situation.¹⁸

Yoshida told Head Office, “We know we must open the SR valve, and we were just talking about going with an ‘old fogeys’ suicide squad.’ ”¹⁹

Yoshida said, “We know we must open the SR valve,” but the control panel that opened and closed the safety relief (SR) valve ran on batteries. Accordingly, batteries were needed, but they had not been prepared.²⁰

At the local NERHQ, they attempted to gather up batteries to open up the SR valve from the workers’ cars, but the radiation dose onsite had risen and their protective masks were insufficient.

They needed 120 volts to open the SR valve. If they could get ten 12v batteries lined up, they could, of course, solve the problem. But on that day (March 13), they didn’t even have ten of those batteries at their disposal. So, they removed twenty batteries from the workers’ personal vehicles, brought them into the Central Control Room for Units 3 and 2, and hooked them up to the terminals behind the control panels for each of the SR valves.

In the meantime, staff had been scouring retail stores fifty kilometers away, where Fukushima Prefecture bordered Ibaraki Prefecture, but they were only able to buy eight.

On the morning of March 12, Head Office ordered 1,000 12v batteries, but since the trucks carrying them were not allowed to use the freeway, it was taking time for them to reach the site. Toshiba delivered 1,200 batteries to TEPCO’s Onahama Coal Center. They had trouble securing trucks and drivers to travel from there to Fukushima Daiichi NPS. It was close to nine p.m. on March 14 when 320 batteries were delivered to Fukushima Daiichi.²¹

Around 9:41 a.m. on March 13, Yoshida appealed to the Head Office via videoconference.

“We don’t know for sure if hydrogen was responsible for yesterday [March 12], but it’s crucial that we don’t have another explosion like Unit 1. We need to put our heads together, Head Office included.”

Head Office’s managing director, Akio Komori, responded to that. Komori had served as deputy manager of the Nuclear Power Location Headquarters.

“Maybe that’s it. Open the blowout panels.”

The blowout panels were like exhausts that were opened to prevent damage to the building or equipment in the case of a sudden rise in pressure inside the reactor. Turbine buildings were the main vapor pipes to break. They were attached to the walls of the highest floor of the reactor building.

However, at the time of the 2007 Chuetsu earthquake, Kashiwazaki-Kariwa Nuclear Power Station’s blowout panels were opened, and since then they had been improved to be sturdier and not open easily. This time, they became the enemy and wouldn’t open through sheer manpower. There was a strong possibility that hydrogen was accumulating on the top floor of the Unit 3 Reactor Building. Since the radiation dose was high around Unit 3, however, it would be difficult to go inside to open them.

1:34 P.M., MARCH 13. A voice rang out in the ERC, calling Yoshida, “Station manager, station manager. May I have a word?”

“I’m worried about the haze on the far side of the double doors at Unit 3 (RB) and the fact that 300 millisieverts has been recorded. It’s just like Unit 1 yesterday.”

A white haze had appeared about an hour before the explosion at Unit 1 on the afternoon of March 12. The security team in the ERC was on the watch for this “white haze” more than anything else. They were afraid that a similar situation had emerged in Unit 3. They had to hurry with a response. A proposal was made by Fukushima Daiichi over the videoconference.

“We were talking about, at worst, the blowout panels being blown some distance from the reactor building this morning. I think we should also be thinking about things like that.”

However, the Head Office recovery team objected.

“We’ve looked into various possibilities, but we think that would be difficult in terms of physical problems and safety issues. We believe opening the top floor of the Unit 3 Reactor [building] is difficult.”²²

Around that time, the information from onsite that the Unit 2 blowout panels were somehow open got to Yoshida. It looked like hydrogen could be released from Unit 2. On the face of it, it appeared the danger of a hydrogen explosion in Unit 2 had become remote.

We should narrow our response to Unit 3. Won’t the blowout panels of Unit 3 open somehow?

Besides the blowout panels, perhaps an opening on the first corner of the building could be made.

Yoshida imagined even more “extreme things.”

Maybe the SDF’s jet planes or something could come and open a hole using a machine gun or something like that.

Yoshida urged the Head Office to “think of a way to break open the top of the nuclear reactor building from the outside.”²³

2:45 P.M., MARCH 13. The following exchange took place via videoconference.

Fukushima Daiichi: “If we can’t get close (to the blowout panel), fly in by helicopter and pierce the roof with something.”

Head Office: “We thought of that here at the Head Office, too, but we’re worried that sparks might ignite and we’d end up in the same boat as an explosion …”

Head Office Fellow Akio Takahashi: “We need to think about the question of evacuation as well.”

After a while, the following was also voiced.

Head Office: “Takahashi, it’s pretty preposterous, but how about asking the Self-Defense Forces to blast the panels with firearms, from the ocean side?”

Takahashi: “There’s stacks of important stuff below.”

Head Office: “It’s going to blow anyway.”

Takahashi: “There must be a way of blowing just the top off, you know, like dropping something from above.”

Head Office: “A helicopter might be blown out of the sky …”

There was still no conclusion.²⁴

In that time, the instruction to “think of measures to open the blowout panels” came to Yoshida from NISA via the TEPCO Head Office. Yoshida felt an insuppressible feeling of sickness.

Being told to “think of measures”! All they can do is throw out these stupid orders. ²⁵