Chernobyl Unit 4: Toptunov and the Poisoned Core

The disaster actually unfolded during those ten hours.

I'm not totally sold on that framing. It wasn't dying. It was being strangled. A ten-hour delay from the power grid controller in Kiev forced the night shift to inherit a mess. By the time Leonid Toptunov took over at midnight, he had only been in that seat for four months. The reactor was in what we call a Xenon Pit. A massive buildup of Xenon-one-thirty-five was acting as a brake and stalling the nuclear reaction. That detail really sticks with you. Toptunov was only twenty-five years old. He was a kid holding the leash of a giant.

It came down to pressure. There was pure, top-down pressure to finish the test. To get the power back up, they had to pull the control rods out. Soviet regulations were clear that you need at least fifteen to thirty rods in the core to keep it stable. Toptunov and his boss, Dyatlov, pulled almost all two hundred and eleven of them. They were down to a margin of maybe six or eight rods. They were flying a seven-forty-seven with no landing gear.

The manual was actually a bit vague about the danger of a low margin at low power. They thought they were just being aggressive to overcome the Xenon. At one-twenty-three and forty seconds in the morning, they finally hit the A-Z-five emergency button to shut it down. But the control rods had these graphite tips. Instead of stopping the reaction, those tips momentarily pushed the water out of the way. It caused a surge at the bottom of the core. It didn't stop the reactor. It turned the core into a bomb.

I struggle to wrap my head around the psychology of those first few minutes. It is a mix of shock and this rigid, almost mechanical denial. I have read the testimonies a dozen times, and I still do not know how they ignored the physical evidence. Their instruments were telling them a lie.

It did not lie, exactly. It just could not see high enough. The shift supervisor, Aleksandr Akimov, was using a small dosimeter that maxed out at three point six roentgens per hour. So, that is what he saw: three point six. He reported that safe number to his superiors. He was completely unaware that the actual level near the core was over twenty thousand. He was off by a factor of thousands.

You would think so, but the environment was surreal. Workers outside saw this shimmering blue pillar of light shooting into the night sky. It looked beautiful, not deadly. Then there was the taste. Several men described a distinct metallic, lead-like flavor on their tongues. That is a physiological sign of massive exposure, but they did not have a name for it yet. When Lieutenant Pravik’s fire brigade arrived at one twenty-eight in the morning, they were literally kicking aside these heavy black chunks on the roof to get to the flames. They had no idea those were pieces of the reactor's graphite moderator.

It was, but they did not know it. The most futile part was what Akimov and Toptunov did. They went down into the basement, in the dark, wading through waist-deep radioactive water. They were trying to manually open feed-water valves to cool a reactor that no longer existed. They took doses of well over fifteen hundred rem. That is three times the lethal limit. They were pumping water into a pile of rubble open to the air. They were fighting a ghost.

They died because the system they trusted was incapable of telling them the truth.

They never looked out the window. They stayed at their posts and trusted broken dials, even while the reactor was already scattered across the roof. These men absorbed lethal doses of radiation. They were trying to save a machine that simply wasn't there anymore.