[…]
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.
[…]
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.
Read more at A melted shoe and a farewell letter in the dark
