15 Septembre 2014
September 14, 2014
FUKUSHIMA – While most had focused their attention on the state of reactors 1 and 2 at the Fukushima No. 1 complex as the 2011 nuclear crisis unfolded, Tokyo Electric’s equipment restoration team headed to reactor 3 on March 13.
The two team members each carried three 12.5-kg batteries. The batteries, brought from a thermal power plant 20 km south of the nuclear power plant, were to be used to revive the No. 3 reactor’s water gauges.
The control room seemed quiet from outside. But when the two stepped in, they were greeted by senior reactor operator Kazumi Takamiya, 39.
“We were aware that the priority was on reactor Nos. 1 and 2 and that Nos. 3 and 4 had been put aside. So when the two came in, we thought we were finally getting some attention,” Takamiya said.
Reactors 1 to 3 were running before the megaquake and ensuing tsunami knocked out the plant’s power supply and crippled its emergency diesel generators on March 11.
Luckily, the battery system for the No. 3 reactor had survived.
In the early hours of March 13, the High Pressure Coolant Injection system, which uses steam generated by the reactor to drive a turbine pump to inject water into the reactor, was operating. The HPCI was designed to pour in water when reactor pressure is high.
It was around 2 a.m. when the pressure in reactor No. 3 began falling. The HPCI is supposed to stop automatically when there is a substantial fall in pressure substantially, but did not.
Fearing a breakdown that would result in a steam release from the reactor, Takamiya decided to manually suspend the HPCI. But it couldn’t be switched off, and the operators had to close a valve on a steam pipe to stop it. Takamiya felt the battery was dying because devices were not reacting to the control panel’s switches.
To replace the HPCI with a different reactor-cooling method, they contemplated injecting water through a diesel-powered firefighting pump.
Since the pressure from the firefighting pump wasn’t strong enough for the task, however, they first had to depressurize the pressure vessel, which contains the nuclear fuel, so the water could enter.
Takamiya ordered that valves be opened to redirect steam in the pressure vessel to the reactor’s suppression chamber. They thought they could operate the valves via the control panel because the indicator lamps were on.
“It won’t open!” an operator shouted. None of the eight valves could.
Takamiya then tried to restart the HPCI but failed because the battery was dead, halting all water injection into the reactor 35 hours after the tsunami struck.
The moment the water injection stopped, the pressure in the reactor started to rise, indicating steam was being generated from the water that had been used to cool the fuel.
Takamiya saw what happened to the No. 1 reactor building after the explosion on March 12. Only the steel frame remained on the upper part, and the windows of nearby cars had been shattered.
“It was like Chernobyl,” he recalled, referring to the 1986 nuclear catastrophe in Ukraine.
Satoru Hayashizaki, a 24-year-old auxiliary equipment operator, was among the younger members in the control room who had become increasingly anxious about the No. 3 reactor.
Born and raised in a town less than 20 km from the plant, Hayashizaki joined Tokyo Electric Power Co. after graduating from a local high school. Six years had passed since he was put in charge of reactors 3 and 4, although he was not yet authorized to operate them.
At 5:15 a.m. on March 13, the control room was ordered to prepare to ease the pressure in No. 3′s pressure vessel.
Hayashizaki had orders to go to the suppression chamber and confirm that an air-operated vent valve had opened as planned. At the time, the operators didn’t think a meltdown was in progress and considered the radiation levels not so high.
But the moment Hayashizaki and his coworker opened the door to the suppression chamber’s room in the basement, he felt intense heat.
“It was like being in a sauna. The palms of my hands, covered by rubber gloves, instantly got hot,” he said.
After walking up a few stairs and into a narrow passageway, Hayashizaki felt groggy. The valve he had to check was just nearby, but to know how much it opened he had to step over the rail and walk 5 meters directly above the suppression chamber.
The heat was apparently coming from the chamber, and he had a bad feeling. Cautiously, he put his right foot down on it only to see the rubber sole of his shoe melt instantly, leaving a black smear.
“The moment I put my foot down, I felt my shoe slip. The distance is normally nothing to worry about, but I was scared of what could happen to me if I tripped in a place where the temperature was that high,” Hayashizaki said.
The heat in the chamber can normally be controlled by a cooling system that uses seawater. But the heat control mechanism had been rendered inoperable because the seawater pumps were submerged by tsunami.
“There was no way to release the heat. I didn’t know what would happen thereafter,” he recalled. He gave up on checking on the valve and returned to the control room.
Taking stock of his radiation exposure, Hayashizaki checked his pocket dosimeter and was alarmed to see the number rising rapidly, even though he was in the control room.
And it didn’t seem to be a glitch, because everyone else’s dosimeters were rising, too.
The figures were unmistakable signs that the reactor fuel was melting, and for the first time, Hayashizaki thought he might die.
Trapped in the darkness, he ripped a page out of his pocket planner and started writing a farewell letter to his parents.
The letter read: “Father, Mother, please forgive me for dying before I could fulfill my duty as a son. After the earthquake, I would have wished to hear your voices even once.”
He urged his parents to live through hardship.
“I did not give up on life until the very end.”
He ended by apologizing should the letter become the only thing left of him, then folded it up and put it in the right chest pocket of his uniform.