Читать книгу Meltdown - Yoichi Funabashi - Страница 26

After leaving Kan, Yoshida returned to the ERC sometime after eight a.m. He gave a direction.

“We’re going to aim for venting at nine o’clock.”

In order to open the necessary valves for venting, someone had to go into the Unit 1 (RB), which they could not get into, because the radiation levels were already rising. Since there was no power, the remote valve operating system was offline. They could only open the containment vessel and suppression chamber valves manually.

The suppression chamber (SC) was a doughnut-shaped container at the bottom of the containment vessel connected to the dry well (DW) by vent pipes. It was filled with a huge amount of water—1,750 tons in Unit 1 and 2,980 tons in Units 2 through 4. During an accident, such as a pipe rupture or when the SR valve was opened and high-temperature steam came rushing in, the steam would be cooled by this water, returning to water itself and suppressing the rise in pressure of the entire containment vessel.

The most important valve for venting was the air-operated (AO) valve attached to the upper part of the SC in the basement of the reactor building. The AO valve consisted of a main valve called the “large valve” and a spare valve called the “small valve,” which were attached parallel to the vent line.

Since neither had a handle, workers could not open them, barring one exception.

This was the “small valve” of Unit 1’s AO valve. The onsite operators were aware of this from blueprints.

Yoshida called for the shift supervisor via the power-generation team at the power plant ERC.

“There’s a danger of considerable exposure. But I want you to go to the site and open it manually.”

The interior of the reactor building had already been placed off limits late on the night of March 11. In short, he was asking for a “suicide squad” to go in. It is not clear who first started using the phrase “suicide squad,” but it is likely that it came from among those on duty at Unit 1 and 2’s Central Control Room. Agreeing to work in an area that was out of bounds could be nothing other than a suicide mission. The shift supervisor acknowledged the request from the power-generation team.²⁰

Five units of logistical staff, about twenty people each, were lined up with members of the Radiation Management Group dressing them, one by one, in protective gear. A woman in her twenties taped up the joints of the protective gear they had donned on her. She had volunteered to stay behind there.

The operators were as white as sheets.²¹ It was not just that the exposure was high.

The shift supervisor, still in his full-face mask and protective gear, was in the Central Control Room on the side of Unit 2. They had to go into the building of Unit 1 and open the venting valves.

The “suicide squad” was divided up into three two-man teams. There was a fear that, if all three teams went to the site at the same time, they would be out of contact with the Central Control Room and unable to carry out an emergency evacuation. So, it was decided that one team at a time would go to the site, and when they had returned to the Central Control Room at the completion of their operations, the next team would go.²²

They would still have to be prepared for considerably high levels of exposure. For that reason, young officers were relieved of their duty and each team was made up of a shift supervisor and other senior officers.²³

To operate its nuclear power plants, TEPCO relied on the workers from its subcontractors, which were referred to as associate companies. The plant control room was the only domain in which the utility bore the sole responsibility and did not rely on subcontractors. It was a hallowed sanctum where the operators shared strong ties and a pride in their mutual professionalism.²⁴

That morning, the first sign of a radiation leak had already emerged.

At 4:50 a.m., the place was in front of the main gate of Fukushima Daiichi NPS. Emission sources could not be identified immediately, but they had occurred at the same time as the almost mysterious gradual drop in pressure in the containment vessel, even though they had not vented.

By five a.m., staff members in the field and central control rooms were told to wear coveralls and full-face charcoal filter masks. Since the dose in the Central Control Room of Unit 1 had risen, staff members temporarily moved to the Unit 2 side, where the dose was lower.²⁵

9:02 A.M. TEPCO verified the evacuation of surrounding residents.²⁶

Two minutes later, the ERC ordered the venting. In response, the Units 1 and 2 Central Control Room Duty Manager Ikuo Izawa (age 52) issued his command.

“We’ve got the order from Emergency Response. Carry out the venting operation.”

A directive had already come in from the ERC around midnight to “choose the staff so you can vent.”

Around three a.m., Izawa told the operators in the Central Control Room, “When we get the green light from the ERC, we’ll go to vent. I want to choose the members … I’m sorry, but I can’t let young people go. On that understanding, those of you willing to go please raise your hands.”

No one said a word. They all looked at Izawa. No one dropped their eyes. Everyone seemed to be looking for words. Five seconds, ten seconds … a silence ensued. It was the fifty-two-year-old Izawa himself who broke the silence.

“I’ll go to the site first. Is there anyone who’ll come with me?”

Kikuo Otomo, a fifty-five-year-old who was standing behind Izawa, volunteered then.

“I’ll go to the site. Izawa, take command until the end. You have to stay here.”

Otomo was head of the Power Generation Unit’s Work Management Group. It was his group’s job to organize the work setup and carry out safety reviews when the reactors were operating and during periodic inspections. Their office was a few tens of meters from the Central Control Room for Units 1 and 2.

The next was Katsuaki Hirano, who was also standing behind Izawa.

“That’s right. You stay behind and take the helm. I’ll go.”

Otomo was older than Izawa by three years and had worked his way up from operator. Although he now belonged to the Power Generation Unit, he had immediately rushed over to the Central Control Room for Units 1 and 2 after the earthquake. Hirano was also older than Izawa, by four years. Hirano was originally supposed to be the on-duty shift supervisor for Units 1 and 2 that day, but had asked Izawa to switch with him because he was scheduled for some medical tests at the hospital. That afternoon after the earthquake, Hirano had returned, in despair, to Fukushima Daiichi NPS and joined Izawa’s team.

