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Tuesday, 23 September 2014

Helplessness as reactor 2 lost cooling On verge of meltdown, operators feared evacuation of Tokyo possible

  Reporters in protective suits crowd around Environment Minister Goshi Hosono and Fukushima No. 1 head Masao Yoshida (at rear) in the emergency operation center of the wrecked nuclear plant on Nov. 12, 2011, the first time the media was allowed on-site after the Great East Japan Earthquake and tsunami had triggered the three core meltdowns eight months earlier. Right: Yoshida in May 2011 oversees the emergency response headquarters set up to contain the crisis.

This is the ninth in a series on the Fukushima nuclear catastrophe based on the accounts of people who struggled to contain the crisis in its early stages. Job titles and ages are as of March 2011.

While reactors 1 and 3 at the Fukushima No. 1 nuclear complex suffered core meltdowns, the cooling system for reactor 2 continued to work for three days despite the loss of power following the earthquake and tsunami of March 11, 2011.
The fact that the reactor 2 core isolation cooling system lasted much longer than expected was a “blessed relief,” Fukushima No. 1 chief Masao Yoshida would later say. If it hadn’t been for that, all three units could have spun out of control simultaneously.
Reactor 2′s cooling system finally stopped functioning at 1:25 p.m. on March 14. With no electricity to reactivate it, workers had to depressurize the reactor pressure vessel housing the nuclear fuel so that firetrucks could pump in seawater.
Using car batteries to manipulate valves and release steam from the vessel, the depressurization process finally started at 6:02 p.m. About 20 minutes later, however, the central control room for reactors 1 and 2 reported that the water level had drained to 3.7 meters below the top of the nuclear fuel in reactor 2, leaving it fully exposed. There was also no sign the seawater was entering the reactor.
Just then, a member of Tokyo Electric Power Co.’s firefighting unit returned to the emergency response office and said the firetrucks that were supposed to be injecting water into the reactor had run out of fuel. Yoshida, 56, had already issued instructions that the trucks be kept refueled on a continuous basis.
“Didn’t I tell you?” Yoshida asked, looking up helplessly from his desk at the center of the emergency response office.
Yoshida would later recall that this felt like a “turning point,” beyond which “we had run out of all options and I thought I might really die.”
With no time to lose, the firefighting team immediately rushed back to the firetrucks, having to carry the fuel containers themselves because the tanker had a flat tire after driving over rubble scattered by the hydrogen explosion that had ripped through the reactor 3 building earlier that day.
In the emergency response office, Toshiko Kogusuri, 55, of Tepco’s management team, had been secretly ordered by the head of the team to secure as many buses at the plant as possible. Kogusuri felt Yoshida was starting to consider an evacuation. She asked officials of partner companies in the office building to lend their buses, saying she needed them for on-site transportation of workers.
That was a lie, but the companies did not ask questions and agreed to cooperate.
Just before 8 p.m., about 700 Tepco employees and 150 other workers from other companies, including plant manufacturers and Tepco-affiliated firms, were inside the building. More than 90 minutes had passed since the firetrucks had stopped injecting water into the reactor.
Yoshida felt he should no longer keep contract workers, who had worked day and night from the beginning of the crisis on March 11, on-site.
Many workers were sitting in a corridor on the second floor and on the stairs of the office building. Yoshida went up to them and said: “Thank you for dealing with the situation until now. It is OK to go home. Please evacuate carefully as roads on the way may have caved in.”
He spoke in such a calm tone that the workers did not realize the gravity of the situation.
The contract workers all departed, some in their cars, by roughly 8:30 p.m., leaving only Tepco employees at the plant. By that time, Kogusuri had managed to secure six buses. Yoshida then asked the head of Tepco’s management team whether there was any place people could evacuate to.
Tepco’s local thermal power station and the Fukushima No. 2 nuclear plant were nominated. The team head told Yoshida that the No. 2 plant was ready, having prepared a facility for the injured and a gymnasium to house the others.
At about 8 p.m., the injection of seawater into reactor 2 started after the firetrucks had been refueled, to the relief of the emergency response office. Even so, the situation remained tense because radioactive steam still had to be vented from the reactor to prevent the containment vessel from rupturing, which would expose the nuclear fuel to the external environment.
With workers unable to operate the venting valves, the pressure continued to build, to the point that the water injection had to be halted again.
Shiro Hikita, at 56 an experienced leader of one of the equipment restoration teams, felt that the reactor’s containment vessel could break at any time. “If there was a switch somewhere to end this situation, I would go out there to push it. I wouldn’t even mind dying in order to do it,” he thought to himself.
Early on March 15, silence engulfed the emergency response office as the point of no return neared. Yoshida stood up and started staggering around, mumbling to himself, “It’s all over.”
As he returned to his seat, he leaned back in his chair, crossed his arms and closed his eyes.
He was later quoted by aides as saying that he was thinking about what might happen if the reactor 2 containment vessel failed, discharging a catastrophic amount of radioactive materials: Tepco would have to abandon any pretense of controlling the situation inside the No. 1 plant and might even have to abandon the No. 2 facility. People from Fukushima to Tokyo, about 220 km away, might have to evacuate.
He could not think of a way to avoid such a scenario.
Hikita, the equipment team leader, saw Yoshida’s body slide from the chair onto the floor. At first he thought Yoshida had collapsed but then realized he was sitting cross-legged as if meditating. With his eyes closed, Yoshida did not move for several minutes.
Yoshida later said he was calling to mind the faces of his longest-serving colleagues: “There were about 10 or so. I thought those guys might be willing to die with me.”
At that point, the building housing the emergency response office was still the safest place at the plant, but there was the risk of contamination if the reactor 2 containment vessel ruptured.
Yoshida was searching for the right time to allow Tepco employees to leave the plant, except for a skeleton crew to keep watch over the reactors’ condition and to continue the water injection process. But even if all of his crew stayed on-site, there was only so much they could do, Yoshida thought to himself.
Source: Japan Times
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