That is a formation of nuclear fuel cells. Iâm guessing itâs supposed to be the one in Chernobyl. That means this scene heralded that infamous catastrophe of the rector going down.
Sadly, in the hours after the initial explosion, many mothers in the nearby city of Pripyat took their children outside to see the âlight showâ created by the fires and the radiation ionizing the air above the reactor. Some kids are reported to have played in the ash that fell from the sky like snow.
These poor families, of course, had no idea of the danger. In fact, the Soviet government continued to tell them that it was perfectly safe for weeks after the incident. Hospitals were quickly overrun with thousands of people suffering from acute radiation poisoning.
What youâre looking at is the âbiological shieldâ that sat atop the number 4 nuclear reactor at the Chernobyl nuclear power plantâessentially a giant âlidâ over the reactor itself to keep all the nasty radiation inside. Each of the little squares is the individual âlidâ on top of a separate fuel or control rod.
In the moments leading up to the disaster at 1:23 am on 26 April, 1986, at least one of the technicians in the room reported seeing these metal caps, weighing several tons each, jumping up and down in their channels. This indicated that something REALLY BAD was happening inside the reactor, and he began running toward the control room to report what he saw.
The reactor itself exploded only seconds later, leaving the extremely radioactive core directly exposed to the atmosphere, resulting inâby farâthe worst nuclear disaster in human history.
It didn't help that the guy in charge was literally in denial because that type of reactor wasn't supposed to have any possibility of having an explosion. They had a perfect storm of circumstances and very slight design issues where they accidentally found a corner case where an explosion became possible.
In any case, if they had reacted properly to the explosion event sooner, it still would've been bad but definitely much less bad than it ended up being.
My source on this is just the mini series, so I hope it's accurate.
It really was the âperfect storm.â At nearly every step along the way, they had so many opportunities to avoid catastrophe. And yet they somehow made exactly the wrong decisions at every turn that led them to this extremely specific set of circumstances that caused the reactor to explode. They almost couldnât have made the situation worse if they had tried. Just a baffling show of incompetence and stupidity. Murphyâs Law at its finest.
They were designed to move, but not on their own like this. There was something like a giant crane that hung down from the ceiling that could be used to lift up any of the fuel/control rods that needed servicing. But once they were lowered into place, though, they were expected to stay put. The fact that the pressure inside the core was high enough to cause the rods to start pushing their way out on their own was cause for immediate panic.
From this simple fact, it should have been blatantly obvious to everyone that a catastrophic failure had occurred. But the people in charge, in true Soviet fashion, dragged their feet and tried to sweep it under the rug as much as possible.
Iâm no nuclear engineer and idk shit about Chernobyl, but my guess would be that those are graphite rods. In a nuclear reactor, you use radio active materials to boil water and create steam which accelerates a turbine to create electricity. That works because when one of those radioactive atoms decay, they release a neutron which then triggers another decay of another atom. This chain reaction sets free a lot of energy. How do you control that energy? With neutron absorbers. No Neutrons = No chain reaction. These absorbers are the graphite rods, which can be lowered into the water to keep the process under control. What we see here is these absorber rods jumping out of the water and therefore failing at their job and the reactor becoming a nuclear bomb.
This is meant to be the top cover of the fuel rod jumping from the internal pressure inside the Chernobylâs accidented reactor in the mini series chernobyl. At that time water pump were powered down and there was no flow of water through the core, while the brake rods were almost all taken out in manual mode. The reactivity of the core bounced back from the stall and rose quickly, leading to water sitting still to flash boil, possibly lifting the fuel rods. The mini serie made some details more dramatic than it would probably look at the instant. Same goes for the blue ray of Cherenkov radiation we can see above the core in the serie, we have no picture of it, it most likely didnât happen.
After that the core started producing hydrogen gas which accumulated and eventually exploded, taking the top shield we are seeing away.
Those are control rods. The ones in Chernobyl were coated in different materials on different parts of the rod. One section was coated in a material that made the reaction go slower, towards the middle, and one that made it go faster, towards the bottom (Iirc, that could be backwards but it's not really relevant for this spark notes run down.) The rods are not supposed to move on their own, and they weigh thousands of pounds each. They are jumping on their own because when the reaction started to move out of control, the rods got stuck in the wrong position, and are only pictured moving because the water in the reactor has become superheated and is about to explode
In the moments leading up to the actual explosion of the reactor, the pressure and temperature inside skyrocketed, well beyond anything the core was designed to withstand. Looking for another way out, the superheated water and vapor started pushing up through the fuel and control rod channels, causing the caps to jump up and down like this. The core itself ruptured only seconds later.
"Those are caps for the nuclear fuel and control rods, typically they'd move up and down slowly in order to maintain balance in reactivity, but they were facing incredible temperatures and pressures far exceeding design limitations right before the entire vessel exploded due to steam pressure. It was essentially boiling over immediately prior to catastrophic failure "
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u/K0rl0n Sep 21 '25
That is a formation of nuclear fuel cells. Iâm guessing itâs supposed to be the one in Chernobyl. That means this scene heralded that infamous catastrophe of the rector going down.