A Short History of the Chernobyl Accident

Wednesday, March 18th, 2009 | project wormwood

Chernobyl Disaster Aftermath (Source: Wikipedia)

On ~~October~~ April 26, 1986, the operators of the Chernobyl nuclear power reactor #4 started a test. They wanted to find out if, in the event of a external power failure, power from the reactor turbine could be used to keep the cooling water flow until the emergency generators were powered on. Because if the cooling water couldn’t be exchanged, the reactor would overheat, triggering a nuclear meltdown.

The test was high on their priority list, because it concerned a primary safety feature of the reactor. It had been signed off without being properly tested in order to keep deadlines for launching unit operations in 1984. Not keeping this deadline would have meant cut bonuses and extras for thousands of workers and engineers, and records were falsified to hide the missing test. In other words: The crew wanted to test something that was supposed to have been tested two years before.

It’s important to understand that the nuclear reaction inside a reactor represents a delicate balance to produce just enough heat to power the turbine (which produces electric current). Too little, and the power will be too low and inefficient, to high and the reactor damages itself. As long as nuclear fission material is inside the reactor, the nuclear reaction goes on, and run amok if not controlled. Because of this, a nuclear power plant can’t be just “turned off”; it needs to be gradually slowed down (scrammed) by inserting control rods.

On the day of the disaster, a combination of fatal circumstances came together: A flawed reactor, insufficient knowledge and experience of its operators, bad timing of the test, the inhibition of virtually all automatic safety mechanisms and wrong reactions and interpretations. At 1:23 in the morning the operators conducted a shutdown of the reactors – the reasons for which remain unknown. One minute later, a steam explosions tore the roof off reactor #4, a second explosion sprinkled radioactive material around the area, starting graphite fires on the roof. Two workers were killed by the explosion, while many more were terminally irradiated.

In the course of the following hours, emergency crews put out the fires to protect the neighboring reactor #3, fatally irradiating many firefighters. Two days later (!) officials acknowledged the seriousness of the situation and ordered the evacuation of the city of Prypiat 20km north-west of the reactor. Teams of “liquidators” were tasked with clearing the debris of the roof, securing the “bubble pool” underneath the reactor, dropping tons of sand, lead, and boric acid to contain the reactor fires and creating a concrete structure around the damaged hull. A second, even bigger disaster was averted by a team of coal miners who prevented that the hot reactor core reached the ground water (which would have caused an enormous explosion).

The radioactive cloud released by the accident drifted over Europe and contaminated the area around Chernobyl to an extent that a “zone of exclusion” had to be established. This zone will remain inhabitable for hundreds of years.

Nowadays, Chernobyl is synonymous with the biggest nuclear incident ever to occor. Due to the degradation of the haphazardly built shelter casing, the construction of a new shelter object – an enormous structure – has been approved in 2007. Considering the current economic situation in the Ukraine, it’s doubtful that it will be built on schedule. We certainly won’t see it when we visit the area next week.