Amazing un-seen photos from the Chernobyl disaster (Page 3)
All four reactors were of the relatively new RBMK-1000 type, which stood for Reaktor Bolshoy Moshchnosti Kanalnyy (“High Power Channel-type Reactor” in English). Measuring a massive 7 metres tall by 11.8 metres wide, with each capable of outputting 1000 Megawatts (MW) of electrical power via two 500MW steam turbogenerators, they were unusually large reactors. A further two were under construction at the time of the accident in 1986, with Unit 5 expected to be completed later that year. Here is a diagram showing how the RBMK system works.
Vertical graphite blocks surrounding the fuel channels slow down the speed of the moving neutrons in the fuel, because slowed neutrons are far more likely collide with uranium-235 nuclei and split. In other words, the graphite moderator creates the right environment for a chain reaction to occur. Think of the graphite as oxygen in a conventional fire: even with all the fuel in the world, there will be no flame without oxygen.
This diagram shows how the building is laid out, including where the pumps, steam separators and turbines are.
Here you can see engineers working on the water pipes below where the reactor will be.
Fueling the reactor.
Brand new fuel rods are fairly harmless.
This was printed a few years before the accident.
Once the power station was up and running, all staff entering and exiting the complex had to go through these radiation detectors. They’re still used at the site today.
Here you can see one of the gigantic pumps used to feed water into the core. Water is pumped into the bottom of the reactor at a very high pressure (approximately 1000psi, or 65 atmospheres), where it boils and passes up, out of the reactor and through a condensator which separates steam from water. The remaining water is pushed through another pump and fed back into the reactor.
On the right is a refueling machine. Once it is positioned over the right fuel channel, it withdraws the fuel rod and replaces it with a fresh one.
The completed turbine hall. Steam from the condensator enters these steam turbines, which turn and generate electricity. Having passed through the turbogenerator, the steam is condensed back into water and fed back to the pumps, where it begins its cycle again.
Here is one of the control rooms. There’s one control room for each reactor – 4 in all at Chernobyl.
Nuclear reactors have to be constantly fed with a huge volume of water by pumps. In the event that there’s ever a problem with the electricity supply, the pumps would stop, so enormous diesel engines like this one were there as a backup. Unfortunately, these engines took almost a minute to reach capacity, and couldn’t be relied upon by themselves.
In the early morning of April 26th 1986, a team of men at the power station were testing a safety feature of the RBMK design that allowed to system to power the pumps by itself for that vital minute before the diesel engines took over. This was done by taking electricity generated by the risidual steam in the turbines to power the pumps.
This is the only good image I’ve ever found of the power station from the angle it’s most commonly now seen from.
This is Leonid Toptunov, one of the control room operators. He made a mistake when switching from manual to automatic control of the control rods, causing them to descend much further into the core than intended. This resulted in an almost total shutdown of the reactor. Safety procedures required that the operators fully shutdown the reactor, as the RBMK became unstable at very low power.
At precisely 01:23:40, Akimov pressed the emergency shutdown button. 18 seconds later, the reactor exploded.
Unfortunately for the whole world, the Deputy Chief Engineer in charge of the test – Anatoly Dyatlov – insisted that they continue. The men struggled to bring the reactor up to power, and then commenced the test. Toptunov saw that the reactor readings were heading for danger, so he told the man seen here, senior engineer Alexander Akimov.