The Chernobyl Nuclear Power Plant Disaster

It is a silent enemy, it has no odor, no smell, no shape, yet it is one of man’s deadliest foes. Radiation is not something most people face on a daily basis, but for the town of Prypiat in the Ukraine it is a barren wasteland because of it. The Chernobyl Nuclear Power Plant disaster was the worst nuclear catastrophe to have ever occurred and, is a perfect example of what can happen when the blind and unmasked furry of atomic power is left unharnessed. The Chernobyl Nuclear Power Plant is near the town of Prypiat, Ukraine, 18 km northwest of the city of Chernobyl, 16 km from the border of Ukraine and Belarus, and about 110 km north of Kyiv. The Chernobyl Nuclear Power Plant
Because of the positive void coefficient of the reactor at low reactor power levels, it was now primed to start on a positive feedback loop, in which the formation of steam voids decreased the ability of the liquid water coolant to absorb neutrons, which increased the reactor's power output, causing yet more water to flash into steam, and yet a further power increase. However, during almost the entire period of the experiment the automatic control system successfully counteracted this positive feedback, continuously inserting control rods into the reactor core to limit the power rise. (Marples 35-37)

At 1:23:40, as recorded by the centralized control system, the EPS-5 button of the reactor emergency protection system was pressed. This action initiated a shutdown of the reactor, fully inserting all control rods, including the manual control rods that had been incautiously withdrawn earlier. The exact reason why the EPS-5 button was pressed is not known, whether it was done as an emergency measure, or simply as a routine method of shutting down the reactor upon the completion of the experiment. There is a theory that the scram may have been ordered as a response to the unexpected rapid power increase; although there is no recorded data which confirms to this. (Marples 41-44)

The control rod insertion mechanism operated at a relatively slow speed taking 18–20 seconds to travel the approximately 7 meter