The moment the two senior shift supervisors spoke up, the younger members of staff raised their voices. “I’ll go.” “I’ll go, too.”

Izawa felt on the verge of tears. And, as if to hide that fact, he turned to face the whiteboard. He began to write on it the names of some ten people, one by one, in order of their age. He then selected a total of six people—the four shift supervisors and two deputy shift supervisors—making three teams of two each.²⁷

Ikuo Izawa was the eldest son of a local farmer from Futaba Town. As a boy, he had ridden his bicycle over to Fukushima Daiichi NPS and played there with his friends. It was a huge site at the top of a thirty-meter cliff. He liked gazing out at the Pacific Ocean from there. No matter when he came, the sea was always a dark color, and beyond the horizon, a sparkling white.

It was the former site of the Iwaki Army Airfield, an aviation-training base near the end of the Pacific War. Suicide flight training took place here. Young pilots would take off from here to the southern frontlines in search of death. The broad, cracked concrete of the airfield was covered in the residue from salty air.

Construction work suddenly started there when Izawa was in elementary school. Dozens of one-story houses appeared out of nowhere in the forest. So had begun the construction of Unit 1, the first nuclear reactor at TEPCO’s Fukushima Nuclear Power Station.

The houses were a “village” for General Electric, which had come from the U.S. mainland to build Fukushima NPS’s Unit 1. The Americans turned the old airfield’s huge expanse of concrete into tennis courts. There was also a hall and a small park in the village.

Izawa’s gang made friends with the American children in the village. The radio-controlled toys they had were something new. The Japanese kids taught them Japanese marbles and card games, and the American kids taught them how to play with the radio-controlled gadgets.

After the Unit 1 containment vessel was built in June 1968, the Americans disappeared like Cinderella.

Later, after graduating from a local technical high school, Izawa was employed by TEPCO. He had many years of experience as an operator at Fukushima Daiichi Units 1 and 2. In 2009, he had become a duty manager for Units 1 and 2 at Fukushima Daiichi NPS.²⁸

The previous day, Izawa had finished a night shift. That morning, he was practicing golf at a golf park with Ryuta Idogawa, who also worked as an operator at Units 1 and 2 for team D. The fortieth anniversary party of Fukushima Daiichi was to be held soon, and golf park games were one of the attractions during the party. It was supposed to be his day off, but he came to work as the duty manager for the day as a substitute for Katsuaki Hirano, the actual duty manager who was not able to come due to medical tests.

Team No. 1 was Kikuo Otomo and Tsutomu Oigawa, who was forty-seven years old. On top of their protective suits, they were clad in armor-like fireproof gear, rubber boots, masks, and yellow helmets. They carried huge air tanks on their backs. They each put an alarm pocket dosimeter (APD) into their breast pockets, set to go off at 80 millisieverts.

The two men carried flashlights in their hands. Oigawa, walking in front and carrying a box-shaped portable survey meter to measure the exposure, entered Unit 1 (RB). The temperature inside was over 40 degrees Celsius. It was pitch-dark. Steam was billowing out. The exposure was high.²⁹

They had to finish their job within fifteen minutes. The two men found their way by the light of their flashlights to the containment vessel’s venting valve on the second floor. Oigawa started turning the valve handle. It was some twenty centimeters long and very heavy. The opening gauge attached to the side of the valve was in 5-percent increments. Each time Oigawa turned the handle, the needle of the gauge would rise to 5 percent, 10 percent, and 15 percent. Otomo’s flashlight illuminated the figures.

Perhaps a minute had passed. Oigawa asked Otomo, “Please check the opening.”

Once again, Otomo checked. It definitely indicated 25 percent. Otomo shouted and Oigawa nodded decisively. “Okay!”

The two men made sure to check the onsite pressure instrument for the containment and pressure vessels. They were trying to ascertain whether the figures they were seeing in the Central Control Room with the battery connection matched the actual numerical pressure. The pressure was higher than expected.

At 9:15 a.m., the two men came back to the Central Control Room. As soon as Otomo returned, he chugged a bottle of water from the emergency supply and immediately spewed it up on the floor. He was apparently not feeling well.

Izawa was encouraged, because they had come back sooner than he thought they would.³⁰

At 9:24 a.m., Team No. 2 went in to open by hand the suppression chamber’s venting valve. They had to make sure they did not lower the level of oxygen consumption.

We’ll have to watch our breathing as well.

That was what they were thinking in their heads as they left, but by the time they reached the Unit 1 (RB), they were moving at a trot.

In front of the double doors, they braced themselves. “Right!”

They had no idea what was waiting for them on the other side. With only their flashlights to guide them, they made it halfway to the torus room, and when they looked at the survey meter as they reached the stairs leading to the catwalk, the needle was showing 900–1,000 millisieverts/hour.

The torus room was a doughnut-shaped room that housed the suppression chamber. The catwalk was the inspection walkway above the torus room. The survey meter was going wild. Team No. 2 turned back to the Central Control Room. During this time, the two men were exposed to 89 and 95 millisieverts, respectively.

Izawa decided that further operations in the reactor building were too difficult. However, Team No. 3 was already making its way to the reactor building. Izawa dispatched someone to tell them to return immediately. It was just as the two men were about to try entering the building from the front double doors.

Izawa immediately evacuated the two men from Team No. 2 to the Anti-Seismic Building. They worked in the ERC after that, but they both became the first staff members at Fukushima Daiichi NPS exposed to more than 100 millisieverts.³¹